ext4: quota macros cleanup
[linux-2.6.git] / fs / ext4 / inode.c
1 /*
2  *  linux/fs/ext4/inode.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/inode.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  Goal-directed block allocation by Stephen Tweedie
16  *      (sct@redhat.com), 1993, 1998
17  *  Big-endian to little-endian byte-swapping/bitmaps by
18  *        David S. Miller (davem@caip.rutgers.edu), 1995
19  *  64-bit file support on 64-bit platforms by Jakub Jelinek
20  *      (jj@sunsite.ms.mff.cuni.cz)
21  *
22  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
23  */
24
25 #include <linux/module.h>
26 #include <linux/fs.h>
27 #include <linux/time.h>
28 #include <linux/jbd2.h>
29 #include <linux/highuid.h>
30 #include <linux/pagemap.h>
31 #include <linux/quotaops.h>
32 #include <linux/string.h>
33 #include <linux/buffer_head.h>
34 #include <linux/writeback.h>
35 #include <linux/pagevec.h>
36 #include <linux/mpage.h>
37 #include <linux/namei.h>
38 #include <linux/uio.h>
39 #include <linux/bio.h>
40 #include <linux/workqueue.h>
41
42 #include "ext4_jbd2.h"
43 #include "xattr.h"
44 #include "acl.h"
45 #include "ext4_extents.h"
46
47 #include <trace/events/ext4.h>
48
49 #define MPAGE_DA_EXTENT_TAIL 0x01
50
51 static inline int ext4_begin_ordered_truncate(struct inode *inode,
52                                               loff_t new_size)
53 {
54         return jbd2_journal_begin_ordered_truncate(
55                                         EXT4_SB(inode->i_sb)->s_journal,
56                                         &EXT4_I(inode)->jinode,
57                                         new_size);
58 }
59
60 static void ext4_invalidatepage(struct page *page, unsigned long offset);
61
62 /*
63  * Test whether an inode is a fast symlink.
64  */
65 static int ext4_inode_is_fast_symlink(struct inode *inode)
66 {
67         int ea_blocks = EXT4_I(inode)->i_file_acl ?
68                 (inode->i_sb->s_blocksize >> 9) : 0;
69
70         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
71 }
72
73 /*
74  * Work out how many blocks we need to proceed with the next chunk of a
75  * truncate transaction.
76  */
77 static unsigned long blocks_for_truncate(struct inode *inode)
78 {
79         ext4_lblk_t needed;
80
81         needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
82
83         /* Give ourselves just enough room to cope with inodes in which
84          * i_blocks is corrupt: we've seen disk corruptions in the past
85          * which resulted in random data in an inode which looked enough
86          * like a regular file for ext4 to try to delete it.  Things
87          * will go a bit crazy if that happens, but at least we should
88          * try not to panic the whole kernel. */
89         if (needed < 2)
90                 needed = 2;
91
92         /* But we need to bound the transaction so we don't overflow the
93          * journal. */
94         if (needed > EXT4_MAX_TRANS_DATA)
95                 needed = EXT4_MAX_TRANS_DATA;
96
97         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
98 }
99
100 /*
101  * Truncate transactions can be complex and absolutely huge.  So we need to
102  * be able to restart the transaction at a conventient checkpoint to make
103  * sure we don't overflow the journal.
104  *
105  * start_transaction gets us a new handle for a truncate transaction,
106  * and extend_transaction tries to extend the existing one a bit.  If
107  * extend fails, we need to propagate the failure up and restart the
108  * transaction in the top-level truncate loop. --sct
109  */
110 static handle_t *start_transaction(struct inode *inode)
111 {
112         handle_t *result;
113
114         result = ext4_journal_start(inode, blocks_for_truncate(inode));
115         if (!IS_ERR(result))
116                 return result;
117
118         ext4_std_error(inode->i_sb, PTR_ERR(result));
119         return result;
120 }
121
122 /*
123  * Try to extend this transaction for the purposes of truncation.
124  *
125  * Returns 0 if we managed to create more room.  If we can't create more
126  * room, and the transaction must be restarted we return 1.
127  */
128 static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
129 {
130         if (!ext4_handle_valid(handle))
131                 return 0;
132         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
133                 return 0;
134         if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
135                 return 0;
136         return 1;
137 }
138
139 /*
140  * Restart the transaction associated with *handle.  This does a commit,
141  * so before we call here everything must be consistently dirtied against
142  * this transaction.
143  */
144 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
145                                  int nblocks)
146 {
147         int ret;
148
149         /*
150          * Drop i_data_sem to avoid deadlock with ext4_get_blocks At this
151          * moment, get_block can be called only for blocks inside i_size since
152          * page cache has been already dropped and writes are blocked by
153          * i_mutex. So we can safely drop the i_data_sem here.
154          */
155         BUG_ON(EXT4_JOURNAL(inode) == NULL);
156         jbd_debug(2, "restarting handle %p\n", handle);
157         up_write(&EXT4_I(inode)->i_data_sem);
158         ret = ext4_journal_restart(handle, blocks_for_truncate(inode));
159         down_write(&EXT4_I(inode)->i_data_sem);
160         ext4_discard_preallocations(inode);
161
162         return ret;
163 }
164
165 /*
166  * Called at the last iput() if i_nlink is zero.
167  */
168 void ext4_delete_inode(struct inode *inode)
169 {
170         handle_t *handle;
171         int err;
172
173         if (ext4_should_order_data(inode))
174                 ext4_begin_ordered_truncate(inode, 0);
175         truncate_inode_pages(&inode->i_data, 0);
176
177         if (is_bad_inode(inode))
178                 goto no_delete;
179
180         handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
181         if (IS_ERR(handle)) {
182                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
183                 /*
184                  * If we're going to skip the normal cleanup, we still need to
185                  * make sure that the in-core orphan linked list is properly
186                  * cleaned up.
187                  */
188                 ext4_orphan_del(NULL, inode);
189                 goto no_delete;
190         }
191
192         if (IS_SYNC(inode))
193                 ext4_handle_sync(handle);
194         inode->i_size = 0;
195         err = ext4_mark_inode_dirty(handle, inode);
196         if (err) {
197                 ext4_warning(inode->i_sb, __func__,
198                              "couldn't mark inode dirty (err %d)", err);
199                 goto stop_handle;
200         }
201         if (inode->i_blocks)
202                 ext4_truncate(inode);
203
204         /*
205          * ext4_ext_truncate() doesn't reserve any slop when it
206          * restarts journal transactions; therefore there may not be
207          * enough credits left in the handle to remove the inode from
208          * the orphan list and set the dtime field.
209          */
210         if (!ext4_handle_has_enough_credits(handle, 3)) {
211                 err = ext4_journal_extend(handle, 3);
212                 if (err > 0)
213                         err = ext4_journal_restart(handle, 3);
214                 if (err != 0) {
215                         ext4_warning(inode->i_sb, __func__,
216                                      "couldn't extend journal (err %d)", err);
217                 stop_handle:
218                         ext4_journal_stop(handle);
219                         goto no_delete;
220                 }
221         }
222
223         /*
224          * Kill off the orphan record which ext4_truncate created.
225          * AKPM: I think this can be inside the above `if'.
226          * Note that ext4_orphan_del() has to be able to cope with the
227          * deletion of a non-existent orphan - this is because we don't
228          * know if ext4_truncate() actually created an orphan record.
229          * (Well, we could do this if we need to, but heck - it works)
230          */
231         ext4_orphan_del(handle, inode);
232         EXT4_I(inode)->i_dtime  = get_seconds();
233
234         /*
235          * One subtle ordering requirement: if anything has gone wrong
236          * (transaction abort, IO errors, whatever), then we can still
237          * do these next steps (the fs will already have been marked as
238          * having errors), but we can't free the inode if the mark_dirty
239          * fails.
240          */
241         if (ext4_mark_inode_dirty(handle, inode))
242                 /* If that failed, just do the required in-core inode clear. */
243                 clear_inode(inode);
244         else
245                 ext4_free_inode(handle, inode);
246         ext4_journal_stop(handle);
247         return;
248 no_delete:
249         clear_inode(inode);     /* We must guarantee clearing of inode... */
250 }
251
252 typedef struct {
253         __le32  *p;
254         __le32  key;
255         struct buffer_head *bh;
256 } Indirect;
257
258 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
259 {
260         p->key = *(p->p = v);
261         p->bh = bh;
262 }
263
264 /**
265  *      ext4_block_to_path - parse the block number into array of offsets
266  *      @inode: inode in question (we are only interested in its superblock)
267  *      @i_block: block number to be parsed
268  *      @offsets: array to store the offsets in
269  *      @boundary: set this non-zero if the referred-to block is likely to be
270  *             followed (on disk) by an indirect block.
271  *
272  *      To store the locations of file's data ext4 uses a data structure common
273  *      for UNIX filesystems - tree of pointers anchored in the inode, with
274  *      data blocks at leaves and indirect blocks in intermediate nodes.
275  *      This function translates the block number into path in that tree -
276  *      return value is the path length and @offsets[n] is the offset of
277  *      pointer to (n+1)th node in the nth one. If @block is out of range
278  *      (negative or too large) warning is printed and zero returned.
279  *
280  *      Note: function doesn't find node addresses, so no IO is needed. All
281  *      we need to know is the capacity of indirect blocks (taken from the
282  *      inode->i_sb).
283  */
284
285 /*
286  * Portability note: the last comparison (check that we fit into triple
287  * indirect block) is spelled differently, because otherwise on an
288  * architecture with 32-bit longs and 8Kb pages we might get into trouble
289  * if our filesystem had 8Kb blocks. We might use long long, but that would
290  * kill us on x86. Oh, well, at least the sign propagation does not matter -
291  * i_block would have to be negative in the very beginning, so we would not
292  * get there at all.
293  */
294
295 static int ext4_block_to_path(struct inode *inode,
296                               ext4_lblk_t i_block,
297                               ext4_lblk_t offsets[4], int *boundary)
298 {
299         int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
300         int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
301         const long direct_blocks = EXT4_NDIR_BLOCKS,
302                 indirect_blocks = ptrs,
303                 double_blocks = (1 << (ptrs_bits * 2));
304         int n = 0;
305         int final = 0;
306
307         if (i_block < direct_blocks) {
308                 offsets[n++] = i_block;
309                 final = direct_blocks;
310         } else if ((i_block -= direct_blocks) < indirect_blocks) {
311                 offsets[n++] = EXT4_IND_BLOCK;
312                 offsets[n++] = i_block;
313                 final = ptrs;
314         } else if ((i_block -= indirect_blocks) < double_blocks) {
315                 offsets[n++] = EXT4_DIND_BLOCK;
316                 offsets[n++] = i_block >> ptrs_bits;
317                 offsets[n++] = i_block & (ptrs - 1);
318                 final = ptrs;
319         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
320                 offsets[n++] = EXT4_TIND_BLOCK;
321                 offsets[n++] = i_block >> (ptrs_bits * 2);
322                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
323                 offsets[n++] = i_block & (ptrs - 1);
324                 final = ptrs;
325         } else {
326                 ext4_warning(inode->i_sb, "ext4_block_to_path",
327                              "block %lu > max in inode %lu",
328                              i_block + direct_blocks +
329                              indirect_blocks + double_blocks, inode->i_ino);
330         }
331         if (boundary)
332                 *boundary = final - 1 - (i_block & (ptrs - 1));
333         return n;
334 }
335
336 static int __ext4_check_blockref(const char *function, struct inode *inode,
337                                  __le32 *p, unsigned int max)
338 {
339         __le32 *bref = p;
340         unsigned int blk;
341
342         while (bref < p+max) {
343                 blk = le32_to_cpu(*bref++);
344                 if (blk &&
345                     unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
346                                                     blk, 1))) {
347                         ext4_error(inode->i_sb, function,
348                                    "invalid block reference %u "
349                                    "in inode #%lu", blk, inode->i_ino);
350                         return -EIO;
351                 }
352         }
353         return 0;
354 }
355
356
357 #define ext4_check_indirect_blockref(inode, bh)                         \
358         __ext4_check_blockref(__func__, inode, (__le32 *)(bh)->b_data,  \
359                               EXT4_ADDR_PER_BLOCK((inode)->i_sb))
360
361 #define ext4_check_inode_blockref(inode)                                \
362         __ext4_check_blockref(__func__, inode, EXT4_I(inode)->i_data,   \
363                               EXT4_NDIR_BLOCKS)
364
365 /**
366  *      ext4_get_branch - read the chain of indirect blocks leading to data
367  *      @inode: inode in question
368  *      @depth: depth of the chain (1 - direct pointer, etc.)
369  *      @offsets: offsets of pointers in inode/indirect blocks
370  *      @chain: place to store the result
371  *      @err: here we store the error value
372  *
373  *      Function fills the array of triples <key, p, bh> and returns %NULL
374  *      if everything went OK or the pointer to the last filled triple
375  *      (incomplete one) otherwise. Upon the return chain[i].key contains
376  *      the number of (i+1)-th block in the chain (as it is stored in memory,
377  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
378  *      number (it points into struct inode for i==0 and into the bh->b_data
379  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
380  *      block for i>0 and NULL for i==0. In other words, it holds the block
381  *      numbers of the chain, addresses they were taken from (and where we can
382  *      verify that chain did not change) and buffer_heads hosting these
383  *      numbers.
384  *
385  *      Function stops when it stumbles upon zero pointer (absent block)
386  *              (pointer to last triple returned, *@err == 0)
387  *      or when it gets an IO error reading an indirect block
388  *              (ditto, *@err == -EIO)
389  *      or when it reads all @depth-1 indirect blocks successfully and finds
390  *      the whole chain, all way to the data (returns %NULL, *err == 0).
391  *
392  *      Need to be called with
393  *      down_read(&EXT4_I(inode)->i_data_sem)
394  */
395 static Indirect *ext4_get_branch(struct inode *inode, int depth,
396                                  ext4_lblk_t  *offsets,
397                                  Indirect chain[4], int *err)
398 {
399         struct super_block *sb = inode->i_sb;
400         Indirect *p = chain;
401         struct buffer_head *bh;
402
403         *err = 0;
404         /* i_data is not going away, no lock needed */
405         add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
406         if (!p->key)
407                 goto no_block;
408         while (--depth) {
409                 bh = sb_getblk(sb, le32_to_cpu(p->key));
410                 if (unlikely(!bh))
411                         goto failure;
412
413                 if (!bh_uptodate_or_lock(bh)) {
414                         if (bh_submit_read(bh) < 0) {
415                                 put_bh(bh);
416                                 goto failure;
417                         }
418                         /* validate block references */
419                         if (ext4_check_indirect_blockref(inode, bh)) {
420                                 put_bh(bh);
421                                 goto failure;
422                         }
423                 }
424
425                 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
426                 /* Reader: end */
427                 if (!p->key)
428                         goto no_block;
429         }
430         return NULL;
431
432 failure:
433         *err = -EIO;
434 no_block:
435         return p;
436 }
437
438 /**
439  *      ext4_find_near - find a place for allocation with sufficient locality
440  *      @inode: owner
441  *      @ind: descriptor of indirect block.
442  *
443  *      This function returns the preferred place for block allocation.
444  *      It is used when heuristic for sequential allocation fails.
445  *      Rules are:
446  *        + if there is a block to the left of our position - allocate near it.
447  *        + if pointer will live in indirect block - allocate near that block.
448  *        + if pointer will live in inode - allocate in the same
449  *          cylinder group.
450  *
451  * In the latter case we colour the starting block by the callers PID to
452  * prevent it from clashing with concurrent allocations for a different inode
453  * in the same block group.   The PID is used here so that functionally related
454  * files will be close-by on-disk.
455  *
456  *      Caller must make sure that @ind is valid and will stay that way.
457  */
458 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
459 {
460         struct ext4_inode_info *ei = EXT4_I(inode);
461         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
462         __le32 *p;
463         ext4_fsblk_t bg_start;
464         ext4_fsblk_t last_block;
465         ext4_grpblk_t colour;
466         ext4_group_t block_group;
467         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
468
469         /* Try to find previous block */
470         for (p = ind->p - 1; p >= start; p--) {
471                 if (*p)
472                         return le32_to_cpu(*p);
473         }
474
475         /* No such thing, so let's try location of indirect block */
476         if (ind->bh)
477                 return ind->bh->b_blocknr;
478
479         /*
480          * It is going to be referred to from the inode itself? OK, just put it
481          * into the same cylinder group then.
482          */
483         block_group = ei->i_block_group;
484         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
485                 block_group &= ~(flex_size-1);
486                 if (S_ISREG(inode->i_mode))
487                         block_group++;
488         }
489         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
490         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
491
492         /*
493          * If we are doing delayed allocation, we don't need take
494          * colour into account.
495          */
496         if (test_opt(inode->i_sb, DELALLOC))
497                 return bg_start;
498
499         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
500                 colour = (current->pid % 16) *
501                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
502         else
503                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
504         return bg_start + colour;
505 }
506
507 /**
508  *      ext4_find_goal - find a preferred place for allocation.
509  *      @inode: owner
510  *      @block:  block we want
511  *      @partial: pointer to the last triple within a chain
512  *
513  *      Normally this function find the preferred place for block allocation,
514  *      returns it.
515  *      Because this is only used for non-extent files, we limit the block nr
516  *      to 32 bits.
517  */
518 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
519                                    Indirect *partial)
520 {
521         ext4_fsblk_t goal;
522
523         /*
524          * XXX need to get goal block from mballoc's data structures
525          */
526
527         goal = ext4_find_near(inode, partial);
528         goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
529         return goal;
530 }
531
532 /**
533  *      ext4_blks_to_allocate: Look up the block map and count the number
534  *      of direct blocks need to be allocated for the given branch.
535  *
536  *      @branch: chain of indirect blocks
537  *      @k: number of blocks need for indirect blocks
538  *      @blks: number of data blocks to be mapped.
539  *      @blocks_to_boundary:  the offset in the indirect block
540  *
541  *      return the total number of blocks to be allocate, including the
542  *      direct and indirect blocks.
543  */
544 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
545                                  int blocks_to_boundary)
546 {
547         unsigned int count = 0;
548
549         /*
550          * Simple case, [t,d]Indirect block(s) has not allocated yet
551          * then it's clear blocks on that path have not allocated
552          */
553         if (k > 0) {
554                 /* right now we don't handle cross boundary allocation */
555                 if (blks < blocks_to_boundary + 1)
556                         count += blks;
557                 else
558                         count += blocks_to_boundary + 1;
559                 return count;
560         }
561
562         count++;
563         while (count < blks && count <= blocks_to_boundary &&
564                 le32_to_cpu(*(branch[0].p + count)) == 0) {
565                 count++;
566         }
567         return count;
568 }
569
570 /**
571  *      ext4_alloc_blocks: multiple allocate blocks needed for a branch
572  *      @indirect_blks: the number of blocks need to allocate for indirect
573  *                      blocks
574  *
575  *      @new_blocks: on return it will store the new block numbers for
576  *      the indirect blocks(if needed) and the first direct block,
577  *      @blks:  on return it will store the total number of allocated
578  *              direct blocks
579  */
580 static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
581                              ext4_lblk_t iblock, ext4_fsblk_t goal,
582                              int indirect_blks, int blks,
583                              ext4_fsblk_t new_blocks[4], int *err)
584 {
585         struct ext4_allocation_request ar;
586         int target, i;
587         unsigned long count = 0, blk_allocated = 0;
588         int index = 0;
589         ext4_fsblk_t current_block = 0;
590         int ret = 0;
591
592         /*
593          * Here we try to allocate the requested multiple blocks at once,
594          * on a best-effort basis.
595          * To build a branch, we should allocate blocks for
596          * the indirect blocks(if not allocated yet), and at least
597          * the first direct block of this branch.  That's the
598          * minimum number of blocks need to allocate(required)
599          */
600         /* first we try to allocate the indirect blocks */
601         target = indirect_blks;
602         while (target > 0) {
603                 count = target;
604                 /* allocating blocks for indirect blocks and direct blocks */
605                 current_block = ext4_new_meta_blocks(handle, inode,
606                                                         goal, &count, err);
607                 if (*err)
608                         goto failed_out;
609
610                 BUG_ON(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS);
611
612                 target -= count;
613                 /* allocate blocks for indirect blocks */
614                 while (index < indirect_blks && count) {
615                         new_blocks[index++] = current_block++;
616                         count--;
617                 }
618                 if (count > 0) {
619                         /*
620                          * save the new block number
621                          * for the first direct block
622                          */
623                         new_blocks[index] = current_block;
624                         printk(KERN_INFO "%s returned more blocks than "
625                                                 "requested\n", __func__);
626                         WARN_ON(1);
627                         break;
628                 }
629         }
630
631         target = blks - count ;
632         blk_allocated = count;
633         if (!target)
634                 goto allocated;
635         /* Now allocate data blocks */
636         memset(&ar, 0, sizeof(ar));
637         ar.inode = inode;
638         ar.goal = goal;
639         ar.len = target;
640         ar.logical = iblock;
641         if (S_ISREG(inode->i_mode))
642                 /* enable in-core preallocation only for regular files */
643                 ar.flags = EXT4_MB_HINT_DATA;
644
645         current_block = ext4_mb_new_blocks(handle, &ar, err);
646         BUG_ON(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS);
647
648         if (*err && (target == blks)) {
649                 /*
650                  * if the allocation failed and we didn't allocate
651                  * any blocks before
652                  */
653                 goto failed_out;
654         }
655         if (!*err) {
656                 if (target == blks) {
657                         /*
658                          * save the new block number
659                          * for the first direct block
660                          */
661                         new_blocks[index] = current_block;
662                 }
663                 blk_allocated += ar.len;
664         }
665 allocated:
666         /* total number of blocks allocated for direct blocks */
667         ret = blk_allocated;
668         *err = 0;
669         return ret;
670 failed_out:
671         for (i = 0; i < index; i++)
672                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0);
673         return ret;
674 }
675
676 /**
677  *      ext4_alloc_branch - allocate and set up a chain of blocks.
678  *      @inode: owner
679  *      @indirect_blks: number of allocated indirect blocks
680  *      @blks: number of allocated direct blocks
681  *      @offsets: offsets (in the blocks) to store the pointers to next.
682  *      @branch: place to store the chain in.
683  *
684  *      This function allocates blocks, zeroes out all but the last one,
685  *      links them into chain and (if we are synchronous) writes them to disk.
686  *      In other words, it prepares a branch that can be spliced onto the
687  *      inode. It stores the information about that chain in the branch[], in
688  *      the same format as ext4_get_branch() would do. We are calling it after
689  *      we had read the existing part of chain and partial points to the last
690  *      triple of that (one with zero ->key). Upon the exit we have the same
691  *      picture as after the successful ext4_get_block(), except that in one
692  *      place chain is disconnected - *branch->p is still zero (we did not
693  *      set the last link), but branch->key contains the number that should
694  *      be placed into *branch->p to fill that gap.
695  *
696  *      If allocation fails we free all blocks we've allocated (and forget
697  *      their buffer_heads) and return the error value the from failed
698  *      ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
699  *      as described above and return 0.
700  */
701 static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
702                              ext4_lblk_t iblock, int indirect_blks,
703                              int *blks, ext4_fsblk_t goal,
704                              ext4_lblk_t *offsets, Indirect *branch)
705 {
706         int blocksize = inode->i_sb->s_blocksize;
707         int i, n = 0;
708         int err = 0;
709         struct buffer_head *bh;
710         int num;
711         ext4_fsblk_t new_blocks[4];
712         ext4_fsblk_t current_block;
713
714         num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
715                                 *blks, new_blocks, &err);
716         if (err)
717                 return err;
718
719         branch[0].key = cpu_to_le32(new_blocks[0]);
720         /*
721          * metadata blocks and data blocks are allocated.
722          */
723         for (n = 1; n <= indirect_blks;  n++) {
724                 /*
725                  * Get buffer_head for parent block, zero it out
726                  * and set the pointer to new one, then send
727                  * parent to disk.
728                  */
729                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
730                 branch[n].bh = bh;
731                 lock_buffer(bh);
732                 BUFFER_TRACE(bh, "call get_create_access");
733                 err = ext4_journal_get_create_access(handle, bh);
734                 if (err) {
735                         /* Don't brelse(bh) here; it's done in
736                          * ext4_journal_forget() below */
737                         unlock_buffer(bh);
738                         goto failed;
739                 }
740
741                 memset(bh->b_data, 0, blocksize);
742                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
743                 branch[n].key = cpu_to_le32(new_blocks[n]);
744                 *branch[n].p = branch[n].key;
745                 if (n == indirect_blks) {
746                         current_block = new_blocks[n];
747                         /*
748                          * End of chain, update the last new metablock of
749                          * the chain to point to the new allocated
750                          * data blocks numbers
751                          */
752                         for (i = 1; i < num; i++)
753                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
754                 }
755                 BUFFER_TRACE(bh, "marking uptodate");
756                 set_buffer_uptodate(bh);
757                 unlock_buffer(bh);
758
759                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
760                 err = ext4_handle_dirty_metadata(handle, inode, bh);
761                 if (err)
762                         goto failed;
763         }
764         *blks = num;
765         return err;
766 failed:
767         /* Allocation failed, free what we already allocated */
768         ext4_free_blocks(handle, inode, 0, new_blocks[0], 1, 0);
769         for (i = 1; i <= n ; i++) {
770                 /* 
771                  * branch[i].bh is newly allocated, so there is no
772                  * need to revoke the block, which is why we don't
773                  * need to set EXT4_FREE_BLOCKS_METADATA.
774                  */
775                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1,
776                                  EXT4_FREE_BLOCKS_FORGET);
777         }
778         for (i = n+1; i < indirect_blks; i++)
779                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0);
780
781         ext4_free_blocks(handle, inode, 0, new_blocks[i], num, 0);
782
783         return err;
784 }
785
786 /**
787  * ext4_splice_branch - splice the allocated branch onto inode.
788  * @inode: owner
789  * @block: (logical) number of block we are adding
790  * @chain: chain of indirect blocks (with a missing link - see
791  *      ext4_alloc_branch)
792  * @where: location of missing link
793  * @num:   number of indirect blocks we are adding
794  * @blks:  number of direct blocks we are adding
795  *
796  * This function fills the missing link and does all housekeeping needed in
797  * inode (->i_blocks, etc.). In case of success we end up with the full
798  * chain to new block and return 0.
799  */
800 static int ext4_splice_branch(handle_t *handle, struct inode *inode,
801                               ext4_lblk_t block, Indirect *where, int num,
802                               int blks)
803 {
804         int i;
805         int err = 0;
806         ext4_fsblk_t current_block;
807
808         /*
809          * If we're splicing into a [td]indirect block (as opposed to the
810          * inode) then we need to get write access to the [td]indirect block
811          * before the splice.
812          */
813         if (where->bh) {
814                 BUFFER_TRACE(where->bh, "get_write_access");
815                 err = ext4_journal_get_write_access(handle, where->bh);
816                 if (err)
817                         goto err_out;
818         }
819         /* That's it */
820
821         *where->p = where->key;
822
823         /*
824          * Update the host buffer_head or inode to point to more just allocated
825          * direct blocks blocks
826          */
827         if (num == 0 && blks > 1) {
828                 current_block = le32_to_cpu(where->key) + 1;
829                 for (i = 1; i < blks; i++)
830                         *(where->p + i) = cpu_to_le32(current_block++);
831         }
832
833         /* We are done with atomic stuff, now do the rest of housekeeping */
834         /* had we spliced it onto indirect block? */
835         if (where->bh) {
836                 /*
837                  * If we spliced it onto an indirect block, we haven't
838                  * altered the inode.  Note however that if it is being spliced
839                  * onto an indirect block at the very end of the file (the
840                  * file is growing) then we *will* alter the inode to reflect
841                  * the new i_size.  But that is not done here - it is done in
842                  * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
843                  */
844                 jbd_debug(5, "splicing indirect only\n");
845                 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
846                 err = ext4_handle_dirty_metadata(handle, inode, where->bh);
847                 if (err)
848                         goto err_out;
849         } else {
850                 /*
851                  * OK, we spliced it into the inode itself on a direct block.
852                  */
853                 ext4_mark_inode_dirty(handle, inode);
854                 jbd_debug(5, "splicing direct\n");
855         }
856         return err;
857
858 err_out:
859         for (i = 1; i <= num; i++) {
860                 /* 
861                  * branch[i].bh is newly allocated, so there is no
862                  * need to revoke the block, which is why we don't
863                  * need to set EXT4_FREE_BLOCKS_METADATA.
864                  */
865                 ext4_free_blocks(handle, inode, where[i].bh, 0, 1,
866                                  EXT4_FREE_BLOCKS_FORGET);
867         }
868         ext4_free_blocks(handle, inode, 0, le32_to_cpu(where[num].key),
869                          blks, 0);
870
871         return err;
872 }
873
874 /*
875  * The ext4_ind_get_blocks() function handles non-extents inodes
876  * (i.e., using the traditional indirect/double-indirect i_blocks
877  * scheme) for ext4_get_blocks().
878  *
879  * Allocation strategy is simple: if we have to allocate something, we will
880  * have to go the whole way to leaf. So let's do it before attaching anything
881  * to tree, set linkage between the newborn blocks, write them if sync is
882  * required, recheck the path, free and repeat if check fails, otherwise
883  * set the last missing link (that will protect us from any truncate-generated
884  * removals - all blocks on the path are immune now) and possibly force the
885  * write on the parent block.
886  * That has a nice additional property: no special recovery from the failed
887  * allocations is needed - we simply release blocks and do not touch anything
888  * reachable from inode.
889  *
890  * `handle' can be NULL if create == 0.
891  *
892  * return > 0, # of blocks mapped or allocated.
893  * return = 0, if plain lookup failed.
894  * return < 0, error case.
895  *
896  * The ext4_ind_get_blocks() function should be called with
897  * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
898  * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
899  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
900  * blocks.
901  */
902 static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
903                                ext4_lblk_t iblock, unsigned int maxblocks,
904                                struct buffer_head *bh_result,
905                                int flags)
906 {
907         int err = -EIO;
908         ext4_lblk_t offsets[4];
909         Indirect chain[4];
910         Indirect *partial;
911         ext4_fsblk_t goal;
912         int indirect_blks;
913         int blocks_to_boundary = 0;
914         int depth;
915         int count = 0;
916         ext4_fsblk_t first_block = 0;
917
918         J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
919         J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
920         depth = ext4_block_to_path(inode, iblock, offsets,
921                                    &blocks_to_boundary);
922
923         if (depth == 0)
924                 goto out;
925
926         partial = ext4_get_branch(inode, depth, offsets, chain, &err);
927
928         /* Simplest case - block found, no allocation needed */
929         if (!partial) {
930                 first_block = le32_to_cpu(chain[depth - 1].key);
931                 clear_buffer_new(bh_result);
932                 count++;
933                 /*map more blocks*/
934                 while (count < maxblocks && count <= blocks_to_boundary) {
935                         ext4_fsblk_t blk;
936
937                         blk = le32_to_cpu(*(chain[depth-1].p + count));
938
939                         if (blk == first_block + count)
940                                 count++;
941                         else
942                                 break;
943                 }
944                 goto got_it;
945         }
946
947         /* Next simple case - plain lookup or failed read of indirect block */
948         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
949                 goto cleanup;
950
951         /*
952          * Okay, we need to do block allocation.
953         */
954         goal = ext4_find_goal(inode, iblock, partial);
955
956         /* the number of blocks need to allocate for [d,t]indirect blocks */
957         indirect_blks = (chain + depth) - partial - 1;
958
959         /*
960          * Next look up the indirect map to count the totoal number of
961          * direct blocks to allocate for this branch.
962          */
963         count = ext4_blks_to_allocate(partial, indirect_blks,
964                                         maxblocks, blocks_to_boundary);
965         /*
966          * Block out ext4_truncate while we alter the tree
967          */
968         err = ext4_alloc_branch(handle, inode, iblock, indirect_blks,
969                                 &count, goal,
970                                 offsets + (partial - chain), partial);
971
972         /*
973          * The ext4_splice_branch call will free and forget any buffers
974          * on the new chain if there is a failure, but that risks using
975          * up transaction credits, especially for bitmaps where the
976          * credits cannot be returned.  Can we handle this somehow?  We
977          * may need to return -EAGAIN upwards in the worst case.  --sct
978          */
979         if (!err)
980                 err = ext4_splice_branch(handle, inode, iblock,
981                                          partial, indirect_blks, count);
982         if (err)
983                 goto cleanup;
984
985         set_buffer_new(bh_result);
986 got_it:
987         map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
988         if (count > blocks_to_boundary)
989                 set_buffer_boundary(bh_result);
990         err = count;
991         /* Clean up and exit */
992         partial = chain + depth - 1;    /* the whole chain */
993 cleanup:
994         while (partial > chain) {
995                 BUFFER_TRACE(partial->bh, "call brelse");
996                 brelse(partial->bh);
997                 partial--;
998         }
999         BUFFER_TRACE(bh_result, "returned");
1000 out:
1001         return err;
1002 }
1003
1004 qsize_t ext4_get_reserved_space(struct inode *inode)
1005 {
1006         unsigned long long total;
1007
1008         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1009         total = EXT4_I(inode)->i_reserved_data_blocks +
1010                 EXT4_I(inode)->i_reserved_meta_blocks;
1011         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1012
1013         return (total << inode->i_blkbits);
1014 }
1015 /*
1016  * Calculate the number of metadata blocks need to reserve
1017  * to allocate @blocks for non extent file based file
1018  */
1019 static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
1020 {
1021         int icap = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1022         int ind_blks, dind_blks, tind_blks;
1023
1024         /* number of new indirect blocks needed */
1025         ind_blks = (blocks + icap - 1) / icap;
1026
1027         dind_blks = (ind_blks + icap - 1) / icap;
1028
1029         tind_blks = 1;
1030
1031         return ind_blks + dind_blks + tind_blks;
1032 }
1033
1034 /*
1035  * Calculate the number of metadata blocks need to reserve
1036  * to allocate given number of blocks
1037  */
1038 static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
1039 {
1040         if (!blocks)
1041                 return 0;
1042
1043         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
1044                 return ext4_ext_calc_metadata_amount(inode, blocks);
1045
1046         return ext4_indirect_calc_metadata_amount(inode, blocks);
1047 }
1048
1049 static void ext4_da_update_reserve_space(struct inode *inode, int used)
1050 {
1051         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1052         int total, mdb, mdb_free;
1053
1054         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1055         /* recalculate the number of metablocks still need to be reserved */
1056         total = EXT4_I(inode)->i_reserved_data_blocks - used;
1057         mdb = ext4_calc_metadata_amount(inode, total);
1058
1059         /* figure out how many metablocks to release */
1060         BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
1061         mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
1062
1063         if (mdb_free) {
1064                 /* Account for allocated meta_blocks */
1065                 mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
1066
1067                 /* update fs dirty blocks counter */
1068                 percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
1069                 EXT4_I(inode)->i_allocated_meta_blocks = 0;
1070                 EXT4_I(inode)->i_reserved_meta_blocks = mdb;
1071         }
1072
1073         /* update per-inode reservations */
1074         BUG_ON(used  > EXT4_I(inode)->i_reserved_data_blocks);
1075         EXT4_I(inode)->i_reserved_data_blocks -= used;
1076         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1077
1078         /*
1079          * free those over-booking quota for metadata blocks
1080          */
1081         if (mdb_free)
1082                 vfs_dq_release_reservation_block(inode, mdb_free);
1083
1084         /*
1085          * If we have done all the pending block allocations and if
1086          * there aren't any writers on the inode, we can discard the
1087          * inode's preallocations.
1088          */
1089         if (!total && (atomic_read(&inode->i_writecount) == 0))
1090                 ext4_discard_preallocations(inode);
1091 }
1092
1093 static int check_block_validity(struct inode *inode, const char *msg,
1094                                 sector_t logical, sector_t phys, int len)
1095 {
1096         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), phys, len)) {
1097                 ext4_error(inode->i_sb, msg,
1098                            "inode #%lu logical block %llu mapped to %llu "
1099                            "(size %d)", inode->i_ino,
1100                            (unsigned long long) logical,
1101                            (unsigned long long) phys, len);
1102                 return -EIO;
1103         }
1104         return 0;
1105 }
1106
1107 /*
1108  * Return the number of contiguous dirty pages in a given inode
1109  * starting at page frame idx.
1110  */
1111 static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
1112                                     unsigned int max_pages)
1113 {
1114         struct address_space *mapping = inode->i_mapping;
1115         pgoff_t index;
1116         struct pagevec pvec;
1117         pgoff_t num = 0;
1118         int i, nr_pages, done = 0;
1119
1120         if (max_pages == 0)
1121                 return 0;
1122         pagevec_init(&pvec, 0);
1123         while (!done) {
1124                 index = idx;
1125                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
1126                                               PAGECACHE_TAG_DIRTY,
1127                                               (pgoff_t)PAGEVEC_SIZE);
1128                 if (nr_pages == 0)
1129                         break;
1130                 for (i = 0; i < nr_pages; i++) {
1131                         struct page *page = pvec.pages[i];
1132                         struct buffer_head *bh, *head;
1133
1134                         lock_page(page);
1135                         if (unlikely(page->mapping != mapping) ||
1136                             !PageDirty(page) ||
1137                             PageWriteback(page) ||
1138                             page->index != idx) {
1139                                 done = 1;
1140                                 unlock_page(page);
1141                                 break;
1142                         }
1143                         if (page_has_buffers(page)) {
1144                                 bh = head = page_buffers(page);
1145                                 do {
1146                                         if (!buffer_delay(bh) &&
1147                                             !buffer_unwritten(bh))
1148                                                 done = 1;
1149                                         bh = bh->b_this_page;
1150                                 } while (!done && (bh != head));
1151                         }
1152                         unlock_page(page);
1153                         if (done)
1154                                 break;
1155                         idx++;
1156                         num++;
1157                         if (num >= max_pages)
1158                                 break;
1159                 }
1160                 pagevec_release(&pvec);
1161         }
1162         return num;
1163 }
1164
1165 /*
1166  * The ext4_get_blocks() function tries to look up the requested blocks,
1167  * and returns if the blocks are already mapped.
1168  *
1169  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
1170  * and store the allocated blocks in the result buffer head and mark it
1171  * mapped.
1172  *
1173  * If file type is extents based, it will call ext4_ext_get_blocks(),
1174  * Otherwise, call with ext4_ind_get_blocks() to handle indirect mapping
1175  * based files
1176  *
1177  * On success, it returns the number of blocks being mapped or allocate.
1178  * if create==0 and the blocks are pre-allocated and uninitialized block,
1179  * the result buffer head is unmapped. If the create ==1, it will make sure
1180  * the buffer head is mapped.
1181  *
1182  * It returns 0 if plain look up failed (blocks have not been allocated), in
1183  * that casem, buffer head is unmapped
1184  *
1185  * It returns the error in case of allocation failure.
1186  */
1187 int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
1188                     unsigned int max_blocks, struct buffer_head *bh,
1189                     int flags)
1190 {
1191         int retval;
1192
1193         clear_buffer_mapped(bh);
1194         clear_buffer_unwritten(bh);
1195
1196         ext_debug("ext4_get_blocks(): inode %lu, flag %d, max_blocks %u,"
1197                   "logical block %lu\n", inode->i_ino, flags, max_blocks,
1198                   (unsigned long)block);
1199         /*
1200          * Try to see if we can get the block without requesting a new
1201          * file system block.
1202          */
1203         down_read((&EXT4_I(inode)->i_data_sem));
1204         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
1205                 retval =  ext4_ext_get_blocks(handle, inode, block, max_blocks,
1206                                 bh, 0);
1207         } else {
1208                 retval = ext4_ind_get_blocks(handle, inode, block, max_blocks,
1209                                              bh, 0);
1210         }
1211         up_read((&EXT4_I(inode)->i_data_sem));
1212
1213         if (retval > 0 && buffer_mapped(bh)) {
1214                 int ret = check_block_validity(inode, "file system corruption",
1215                                                block, bh->b_blocknr, retval);
1216                 if (ret != 0)
1217                         return ret;
1218         }
1219
1220         /* If it is only a block(s) look up */
1221         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
1222                 return retval;
1223
1224         /*
1225          * Returns if the blocks have already allocated
1226          *
1227          * Note that if blocks have been preallocated
1228          * ext4_ext_get_block() returns th create = 0
1229          * with buffer head unmapped.
1230          */
1231         if (retval > 0 && buffer_mapped(bh))
1232                 return retval;
1233
1234         /*
1235          * When we call get_blocks without the create flag, the
1236          * BH_Unwritten flag could have gotten set if the blocks
1237          * requested were part of a uninitialized extent.  We need to
1238          * clear this flag now that we are committed to convert all or
1239          * part of the uninitialized extent to be an initialized
1240          * extent.  This is because we need to avoid the combination
1241          * of BH_Unwritten and BH_Mapped flags being simultaneously
1242          * set on the buffer_head.
1243          */
1244         clear_buffer_unwritten(bh);
1245
1246         /*
1247          * New blocks allocate and/or writing to uninitialized extent
1248          * will possibly result in updating i_data, so we take
1249          * the write lock of i_data_sem, and call get_blocks()
1250          * with create == 1 flag.
1251          */
1252         down_write((&EXT4_I(inode)->i_data_sem));
1253
1254         /*
1255          * if the caller is from delayed allocation writeout path
1256          * we have already reserved fs blocks for allocation
1257          * let the underlying get_block() function know to
1258          * avoid double accounting
1259          */
1260         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1261                 EXT4_I(inode)->i_delalloc_reserved_flag = 1;
1262         /*
1263          * We need to check for EXT4 here because migrate
1264          * could have changed the inode type in between
1265          */
1266         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
1267                 retval =  ext4_ext_get_blocks(handle, inode, block, max_blocks,
1268                                               bh, flags);
1269         } else {
1270                 retval = ext4_ind_get_blocks(handle, inode, block,
1271                                              max_blocks, bh, flags);
1272
1273                 if (retval > 0 && buffer_new(bh)) {
1274                         /*
1275                          * We allocated new blocks which will result in
1276                          * i_data's format changing.  Force the migrate
1277                          * to fail by clearing migrate flags
1278                          */
1279                         EXT4_I(inode)->i_state &= ~EXT4_STATE_EXT_MIGRATE;
1280                 }
1281         }
1282
1283         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1284                 EXT4_I(inode)->i_delalloc_reserved_flag = 0;
1285
1286         /*
1287          * Update reserved blocks/metadata blocks after successful
1288          * block allocation which had been deferred till now.
1289          */
1290         if ((retval > 0) && (flags & EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE))
1291                 ext4_da_update_reserve_space(inode, retval);
1292
1293         up_write((&EXT4_I(inode)->i_data_sem));
1294         if (retval > 0 && buffer_mapped(bh)) {
1295                 int ret = check_block_validity(inode, "file system "
1296                                                "corruption after allocation",
1297                                                block, bh->b_blocknr, retval);
1298                 if (ret != 0)
1299                         return ret;
1300         }
1301         return retval;
1302 }
1303
1304 /* Maximum number of blocks we map for direct IO at once. */
1305 #define DIO_MAX_BLOCKS 4096
1306
1307 int ext4_get_block(struct inode *inode, sector_t iblock,
1308                    struct buffer_head *bh_result, int create)
1309 {
1310         handle_t *handle = ext4_journal_current_handle();
1311         int ret = 0, started = 0;
1312         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
1313         int dio_credits;
1314
1315         if (create && !handle) {
1316                 /* Direct IO write... */
1317                 if (max_blocks > DIO_MAX_BLOCKS)
1318                         max_blocks = DIO_MAX_BLOCKS;
1319                 dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
1320                 handle = ext4_journal_start(inode, dio_credits);
1321                 if (IS_ERR(handle)) {
1322                         ret = PTR_ERR(handle);
1323                         goto out;
1324                 }
1325                 started = 1;
1326         }
1327
1328         ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
1329                               create ? EXT4_GET_BLOCKS_CREATE : 0);
1330         if (ret > 0) {
1331                 bh_result->b_size = (ret << inode->i_blkbits);
1332                 ret = 0;
1333         }
1334         if (started)
1335                 ext4_journal_stop(handle);
1336 out:
1337         return ret;
1338 }
1339
1340 /*
1341  * `handle' can be NULL if create is zero
1342  */
1343 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
1344                                 ext4_lblk_t block, int create, int *errp)
1345 {
1346         struct buffer_head dummy;
1347         int fatal = 0, err;
1348         int flags = 0;
1349
1350         J_ASSERT(handle != NULL || create == 0);
1351
1352         dummy.b_state = 0;
1353         dummy.b_blocknr = -1000;
1354         buffer_trace_init(&dummy.b_history);
1355         if (create)
1356                 flags |= EXT4_GET_BLOCKS_CREATE;
1357         err = ext4_get_blocks(handle, inode, block, 1, &dummy, flags);
1358         /*
1359          * ext4_get_blocks() returns number of blocks mapped. 0 in
1360          * case of a HOLE.
1361          */
1362         if (err > 0) {
1363                 if (err > 1)
1364                         WARN_ON(1);
1365                 err = 0;
1366         }
1367         *errp = err;
1368         if (!err && buffer_mapped(&dummy)) {
1369                 struct buffer_head *bh;
1370                 bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
1371                 if (!bh) {
1372                         *errp = -EIO;
1373                         goto err;
1374                 }
1375                 if (buffer_new(&dummy)) {
1376                         J_ASSERT(create != 0);
1377                         J_ASSERT(handle != NULL);
1378
1379                         /*
1380                          * Now that we do not always journal data, we should
1381                          * keep in mind whether this should always journal the
1382                          * new buffer as metadata.  For now, regular file
1383                          * writes use ext4_get_block instead, so it's not a
1384                          * problem.
1385                          */
1386                         lock_buffer(bh);
1387                         BUFFER_TRACE(bh, "call get_create_access");
1388                         fatal = ext4_journal_get_create_access(handle, bh);
1389                         if (!fatal && !buffer_uptodate(bh)) {
1390                                 memset(bh->b_data, 0, inode->i_sb->s_blocksize);
1391                                 set_buffer_uptodate(bh);
1392                         }
1393                         unlock_buffer(bh);
1394                         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
1395                         err = ext4_handle_dirty_metadata(handle, inode, bh);
1396                         if (!fatal)
1397                                 fatal = err;
1398                 } else {
1399                         BUFFER_TRACE(bh, "not a new buffer");
1400                 }
1401                 if (fatal) {
1402                         *errp = fatal;
1403                         brelse(bh);
1404                         bh = NULL;
1405                 }
1406                 return bh;
1407         }
1408 err:
1409         return NULL;
1410 }
1411
1412 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1413                                ext4_lblk_t block, int create, int *err)
1414 {
1415         struct buffer_head *bh;
1416
1417         bh = ext4_getblk(handle, inode, block, create, err);
1418         if (!bh)
1419                 return bh;
1420         if (buffer_uptodate(bh))
1421                 return bh;
1422         ll_rw_block(READ_META, 1, &bh);
1423         wait_on_buffer(bh);
1424         if (buffer_uptodate(bh))
1425                 return bh;
1426         put_bh(bh);
1427         *err = -EIO;
1428         return NULL;
1429 }
1430
1431 static int walk_page_buffers(handle_t *handle,
1432                              struct buffer_head *head,
1433                              unsigned from,
1434                              unsigned to,
1435                              int *partial,
1436                              int (*fn)(handle_t *handle,
1437                                        struct buffer_head *bh))
1438 {
1439         struct buffer_head *bh;
1440         unsigned block_start, block_end;
1441         unsigned blocksize = head->b_size;
1442         int err, ret = 0;
1443         struct buffer_head *next;
1444
1445         for (bh = head, block_start = 0;
1446              ret == 0 && (bh != head || !block_start);
1447              block_start = block_end, bh = next) {
1448                 next = bh->b_this_page;
1449                 block_end = block_start + blocksize;
1450                 if (block_end <= from || block_start >= to) {
1451                         if (partial && !buffer_uptodate(bh))
1452                                 *partial = 1;
1453                         continue;
1454                 }
1455                 err = (*fn)(handle, bh);
1456                 if (!ret)
1457                         ret = err;
1458         }
1459         return ret;
1460 }
1461
1462 /*
1463  * To preserve ordering, it is essential that the hole instantiation and
1464  * the data write be encapsulated in a single transaction.  We cannot
1465  * close off a transaction and start a new one between the ext4_get_block()
1466  * and the commit_write().  So doing the jbd2_journal_start at the start of
1467  * prepare_write() is the right place.
1468  *
1469  * Also, this function can nest inside ext4_writepage() ->
1470  * block_write_full_page(). In that case, we *know* that ext4_writepage()
1471  * has generated enough buffer credits to do the whole page.  So we won't
1472  * block on the journal in that case, which is good, because the caller may
1473  * be PF_MEMALLOC.
1474  *
1475  * By accident, ext4 can be reentered when a transaction is open via
1476  * quota file writes.  If we were to commit the transaction while thus
1477  * reentered, there can be a deadlock - we would be holding a quota
1478  * lock, and the commit would never complete if another thread had a
1479  * transaction open and was blocking on the quota lock - a ranking
1480  * violation.
1481  *
1482  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1483  * will _not_ run commit under these circumstances because handle->h_ref
1484  * is elevated.  We'll still have enough credits for the tiny quotafile
1485  * write.
1486  */
1487 static int do_journal_get_write_access(handle_t *handle,
1488                                        struct buffer_head *bh)
1489 {
1490         if (!buffer_mapped(bh) || buffer_freed(bh))
1491                 return 0;
1492         return ext4_journal_get_write_access(handle, bh);
1493 }
1494
1495 /*
1496  * Truncate blocks that were not used by write. We have to truncate the
1497  * pagecache as well so that corresponding buffers get properly unmapped.
1498  */
1499 static void ext4_truncate_failed_write(struct inode *inode)
1500 {
1501         truncate_inode_pages(inode->i_mapping, inode->i_size);
1502         ext4_truncate(inode);
1503 }
1504
1505 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1506                             loff_t pos, unsigned len, unsigned flags,
1507                             struct page **pagep, void **fsdata)
1508 {
1509         struct inode *inode = mapping->host;
1510         int ret, needed_blocks;
1511         handle_t *handle;
1512         int retries = 0;
1513         struct page *page;
1514         pgoff_t index;
1515         unsigned from, to;
1516
1517         trace_ext4_write_begin(inode, pos, len, flags);
1518         /*
1519          * Reserve one block more for addition to orphan list in case
1520          * we allocate blocks but write fails for some reason
1521          */
1522         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1523         index = pos >> PAGE_CACHE_SHIFT;
1524         from = pos & (PAGE_CACHE_SIZE - 1);
1525         to = from + len;
1526
1527 retry:
1528         handle = ext4_journal_start(inode, needed_blocks);
1529         if (IS_ERR(handle)) {
1530                 ret = PTR_ERR(handle);
1531                 goto out;
1532         }
1533
1534         /* We cannot recurse into the filesystem as the transaction is already
1535          * started */
1536         flags |= AOP_FLAG_NOFS;
1537
1538         page = grab_cache_page_write_begin(mapping, index, flags);
1539         if (!page) {
1540                 ext4_journal_stop(handle);
1541                 ret = -ENOMEM;
1542                 goto out;
1543         }
1544         *pagep = page;
1545
1546         ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
1547                                 ext4_get_block);
1548
1549         if (!ret && ext4_should_journal_data(inode)) {
1550                 ret = walk_page_buffers(handle, page_buffers(page),
1551                                 from, to, NULL, do_journal_get_write_access);
1552         }
1553
1554         if (ret) {
1555                 unlock_page(page);
1556                 page_cache_release(page);
1557                 /*
1558                  * block_write_begin may have instantiated a few blocks
1559                  * outside i_size.  Trim these off again. Don't need
1560                  * i_size_read because we hold i_mutex.
1561                  *
1562                  * Add inode to orphan list in case we crash before
1563                  * truncate finishes
1564                  */
1565                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1566                         ext4_orphan_add(handle, inode);
1567
1568                 ext4_journal_stop(handle);
1569                 if (pos + len > inode->i_size) {
1570                         ext4_truncate_failed_write(inode);
1571                         /*
1572                          * If truncate failed early the inode might
1573                          * still be on the orphan list; we need to
1574                          * make sure the inode is removed from the
1575                          * orphan list in that case.
1576                          */
1577                         if (inode->i_nlink)
1578                                 ext4_orphan_del(NULL, inode);
1579                 }
1580         }
1581
1582         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1583                 goto retry;
1584 out:
1585         return ret;
1586 }
1587
1588 /* For write_end() in data=journal mode */
1589 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1590 {
1591         if (!buffer_mapped(bh) || buffer_freed(bh))
1592                 return 0;
1593         set_buffer_uptodate(bh);
1594         return ext4_handle_dirty_metadata(handle, NULL, bh);
1595 }
1596
1597 static int ext4_generic_write_end(struct file *file,
1598                                   struct address_space *mapping,
1599                                   loff_t pos, unsigned len, unsigned copied,
1600                                   struct page *page, void *fsdata)
1601 {
1602         int i_size_changed = 0;
1603         struct inode *inode = mapping->host;
1604         handle_t *handle = ext4_journal_current_handle();
1605
1606         copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1607
1608         /*
1609          * No need to use i_size_read() here, the i_size
1610          * cannot change under us because we hold i_mutex.
1611          *
1612          * But it's important to update i_size while still holding page lock:
1613          * page writeout could otherwise come in and zero beyond i_size.
1614          */
1615         if (pos + copied > inode->i_size) {
1616                 i_size_write(inode, pos + copied);
1617                 i_size_changed = 1;
1618         }
1619
1620         if (pos + copied >  EXT4_I(inode)->i_disksize) {
1621                 /* We need to mark inode dirty even if
1622                  * new_i_size is less that inode->i_size
1623                  * bu greater than i_disksize.(hint delalloc)
1624                  */
1625                 ext4_update_i_disksize(inode, (pos + copied));
1626                 i_size_changed = 1;
1627         }
1628         unlock_page(page);
1629         page_cache_release(page);
1630
1631         /*
1632          * Don't mark the inode dirty under page lock. First, it unnecessarily
1633          * makes the holding time of page lock longer. Second, it forces lock
1634          * ordering of page lock and transaction start for journaling
1635          * filesystems.
1636          */
1637         if (i_size_changed)
1638                 ext4_mark_inode_dirty(handle, inode);
1639
1640         return copied;
1641 }
1642
1643 /*
1644  * We need to pick up the new inode size which generic_commit_write gave us
1645  * `file' can be NULL - eg, when called from page_symlink().
1646  *
1647  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1648  * buffers are managed internally.
1649  */
1650 static int ext4_ordered_write_end(struct file *file,
1651                                   struct address_space *mapping,
1652                                   loff_t pos, unsigned len, unsigned copied,
1653                                   struct page *page, void *fsdata)
1654 {
1655         handle_t *handle = ext4_journal_current_handle();
1656         struct inode *inode = mapping->host;
1657         int ret = 0, ret2;
1658
1659         trace_ext4_ordered_write_end(inode, pos, len, copied);
1660         ret = ext4_jbd2_file_inode(handle, inode);
1661
1662         if (ret == 0) {
1663                 ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1664                                                         page, fsdata);
1665                 copied = ret2;
1666                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1667                         /* if we have allocated more blocks and copied
1668                          * less. We will have blocks allocated outside
1669                          * inode->i_size. So truncate them
1670                          */
1671                         ext4_orphan_add(handle, inode);
1672                 if (ret2 < 0)
1673                         ret = ret2;
1674         }
1675         ret2 = ext4_journal_stop(handle);
1676         if (!ret)
1677                 ret = ret2;
1678
1679         if (pos + len > inode->i_size) {
1680                 ext4_truncate_failed_write(inode);
1681                 /*
1682                  * If truncate failed early the inode might still be
1683                  * on the orphan list; we need to make sure the inode
1684                  * is removed from the orphan list in that case.
1685                  */
1686                 if (inode->i_nlink)
1687                         ext4_orphan_del(NULL, inode);
1688         }
1689
1690
1691         return ret ? ret : copied;
1692 }
1693
1694 static int ext4_writeback_write_end(struct file *file,
1695                                     struct address_space *mapping,
1696                                     loff_t pos, unsigned len, unsigned copied,
1697                                     struct page *page, void *fsdata)
1698 {
1699         handle_t *handle = ext4_journal_current_handle();
1700         struct inode *inode = mapping->host;
1701         int ret = 0, ret2;
1702
1703         trace_ext4_writeback_write_end(inode, pos, len, copied);
1704         ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1705                                                         page, fsdata);
1706         copied = ret2;
1707         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1708                 /* if we have allocated more blocks and copied
1709                  * less. We will have blocks allocated outside
1710                  * inode->i_size. So truncate them
1711                  */
1712                 ext4_orphan_add(handle, inode);
1713
1714         if (ret2 < 0)
1715                 ret = ret2;
1716
1717         ret2 = ext4_journal_stop(handle);
1718         if (!ret)
1719                 ret = ret2;
1720
1721         if (pos + len > inode->i_size) {
1722                 ext4_truncate_failed_write(inode);
1723                 /*
1724                  * If truncate failed early the inode might still be
1725                  * on the orphan list; we need to make sure the inode
1726                  * is removed from the orphan list in that case.
1727                  */
1728                 if (inode->i_nlink)
1729                         ext4_orphan_del(NULL, inode);
1730         }
1731
1732         return ret ? ret : copied;
1733 }
1734
1735 static int ext4_journalled_write_end(struct file *file,
1736                                      struct address_space *mapping,
1737                                      loff_t pos, unsigned len, unsigned copied,
1738                                      struct page *page, void *fsdata)
1739 {
1740         handle_t *handle = ext4_journal_current_handle();
1741         struct inode *inode = mapping->host;
1742         int ret = 0, ret2;
1743         int partial = 0;
1744         unsigned from, to;
1745         loff_t new_i_size;
1746
1747         trace_ext4_journalled_write_end(inode, pos, len, copied);
1748         from = pos & (PAGE_CACHE_SIZE - 1);
1749         to = from + len;
1750
1751         if (copied < len) {
1752                 if (!PageUptodate(page))
1753                         copied = 0;
1754                 page_zero_new_buffers(page, from+copied, to);
1755         }
1756
1757         ret = walk_page_buffers(handle, page_buffers(page), from,
1758                                 to, &partial, write_end_fn);
1759         if (!partial)
1760                 SetPageUptodate(page);
1761         new_i_size = pos + copied;
1762         if (new_i_size > inode->i_size)
1763                 i_size_write(inode, pos+copied);
1764         EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
1765         if (new_i_size > EXT4_I(inode)->i_disksize) {
1766                 ext4_update_i_disksize(inode, new_i_size);
1767                 ret2 = ext4_mark_inode_dirty(handle, inode);
1768                 if (!ret)
1769                         ret = ret2;
1770         }
1771
1772         unlock_page(page);
1773         page_cache_release(page);
1774         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1775                 /* if we have allocated more blocks and copied
1776                  * less. We will have blocks allocated outside
1777                  * inode->i_size. So truncate them
1778                  */
1779                 ext4_orphan_add(handle, inode);
1780
1781         ret2 = ext4_journal_stop(handle);
1782         if (!ret)
1783                 ret = ret2;
1784         if (pos + len > inode->i_size) {
1785                 ext4_truncate_failed_write(inode);
1786                 /*
1787                  * If truncate failed early the inode might still be
1788                  * on the orphan list; we need to make sure the inode
1789                  * is removed from the orphan list in that case.
1790                  */
1791                 if (inode->i_nlink)
1792                         ext4_orphan_del(NULL, inode);
1793         }
1794
1795         return ret ? ret : copied;
1796 }
1797
1798 static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
1799 {
1800         int retries = 0;
1801         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1802         unsigned long md_needed, mdblocks, total = 0;
1803
1804         /*
1805          * recalculate the amount of metadata blocks to reserve
1806          * in order to allocate nrblocks
1807          * worse case is one extent per block
1808          */
1809 repeat:
1810         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1811         total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks;
1812         mdblocks = ext4_calc_metadata_amount(inode, total);
1813         BUG_ON(mdblocks < EXT4_I(inode)->i_reserved_meta_blocks);
1814
1815         md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
1816         total = md_needed + nrblocks;
1817
1818         /*
1819          * Make quota reservation here to prevent quota overflow
1820          * later. Real quota accounting is done at pages writeout
1821          * time.
1822          */
1823         if (vfs_dq_reserve_block(inode, total)) {
1824                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1825                 return -EDQUOT;
1826         }
1827
1828         if (ext4_claim_free_blocks(sbi, total)) {
1829                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1830                 vfs_dq_release_reservation_block(inode, total);
1831                 if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1832                         yield();
1833                         goto repeat;
1834                 }
1835                 return -ENOSPC;
1836         }
1837         EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
1838         EXT4_I(inode)->i_reserved_meta_blocks = mdblocks;
1839
1840         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1841         return 0;       /* success */
1842 }
1843
1844 static void ext4_da_release_space(struct inode *inode, int to_free)
1845 {
1846         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1847         int total, mdb, mdb_free, release;
1848
1849         if (!to_free)
1850                 return;         /* Nothing to release, exit */
1851
1852         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1853
1854         if (!EXT4_I(inode)->i_reserved_data_blocks) {
1855                 /*
1856                  * if there is no reserved blocks, but we try to free some
1857                  * then the counter is messed up somewhere.
1858                  * but since this function is called from invalidate
1859                  * page, it's harmless to return without any action
1860                  */
1861                 printk(KERN_INFO "ext4 delalloc try to release %d reserved "
1862                             "blocks for inode %lu, but there is no reserved "
1863                             "data blocks\n", to_free, inode->i_ino);
1864                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1865                 return;
1866         }
1867
1868         /* recalculate the number of metablocks still need to be reserved */
1869         total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
1870         mdb = ext4_calc_metadata_amount(inode, total);
1871
1872         /* figure out how many metablocks to release */
1873         BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
1874         mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
1875
1876         release = to_free + mdb_free;
1877
1878         /* update fs dirty blocks counter for truncate case */
1879         percpu_counter_sub(&sbi->s_dirtyblocks_counter, release);
1880
1881         /* update per-inode reservations */
1882         BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks);
1883         EXT4_I(inode)->i_reserved_data_blocks -= to_free;
1884
1885         BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
1886         EXT4_I(inode)->i_reserved_meta_blocks = mdb;
1887         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1888
1889         vfs_dq_release_reservation_block(inode, release);
1890 }
1891
1892 static void ext4_da_page_release_reservation(struct page *page,
1893                                              unsigned long offset)
1894 {
1895         int to_release = 0;
1896         struct buffer_head *head, *bh;
1897         unsigned int curr_off = 0;
1898
1899         head = page_buffers(page);
1900         bh = head;
1901         do {
1902                 unsigned int next_off = curr_off + bh->b_size;
1903
1904                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1905                         to_release++;
1906                         clear_buffer_delay(bh);
1907                 }
1908                 curr_off = next_off;
1909         } while ((bh = bh->b_this_page) != head);
1910         ext4_da_release_space(page->mapping->host, to_release);
1911 }
1912
1913 /*
1914  * Delayed allocation stuff
1915  */
1916
1917 /*
1918  * mpage_da_submit_io - walks through extent of pages and try to write
1919  * them with writepage() call back
1920  *
1921  * @mpd->inode: inode
1922  * @mpd->first_page: first page of the extent
1923  * @mpd->next_page: page after the last page of the extent
1924  *
1925  * By the time mpage_da_submit_io() is called we expect all blocks
1926  * to be allocated. this may be wrong if allocation failed.
1927  *
1928  * As pages are already locked by write_cache_pages(), we can't use it
1929  */
1930 static int mpage_da_submit_io(struct mpage_da_data *mpd)
1931 {
1932         long pages_skipped;
1933         struct pagevec pvec;
1934         unsigned long index, end;
1935         int ret = 0, err, nr_pages, i;
1936         struct inode *inode = mpd->inode;
1937         struct address_space *mapping = inode->i_mapping;
1938
1939         BUG_ON(mpd->next_page <= mpd->first_page);
1940         /*
1941          * We need to start from the first_page to the next_page - 1
1942          * to make sure we also write the mapped dirty buffer_heads.
1943          * If we look at mpd->b_blocknr we would only be looking
1944          * at the currently mapped buffer_heads.
1945          */
1946         index = mpd->first_page;
1947         end = mpd->next_page - 1;
1948
1949         pagevec_init(&pvec, 0);
1950         while (index <= end) {
1951                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1952                 if (nr_pages == 0)
1953                         break;
1954                 for (i = 0; i < nr_pages; i++) {
1955                         struct page *page = pvec.pages[i];
1956
1957                         index = page->index;
1958                         if (index > end)
1959                                 break;
1960                         index++;
1961
1962                         BUG_ON(!PageLocked(page));
1963                         BUG_ON(PageWriteback(page));
1964
1965                         pages_skipped = mpd->wbc->pages_skipped;
1966                         err = mapping->a_ops->writepage(page, mpd->wbc);
1967                         if (!err && (pages_skipped == mpd->wbc->pages_skipped))
1968                                 /*
1969                                  * have successfully written the page
1970                                  * without skipping the same
1971                                  */
1972                                 mpd->pages_written++;
1973                         /*
1974                          * In error case, we have to continue because
1975                          * remaining pages are still locked
1976                          * XXX: unlock and re-dirty them?
1977                          */
1978                         if (ret == 0)
1979                                 ret = err;
1980                 }
1981                 pagevec_release(&pvec);
1982         }
1983         return ret;
1984 }
1985
1986 /*
1987  * mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
1988  *
1989  * @mpd->inode - inode to walk through
1990  * @exbh->b_blocknr - first block on a disk
1991  * @exbh->b_size - amount of space in bytes
1992  * @logical - first logical block to start assignment with
1993  *
1994  * the function goes through all passed space and put actual disk
1995  * block numbers into buffer heads, dropping BH_Delay and BH_Unwritten
1996  */
1997 static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
1998                                  struct buffer_head *exbh)
1999 {
2000         struct inode *inode = mpd->inode;
2001         struct address_space *mapping = inode->i_mapping;
2002         int blocks = exbh->b_size >> inode->i_blkbits;
2003         sector_t pblock = exbh->b_blocknr, cur_logical;
2004         struct buffer_head *head, *bh;
2005         pgoff_t index, end;
2006         struct pagevec pvec;
2007         int nr_pages, i;
2008
2009         index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2010         end = (logical + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2011         cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2012
2013         pagevec_init(&pvec, 0);
2014
2015         while (index <= end) {
2016                 /* XXX: optimize tail */
2017                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
2018                 if (nr_pages == 0)
2019                         break;
2020                 for (i = 0; i < nr_pages; i++) {
2021                         struct page *page = pvec.pages[i];
2022
2023                         index = page->index;
2024                         if (index > end)
2025                                 break;
2026                         index++;
2027
2028                         BUG_ON(!PageLocked(page));
2029                         BUG_ON(PageWriteback(page));
2030                         BUG_ON(!page_has_buffers(page));
2031
2032                         bh = page_buffers(page);
2033                         head = bh;
2034
2035                         /* skip blocks out of the range */
2036                         do {
2037                                 if (cur_logical >= logical)
2038                                         break;
2039                                 cur_logical++;
2040                         } while ((bh = bh->b_this_page) != head);
2041
2042                         do {
2043                                 if (cur_logical >= logical + blocks)
2044                                         break;
2045
2046                                 if (buffer_delay(bh) ||
2047                                                 buffer_unwritten(bh)) {
2048
2049                                         BUG_ON(bh->b_bdev != inode->i_sb->s_bdev);
2050
2051                                         if (buffer_delay(bh)) {
2052                                                 clear_buffer_delay(bh);
2053                                                 bh->b_blocknr = pblock;
2054                                         } else {
2055                                                 /*
2056                                                  * unwritten already should have
2057                                                  * blocknr assigned. Verify that
2058                                                  */
2059                                                 clear_buffer_unwritten(bh);
2060                                                 BUG_ON(bh->b_blocknr != pblock);
2061                                         }
2062
2063                                 } else if (buffer_mapped(bh))
2064                                         BUG_ON(bh->b_blocknr != pblock);
2065
2066                                 cur_logical++;
2067                                 pblock++;
2068                         } while ((bh = bh->b_this_page) != head);
2069                 }
2070                 pagevec_release(&pvec);
2071         }
2072 }
2073
2074
2075 /*
2076  * __unmap_underlying_blocks - just a helper function to unmap
2077  * set of blocks described by @bh
2078  */
2079 static inline void __unmap_underlying_blocks(struct inode *inode,
2080                                              struct buffer_head *bh)
2081 {
2082         struct block_device *bdev = inode->i_sb->s_bdev;
2083         int blocks, i;
2084
2085         blocks = bh->b_size >> inode->i_blkbits;
2086         for (i = 0; i < blocks; i++)
2087                 unmap_underlying_metadata(bdev, bh->b_blocknr + i);
2088 }
2089
2090 static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
2091                                         sector_t logical, long blk_cnt)
2092 {
2093         int nr_pages, i;
2094         pgoff_t index, end;
2095         struct pagevec pvec;
2096         struct inode *inode = mpd->inode;
2097         struct address_space *mapping = inode->i_mapping;
2098
2099         index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2100         end   = (logical + blk_cnt - 1) >>
2101                                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
2102         while (index <= end) {
2103                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
2104                 if (nr_pages == 0)
2105                         break;
2106                 for (i = 0; i < nr_pages; i++) {
2107                         struct page *page = pvec.pages[i];
2108                         index = page->index;
2109                         if (index > end)
2110                                 break;
2111                         index++;
2112
2113                         BUG_ON(!PageLocked(page));
2114                         BUG_ON(PageWriteback(page));
2115                         block_invalidatepage(page, 0);
2116                         ClearPageUptodate(page);
2117                         unlock_page(page);
2118                 }
2119         }
2120         return;
2121 }
2122
2123 static void ext4_print_free_blocks(struct inode *inode)
2124 {
2125         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2126         printk(KERN_CRIT "Total free blocks count %lld\n",
2127                ext4_count_free_blocks(inode->i_sb));
2128         printk(KERN_CRIT "Free/Dirty block details\n");
2129         printk(KERN_CRIT "free_blocks=%lld\n",
2130                (long long) percpu_counter_sum(&sbi->s_freeblocks_counter));
2131         printk(KERN_CRIT "dirty_blocks=%lld\n",
2132                (long long) percpu_counter_sum(&sbi->s_dirtyblocks_counter));
2133         printk(KERN_CRIT "Block reservation details\n");
2134         printk(KERN_CRIT "i_reserved_data_blocks=%u\n",
2135                EXT4_I(inode)->i_reserved_data_blocks);
2136         printk(KERN_CRIT "i_reserved_meta_blocks=%u\n",
2137                EXT4_I(inode)->i_reserved_meta_blocks);
2138         return;
2139 }
2140
2141 /*
2142  * mpage_da_map_blocks - go through given space
2143  *
2144  * @mpd - bh describing space
2145  *
2146  * The function skips space we know is already mapped to disk blocks.
2147  *
2148  */
2149 static int mpage_da_map_blocks(struct mpage_da_data *mpd)
2150 {
2151         int err, blks, get_blocks_flags;
2152         struct buffer_head new;
2153         sector_t next = mpd->b_blocknr;
2154         unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
2155         loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
2156         handle_t *handle = NULL;
2157
2158         /*
2159          * We consider only non-mapped and non-allocated blocks
2160          */
2161         if ((mpd->b_state  & (1 << BH_Mapped)) &&
2162                 !(mpd->b_state & (1 << BH_Delay)) &&
2163                 !(mpd->b_state & (1 << BH_Unwritten)))
2164                 return 0;
2165
2166         /*
2167          * If we didn't accumulate anything to write simply return
2168          */
2169         if (!mpd->b_size)
2170                 return 0;
2171
2172         handle = ext4_journal_current_handle();
2173         BUG_ON(!handle);
2174
2175         /*
2176          * Call ext4_get_blocks() to allocate any delayed allocation
2177          * blocks, or to convert an uninitialized extent to be
2178          * initialized (in the case where we have written into
2179          * one or more preallocated blocks).
2180          *
2181          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
2182          * indicate that we are on the delayed allocation path.  This
2183          * affects functions in many different parts of the allocation
2184          * call path.  This flag exists primarily because we don't
2185          * want to change *many* call functions, so ext4_get_blocks()
2186          * will set the magic i_delalloc_reserved_flag once the
2187          * inode's allocation semaphore is taken.
2188          *
2189          * If the blocks in questions were delalloc blocks, set
2190          * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
2191          * variables are updated after the blocks have been allocated.
2192          */
2193         new.b_state = 0;
2194         get_blocks_flags = (EXT4_GET_BLOCKS_CREATE |
2195                             EXT4_GET_BLOCKS_DELALLOC_RESERVE);
2196         if (mpd->b_state & (1 << BH_Delay))
2197                 get_blocks_flags |= EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE;
2198         blks = ext4_get_blocks(handle, mpd->inode, next, max_blocks,
2199                                &new, get_blocks_flags);
2200         if (blks < 0) {
2201                 err = blks;
2202                 /*
2203                  * If get block returns with error we simply
2204                  * return. Later writepage will redirty the page and
2205                  * writepages will find the dirty page again
2206                  */
2207                 if (err == -EAGAIN)
2208                         return 0;
2209
2210                 if (err == -ENOSPC &&
2211                     ext4_count_free_blocks(mpd->inode->i_sb)) {
2212                         mpd->retval = err;
2213                         return 0;
2214                 }
2215
2216                 /*
2217                  * get block failure will cause us to loop in
2218                  * writepages, because a_ops->writepage won't be able
2219                  * to make progress. The page will be redirtied by
2220                  * writepage and writepages will again try to write
2221                  * the same.
2222                  */
2223                 ext4_msg(mpd->inode->i_sb, KERN_CRIT,
2224                          "delayed block allocation failed for inode %lu at "
2225                          "logical offset %llu with max blocks %zd with "
2226                          "error %d\n", mpd->inode->i_ino,
2227                          (unsigned long long) next,
2228                          mpd->b_size >> mpd->inode->i_blkbits, err);
2229                 printk(KERN_CRIT "This should not happen!!  "
2230                        "Data will be lost\n");
2231                 if (err == -ENOSPC) {
2232                         ext4_print_free_blocks(mpd->inode);
2233                 }
2234                 /* invalidate all the pages */
2235                 ext4_da_block_invalidatepages(mpd, next,
2236                                 mpd->b_size >> mpd->inode->i_blkbits);
2237                 return err;
2238         }
2239         BUG_ON(blks == 0);
2240
2241         new.b_size = (blks << mpd->inode->i_blkbits);
2242
2243         if (buffer_new(&new))
2244                 __unmap_underlying_blocks(mpd->inode, &new);
2245
2246         /*
2247          * If blocks are delayed marked, we need to
2248          * put actual blocknr and drop delayed bit
2249          */
2250         if ((mpd->b_state & (1 << BH_Delay)) ||
2251             (mpd->b_state & (1 << BH_Unwritten)))
2252                 mpage_put_bnr_to_bhs(mpd, next, &new);
2253
2254         if (ext4_should_order_data(mpd->inode)) {
2255                 err = ext4_jbd2_file_inode(handle, mpd->inode);
2256                 if (err)
2257                         return err;
2258         }
2259
2260         /*
2261          * Update on-disk size along with block allocation.
2262          */
2263         disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
2264         if (disksize > i_size_read(mpd->inode))
2265                 disksize = i_size_read(mpd->inode);
2266         if (disksize > EXT4_I(mpd->inode)->i_disksize) {
2267                 ext4_update_i_disksize(mpd->inode, disksize);
2268                 return ext4_mark_inode_dirty(handle, mpd->inode);
2269         }
2270
2271         return 0;
2272 }
2273
2274 #define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
2275                 (1 << BH_Delay) | (1 << BH_Unwritten))
2276
2277 /*
2278  * mpage_add_bh_to_extent - try to add one more block to extent of blocks
2279  *
2280  * @mpd->lbh - extent of blocks
2281  * @logical - logical number of the block in the file
2282  * @bh - bh of the block (used to access block's state)
2283  *
2284  * the function is used to collect contig. blocks in same state
2285  */
2286 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
2287                                    sector_t logical, size_t b_size,
2288                                    unsigned long b_state)
2289 {
2290         sector_t next;
2291         int nrblocks = mpd->b_size >> mpd->inode->i_blkbits;
2292
2293         /* check if thereserved journal credits might overflow */
2294         if (!(EXT4_I(mpd->inode)->i_flags & EXT4_EXTENTS_FL)) {
2295                 if (nrblocks >= EXT4_MAX_TRANS_DATA) {
2296                         /*
2297                          * With non-extent format we are limited by the journal
2298                          * credit available.  Total credit needed to insert
2299                          * nrblocks contiguous blocks is dependent on the
2300                          * nrblocks.  So limit nrblocks.
2301                          */
2302                         goto flush_it;
2303                 } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
2304                                 EXT4_MAX_TRANS_DATA) {
2305                         /*
2306                          * Adding the new buffer_head would make it cross the
2307                          * allowed limit for which we have journal credit
2308                          * reserved. So limit the new bh->b_size
2309                          */
2310                         b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
2311                                                 mpd->inode->i_blkbits;
2312                         /* we will do mpage_da_submit_io in the next loop */
2313                 }
2314         }
2315         /*
2316          * First block in the extent
2317          */
2318         if (mpd->b_size == 0) {
2319                 mpd->b_blocknr = logical;
2320                 mpd->b_size = b_size;
2321                 mpd->b_state = b_state & BH_FLAGS;
2322                 return;
2323         }
2324
2325         next = mpd->b_blocknr + nrblocks;
2326         /*
2327          * Can we merge the block to our big extent?
2328          */
2329         if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
2330                 mpd->b_size += b_size;
2331                 return;
2332         }
2333
2334 flush_it:
2335         /*
2336          * We couldn't merge the block to our extent, so we
2337          * need to flush current  extent and start new one
2338          */
2339         if (mpage_da_map_blocks(mpd) == 0)
2340                 mpage_da_submit_io(mpd);
2341         mpd->io_done = 1;
2342         return;
2343 }
2344
2345 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
2346 {
2347         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
2348 }
2349
2350 /*
2351  * __mpage_da_writepage - finds extent of pages and blocks
2352  *
2353  * @page: page to consider
2354  * @wbc: not used, we just follow rules
2355  * @data: context
2356  *
2357  * The function finds extents of pages and scan them for all blocks.
2358  */
2359 static int __mpage_da_writepage(struct page *page,
2360                                 struct writeback_control *wbc, void *data)
2361 {
2362         struct mpage_da_data *mpd = data;
2363         struct inode *inode = mpd->inode;
2364         struct buffer_head *bh, *head;
2365         sector_t logical;
2366
2367         if (mpd->io_done) {
2368                 /*
2369                  * Rest of the page in the page_vec
2370                  * redirty then and skip then. We will
2371                  * try to write them again after
2372                  * starting a new transaction
2373                  */
2374                 redirty_page_for_writepage(wbc, page);
2375                 unlock_page(page);
2376                 return MPAGE_DA_EXTENT_TAIL;
2377         }
2378         /*
2379          * Can we merge this page to current extent?
2380          */
2381         if (mpd->next_page != page->index) {
2382                 /*
2383                  * Nope, we can't. So, we map non-allocated blocks
2384                  * and start IO on them using writepage()
2385                  */
2386                 if (mpd->next_page != mpd->first_page) {
2387                         if (mpage_da_map_blocks(mpd) == 0)
2388                                 mpage_da_submit_io(mpd);
2389                         /*
2390                          * skip rest of the page in the page_vec
2391                          */
2392                         mpd->io_done = 1;
2393                         redirty_page_for_writepage(wbc, page);
2394                         unlock_page(page);
2395                         return MPAGE_DA_EXTENT_TAIL;
2396                 }
2397
2398                 /*
2399                  * Start next extent of pages ...
2400                  */
2401                 mpd->first_page = page->index;
2402
2403                 /*
2404                  * ... and blocks
2405                  */
2406                 mpd->b_size = 0;
2407                 mpd->b_state = 0;
2408                 mpd->b_blocknr = 0;
2409         }
2410
2411         mpd->next_page = page->index + 1;
2412         logical = (sector_t) page->index <<
2413                   (PAGE_CACHE_SHIFT - inode->i_blkbits);
2414
2415         if (!page_has_buffers(page)) {
2416                 mpage_add_bh_to_extent(mpd, logical, PAGE_CACHE_SIZE,
2417                                        (1 << BH_Dirty) | (1 << BH_Uptodate));
2418                 if (mpd->io_done)
2419                         return MPAGE_DA_EXTENT_TAIL;
2420         } else {
2421                 /*
2422                  * Page with regular buffer heads, just add all dirty ones
2423                  */
2424                 head = page_buffers(page);
2425                 bh = head;
2426                 do {
2427                         BUG_ON(buffer_locked(bh));
2428                         /*
2429                          * We need to try to allocate
2430                          * unmapped blocks in the same page.
2431                          * Otherwise we won't make progress
2432                          * with the page in ext4_writepage
2433                          */
2434                         if (ext4_bh_delay_or_unwritten(NULL, bh)) {
2435                                 mpage_add_bh_to_extent(mpd, logical,
2436                                                        bh->b_size,
2437                                                        bh->b_state);
2438                                 if (mpd->io_done)
2439                                         return MPAGE_DA_EXTENT_TAIL;
2440                         } else if (buffer_dirty(bh) && (buffer_mapped(bh))) {
2441                                 /*
2442                                  * mapped dirty buffer. We need to update
2443                                  * the b_state because we look at
2444                                  * b_state in mpage_da_map_blocks. We don't
2445                                  * update b_size because if we find an
2446                                  * unmapped buffer_head later we need to
2447                                  * use the b_state flag of that buffer_head.
2448                                  */
2449                                 if (mpd->b_size == 0)
2450                                         mpd->b_state = bh->b_state & BH_FLAGS;
2451                         }
2452                         logical++;
2453                 } while ((bh = bh->b_this_page) != head);
2454         }
2455
2456         return 0;
2457 }
2458
2459 /*
2460  * This is a special get_blocks_t callback which is used by
2461  * ext4_da_write_begin().  It will either return mapped block or
2462  * reserve space for a single block.
2463  *
2464  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
2465  * We also have b_blocknr = -1 and b_bdev initialized properly
2466  *
2467  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
2468  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
2469  * initialized properly.
2470  */
2471 static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
2472                                   struct buffer_head *bh_result, int create)
2473 {
2474         int ret = 0;
2475         sector_t invalid_block = ~((sector_t) 0xffff);
2476
2477         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
2478                 invalid_block = ~0;
2479
2480         BUG_ON(create == 0);
2481         BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
2482
2483         /*
2484          * first, we need to know whether the block is allocated already
2485          * preallocated blocks are unmapped but should treated
2486          * the same as allocated blocks.
2487          */
2488         ret = ext4_get_blocks(NULL, inode, iblock, 1,  bh_result, 0);
2489         if ((ret == 0) && !buffer_delay(bh_result)) {
2490                 /* the block isn't (pre)allocated yet, let's reserve space */
2491                 /*
2492                  * XXX: __block_prepare_write() unmaps passed block,
2493                  * is it OK?
2494                  */
2495                 ret = ext4_da_reserve_space(inode, 1);
2496                 if (ret)
2497                         /* not enough space to reserve */
2498                         return ret;
2499
2500                 map_bh(bh_result, inode->i_sb, invalid_block);
2501                 set_buffer_new(bh_result);
2502                 set_buffer_delay(bh_result);
2503         } else if (ret > 0) {
2504                 bh_result->b_size = (ret << inode->i_blkbits);
2505                 if (buffer_unwritten(bh_result)) {
2506                         /* A delayed write to unwritten bh should
2507                          * be marked new and mapped.  Mapped ensures
2508                          * that we don't do get_block multiple times
2509                          * when we write to the same offset and new
2510                          * ensures that we do proper zero out for
2511                          * partial write.
2512                          */
2513                         set_buffer_new(bh_result);
2514                         set_buffer_mapped(bh_result);
2515                 }
2516                 ret = 0;
2517         }
2518
2519         return ret;
2520 }
2521
2522 /*
2523  * This function is used as a standard get_block_t calback function
2524  * when there is no desire to allocate any blocks.  It is used as a
2525  * callback function for block_prepare_write(), nobh_writepage(), and
2526  * block_write_full_page().  These functions should only try to map a
2527  * single block at a time.
2528  *
2529  * Since this function doesn't do block allocations even if the caller
2530  * requests it by passing in create=1, it is critically important that
2531  * any caller checks to make sure that any buffer heads are returned
2532  * by this function are either all already mapped or marked for
2533  * delayed allocation before calling nobh_writepage() or
2534  * block_write_full_page().  Otherwise, b_blocknr could be left
2535  * unitialized, and the page write functions will be taken by
2536  * surprise.
2537  */
2538 static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
2539                                    struct buffer_head *bh_result, int create)
2540 {
2541         int ret = 0;
2542         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
2543
2544         BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
2545
2546         /*
2547          * we don't want to do block allocation in writepage
2548          * so call get_block_wrap with create = 0
2549          */
2550         ret = ext4_get_blocks(NULL, inode, iblock, max_blocks, bh_result, 0);
2551         if (ret > 0) {
2552                 bh_result->b_size = (ret << inode->i_blkbits);
2553                 ret = 0;
2554         }
2555         return ret;
2556 }
2557
2558 static int bget_one(handle_t *handle, struct buffer_head *bh)
2559 {
2560         get_bh(bh);
2561         return 0;
2562 }
2563
2564 static int bput_one(handle_t *handle, struct buffer_head *bh)
2565 {
2566         put_bh(bh);
2567         return 0;
2568 }
2569
2570 static int __ext4_journalled_writepage(struct page *page,
2571                                        unsigned int len)
2572 {
2573         struct address_space *mapping = page->mapping;
2574         struct inode *inode = mapping->host;
2575         struct buffer_head *page_bufs;
2576         handle_t *handle = NULL;
2577         int ret = 0;
2578         int err;
2579
2580         page_bufs = page_buffers(page);
2581         BUG_ON(!page_bufs);
2582         walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
2583         /* As soon as we unlock the page, it can go away, but we have
2584          * references to buffers so we are safe */
2585         unlock_page(page);
2586
2587         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
2588         if (IS_ERR(handle)) {
2589                 ret = PTR_ERR(handle);
2590                 goto out;
2591         }
2592
2593         ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2594                                 do_journal_get_write_access);
2595
2596         err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2597                                 write_end_fn);
2598         if (ret == 0)
2599                 ret = err;
2600         err = ext4_journal_stop(handle);
2601         if (!ret)
2602                 ret = err;
2603
2604         walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
2605         EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
2606 out:
2607         return ret;
2608 }
2609
2610 /*
2611  * Note that we don't need to start a transaction unless we're journaling data
2612  * because we should have holes filled from ext4_page_mkwrite(). We even don't
2613  * need to file the inode to the transaction's list in ordered mode because if
2614  * we are writing back data added by write(), the inode is already there and if
2615  * we are writing back data modified via mmap(), noone guarantees in which
2616  * transaction the data will hit the disk. In case we are journaling data, we
2617  * cannot start transaction directly because transaction start ranks above page
2618  * lock so we have to do some magic.
2619  *
2620  * This function can get called via...
2621  *   - ext4_da_writepages after taking page lock (have journal handle)
2622  *   - journal_submit_inode_data_buffers (no journal handle)
2623  *   - shrink_page_list via pdflush (no journal handle)
2624  *   - grab_page_cache when doing write_begin (have journal handle)
2625  *
2626  * We don't do any block allocation in this function. If we have page with
2627  * multiple blocks we need to write those buffer_heads that are mapped. This
2628  * is important for mmaped based write. So if we do with blocksize 1K
2629  * truncate(f, 1024);
2630  * a = mmap(f, 0, 4096);
2631  * a[0] = 'a';
2632  * truncate(f, 4096);
2633  * we have in the page first buffer_head mapped via page_mkwrite call back
2634  * but other bufer_heads would be unmapped but dirty(dirty done via the
2635  * do_wp_page). So writepage should write the first block. If we modify
2636  * the mmap area beyond 1024 we will again get a page_fault and the
2637  * page_mkwrite callback will do the block allocation and mark the
2638  * buffer_heads mapped.
2639  *
2640  * We redirty the page if we have any buffer_heads that is either delay or
2641  * unwritten in the page.
2642  *
2643  * We can get recursively called as show below.
2644  *
2645  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2646  *              ext4_writepage()
2647  *
2648  * But since we don't do any block allocation we should not deadlock.
2649  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2650  */
2651 static int ext4_writepage(struct page *page,
2652                           struct writeback_control *wbc)
2653 {
2654         int ret = 0;
2655         loff_t size;
2656         unsigned int len;
2657         struct buffer_head *page_bufs;
2658         struct inode *inode = page->mapping->host;
2659
2660         trace_ext4_writepage(inode, page);
2661         size = i_size_read(inode);
2662         if (page->index == size >> PAGE_CACHE_SHIFT)
2663                 len = size & ~PAGE_CACHE_MASK;
2664         else
2665                 len = PAGE_CACHE_SIZE;
2666
2667         if (page_has_buffers(page)) {
2668                 page_bufs = page_buffers(page);
2669                 if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2670                                         ext4_bh_delay_or_unwritten)) {
2671                         /*
2672                          * We don't want to do  block allocation
2673                          * So redirty the page and return
2674                          * We may reach here when we do a journal commit
2675                          * via journal_submit_inode_data_buffers.
2676                          * If we don't have mapping block we just ignore
2677                          * them. We can also reach here via shrink_page_list
2678                          */
2679                         redirty_page_for_writepage(wbc, page);
2680                         unlock_page(page);
2681                         return 0;
2682                 }
2683         } else {
2684                 /*
2685                  * The test for page_has_buffers() is subtle:
2686                  * We know the page is dirty but it lost buffers. That means
2687                  * that at some moment in time after write_begin()/write_end()
2688                  * has been called all buffers have been clean and thus they
2689                  * must have been written at least once. So they are all
2690                  * mapped and we can happily proceed with mapping them
2691                  * and writing the page.
2692                  *
2693                  * Try to initialize the buffer_heads and check whether
2694                  * all are mapped and non delay. We don't want to
2695                  * do block allocation here.
2696                  */
2697                 ret = block_prepare_write(page, 0, len,
2698                                           noalloc_get_block_write);
2699                 if (!ret) {
2700                         page_bufs = page_buffers(page);
2701                         /* check whether all are mapped and non delay */
2702                         if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2703                                                 ext4_bh_delay_or_unwritten)) {
2704                                 redirty_page_for_writepage(wbc, page);
2705                                 unlock_page(page);
2706                                 return 0;
2707                         }
2708                 } else {
2709                         /*
2710                          * We can't do block allocation here
2711                          * so just redity the page and unlock
2712                          * and return
2713                          */
2714                         redirty_page_for_writepage(wbc, page);
2715                         unlock_page(page);
2716                         return 0;
2717                 }
2718                 /* now mark the buffer_heads as dirty and uptodate */
2719                 block_commit_write(page, 0, len);
2720         }
2721
2722         if (PageChecked(page) && ext4_should_journal_data(inode)) {
2723                 /*
2724                  * It's mmapped pagecache.  Add buffers and journal it.  There
2725                  * doesn't seem much point in redirtying the page here.
2726                  */
2727                 ClearPageChecked(page);
2728                 return __ext4_journalled_writepage(page, len);
2729         }
2730
2731         if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
2732                 ret = nobh_writepage(page, noalloc_get_block_write, wbc);
2733         else
2734                 ret = block_write_full_page(page, noalloc_get_block_write,
2735                                             wbc);
2736
2737         return ret;
2738 }
2739
2740 /*
2741  * This is called via ext4_da_writepages() to
2742  * calulate the total number of credits to reserve to fit
2743  * a single extent allocation into a single transaction,
2744  * ext4_da_writpeages() will loop calling this before
2745  * the block allocation.
2746  */
2747
2748 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2749 {
2750         int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
2751
2752         /*
2753          * With non-extent format the journal credit needed to
2754          * insert nrblocks contiguous block is dependent on
2755          * number of contiguous block. So we will limit
2756          * number of contiguous block to a sane value
2757          */
2758         if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) &&
2759             (max_blocks > EXT4_MAX_TRANS_DATA))
2760                 max_blocks = EXT4_MAX_TRANS_DATA;
2761
2762         return ext4_chunk_trans_blocks(inode, max_blocks);
2763 }
2764
2765 static int ext4_da_writepages(struct address_space *mapping,
2766                               struct writeback_control *wbc)
2767 {
2768         pgoff_t index;
2769         int range_whole = 0;
2770         handle_t *handle = NULL;
2771         struct mpage_da_data mpd;
2772         struct inode *inode = mapping->host;
2773         int no_nrwrite_index_update;
2774         int pages_written = 0;
2775         long pages_skipped;
2776         unsigned int max_pages;
2777         int range_cyclic, cycled = 1, io_done = 0;
2778         int needed_blocks, ret = 0;
2779         long desired_nr_to_write, nr_to_writebump = 0;
2780         loff_t range_start = wbc->range_start;
2781         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2782
2783         trace_ext4_da_writepages(inode, wbc);
2784
2785         /*
2786          * No pages to write? This is mainly a kludge to avoid starting
2787          * a transaction for special inodes like journal inode on last iput()
2788          * because that could violate lock ordering on umount
2789          */
2790         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2791                 return 0;
2792
2793         /*
2794          * If the filesystem has aborted, it is read-only, so return
2795          * right away instead of dumping stack traces later on that
2796          * will obscure the real source of the problem.  We test
2797          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2798          * the latter could be true if the filesystem is mounted
2799          * read-only, and in that case, ext4_da_writepages should
2800          * *never* be called, so if that ever happens, we would want
2801          * the stack trace.
2802          */
2803         if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2804                 return -EROFS;
2805
2806         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2807                 range_whole = 1;
2808
2809         range_cyclic = wbc->range_cyclic;
2810         if (wbc->range_cyclic) {
2811                 index = mapping->writeback_index;
2812                 if (index)
2813                         cycled = 0;
2814                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2815                 wbc->range_end  = LLONG_MAX;
2816                 wbc->range_cyclic = 0;
2817         } else
2818                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2819
2820         /*
2821          * This works around two forms of stupidity.  The first is in
2822          * the writeback code, which caps the maximum number of pages
2823          * written to be 1024 pages.  This is wrong on multiple
2824          * levels; different architectues have a different page size,
2825          * which changes the maximum amount of data which gets
2826          * written.  Secondly, 4 megabytes is way too small.  XFS
2827          * forces this value to be 16 megabytes by multiplying
2828          * nr_to_write parameter by four, and then relies on its
2829          * allocator to allocate larger extents to make them
2830          * contiguous.  Unfortunately this brings us to the second
2831          * stupidity, which is that ext4's mballoc code only allocates
2832          * at most 2048 blocks.  So we force contiguous writes up to
2833          * the number of dirty blocks in the inode, or
2834          * sbi->max_writeback_mb_bump whichever is smaller.
2835          */
2836         max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT);
2837         if (!range_cyclic && range_whole)
2838                 desired_nr_to_write = wbc->nr_to_write * 8;
2839         else
2840                 desired_nr_to_write = ext4_num_dirty_pages(inode, index,
2841                                                            max_pages);
2842         if (desired_nr_to_write > max_pages)
2843                 desired_nr_to_write = max_pages;
2844
2845         if (wbc->nr_to_write < desired_nr_to_write) {
2846                 nr_to_writebump = desired_nr_to_write - wbc->nr_to_write;
2847                 wbc->nr_to_write = desired_nr_to_write;
2848         }
2849
2850         mpd.wbc = wbc;
2851         mpd.inode = mapping->host;
2852
2853         /*
2854          * we don't want write_cache_pages to update
2855          * nr_to_write and writeback_index
2856          */
2857         no_nrwrite_index_update = wbc->no_nrwrite_index_update;
2858         wbc->no_nrwrite_index_update = 1;
2859         pages_skipped = wbc->pages_skipped;
2860
2861 retry:
2862         while (!ret && wbc->nr_to_write > 0) {
2863
2864                 /*
2865                  * we  insert one extent at a time. So we need
2866                  * credit needed for single extent allocation.
2867                  * journalled mode is currently not supported
2868                  * by delalloc
2869                  */
2870                 BUG_ON(ext4_should_journal_data(inode));
2871                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
2872
2873                 /* start a new transaction*/
2874                 handle = ext4_journal_start(inode, needed_blocks);
2875                 if (IS_ERR(handle)) {
2876                         ret = PTR_ERR(handle);
2877                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2878                                "%ld pages, ino %lu; err %d\n", __func__,
2879                                 wbc->nr_to_write, inode->i_ino, ret);
2880                         goto out_writepages;
2881                 }
2882
2883                 /*
2884                  * Now call __mpage_da_writepage to find the next
2885                  * contiguous region of logical blocks that need
2886                  * blocks to be allocated by ext4.  We don't actually
2887                  * submit the blocks for I/O here, even though
2888                  * write_cache_pages thinks it will, and will set the
2889                  * pages as clean for write before calling
2890                  * __mpage_da_writepage().
2891                  */
2892                 mpd.b_size = 0;
2893                 mpd.b_state = 0;
2894                 mpd.b_blocknr = 0;
2895                 mpd.first_page = 0;
2896                 mpd.next_page = 0;
2897                 mpd.io_done = 0;
2898                 mpd.pages_written = 0;
2899                 mpd.retval = 0;
2900                 ret = write_cache_pages(mapping, wbc, __mpage_da_writepage,
2901                                         &mpd);
2902                 /*
2903                  * If we have a contigous extent of pages and we
2904                  * haven't done the I/O yet, map the blocks and submit
2905                  * them for I/O.
2906                  */
2907                 if (!mpd.io_done && mpd.next_page != mpd.first_page) {
2908                         if (mpage_da_map_blocks(&mpd) == 0)
2909                                 mpage_da_submit_io(&mpd);
2910                         mpd.io_done = 1;
2911                         ret = MPAGE_DA_EXTENT_TAIL;
2912                 }
2913                 trace_ext4_da_write_pages(inode, &mpd);
2914                 wbc->nr_to_write -= mpd.pages_written;
2915
2916                 ext4_journal_stop(handle);
2917
2918                 if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
2919                         /* commit the transaction which would
2920                          * free blocks released in the transaction
2921                          * and try again
2922                          */
2923                         jbd2_journal_force_commit_nested(sbi->s_journal);
2924                         wbc->pages_skipped = pages_skipped;
2925                         ret = 0;
2926                 } else if (ret == MPAGE_DA_EXTENT_TAIL) {
2927                         /*
2928                          * got one extent now try with
2929                          * rest of the pages
2930                          */
2931                         pages_written += mpd.pages_written;
2932                         wbc->pages_skipped = pages_skipped;
2933                         ret = 0;
2934                         io_done = 1;
2935                 } else if (wbc->nr_to_write)
2936                         /*
2937                          * There is no more writeout needed
2938                          * or we requested for a noblocking writeout
2939                          * and we found the device congested
2940                          */
2941                         break;
2942         }
2943         if (!io_done && !cycled) {
2944                 cycled = 1;
2945                 index = 0;
2946                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2947                 wbc->range_end  = mapping->writeback_index - 1;
2948                 goto retry;
2949         }
2950         if (pages_skipped != wbc->pages_skipped)
2951                 ext4_msg(inode->i_sb, KERN_CRIT,
2952                          "This should not happen leaving %s "
2953                          "with nr_to_write = %ld ret = %d\n",
2954                          __func__, wbc->nr_to_write, ret);
2955
2956         /* Update index */
2957         index += pages_written;
2958         wbc->range_cyclic = range_cyclic;
2959         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2960                 /*
2961                  * set the writeback_index so that range_cyclic
2962                  * mode will write it back later
2963                  */
2964                 mapping->writeback_index = index;
2965
2966 out_writepages:
2967         if (!no_nrwrite_index_update)
2968                 wbc->no_nrwrite_index_update = 0;
2969         if (wbc->nr_to_write > nr_to_writebump)
2970                 wbc->nr_to_write -= nr_to_writebump;
2971         wbc->range_start = range_start;
2972         trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
2973         return ret;
2974 }
2975
2976 #define FALL_BACK_TO_NONDELALLOC 1
2977 static int ext4_nonda_switch(struct super_block *sb)
2978 {
2979         s64 free_blocks, dirty_blocks;
2980         struct ext4_sb_info *sbi = EXT4_SB(sb);
2981
2982         /*
2983          * switch to non delalloc mode if we are running low
2984          * on free block. The free block accounting via percpu
2985          * counters can get slightly wrong with percpu_counter_batch getting
2986          * accumulated on each CPU without updating global counters
2987          * Delalloc need an accurate free block accounting. So switch
2988          * to non delalloc when we are near to error range.
2989          */
2990         free_blocks  = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
2991         dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyblocks_counter);
2992         if (2 * free_blocks < 3 * dirty_blocks ||
2993                 free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
2994                 /*
2995                  * free block count is less that 150% of dirty blocks
2996                  * or free blocks is less that watermark
2997                  */
2998                 return 1;
2999         }
3000         return 0;
3001 }
3002
3003 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
3004                                loff_t pos, unsigned len, unsigned flags,
3005                                struct page **pagep, void **fsdata)
3006 {
3007         int ret, retries = 0;
3008         struct page *page;
3009         pgoff_t index;
3010         unsigned from, to;
3011         struct inode *inode = mapping->host;
3012         handle_t *handle;
3013
3014         index = pos >> PAGE_CACHE_SHIFT;
3015         from = pos & (PAGE_CACHE_SIZE - 1);
3016         to = from + len;
3017
3018         if (ext4_nonda_switch(inode->i_sb)) {
3019                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
3020                 return ext4_write_begin(file, mapping, pos,
3021                                         len, flags, pagep, fsdata);
3022         }
3023         *fsdata = (void *)0;
3024         trace_ext4_da_write_begin(inode, pos, len, flags);
3025 retry:
3026         /*
3027          * With delayed allocation, we don't log the i_disksize update
3028          * if there is delayed block allocation. But we still need
3029          * to journalling the i_disksize update if writes to the end
3030          * of file which has an already mapped buffer.
3031          */
3032         handle = ext4_journal_start(inode, 1);
3033         if (IS_ERR(handle)) {
3034                 ret = PTR_ERR(handle);
3035                 goto out;
3036         }
3037         /* We cannot recurse into the filesystem as the transaction is already
3038          * started */
3039         flags |= AOP_FLAG_NOFS;
3040
3041         page = grab_cache_page_write_begin(mapping, index, flags);
3042         if (!page) {
3043                 ext4_journal_stop(handle);
3044                 ret = -ENOMEM;
3045                 goto out;
3046         }
3047         *pagep = page;
3048
3049         ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
3050                                 ext4_da_get_block_prep);
3051         if (ret < 0) {
3052                 unlock_page(page);
3053                 ext4_journal_stop(handle);
3054                 page_cache_release(page);
3055                 /*
3056                  * block_write_begin may have instantiated a few blocks
3057                  * outside i_size.  Trim these off again. Don't need
3058                  * i_size_read because we hold i_mutex.
3059                  */
3060                 if (pos + len > inode->i_size)
3061                         ext4_truncate_failed_write(inode);
3062         }
3063
3064         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
3065                 goto retry;
3066 out:
3067         return ret;
3068 }
3069
3070 /*
3071  * Check if we should update i_disksize
3072  * when write to the end of file but not require block allocation
3073  */
3074 static int ext4_da_should_update_i_disksize(struct page *page,
3075                                             unsigned long offset)
3076 {
3077         struct buffer_head *bh;
3078         struct inode *inode = page->mapping->host;
3079         unsigned int idx;
3080         int i;
3081
3082         bh = page_buffers(page);
3083         idx = offset >> inode->i_blkbits;
3084
3085         for (i = 0; i < idx; i++)
3086                 bh = bh->b_this_page;
3087
3088         if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
3089                 return 0;
3090         return 1;
3091 }
3092
3093 static int ext4_da_write_end(struct file *file,
3094                              struct address_space *mapping,
3095                              loff_t pos, unsigned len, unsigned copied,
3096                              struct page *page, void *fsdata)
3097 {
3098         struct inode *inode = mapping->host;
3099         int ret = 0, ret2;
3100         handle_t *handle = ext4_journal_current_handle();
3101         loff_t new_i_size;
3102         unsigned long start, end;
3103         int write_mode = (int)(unsigned long)fsdata;
3104
3105         if (write_mode == FALL_BACK_TO_NONDELALLOC) {
3106                 if (ext4_should_order_data(inode)) {
3107                         return ext4_ordered_write_end(file, mapping, pos,
3108                                         len, copied, page, fsdata);
3109                 } else if (ext4_should_writeback_data(inode)) {
3110                         return ext4_writeback_write_end(file, mapping, pos,
3111                                         len, copied, page, fsdata);
3112                 } else {
3113                         BUG();
3114                 }
3115         }
3116
3117         trace_ext4_da_write_end(inode, pos, len, copied);
3118         start = pos & (PAGE_CACHE_SIZE - 1);
3119         end = start + copied - 1;
3120
3121         /*
3122          * generic_write_end() will run mark_inode_dirty() if i_size
3123          * changes.  So let's piggyback the i_disksize mark_inode_dirty
3124          * into that.
3125          */
3126
3127         new_i_size = pos + copied;
3128         if (new_i_size > EXT4_I(inode)->i_disksize) {
3129                 if (ext4_da_should_update_i_disksize(page, end)) {
3130                         down_write(&EXT4_I(inode)->i_data_sem);
3131                         if (new_i_size > EXT4_I(inode)->i_disksize) {
3132                                 /*
3133                                  * Updating i_disksize when extending file
3134                                  * without needing block allocation
3135                                  */
3136                                 if (ext4_should_order_data(inode))
3137                                         ret = ext4_jbd2_file_inode(handle,
3138                                                                    inode);
3139
3140                                 EXT4_I(inode)->i_disksize = new_i_size;
3141                         }
3142                         up_write(&EXT4_I(inode)->i_data_sem);
3143                         /* We need to mark inode dirty even if
3144                          * new_i_size is less that inode->i_size
3145                          * bu greater than i_disksize.(hint delalloc)
3146                          */
3147                         ext4_mark_inode_dirty(handle, inode);
3148                 }
3149         }
3150         ret2 = generic_write_end(file, mapping, pos, len, copied,
3151                                                         page, fsdata);
3152         copied = ret2;
3153         if (ret2 < 0)
3154                 ret = ret2;
3155         ret2 = ext4_journal_stop(handle);
3156         if (!ret)
3157                 ret = ret2;
3158
3159         return ret ? ret : copied;
3160 }
3161
3162 static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
3163 {
3164         /*
3165          * Drop reserved blocks
3166          */
3167         BUG_ON(!PageLocked(page));
3168         if (!page_has_buffers(page))
3169                 goto out;
3170
3171         ext4_da_page_release_reservation(page, offset);
3172
3173 out:
3174         ext4_invalidatepage(page, offset);
3175
3176         return;
3177 }
3178
3179 /*
3180  * Force all delayed allocation blocks to be allocated for a given inode.
3181  */
3182 int ext4_alloc_da_blocks(struct inode *inode)
3183 {
3184         trace_ext4_alloc_da_blocks(inode);
3185
3186         if (!EXT4_I(inode)->i_reserved_data_blocks &&
3187             !EXT4_I(inode)->i_reserved_meta_blocks)
3188                 return 0;
3189
3190         /*
3191          * We do something simple for now.  The filemap_flush() will
3192          * also start triggering a write of the data blocks, which is
3193          * not strictly speaking necessary (and for users of
3194          * laptop_mode, not even desirable).  However, to do otherwise
3195          * would require replicating code paths in:
3196          *
3197          * ext4_da_writepages() ->
3198          *    write_cache_pages() ---> (via passed in callback function)
3199          *        __mpage_da_writepage() -->
3200          *           mpage_add_bh_to_extent()
3201          *           mpage_da_map_blocks()
3202          *
3203          * The problem is that write_cache_pages(), located in
3204          * mm/page-writeback.c, marks pages clean in preparation for
3205          * doing I/O, which is not desirable if we're not planning on
3206          * doing I/O at all.
3207          *
3208          * We could call write_cache_pages(), and then redirty all of
3209          * the pages by calling redirty_page_for_writeback() but that
3210          * would be ugly in the extreme.  So instead we would need to
3211          * replicate parts of the code in the above functions,
3212          * simplifying them becuase we wouldn't actually intend to
3213          * write out the pages, but rather only collect contiguous
3214          * logical block extents, call the multi-block allocator, and
3215          * then update the buffer heads with the block allocations.
3216          *
3217          * For now, though, we'll cheat by calling filemap_flush(),
3218          * which will map the blocks, and start the I/O, but not
3219          * actually wait for the I/O to complete.
3220          */
3221         return filemap_flush(inode->i_mapping);
3222 }
3223
3224 /*
3225  * bmap() is special.  It gets used by applications such as lilo and by
3226  * the swapper to find the on-disk block of a specific piece of data.
3227  *
3228  * Naturally, this is dangerous if the block concerned is still in the
3229  * journal.  If somebody makes a swapfile on an ext4 data-journaling
3230  * filesystem and enables swap, then they may get a nasty shock when the
3231  * data getting swapped to that swapfile suddenly gets overwritten by
3232  * the original zero's written out previously to the journal and
3233  * awaiting writeback in the kernel's buffer cache.
3234  *
3235  * So, if we see any bmap calls here on a modified, data-journaled file,
3236  * take extra steps to flush any blocks which might be in the cache.
3237  */
3238 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
3239 {
3240         struct inode *inode = mapping->host;
3241         journal_t *journal;
3242         int err;
3243
3244         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
3245                         test_opt(inode->i_sb, DELALLOC)) {
3246                 /*
3247                  * With delalloc we want to sync the file
3248                  * so that we can make sure we allocate
3249                  * blocks for file
3250                  */
3251                 filemap_write_and_wait(mapping);
3252         }
3253
3254         if (EXT4_JOURNAL(inode) && EXT4_I(inode)->i_state & EXT4_STATE_JDATA) {
3255                 /*
3256                  * This is a REALLY heavyweight approach, but the use of
3257                  * bmap on dirty files is expected to be extremely rare:
3258                  * only if we run lilo or swapon on a freshly made file
3259                  * do we expect this to happen.
3260                  *
3261                  * (bmap requires CAP_SYS_RAWIO so this does not
3262                  * represent an unprivileged user DOS attack --- we'd be
3263                  * in trouble if mortal users could trigger this path at
3264                  * will.)
3265                  *
3266                  * NB. EXT4_STATE_JDATA is not set on files other than
3267                  * regular files.  If somebody wants to bmap a directory
3268                  * or symlink and gets confused because the buffer
3269                  * hasn't yet been flushed to disk, they deserve
3270                  * everything they get.
3271                  */
3272
3273                 EXT4_I(inode)->i_state &= ~EXT4_STATE_JDATA;
3274                 journal = EXT4_JOURNAL(inode);
3275                 jbd2_journal_lock_updates(journal);
3276                 err = jbd2_journal_flush(journal);
3277                 jbd2_journal_unlock_updates(journal);
3278
3279                 if (err)
3280                         return 0;
3281         }
3282
3283         return generic_block_bmap(mapping, block, ext4_get_block);
3284 }
3285
3286 static int ext4_readpage(struct file *file, struct page *page)
3287 {
3288         return mpage_readpage(page, ext4_get_block);
3289 }
3290
3291 static int
3292 ext4_readpages(struct file *file, struct address_space *mapping,
3293                 struct list_head *pages, unsigned nr_pages)
3294 {
3295         return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
3296 }
3297
3298 static void ext4_invalidatepage(struct page *page, unsigned long offset)
3299 {
3300         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3301
3302         /*
3303          * If it's a full truncate we just forget about the pending dirtying
3304          */
3305         if (offset == 0)
3306                 ClearPageChecked(page);
3307
3308         if (journal)
3309                 jbd2_journal_invalidatepage(journal, page, offset);
3310         else
3311                 block_invalidatepage(page, offset);
3312 }
3313
3314 static int ext4_releasepage(struct page *page, gfp_t wait)
3315 {
3316         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3317
3318         WARN_ON(PageChecked(page));
3319         if (!page_has_buffers(page))
3320                 return 0;
3321         if (journal)
3322                 return jbd2_journal_try_to_free_buffers(journal, page, wait);
3323         else
3324                 return try_to_free_buffers(page);
3325 }
3326
3327 /*
3328  * O_DIRECT for ext3 (or indirect map) based files
3329  *
3330  * If the O_DIRECT write will extend the file then add this inode to the
3331  * orphan list.  So recovery will truncate it back to the original size
3332  * if the machine crashes during the write.
3333  *
3334  * If the O_DIRECT write is intantiating holes inside i_size and the machine
3335  * crashes then stale disk data _may_ be exposed inside the file. But current
3336  * VFS code falls back into buffered path in that case so we are safe.
3337  */
3338 static ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
3339                               const struct iovec *iov, loff_t offset,
3340                               unsigned long nr_segs)
3341 {
3342         struct file *file = iocb->ki_filp;
3343         struct inode *inode = file->f_mapping->host;
3344         struct ext4_inode_info *ei = EXT4_I(inode);
3345         handle_t *handle;
3346         ssize_t ret;
3347         int orphan = 0;
3348         size_t count = iov_length(iov, nr_segs);
3349         int retries = 0;
3350
3351         if (rw == WRITE) {
3352                 loff_t final_size = offset + count;
3353
3354                 if (final_size > inode->i_size) {
3355                         /* Credits for sb + inode write */
3356                         handle = ext4_journal_start(inode, 2);
3357                         if (IS_ERR(handle)) {
3358                                 ret = PTR_ERR(handle);
3359                                 goto out;
3360                         }
3361                         ret = ext4_orphan_add(handle, inode);
3362                         if (ret) {
3363                                 ext4_journal_stop(handle);
3364                                 goto out;
3365                         }
3366                         orphan = 1;
3367                         ei->i_disksize = inode->i_size;
3368                         ext4_journal_stop(handle);
3369                 }
3370         }
3371
3372 retry:
3373         ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
3374                                  offset, nr_segs,
3375                                  ext4_get_block, NULL);
3376         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
3377                 goto retry;
3378
3379         if (orphan) {
3380                 int err;
3381
3382                 /* Credits for sb + inode write */
3383                 handle = ext4_journal_start(inode, 2);
3384                 if (IS_ERR(handle)) {
3385                         /* This is really bad luck. We've written the data
3386                          * but cannot extend i_size. Bail out and pretend
3387                          * the write failed... */
3388                         ret = PTR_ERR(handle);
3389                         goto out;
3390                 }
3391                 if (inode->i_nlink)
3392                         ext4_orphan_del(handle, inode);
3393                 if (ret > 0) {
3394                         loff_t end = offset + ret;
3395                         if (end > inode->i_size) {
3396                                 ei->i_disksize = end;
3397                                 i_size_write(inode, end);
3398                                 /*
3399                                  * We're going to return a positive `ret'
3400                                  * here due to non-zero-length I/O, so there's
3401                                  * no way of reporting error returns from
3402                                  * ext4_mark_inode_dirty() to userspace.  So
3403                                  * ignore it.
3404                                  */
3405                                 ext4_mark_inode_dirty(handle, inode);
3406                         }
3407                 }
3408                 err = ext4_journal_stop(handle);
3409                 if (ret == 0)
3410                         ret = err;
3411         }
3412 out:
3413         return ret;
3414 }
3415
3416 static int ext4_get_block_dio_write(struct inode *inode, sector_t iblock,
3417                    struct buffer_head *bh_result, int create)
3418 {
3419         handle_t *handle = NULL;
3420         int ret = 0;
3421         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
3422         int dio_credits;
3423
3424         ext4_debug("ext4_get_block_dio_write: inode %lu, create flag %d\n",
3425                    inode->i_ino, create);
3426         /*
3427          * DIO VFS code passes create = 0 flag for write to
3428          * the middle of file. It does this to avoid block
3429          * allocation for holes, to prevent expose stale data
3430          * out when there is parallel buffered read (which does
3431          * not hold the i_mutex lock) while direct IO write has
3432          * not completed. DIO request on holes finally falls back
3433          * to buffered IO for this reason.
3434          *
3435          * For ext4 extent based file, since we support fallocate,
3436          * new allocated extent as uninitialized, for holes, we
3437          * could fallocate blocks for holes, thus parallel
3438          * buffered IO read will zero out the page when read on
3439          * a hole while parallel DIO write to the hole has not completed.
3440          *
3441          * when we come here, we know it's a direct IO write to
3442          * to the middle of file (<i_size)
3443          * so it's safe to override the create flag from VFS.
3444          */
3445         create = EXT4_GET_BLOCKS_DIO_CREATE_EXT;
3446
3447         if (max_blocks > DIO_MAX_BLOCKS)
3448                 max_blocks = DIO_MAX_BLOCKS;
3449         dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
3450         handle = ext4_journal_start(inode, dio_credits);
3451         if (IS_ERR(handle)) {
3452                 ret = PTR_ERR(handle);
3453                 goto out;
3454         }
3455         ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
3456                               create);
3457         if (ret > 0) {
3458                 bh_result->b_size = (ret << inode->i_blkbits);
3459                 ret = 0;
3460         }
3461         ext4_journal_stop(handle);
3462 out:
3463         return ret;
3464 }
3465
3466 static void ext4_free_io_end(ext4_io_end_t *io)
3467 {
3468         BUG_ON(!io);
3469         iput(io->inode);
3470         kfree(io);
3471 }
3472 static void dump_aio_dio_list(struct inode * inode)
3473 {
3474 #ifdef  EXT4_DEBUG
3475         struct list_head *cur, *before, *after;
3476         ext4_io_end_t *io, *io0, *io1;
3477
3478         if (list_empty(&EXT4_I(inode)->i_aio_dio_complete_list)){
3479                 ext4_debug("inode %lu aio dio list is empty\n", inode->i_ino);
3480                 return;
3481         }
3482
3483         ext4_debug("Dump inode %lu aio_dio_completed_IO list \n", inode->i_ino);
3484         list_for_each_entry(io, &EXT4_I(inode)->i_aio_dio_complete_list, list){
3485                 cur = &io->list;
3486                 before = cur->prev;
3487                 io0 = container_of(before, ext4_io_end_t, list);
3488                 after = cur->next;
3489                 io1 = container_of(after, ext4_io_end_t, list);
3490
3491                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
3492                             io, inode->i_ino, io0, io1);
3493         }
3494 #endif
3495 }
3496
3497 /*
3498  * check a range of space and convert unwritten extents to written.
3499  */
3500 static int ext4_end_aio_dio_nolock(ext4_io_end_t *io)
3501 {
3502         struct inode *inode = io->inode;
3503         loff_t offset = io->offset;
3504         size_t size = io->size;
3505         int ret = 0;
3506
3507         ext4_debug("end_aio_dio_onlock: io 0x%p from inode %lu,list->next 0x%p,"
3508                    "list->prev 0x%p\n",
3509                    io, inode->i_ino, io->list.next, io->list.prev);
3510
3511         if (list_empty(&io->list))
3512                 return ret;
3513
3514         if (io->flag != DIO_AIO_UNWRITTEN)
3515                 return ret;
3516
3517         if (offset + size <= i_size_read(inode))
3518                 ret = ext4_convert_unwritten_extents(inode, offset, size);
3519
3520         if (ret < 0) {
3521                 printk(KERN_EMERG "%s: failed to convert unwritten"
3522                         "extents to written extents, error is %d"
3523                         " io is still on inode %lu aio dio list\n",
3524                        __func__, ret, inode->i_ino);
3525                 return ret;
3526         }
3527
3528         /* clear the DIO AIO unwritten flag */
3529         io->flag = 0;
3530         return ret;
3531 }
3532 /*
3533  * work on completed aio dio IO, to convert unwritten extents to extents
3534  */
3535 static void ext4_end_aio_dio_work(struct work_struct *work)
3536 {
3537         ext4_io_end_t *io  = container_of(work, ext4_io_end_t, work);
3538         struct inode *inode = io->inode;
3539         int ret = 0;
3540
3541         mutex_lock(&inode->i_mutex);
3542         ret = ext4_end_aio_dio_nolock(io);
3543         if (ret >= 0) {
3544                 if (!list_empty(&io->list))
3545                         list_del_init(&io->list);
3546                 ext4_free_io_end(io);
3547         }
3548         mutex_unlock(&inode->i_mutex);
3549 }
3550 /*
3551  * This function is called from ext4_sync_file().
3552  *
3553  * When AIO DIO IO is completed, the work to convert unwritten
3554  * extents to written is queued on workqueue but may not get immediately
3555  * scheduled. When fsync is called, we need to ensure the
3556  * conversion is complete before fsync returns.
3557  * The inode keeps track of a list of completed AIO from DIO path
3558  * that might needs to do the conversion. This function walks through
3559  * the list and convert the related unwritten extents to written.
3560  */
3561 int flush_aio_dio_completed_IO(struct inode *inode)
3562 {
3563         ext4_io_end_t *io;
3564         int ret = 0;
3565         int ret2 = 0;
3566
3567         if (list_empty(&EXT4_I(inode)->i_aio_dio_complete_list))
3568                 return ret;
3569
3570         dump_aio_dio_list(inode);
3571         while (!list_empty(&EXT4_I(inode)->i_aio_dio_complete_list)){
3572                 io = list_entry(EXT4_I(inode)->i_aio_dio_complete_list.next,
3573                                 ext4_io_end_t, list);
3574                 /*
3575                  * Calling ext4_end_aio_dio_nolock() to convert completed
3576                  * IO to written.
3577                  *
3578                  * When ext4_sync_file() is called, run_queue() may already
3579                  * about to flush the work corresponding to this io structure.
3580                  * It will be upset if it founds the io structure related
3581                  * to the work-to-be schedule is freed.
3582                  *
3583                  * Thus we need to keep the io structure still valid here after
3584                  * convertion finished. The io structure has a flag to
3585                  * avoid double converting from both fsync and background work
3586                  * queue work.
3587                  */
3588                 ret = ext4_end_aio_dio_nolock(io);
3589                 if (ret < 0)
3590                         ret2 = ret;
3591                 else
3592                         list_del_init(&io->list);
3593         }
3594         return (ret2 < 0) ? ret2 : 0;
3595 }
3596
3597 static ext4_io_end_t *ext4_init_io_end (struct inode *inode)
3598 {
3599         ext4_io_end_t *io = NULL;
3600
3601         io = kmalloc(sizeof(*io), GFP_NOFS);
3602
3603         if (io) {
3604                 igrab(inode);
3605                 io->inode = inode;
3606                 io->flag = 0;
3607                 io->offset = 0;
3608                 io->size = 0;
3609                 io->error = 0;
3610                 INIT_WORK(&io->work, ext4_end_aio_dio_work);
3611                 INIT_LIST_HEAD(&io->list);
3612         }
3613
3614         return io;
3615 }
3616
3617 static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
3618                             ssize_t size, void *private)
3619 {
3620         ext4_io_end_t *io_end = iocb->private;
3621         struct workqueue_struct *wq;
3622
3623         /* if not async direct IO or dio with 0 bytes write, just return */
3624         if (!io_end || !size)
3625                 return;
3626
3627         ext_debug("ext4_end_io_dio(): io_end 0x%p"
3628                   "for inode %lu, iocb 0x%p, offset %llu, size %llu\n",
3629                   iocb->private, io_end->inode->i_ino, iocb, offset,
3630                   size);
3631
3632         /* if not aio dio with unwritten extents, just free io and return */
3633         if (io_end->flag != DIO_AIO_UNWRITTEN){
3634                 ext4_free_io_end(io_end);
3635                 iocb->private = NULL;
3636                 return;
3637         }
3638
3639         io_end->offset = offset;
3640         io_end->size = size;
3641         wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
3642
3643         /* queue the work to convert unwritten extents to written */
3644         queue_work(wq, &io_end->work);
3645
3646         /* Add the io_end to per-inode completed aio dio list*/
3647         list_add_tail(&io_end->list,
3648                  &EXT4_I(io_end->inode)->i_aio_dio_complete_list);
3649         iocb->private = NULL;
3650 }
3651 /*
3652  * For ext4 extent files, ext4 will do direct-io write to holes,
3653  * preallocated extents, and those write extend the file, no need to
3654  * fall back to buffered IO.
3655  *
3656  * For holes, we fallocate those blocks, mark them as unintialized
3657  * If those blocks were preallocated, we mark sure they are splited, but
3658  * still keep the range to write as unintialized.
3659  *
3660  * The unwrritten extents will be converted to written when DIO is completed.
3661  * For async direct IO, since the IO may still pending when return, we
3662  * set up an end_io call back function, which will do the convertion
3663  * when async direct IO completed.
3664  *
3665  * If the O_DIRECT write will extend the file then add this inode to the
3666  * orphan list.  So recovery will truncate it back to the original size
3667  * if the machine crashes during the write.
3668  *
3669  */
3670 static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
3671                               const struct iovec *iov, loff_t offset,
3672                               unsigned long nr_segs)
3673 {
3674         struct file *file = iocb->ki_filp;
3675         struct inode *inode = file->f_mapping->host;
3676         ssize_t ret;
3677         size_t count = iov_length(iov, nr_segs);
3678
3679         loff_t final_size = offset + count;
3680         if (rw == WRITE && final_size <= inode->i_size) {
3681                 /*
3682                  * We could direct write to holes and fallocate.
3683                  *
3684                  * Allocated blocks to fill the hole are marked as uninitialized
3685                  * to prevent paralel buffered read to expose the stale data
3686                  * before DIO complete the data IO.
3687                  *
3688                  * As to previously fallocated extents, ext4 get_block
3689                  * will just simply mark the buffer mapped but still
3690                  * keep the extents uninitialized.
3691                  *
3692                  * for non AIO case, we will convert those unwritten extents
3693                  * to written after return back from blockdev_direct_IO.
3694                  *
3695                  * for async DIO, the conversion needs to be defered when
3696                  * the IO is completed. The ext4 end_io callback function
3697                  * will be called to take care of the conversion work.
3698                  * Here for async case, we allocate an io_end structure to
3699                  * hook to the iocb.
3700                  */
3701                 iocb->private = NULL;
3702                 EXT4_I(inode)->cur_aio_dio = NULL;
3703                 if (!is_sync_kiocb(iocb)) {
3704                         iocb->private = ext4_init_io_end(inode);
3705                         if (!iocb->private)
3706                                 return -ENOMEM;
3707                         /*
3708                          * we save the io structure for current async
3709                          * direct IO, so that later ext4_get_blocks()
3710                          * could flag the io structure whether there
3711                          * is a unwritten extents needs to be converted
3712                          * when IO is completed.
3713                          */
3714                         EXT4_I(inode)->cur_aio_dio = iocb->private;
3715                 }
3716
3717                 ret = blockdev_direct_IO(rw, iocb, inode,
3718                                          inode->i_sb->s_bdev, iov,
3719                                          offset, nr_segs,
3720                                          ext4_get_block_dio_write,
3721                                          ext4_end_io_dio);
3722                 if (iocb->private)
3723                         EXT4_I(inode)->cur_aio_dio = NULL;
3724                 /*
3725                  * The io_end structure takes a reference to the inode,
3726                  * that structure needs to be destroyed and the
3727                  * reference to the inode need to be dropped, when IO is
3728                  * complete, even with 0 byte write, or failed.
3729                  *
3730                  * In the successful AIO DIO case, the io_end structure will be
3731                  * desctroyed and the reference to the inode will be dropped
3732                  * after the end_io call back function is called.
3733                  *
3734                  * In the case there is 0 byte write, or error case, since
3735                  * VFS direct IO won't invoke the end_io call back function,
3736                  * we need to free the end_io structure here.
3737                  */
3738                 if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
3739                         ext4_free_io_end(iocb->private);
3740                         iocb->private = NULL;
3741                 } else if (ret > 0 && (EXT4_I(inode)->i_state &
3742                                        EXT4_STATE_DIO_UNWRITTEN)) {
3743                         int err;
3744                         /*
3745                          * for non AIO case, since the IO is already
3746                          * completed, we could do the convertion right here
3747                          */
3748                         err = ext4_convert_unwritten_extents(inode,
3749                                                              offset, ret);
3750                         if (err < 0)
3751                                 ret = err;
3752                         EXT4_I(inode)->i_state &= ~EXT4_STATE_DIO_UNWRITTEN;
3753                 }
3754                 return ret;
3755         }
3756
3757         /* for write the the end of file case, we fall back to old way */
3758         return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
3759 }
3760
3761 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
3762                               const struct iovec *iov, loff_t offset,
3763                               unsigned long nr_segs)
3764 {
3765         struct file *file = iocb->ki_filp;
3766         struct inode *inode = file->f_mapping->host;
3767
3768         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
3769                 return ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
3770
3771         return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
3772 }
3773
3774 /*
3775  * Pages can be marked dirty completely asynchronously from ext4's journalling
3776  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
3777  * much here because ->set_page_dirty is called under VFS locks.  The page is
3778  * not necessarily locked.
3779  *
3780  * We cannot just dirty the page and leave attached buffers clean, because the
3781  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
3782  * or jbddirty because all the journalling code will explode.
3783  *
3784  * So what we do is to mark the page "pending dirty" and next time writepage
3785  * is called, propagate that into the buffers appropriately.
3786  */
3787 static int ext4_journalled_set_page_dirty(struct page *page)
3788 {
3789         SetPageChecked(page);
3790         return __set_page_dirty_nobuffers(page);
3791 }
3792
3793 static const struct address_space_operations ext4_ordered_aops = {
3794         .readpage               = ext4_readpage,
3795         .readpages              = ext4_readpages,
3796         .writepage              = ext4_writepage,
3797         .sync_page              = block_sync_page,
3798         .write_begin            = ext4_write_begin,
3799         .write_end              = ext4_ordered_write_end,
3800         .bmap                   = ext4_bmap,
3801         .invalidatepage         = ext4_invalidatepage,
3802         .releasepage            = ext4_releasepage,
3803         .direct_IO              = ext4_direct_IO,
3804         .migratepage            = buffer_migrate_page,
3805         .is_partially_uptodate  = block_is_partially_uptodate,
3806         .error_remove_page      = generic_error_remove_page,
3807 };
3808
3809 static const struct address_space_operations ext4_writeback_aops = {
3810         .readpage               = ext4_readpage,
3811         .readpages              = ext4_readpages,
3812         .writepage              = ext4_writepage,
3813         .sync_page              = block_sync_page,
3814         .write_begin            = ext4_write_begin,
3815         .write_end              = ext4_writeback_write_end,
3816         .bmap                   = ext4_bmap,
3817         .invalidatepage         = ext4_invalidatepage,
3818         .releasepage            = ext4_releasepage,
3819         .direct_IO              = ext4_direct_IO,
3820         .migratepage            = buffer_migrate_page,
3821         .is_partially_uptodate  = block_is_partially_uptodate,
3822         .error_remove_page      = generic_error_remove_page,
3823 };
3824
3825 static const struct address_space_operations ext4_journalled_aops = {
3826         .readpage               = ext4_readpage,
3827         .readpages              = ext4_readpages,
3828         .writepage              = ext4_writepage,
3829         .sync_page              = block_sync_page,
3830         .write_begin            = ext4_write_begin,
3831         .write_end              = ext4_journalled_write_end,
3832         .set_page_dirty         = ext4_journalled_set_page_dirty,
3833         .bmap                   = ext4_bmap,
3834         .invalidatepage         = ext4_invalidatepage,
3835         .releasepage            = ext4_releasepage,
3836         .is_partially_uptodate  = block_is_partially_uptodate,
3837         .error_remove_page      = generic_error_remove_page,
3838 };
3839
3840 static const struct address_space_operations ext4_da_aops = {
3841         .readpage               = ext4_readpage,
3842         .readpages              = ext4_readpages,
3843         .writepage              = ext4_writepage,
3844         .writepages             = ext4_da_writepages,
3845         .sync_page              = block_sync_page,
3846         .write_begin            = ext4_da_write_begin,
3847         .write_end              = ext4_da_write_end,
3848         .bmap                   = ext4_bmap,
3849         .invalidatepage         = ext4_da_invalidatepage,
3850         .releasepage            = ext4_releasepage,
3851         .direct_IO              = ext4_direct_IO,
3852         .migratepage            = buffer_migrate_page,
3853         .is_partially_uptodate  = block_is_partially_uptodate,
3854         .error_remove_page      = generic_error_remove_page,
3855 };
3856
3857 void ext4_set_aops(struct inode *inode)
3858 {
3859         if (ext4_should_order_data(inode) &&
3860                 test_opt(inode->i_sb, DELALLOC))
3861                 inode->i_mapping->a_ops = &ext4_da_aops;
3862         else if (ext4_should_order_data(inode))
3863                 inode->i_mapping->a_ops = &ext4_ordered_aops;
3864         else if (ext4_should_writeback_data(inode) &&
3865                  test_opt(inode->i_sb, DELALLOC))
3866                 inode->i_mapping->a_ops = &ext4_da_aops;
3867         else if (ext4_should_writeback_data(inode))
3868                 inode->i_mapping->a_ops = &ext4_writeback_aops;
3869         else
3870                 inode->i_mapping->a_ops = &ext4_journalled_aops;
3871 }
3872
3873 /*
3874  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
3875  * up to the end of the block which corresponds to `from'.
3876  * This required during truncate. We need to physically zero the tail end
3877  * of that block so it doesn't yield old data if the file is later grown.
3878  */
3879 int ext4_block_truncate_page(handle_t *handle,
3880                 struct address_space *mapping, loff_t from)
3881 {
3882         ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
3883         unsigned offset = from & (PAGE_CACHE_SIZE-1);
3884         unsigned blocksize, length, pos;
3885         ext4_lblk_t iblock;
3886         struct inode *inode = mapping->host;
3887         struct buffer_head *bh;
3888         struct page *page;
3889         int err = 0;
3890
3891         page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
3892                                    mapping_gfp_mask(mapping) & ~__GFP_FS);
3893         if (!page)
3894                 return -EINVAL;
3895
3896         blocksize = inode->i_sb->s_blocksize;
3897         length = blocksize - (offset & (blocksize - 1));
3898         iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
3899
3900         /*
3901          * For "nobh" option,  we can only work if we don't need to
3902          * read-in the page - otherwise we create buffers to do the IO.
3903          */
3904         if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
3905              ext4_should_writeback_data(inode) && PageUptodate(page)) {
3906                 zero_user(page, offset, length);
3907                 set_page_dirty(page);
3908                 goto unlock;
3909         }
3910
3911         if (!page_has_buffers(page))
3912                 create_empty_buffers(page, blocksize, 0);
3913
3914         /* Find the buffer that contains "offset" */
3915         bh = page_buffers(page);
3916         pos = blocksize;
3917         while (offset >= pos) {
3918                 bh = bh->b_this_page;
3919                 iblock++;
3920                 pos += blocksize;
3921         }
3922
3923         err = 0;
3924         if (buffer_freed(bh)) {
3925                 BUFFER_TRACE(bh, "freed: skip");
3926                 goto unlock;
3927         }
3928
3929         if (!buffer_mapped(bh)) {
3930                 BUFFER_TRACE(bh, "unmapped");
3931                 ext4_get_block(inode, iblock, bh, 0);
3932                 /* unmapped? It's a hole - nothing to do */
3933                 if (!buffer_mapped(bh)) {
3934                         BUFFER_TRACE(bh, "still unmapped");
3935                         goto unlock;
3936                 }
3937         }
3938
3939         /* Ok, it's mapped. Make sure it's up-to-date */
3940         if (PageUptodate(page))
3941                 set_buffer_uptodate(bh);
3942
3943         if (!buffer_uptodate(bh)) {
3944                 err = -EIO;
3945                 ll_rw_block(READ, 1, &bh);
3946                 wait_on_buffer(bh);
3947                 /* Uhhuh. Read error. Complain and punt. */
3948                 if (!buffer_uptodate(bh))
3949                         goto unlock;
3950         }
3951
3952         if (ext4_should_journal_data(inode)) {
3953                 BUFFER_TRACE(bh, "get write access");
3954                 err = ext4_journal_get_write_access(handle, bh);
3955                 if (err)
3956                         goto unlock;
3957         }
3958
3959         zero_user(page, offset, length);
3960
3961         BUFFER_TRACE(bh, "zeroed end of block");
3962
3963         err = 0;
3964         if (ext4_should_journal_data(inode)) {
3965                 err = ext4_handle_dirty_metadata(handle, inode, bh);
3966         } else {
3967                 if (ext4_should_order_data(inode))
3968                         err = ext4_jbd2_file_inode(handle, inode);
3969                 mark_buffer_dirty(bh);
3970         }
3971
3972 unlock:
3973         unlock_page(page);
3974         page_cache_release(page);
3975         return err;
3976 }
3977
3978 /*
3979  * Probably it should be a library function... search for first non-zero word
3980  * or memcmp with zero_page, whatever is better for particular architecture.
3981  * Linus?
3982  */
3983 static inline int all_zeroes(__le32 *p, __le32 *q)
3984 {
3985         while (p < q)
3986                 if (*p++)
3987                         return 0;
3988         return 1;
3989 }
3990
3991 /**
3992  *      ext4_find_shared - find the indirect blocks for partial truncation.
3993  *      @inode:   inode in question
3994  *      @depth:   depth of the affected branch
3995  *      @offsets: offsets of pointers in that branch (see ext4_block_to_path)
3996  *      @chain:   place to store the pointers to partial indirect blocks
3997  *      @top:     place to the (detached) top of branch
3998  *
3999  *      This is a helper function used by ext4_truncate().
4000  *
4001  *      When we do truncate() we may have to clean the ends of several
4002  *      indirect blocks but leave the blocks themselves alive. Block is
4003  *      partially truncated if some data below the new i_size is refered
4004  *      from it (and it is on the path to the first completely truncated
4005  *      data block, indeed).  We have to free the top of that path along
4006  *      with everything to the right of the path. Since no allocation
4007  *      past the truncation point is possible until ext4_truncate()
4008  *      finishes, we may safely do the latter, but top of branch may
4009  *      require special attention - pageout below the truncation point
4010  *      might try to populate it.
4011  *
4012  *      We atomically detach the top of branch from the tree, store the
4013  *      block number of its root in *@top, pointers to buffer_heads of
4014  *      partially truncated blocks - in @chain[].bh and pointers to
4015  *      their last elements that should not be removed - in
4016  *      @chain[].p. Return value is the pointer to last filled element
4017  *      of @chain.
4018  *
4019  *      The work left to caller to do the actual freeing of subtrees:
4020  *              a) free the subtree starting from *@top
4021  *              b) free the subtrees whose roots are stored in
4022  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
4023  *              c) free the subtrees growing from the inode past the @chain[0].
4024  *                      (no partially truncated stuff there).  */
4025
4026 static Indirect *ext4_find_shared(struct inode *inode, int depth,
4027                                   ext4_lblk_t offsets[4], Indirect chain[4],
4028                                   __le32 *top)
4029 {
4030         Indirect *partial, *p;
4031         int k, err;
4032
4033         *top = 0;
4034         /* Make k index the deepest non-null offest + 1 */
4035         for (k = depth; k > 1 && !offsets[k-1]; k--)
4036                 ;
4037         partial = ext4_get_branch(inode, k, offsets, chain, &err);
4038         /* Writer: pointers */
4039         if (!partial)
4040                 partial = chain + k-1;
4041         /*
4042          * If the branch acquired continuation since we've looked at it -
4043          * fine, it should all survive and (new) top doesn't belong to us.
4044          */
4045         if (!partial->key && *partial->p)
4046                 /* Writer: end */
4047                 goto no_top;
4048         for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
4049                 ;
4050         /*
4051          * OK, we've found the last block that must survive. The rest of our
4052          * branch should be detached before unlocking. However, if that rest
4053          * of branch is all ours and does not grow immediately from the inode
4054          * it's easier to cheat and just decrement partial->p.
4055          */
4056         if (p == chain + k - 1 && p > chain) {
4057                 p->p--;
4058         } else {
4059                 *top = *p->p;
4060                 /* Nope, don't do this in ext4.  Must leave the tree intact */
4061 #if 0
4062                 *p->p = 0;
4063 #endif
4064         }
4065         /* Writer: end */
4066
4067         while (partial > p) {
4068                 brelse(partial->bh);
4069                 partial--;
4070         }
4071 no_top:
4072         return partial;
4073 }
4074
4075 /*
4076  * Zero a number of block pointers in either an inode or an indirect block.
4077  * If we restart the transaction we must again get write access to the
4078  * indirect block for further modification.
4079  *
4080  * We release `count' blocks on disk, but (last - first) may be greater
4081  * than `count' because there can be holes in there.
4082  */
4083 static void ext4_clear_blocks(handle_t *handle, struct inode *inode,
4084                               struct buffer_head *bh,
4085                               ext4_fsblk_t block_to_free,
4086                               unsigned long count, __le32 *first,
4087                               __le32 *last)
4088 {
4089         __le32 *p;
4090         int     flags = EXT4_FREE_BLOCKS_FORGET;
4091
4092         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
4093                 flags |= EXT4_FREE_BLOCKS_METADATA;
4094
4095         if (try_to_extend_transaction(handle, inode)) {
4096                 if (bh) {
4097                         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
4098                         ext4_handle_dirty_metadata(handle, inode, bh);
4099                 }
4100                 ext4_mark_inode_dirty(handle, inode);
4101                 ext4_truncate_restart_trans(handle, inode,
4102                                             blocks_for_truncate(inode));
4103                 if (bh) {
4104                         BUFFER_TRACE(bh, "retaking write access");
4105                         ext4_journal_get_write_access(handle, bh);
4106                 }
4107         }
4108
4109         for (p = first; p < last; p++)
4110                 *p = 0;
4111
4112         ext4_free_blocks(handle, inode, 0, block_to_free, count, flags);
4113 }
4114
4115 /**
4116  * ext4_free_data - free a list of data blocks
4117  * @handle:     handle for this transaction
4118  * @inode:      inode we are dealing with
4119  * @this_bh:    indirect buffer_head which contains *@first and *@last
4120  * @first:      array of block numbers
4121  * @last:       points immediately past the end of array
4122  *
4123  * We are freeing all blocks refered from that array (numbers are stored as
4124  * little-endian 32-bit) and updating @inode->i_blocks appropriately.
4125  *
4126  * We accumulate contiguous runs of blocks to free.  Conveniently, if these
4127  * blocks are contiguous then releasing them at one time will only affect one
4128  * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
4129  * actually use a lot of journal space.
4130  *
4131  * @this_bh will be %NULL if @first and @last point into the inode's direct
4132  * block pointers.
4133  */
4134 static void ext4_free_data(handle_t *handle, struct inode *inode,
4135                            struct buffer_head *this_bh,
4136                            __le32 *first, __le32 *last)
4137 {
4138         ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
4139         unsigned long count = 0;            /* Number of blocks in the run */
4140         __le32 *block_to_free_p = NULL;     /* Pointer into inode/ind
4141                                                corresponding to
4142                                                block_to_free */
4143         ext4_fsblk_t nr;                    /* Current block # */
4144         __le32 *p;                          /* Pointer into inode/ind
4145                                                for current block */
4146         int err;
4147
4148         if (this_bh) {                          /* For indirect block */
4149                 BUFFER_TRACE(this_bh, "get_write_access");
4150                 err = ext4_journal_get_write_access(handle, this_bh);
4151                 /* Important: if we can't update the indirect pointers
4152                  * to the blocks, we can't free them. */
4153                 if (err)
4154                         return;
4155         }
4156
4157         for (p = first; p < last; p++) {
4158                 nr = le32_to_cpu(*p);
4159                 if (nr) {
4160                         /* accumulate blocks to free if they're contiguous */
4161                         if (count == 0) {
4162                                 block_to_free = nr;
4163                                 block_to_free_p = p;
4164                                 count = 1;
4165                         } else if (nr == block_to_free + count) {
4166                                 count++;
4167                         } else {
4168                                 ext4_clear_blocks(handle, inode, this_bh,
4169                                                   block_to_free,
4170                                                   count, block_to_free_p, p);
4171                                 block_to_free = nr;
4172                                 block_to_free_p = p;
4173                                 count = 1;
4174                         }
4175                 }
4176         }
4177
4178         if (count > 0)
4179                 ext4_clear_blocks(handle, inode, this_bh, block_to_free,
4180                                   count, block_to_free_p, p);
4181
4182         if (this_bh) {
4183                 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
4184
4185                 /*
4186                  * The buffer head should have an attached journal head at this
4187                  * point. However, if the data is corrupted and an indirect
4188                  * block pointed to itself, it would have been detached when
4189                  * the block was cleared. Check for this instead of OOPSing.
4190                  */
4191                 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
4192                         ext4_handle_dirty_metadata(handle, inode, this_bh);
4193                 else
4194                         ext4_error(inode->i_sb, __func__,
4195                                    "circular indirect block detected, "
4196                                    "inode=%lu, block=%llu",
4197                                    inode->i_ino,
4198                                    (unsigned long long) this_bh->b_blocknr);
4199         }
4200 }
4201
4202 /**
4203  *      ext4_free_branches - free an array of branches
4204  *      @handle: JBD handle for this transaction
4205  *      @inode: inode we are dealing with
4206  *      @parent_bh: the buffer_head which contains *@first and *@last
4207  *      @first: array of block numbers
4208  *      @last:  pointer immediately past the end of array
4209  *      @depth: depth of the branches to free
4210  *
4211  *      We are freeing all blocks refered from these branches (numbers are
4212  *      stored as little-endian 32-bit) and updating @inode->i_blocks
4213  *      appropriately.
4214  */
4215 static void ext4_free_branches(handle_t *handle, struct inode *inode,
4216                                struct buffer_head *parent_bh,
4217                                __le32 *first, __le32 *last, int depth)
4218 {
4219         ext4_fsblk_t nr;
4220         __le32 *p;
4221
4222         if (ext4_handle_is_aborted(handle))
4223                 return;
4224
4225         if (depth--) {
4226                 struct buffer_head *bh;
4227                 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
4228                 p = last;
4229                 while (--p >= first) {
4230                         nr = le32_to_cpu(*p);
4231                         if (!nr)
4232                                 continue;               /* A hole */
4233
4234                         /* Go read the buffer for the next level down */
4235                         bh = sb_bread(inode->i_sb, nr);
4236
4237                         /*
4238                          * A read failure? Report error and clear slot
4239                          * (should be rare).
4240                          */
4241                         if (!bh) {
4242                                 ext4_error(inode->i_sb, "ext4_free_branches",
4243                                            "Read failure, inode=%lu, block=%llu",
4244                                            inode->i_ino, nr);
4245                                 continue;
4246                         }
4247
4248                         /* This zaps the entire block.  Bottom up. */
4249                         BUFFER_TRACE(bh, "free child branches");
4250                         ext4_free_branches(handle, inode, bh,
4251                                         (__le32 *) bh->b_data,
4252                                         (__le32 *) bh->b_data + addr_per_block,
4253                                         depth);
4254
4255                         /*
4256                          * We've probably journalled the indirect block several
4257                          * times during the truncate.  But it's no longer
4258                          * needed and we now drop it from the transaction via
4259                          * jbd2_journal_revoke().
4260                          *
4261                          * That's easy if it's exclusively part of this
4262                          * transaction.  But if it's part of the committing
4263                          * transaction then jbd2_journal_forget() will simply
4264                          * brelse() it.  That means that if the underlying
4265                          * block is reallocated in ext4_get_block(),
4266                          * unmap_underlying_metadata() will find this block
4267                          * and will try to get rid of it.  damn, damn.
4268                          *
4269                          * If this block has already been committed to the
4270                          * journal, a revoke record will be written.  And
4271                          * revoke records must be emitted *before* clearing
4272                          * this block's bit in the bitmaps.
4273                          */
4274                         ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
4275
4276                         /*
4277                          * Everything below this this pointer has been
4278                          * released.  Now let this top-of-subtree go.
4279                          *
4280                          * We want the freeing of this indirect block to be
4281                          * atomic in the journal with the updating of the
4282                          * bitmap block which owns it.  So make some room in
4283                          * the journal.
4284                          *
4285                          * We zero the parent pointer *after* freeing its
4286                          * pointee in the bitmaps, so if extend_transaction()
4287                          * for some reason fails to put the bitmap changes and
4288                          * the release into the same transaction, recovery
4289                          * will merely complain about releasing a free block,
4290                          * rather than leaking blocks.
4291                          */
4292                         if (ext4_handle_is_aborted(handle))
4293                                 return;
4294                         if (try_to_extend_transaction(handle, inode)) {
4295                                 ext4_mark_inode_dirty(handle, inode);
4296                                 ext4_truncate_restart_trans(handle, inode,
4297                                             blocks_for_truncate(inode));
4298                         }
4299
4300                         ext4_free_blocks(handle, inode, 0, nr, 1,
4301                                          EXT4_FREE_BLOCKS_METADATA);
4302
4303                         if (parent_bh) {
4304                                 /*
4305                                  * The block which we have just freed is
4306                                  * pointed to by an indirect block: journal it
4307                                  */
4308                                 BUFFER_TRACE(parent_bh, "get_write_access");
4309                                 if (!ext4_journal_get_write_access(handle,
4310                                                                    parent_bh)){
4311                                         *p = 0;
4312                                         BUFFER_TRACE(parent_bh,
4313                                         "call ext4_handle_dirty_metadata");
4314                                         ext4_handle_dirty_metadata(handle,
4315                                                                    inode,
4316                                                                    parent_bh);
4317                                 }
4318                         }
4319                 }
4320         } else {
4321                 /* We have reached the bottom of the tree. */
4322                 BUFFER_TRACE(parent_bh, "free data blocks");
4323                 ext4_free_data(handle, inode, parent_bh, first, last);
4324         }
4325 }
4326
4327 int ext4_can_truncate(struct inode *inode)
4328 {
4329         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
4330                 return 0;
4331         if (S_ISREG(inode->i_mode))
4332                 return 1;
4333         if (S_ISDIR(inode->i_mode))
4334                 return 1;
4335         if (S_ISLNK(inode->i_mode))
4336                 return !ext4_inode_is_fast_symlink(inode);
4337         return 0;
4338 }
4339
4340 /*
4341  * ext4_truncate()
4342  *
4343  * We block out ext4_get_block() block instantiations across the entire
4344  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
4345  * simultaneously on behalf of the same inode.
4346  *
4347  * As we work through the truncate and commmit bits of it to the journal there
4348  * is one core, guiding principle: the file's tree must always be consistent on
4349  * disk.  We must be able to restart the truncate after a crash.
4350  *
4351  * The file's tree may be transiently inconsistent in memory (although it
4352  * probably isn't), but whenever we close off and commit a journal transaction,
4353  * the contents of (the filesystem + the journal) must be consistent and
4354  * restartable.  It's pretty simple, really: bottom up, right to left (although
4355  * left-to-right works OK too).
4356  *
4357  * Note that at recovery time, journal replay occurs *before* the restart of
4358  * truncate against the orphan inode list.
4359  *
4360  * The committed inode has the new, desired i_size (which is the same as
4361  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
4362  * that this inode's truncate did not complete and it will again call
4363  * ext4_truncate() to have another go.  So there will be instantiated blocks
4364  * to the right of the truncation point in a crashed ext4 filesystem.  But
4365  * that's fine - as long as they are linked from the inode, the post-crash
4366  * ext4_truncate() run will find them and release them.
4367  */
4368 void ext4_truncate(struct inode *inode)
4369 {
4370         handle_t *handle;
4371         struct ext4_inode_info *ei = EXT4_I(inode);
4372         __le32 *i_data = ei->i_data;
4373         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
4374         struct address_space *mapping = inode->i_mapping;
4375         ext4_lblk_t offsets[4];
4376         Indirect chain[4];
4377         Indirect *partial;
4378         __le32 nr = 0;
4379         int n;
4380         ext4_lblk_t last_block;
4381         unsigned blocksize = inode->i_sb->s_blocksize;
4382
4383         if (!ext4_can_truncate(inode))
4384                 return;
4385
4386         if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
4387                 ei->i_state |= EXT4_STATE_DA_ALLOC_CLOSE;
4388
4389         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
4390                 ext4_ext_truncate(inode);
4391                 return;
4392         }
4393
4394         handle = start_transaction(inode);
4395         if (IS_ERR(handle))
4396                 return;         /* AKPM: return what? */
4397
4398         last_block = (inode->i_size + blocksize-1)
4399                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
4400
4401         if (inode->i_size & (blocksize - 1))
4402                 if (ext4_block_truncate_page(handle, mapping, inode->i_size))
4403                         goto out_stop;
4404
4405         n = ext4_block_to_path(inode, last_block, offsets, NULL);
4406         if (n == 0)
4407                 goto out_stop;  /* error */
4408
4409         /*
4410          * OK.  This truncate is going to happen.  We add the inode to the
4411          * orphan list, so that if this truncate spans multiple transactions,
4412          * and we crash, we will resume the truncate when the filesystem
4413          * recovers.  It also marks the inode dirty, to catch the new size.
4414          *
4415          * Implication: the file must always be in a sane, consistent
4416          * truncatable state while each transaction commits.
4417          */
4418         if (ext4_orphan_add(handle, inode))
4419                 goto out_stop;
4420
4421         /*
4422          * From here we block out all ext4_get_block() callers who want to
4423          * modify the block allocation tree.
4424          */
4425         down_write(&ei->i_data_sem);
4426
4427         ext4_discard_preallocations(inode);
4428
4429         /*
4430          * The orphan list entry will now protect us from any crash which
4431          * occurs before the truncate completes, so it is now safe to propagate
4432          * the new, shorter inode size (held for now in i_size) into the
4433          * on-disk inode. We do this via i_disksize, which is the value which
4434          * ext4 *really* writes onto the disk inode.
4435          */
4436         ei->i_disksize = inode->i_size;
4437
4438         if (n == 1) {           /* direct blocks */
4439                 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
4440                                i_data + EXT4_NDIR_BLOCKS);
4441                 goto do_indirects;
4442         }
4443
4444         partial = ext4_find_shared(inode, n, offsets, chain, &nr);
4445         /* Kill the top of shared branch (not detached) */
4446         if (nr) {
4447                 if (partial == chain) {
4448                         /* Shared branch grows from the inode */
4449                         ext4_free_branches(handle, inode, NULL,
4450                                            &nr, &nr+1, (chain+n-1) - partial);
4451                         *partial->p = 0;
4452                         /*
4453                          * We mark the inode dirty prior to restart,
4454                          * and prior to stop.  No need for it here.
4455                          */
4456                 } else {
4457                         /* Shared branch grows from an indirect block */
4458                         BUFFER_TRACE(partial->bh, "get_write_access");
4459                         ext4_free_branches(handle, inode, partial->bh,
4460                                         partial->p,
4461                                         partial->p+1, (chain+n-1) - partial);
4462                 }
4463         }
4464         /* Clear the ends of indirect blocks on the shared branch */
4465         while (partial > chain) {
4466                 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
4467                                    (__le32*)partial->bh->b_data+addr_per_block,
4468                                    (chain+n-1) - partial);
4469                 BUFFER_TRACE(partial->bh, "call brelse");
4470                 brelse(partial->bh);
4471                 partial--;
4472         }
4473 do_indirects:
4474         /* Kill the remaining (whole) subtrees */
4475         switch (offsets[0]) {
4476         default:
4477                 nr = i_data[EXT4_IND_BLOCK];
4478                 if (nr) {
4479                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
4480                         i_data[EXT4_IND_BLOCK] = 0;
4481                 }
4482         case EXT4_IND_BLOCK:
4483                 nr = i_data[EXT4_DIND_BLOCK];
4484                 if (nr) {
4485                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
4486                         i_data[EXT4_DIND_BLOCK] = 0;
4487                 }
4488         case EXT4_DIND_BLOCK:
4489                 nr = i_data[EXT4_TIND_BLOCK];
4490                 if (nr) {
4491                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
4492                         i_data[EXT4_TIND_BLOCK] = 0;
4493                 }
4494         case EXT4_TIND_BLOCK:
4495                 ;
4496         }
4497
4498         up_write(&ei->i_data_sem);
4499         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
4500         ext4_mark_inode_dirty(handle, inode);
4501
4502         /*
4503          * In a multi-transaction truncate, we only make the final transaction
4504          * synchronous
4505          */
4506         if (IS_SYNC(inode))
4507                 ext4_handle_sync(handle);
4508 out_stop:
4509         /*
4510          * If this was a simple ftruncate(), and the file will remain alive
4511          * then we need to clear up the orphan record which we created above.
4512          * However, if this was a real unlink then we were called by
4513          * ext4_delete_inode(), and we allow that function to clean up the
4514          * orphan info for us.
4515          */
4516         if (inode->i_nlink)
4517                 ext4_orphan_del(handle, inode);
4518
4519         ext4_journal_stop(handle);
4520 }
4521
4522 /*
4523  * ext4_get_inode_loc returns with an extra refcount against the inode's
4524  * underlying buffer_head on success. If 'in_mem' is true, we have all
4525  * data in memory that is needed to recreate the on-disk version of this
4526  * inode.
4527  */
4528 static int __ext4_get_inode_loc(struct inode *inode,
4529                                 struct ext4_iloc *iloc, int in_mem)
4530 {
4531         struct ext4_group_desc  *gdp;
4532         struct buffer_head      *bh;
4533         struct super_block      *sb = inode->i_sb;
4534         ext4_fsblk_t            block;
4535         int                     inodes_per_block, inode_offset;
4536
4537         iloc->bh = NULL;
4538         if (!ext4_valid_inum(sb, inode->i_ino))
4539                 return -EIO;
4540
4541         iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
4542         gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
4543         if (!gdp)
4544                 return -EIO;
4545
4546         /*
4547          * Figure out the offset within the block group inode table
4548          */
4549         inodes_per_block = (EXT4_BLOCK_SIZE(sb) / EXT4_INODE_SIZE(sb));
4550         inode_offset = ((inode->i_ino - 1) %
4551                         EXT4_INODES_PER_GROUP(sb));
4552         block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
4553         iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
4554
4555         bh = sb_getblk(sb, block);
4556         if (!bh) {
4557                 ext4_error(sb, "ext4_get_inode_loc", "unable to read "
4558                            "inode block - inode=%lu, block=%llu",
4559                            inode->i_ino, block);
4560                 return -EIO;
4561         }
4562         if (!buffer_uptodate(bh)) {
4563                 lock_buffer(bh);
4564
4565                 /*
4566                  * If the buffer has the write error flag, we have failed
4567                  * to write out another inode in the same block.  In this
4568                  * case, we don't have to read the block because we may
4569                  * read the old inode data successfully.
4570                  */
4571                 if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
4572                         set_buffer_uptodate(bh);
4573
4574                 if (buffer_uptodate(bh)) {
4575                         /* someone brought it uptodate while we waited */
4576                         unlock_buffer(bh);
4577                         goto has_buffer;
4578                 }
4579
4580                 /*
4581                  * If we have all information of the inode in memory and this
4582                  * is the only valid inode in the block, we need not read the
4583                  * block.
4584                  */
4585                 if (in_mem) {
4586                         struct buffer_head *bitmap_bh;
4587                         int i, start;
4588
4589                         start = inode_offset & ~(inodes_per_block - 1);
4590
4591                         /* Is the inode bitmap in cache? */
4592                         bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
4593                         if (!bitmap_bh)
4594                                 goto make_io;
4595
4596                         /*
4597                          * If the inode bitmap isn't in cache then the
4598                          * optimisation may end up performing two reads instead
4599                          * of one, so skip it.
4600                          */
4601                         if (!buffer_uptodate(bitmap_bh)) {
4602                                 brelse(bitmap_bh);
4603                                 goto make_io;
4604                         }
4605                         for (i = start; i < start + inodes_per_block; i++) {
4606                                 if (i == inode_offset)
4607                                         continue;
4608                                 if (ext4_test_bit(i, bitmap_bh->b_data))
4609                                         break;
4610                         }
4611                         brelse(bitmap_bh);
4612                         if (i == start + inodes_per_block) {
4613                                 /* all other inodes are free, so skip I/O */
4614                                 memset(bh->b_data, 0, bh->b_size);
4615                                 set_buffer_uptodate(bh);
4616                                 unlock_buffer(bh);
4617                                 goto has_buffer;
4618                         }
4619                 }
4620
4621 make_io:
4622                 /*
4623                  * If we need to do any I/O, try to pre-readahead extra
4624                  * blocks from the inode table.
4625                  */
4626                 if (EXT4_SB(sb)->s_inode_readahead_blks) {
4627                         ext4_fsblk_t b, end, table;
4628                         unsigned num;
4629
4630                         table = ext4_inode_table(sb, gdp);
4631                         /* s_inode_readahead_blks is always a power of 2 */
4632                         b = block & ~(EXT4_SB(sb)->s_inode_readahead_blks-1);
4633                         if (table > b)
4634                                 b = table;
4635                         end = b + EXT4_SB(sb)->s_inode_readahead_blks;
4636                         num = EXT4_INODES_PER_GROUP(sb);
4637                         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
4638                                        EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
4639                                 num -= ext4_itable_unused_count(sb, gdp);
4640                         table += num / inodes_per_block;
4641                         if (end > table)
4642                                 end = table;
4643                         while (b <= end)
4644                                 sb_breadahead(sb, b++);
4645                 }
4646
4647                 /*
4648                  * There are other valid inodes in the buffer, this inode
4649                  * has in-inode xattrs, or we don't have this inode in memory.
4650                  * Read the block from disk.
4651                  */
4652                 get_bh(bh);
4653                 bh->b_end_io = end_buffer_read_sync;
4654                 submit_bh(READ_META, bh);
4655                 wait_on_buffer(bh);
4656                 if (!buffer_uptodate(bh)) {
4657                         ext4_error(sb, __func__,
4658                                    "unable to read inode block - inode=%lu, "
4659                                    "block=%llu", inode->i_ino, block);
4660                         brelse(bh);
4661                         return -EIO;
4662                 }
4663         }
4664 has_buffer:
4665         iloc->bh = bh;
4666         return 0;
4667 }
4668
4669 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
4670 {
4671         /* We have all inode data except xattrs in memory here. */
4672         return __ext4_get_inode_loc(inode, iloc,
4673                 !(EXT4_I(inode)->i_state & EXT4_STATE_XATTR));
4674 }
4675
4676 void ext4_set_inode_flags(struct inode *inode)
4677 {
4678         unsigned int flags = EXT4_I(inode)->i_flags;
4679
4680         inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
4681         if (flags & EXT4_SYNC_FL)
4682                 inode->i_flags |= S_SYNC;
4683         if (flags & EXT4_APPEND_FL)
4684                 inode->i_flags |= S_APPEND;
4685         if (flags & EXT4_IMMUTABLE_FL)
4686                 inode->i_flags |= S_IMMUTABLE;
4687         if (flags & EXT4_NOATIME_FL)
4688                 inode->i_flags |= S_NOATIME;
4689         if (flags & EXT4_DIRSYNC_FL)
4690                 inode->i_flags |= S_DIRSYNC;
4691 }
4692
4693 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
4694 void ext4_get_inode_flags(struct ext4_inode_info *ei)
4695 {
4696         unsigned int flags = ei->vfs_inode.i_flags;
4697
4698         ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
4699                         EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL);
4700         if (flags & S_SYNC)
4701                 ei->i_flags |= EXT4_SYNC_FL;
4702         if (flags & S_APPEND)
4703                 ei->i_flags |= EXT4_APPEND_FL;
4704         if (flags & S_IMMUTABLE)
4705                 ei->i_flags |= EXT4_IMMUTABLE_FL;
4706         if (flags & S_NOATIME)
4707                 ei->i_flags |= EXT4_NOATIME_FL;
4708         if (flags & S_DIRSYNC)
4709                 ei->i_flags |= EXT4_DIRSYNC_FL;
4710 }
4711
4712 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
4713                                   struct ext4_inode_info *ei)
4714 {
4715         blkcnt_t i_blocks ;
4716         struct inode *inode = &(ei->vfs_inode);
4717         struct super_block *sb = inode->i_sb;
4718
4719         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
4720                                 EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
4721                 /* we are using combined 48 bit field */
4722                 i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
4723                                         le32_to_cpu(raw_inode->i_blocks_lo);
4724                 if (ei->i_flags & EXT4_HUGE_FILE_FL) {
4725                         /* i_blocks represent file system block size */
4726                         return i_blocks  << (inode->i_blkbits - 9);
4727                 } else {
4728                         return i_blocks;
4729                 }
4730         } else {
4731                 return le32_to_cpu(raw_inode->i_blocks_lo);
4732         }
4733 }
4734
4735 struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
4736 {
4737         struct ext4_iloc iloc;
4738         struct ext4_inode *raw_inode;
4739         struct ext4_inode_info *ei;
4740         struct inode *inode;
4741         long ret;
4742         int block;
4743
4744         inode = iget_locked(sb, ino);
4745         if (!inode)
4746                 return ERR_PTR(-ENOMEM);
4747         if (!(inode->i_state & I_NEW))
4748                 return inode;
4749
4750         ei = EXT4_I(inode);
4751         iloc.bh = 0;
4752
4753         ret = __ext4_get_inode_loc(inode, &iloc, 0);
4754         if (ret < 0)
4755                 goto bad_inode;
4756         raw_inode = ext4_raw_inode(&iloc);
4757         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
4758         inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
4759         inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
4760         if (!(test_opt(inode->i_sb, NO_UID32))) {
4761                 inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
4762                 inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
4763         }
4764         inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
4765
4766         ei->i_state = 0;
4767         ei->i_dir_start_lookup = 0;
4768         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
4769         /* We now have enough fields to check if the inode was active or not.
4770          * This is needed because nfsd might try to access dead inodes
4771          * the test is that same one that e2fsck uses
4772          * NeilBrown 1999oct15
4773          */
4774         if (inode->i_nlink == 0) {
4775                 if (inode->i_mode == 0 ||
4776                     !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
4777                         /* this inode is deleted */
4778                         ret = -ESTALE;
4779                         goto bad_inode;
4780                 }
4781                 /* The only unlinked inodes we let through here have
4782                  * valid i_mode and are being read by the orphan
4783                  * recovery code: that's fine, we're about to complete
4784                  * the process of deleting those. */
4785         }
4786         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
4787         inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
4788         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
4789         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT))
4790                 ei->i_file_acl |=
4791                         ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
4792         inode->i_size = ext4_isize(raw_inode);
4793         ei->i_disksize = inode->i_size;
4794         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
4795         ei->i_block_group = iloc.block_group;
4796         ei->i_last_alloc_group = ~0;
4797         /*
4798          * NOTE! The in-memory inode i_data array is in little-endian order
4799          * even on big-endian machines: we do NOT byteswap the block numbers!
4800          */
4801         for (block = 0; block < EXT4_N_BLOCKS; block++)
4802                 ei->i_data[block] = raw_inode->i_block[block];
4803         INIT_LIST_HEAD(&ei->i_orphan);
4804
4805         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4806                 ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
4807                 if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
4808                     EXT4_INODE_SIZE(inode->i_sb)) {
4809                         ret = -EIO;
4810                         goto bad_inode;
4811                 }
4812                 if (ei->i_extra_isize == 0) {
4813                         /* The extra space is currently unused. Use it. */
4814                         ei->i_extra_isize = sizeof(struct ext4_inode) -
4815                                             EXT4_GOOD_OLD_INODE_SIZE;
4816                 } else {
4817                         __le32 *magic = (void *)raw_inode +
4818                                         EXT4_GOOD_OLD_INODE_SIZE +
4819                                         ei->i_extra_isize;
4820                         if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
4821                                 ei->i_state |= EXT4_STATE_XATTR;
4822                 }
4823         } else
4824                 ei->i_extra_isize = 0;
4825
4826         EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
4827         EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
4828         EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
4829         EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
4830
4831         inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
4832         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4833                 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
4834                         inode->i_version |=
4835                         (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
4836         }
4837
4838         ret = 0;
4839         if (ei->i_file_acl &&
4840             !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
4841                 ext4_error(sb, __func__,
4842                            "bad extended attribute block %llu in inode #%lu",
4843                            ei->i_file_acl, inode->i_ino);
4844                 ret = -EIO;
4845                 goto bad_inode;
4846         } else if (ei->i_flags & EXT4_EXTENTS_FL) {
4847                 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4848                     (S_ISLNK(inode->i_mode) &&
4849                      !ext4_inode_is_fast_symlink(inode)))
4850                         /* Validate extent which is part of inode */
4851                         ret = ext4_ext_check_inode(inode);
4852         } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4853                    (S_ISLNK(inode->i_mode) &&
4854                     !ext4_inode_is_fast_symlink(inode))) {
4855                 /* Validate block references which are part of inode */
4856                 ret = ext4_check_inode_blockref(inode);
4857         }
4858         if (ret)
4859                 goto bad_inode;
4860
4861         if (S_ISREG(inode->i_mode)) {
4862                 inode->i_op = &ext4_file_inode_operations;
4863                 inode->i_fop = &ext4_file_operations;
4864                 ext4_set_aops(inode);
4865         } else if (S_ISDIR(inode->i_mode)) {
4866                 inode->i_op = &ext4_dir_inode_operations;
4867                 inode->i_fop = &ext4_dir_operations;
4868         } else if (S_ISLNK(inode->i_mode)) {
4869                 if (ext4_inode_is_fast_symlink(inode)) {
4870                         inode->i_op = &ext4_fast_symlink_inode_operations;
4871                         nd_terminate_link(ei->i_data, inode->i_size,
4872                                 sizeof(ei->i_data) - 1);
4873                 } else {
4874                         inode->i_op = &ext4_symlink_inode_operations;
4875                         ext4_set_aops(inode);
4876                 }
4877         } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
4878               S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
4879                 inode->i_op = &ext4_special_inode_operations;
4880                 if (raw_inode->i_block[0])
4881                         init_special_inode(inode, inode->i_mode,
4882                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
4883                 else
4884                         init_special_inode(inode, inode->i_mode,
4885                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
4886         } else {
4887                 ret = -EIO;
4888                 ext4_error(inode->i_sb, __func__,
4889                            "bogus i_mode (%o) for inode=%lu",
4890                            inode->i_mode, inode->i_ino);
4891                 goto bad_inode;
4892         }
4893         brelse(iloc.bh);
4894         ext4_set_inode_flags(inode);
4895         unlock_new_inode(inode);
4896         return inode;
4897
4898 bad_inode:
4899         brelse(iloc.bh);
4900         iget_failed(inode);
4901         return ERR_PTR(ret);
4902 }
4903
4904 static int ext4_inode_blocks_set(handle_t *handle,
4905                                 struct ext4_inode *raw_inode,
4906                                 struct ext4_inode_info *ei)
4907 {
4908         struct inode *inode = &(ei->vfs_inode);
4909         u64 i_blocks = inode->i_blocks;
4910         struct super_block *sb = inode->i_sb;
4911
4912         if (i_blocks <= ~0U) {
4913                 /*
4914                  * i_blocks can be represnted in a 32 bit variable
4915                  * as multiple of 512 bytes
4916                  */
4917                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4918                 raw_inode->i_blocks_high = 0;
4919                 ei->i_flags &= ~EXT4_HUGE_FILE_FL;
4920                 return 0;
4921         }
4922         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE))
4923                 return -EFBIG;
4924
4925         if (i_blocks <= 0xffffffffffffULL) {
4926                 /*
4927                  * i_blocks can be represented in a 48 bit variable
4928                  * as multiple of 512 bytes
4929                  */
4930                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4931                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4932                 ei->i_flags &= ~EXT4_HUGE_FILE_FL;
4933         } else {
4934                 ei->i_flags |= EXT4_HUGE_FILE_FL;
4935                 /* i_block is stored in file system block size */
4936                 i_blocks = i_blocks >> (inode->i_blkbits - 9);
4937                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4938                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4939         }
4940         return 0;
4941 }
4942
4943 /*
4944  * Post the struct inode info into an on-disk inode location in the
4945  * buffer-cache.  This gobbles the caller's reference to the
4946  * buffer_head in the inode location struct.
4947  *
4948  * The caller must have write access to iloc->bh.
4949  */
4950 static int ext4_do_update_inode(handle_t *handle,
4951                                 struct inode *inode,
4952                                 struct ext4_iloc *iloc)
4953 {
4954         struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
4955         struct ext4_inode_info *ei = EXT4_I(inode);
4956         struct buffer_head *bh = iloc->bh;
4957         int err = 0, rc, block;
4958
4959         /* For fields not not tracking in the in-memory inode,
4960          * initialise them to zero for new inodes. */
4961         if (ei->i_state & EXT4_STATE_NEW)
4962                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
4963
4964         ext4_get_inode_flags(ei);
4965         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
4966         if (!(test_opt(inode->i_sb, NO_UID32))) {
4967                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
4968                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
4969 /*
4970  * Fix up interoperability with old kernels. Otherwise, old inodes get
4971  * re-used with the upper 16 bits of the uid/gid intact
4972  */
4973                 if (!ei->i_dtime) {
4974                         raw_inode->i_uid_high =
4975                                 cpu_to_le16(high_16_bits(inode->i_uid));
4976                         raw_inode->i_gid_high =
4977                                 cpu_to_le16(high_16_bits(inode->i_gid));
4978                 } else {
4979                         raw_inode->i_uid_high = 0;
4980                         raw_inode->i_gid_high = 0;
4981                 }
4982         } else {
4983                 raw_inode->i_uid_low =
4984                         cpu_to_le16(fs_high2lowuid(inode->i_uid));
4985                 raw_inode->i_gid_low =
4986                         cpu_to_le16(fs_high2lowgid(inode->i_gid));
4987                 raw_inode->i_uid_high = 0;
4988                 raw_inode->i_gid_high = 0;
4989         }
4990         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
4991
4992         EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
4993         EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
4994         EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
4995         EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
4996
4997         if (ext4_inode_blocks_set(handle, raw_inode, ei))
4998                 goto out_brelse;
4999         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
5000         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
5001         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
5002             cpu_to_le32(EXT4_OS_HURD))
5003                 raw_inode->i_file_acl_high =
5004                         cpu_to_le16(ei->i_file_acl >> 32);
5005         raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
5006         ext4_isize_set(raw_inode, ei->i_disksize);
5007         if (ei->i_disksize > 0x7fffffffULL) {
5008                 struct super_block *sb = inode->i_sb;
5009                 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
5010                                 EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
5011                                 EXT4_SB(sb)->s_es->s_rev_level ==
5012                                 cpu_to_le32(EXT4_GOOD_OLD_REV)) {
5013                         /* If this is the first large file
5014                          * created, add a flag to the superblock.
5015                          */
5016                         err = ext4_journal_get_write_access(handle,
5017                                         EXT4_SB(sb)->s_sbh);
5018                         if (err)
5019                                 goto out_brelse;
5020                         ext4_update_dynamic_rev(sb);
5021                         EXT4_SET_RO_COMPAT_FEATURE(sb,
5022                                         EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
5023                         sb->s_dirt = 1;
5024                         ext4_handle_sync(handle);
5025                         err = ext4_handle_dirty_metadata(handle, inode,
5026                                         EXT4_SB(sb)->s_sbh);
5027                 }
5028         }
5029         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
5030         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
5031                 if (old_valid_dev(inode->i_rdev)) {
5032                         raw_inode->i_block[0] =
5033                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
5034                         raw_inode->i_block[1] = 0;
5035                 } else {
5036                         raw_inode->i_block[0] = 0;
5037                         raw_inode->i_block[1] =
5038                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
5039                         raw_inode->i_block[2] = 0;
5040                 }
5041         } else
5042                 for (block = 0; block < EXT4_N_BLOCKS; block++)
5043                         raw_inode->i_block[block] = ei->i_data[block];
5044
5045         raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
5046         if (ei->i_extra_isize) {
5047                 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
5048                         raw_inode->i_version_hi =
5049                         cpu_to_le32(inode->i_version >> 32);
5050                 raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
5051         }
5052
5053         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
5054         rc = ext4_handle_dirty_metadata(handle, inode, bh);
5055         if (!err)
5056                 err = rc;
5057         ei->i_state &= ~EXT4_STATE_NEW;
5058
5059 out_brelse:
5060         brelse(bh);
5061         ext4_std_error(inode->i_sb, err);
5062         return err;
5063 }
5064
5065 /*
5066  * ext4_write_inode()
5067  *
5068  * We are called from a few places:
5069  *
5070  * - Within generic_file_write() for O_SYNC files.
5071  *   Here, there will be no transaction running. We wait for any running
5072  *   trasnaction to commit.
5073  *
5074  * - Within sys_sync(), kupdate and such.
5075  *   We wait on commit, if tol to.
5076  *
5077  * - Within prune_icache() (PF_MEMALLOC == true)
5078  *   Here we simply return.  We can't afford to block kswapd on the
5079  *   journal commit.
5080  *
5081  * In all cases it is actually safe for us to return without doing anything,
5082  * because the inode has been copied into a raw inode buffer in
5083  * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
5084  * knfsd.
5085  *
5086  * Note that we are absolutely dependent upon all inode dirtiers doing the
5087  * right thing: they *must* call mark_inode_dirty() after dirtying info in
5088  * which we are interested.
5089  *
5090  * It would be a bug for them to not do this.  The code:
5091  *
5092  *      mark_inode_dirty(inode)
5093  *      stuff();
5094  *      inode->i_size = expr;
5095  *
5096  * is in error because a kswapd-driven write_inode() could occur while
5097  * `stuff()' is running, and the new i_size will be lost.  Plus the inode
5098  * will no longer be on the superblock's dirty inode list.
5099  */
5100 int ext4_write_inode(struct inode *inode, int wait)
5101 {
5102         int err;
5103
5104         if (current->flags & PF_MEMALLOC)
5105                 return 0;
5106
5107         if (EXT4_SB(inode->i_sb)->s_journal) {
5108                 if (ext4_journal_current_handle()) {
5109                         jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
5110                         dump_stack();
5111                         return -EIO;
5112                 }
5113
5114                 if (!wait)
5115                         return 0;
5116
5117                 err = ext4_force_commit(inode->i_sb);
5118         } else {
5119                 struct ext4_iloc iloc;
5120
5121                 err = ext4_get_inode_loc(inode, &iloc);
5122                 if (err)
5123                         return err;
5124                 if (wait)
5125                         sync_dirty_buffer(iloc.bh);
5126                 if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
5127                         ext4_error(inode->i_sb, __func__,
5128                                    "IO error syncing inode, "
5129                                    "inode=%lu, block=%llu",
5130                                    inode->i_ino,
5131                                    (unsigned long long)iloc.bh->b_blocknr);
5132                         err = -EIO;
5133                 }
5134         }
5135         return err;
5136 }
5137
5138 /*
5139  * ext4_setattr()
5140  *
5141  * Called from notify_change.
5142  *
5143  * We want to trap VFS attempts to truncate the file as soon as
5144  * possible.  In particular, we want to make sure that when the VFS
5145  * shrinks i_size, we put the inode on the orphan list and modify
5146  * i_disksize immediately, so that during the subsequent flushing of
5147  * dirty pages and freeing of disk blocks, we can guarantee that any
5148  * commit will leave the blocks being flushed in an unused state on
5149  * disk.  (On recovery, the inode will get truncated and the blocks will
5150  * be freed, so we have a strong guarantee that no future commit will
5151  * leave these blocks visible to the user.)
5152  *
5153  * Another thing we have to assure is that if we are in ordered mode
5154  * and inode is still attached to the committing transaction, we must
5155  * we start writeout of all the dirty pages which are being truncated.
5156  * This way we are sure that all the data written in the previous
5157  * transaction are already on disk (truncate waits for pages under
5158  * writeback).
5159  *
5160  * Called with inode->i_mutex down.
5161  */
5162 int ext4_setattr(struct dentry *dentry, struct iattr *attr)
5163 {
5164         struct inode *inode = dentry->d_inode;
5165         int error, rc = 0;
5166         const unsigned int ia_valid = attr->ia_valid;
5167
5168         error = inode_change_ok(inode, attr);
5169         if (error)
5170                 return error;
5171
5172         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
5173                 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
5174                 handle_t *handle;
5175
5176                 /* (user+group)*(old+new) structure, inode write (sb,
5177                  * inode block, ? - but truncate inode update has it) */
5178                 handle = ext4_journal_start(inode, (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)+
5179                                         EXT4_QUOTA_DEL_BLOCKS(inode->i_sb))+3);
5180                 if (IS_ERR(handle)) {
5181                         error = PTR_ERR(handle);
5182                         goto err_out;
5183                 }
5184                 error = vfs_dq_transfer(inode, attr) ? -EDQUOT : 0;
5185                 if (error) {
5186                         ext4_journal_stop(handle);
5187                         return error;
5188                 }
5189                 /* Update corresponding info in inode so that everything is in
5190                  * one transaction */
5191                 if (attr->ia_valid & ATTR_UID)
5192                         inode->i_uid = attr->ia_uid;
5193                 if (attr->ia_valid & ATTR_GID)
5194                         inode->i_gid = attr->ia_gid;
5195                 error = ext4_mark_inode_dirty(handle, inode);
5196                 ext4_journal_stop(handle);
5197         }
5198
5199         if (attr->ia_valid & ATTR_SIZE) {
5200                 if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
5201                         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5202
5203                         if (attr->ia_size > sbi->s_bitmap_maxbytes) {
5204                                 error = -EFBIG;
5205                                 goto err_out;
5206                         }
5207                 }
5208         }
5209
5210         if (S_ISREG(inode->i_mode) &&
5211             attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
5212                 handle_t *handle;
5213
5214                 handle = ext4_journal_start(inode, 3);
5215                 if (IS_ERR(handle)) {
5216                         error = PTR_ERR(handle);
5217                         goto err_out;
5218                 }
5219
5220                 error = ext4_orphan_add(handle, inode);
5221                 EXT4_I(inode)->i_disksize = attr->ia_size;
5222                 rc = ext4_mark_inode_dirty(handle, inode);
5223                 if (!error)
5224                         error = rc;
5225                 ext4_journal_stop(handle);
5226
5227                 if (ext4_should_order_data(inode)) {
5228                         error = ext4_begin_ordered_truncate(inode,
5229                                                             attr->ia_size);
5230                         if (error) {
5231                                 /* Do as much error cleanup as possible */
5232                                 handle = ext4_journal_start(inode, 3);
5233                                 if (IS_ERR(handle)) {
5234                                         ext4_orphan_del(NULL, inode);
5235                                         goto err_out;
5236                                 }
5237                                 ext4_orphan_del(handle, inode);
5238                                 ext4_journal_stop(handle);
5239                                 goto err_out;
5240                         }
5241                 }
5242         }
5243
5244         rc = inode_setattr(inode, attr);
5245
5246         /* If inode_setattr's call to ext4_truncate failed to get a
5247          * transaction handle at all, we need to clean up the in-core
5248          * orphan list manually. */
5249         if (inode->i_nlink)
5250                 ext4_orphan_del(NULL, inode);
5251
5252         if (!rc && (ia_valid & ATTR_MODE))
5253                 rc = ext4_acl_chmod(inode);
5254
5255 err_out:
5256         ext4_std_error(inode->i_sb, error);
5257         if (!error)
5258                 error = rc;
5259         return error;
5260 }
5261
5262 int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
5263                  struct kstat *stat)
5264 {
5265         struct inode *inode;
5266         unsigned long delalloc_blocks;
5267
5268         inode = dentry->d_inode;
5269         generic_fillattr(inode, stat);
5270
5271         /*
5272          * We can't update i_blocks if the block allocation is delayed
5273          * otherwise in the case of system crash before the real block
5274          * allocation is done, we will have i_blocks inconsistent with
5275          * on-disk file blocks.
5276          * We always keep i_blocks updated together with real
5277          * allocation. But to not confuse with user, stat
5278          * will return the blocks that include the delayed allocation
5279          * blocks for this file.
5280          */
5281         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
5282         delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks;
5283         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
5284
5285         stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9;
5286         return 0;
5287 }
5288
5289 static int ext4_indirect_trans_blocks(struct inode *inode, int nrblocks,
5290                                       int chunk)
5291 {
5292         int indirects;
5293
5294         /* if nrblocks are contiguous */
5295         if (chunk) {
5296                 /*
5297                  * With N contiguous data blocks, it need at most
5298                  * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks
5299                  * 2 dindirect blocks
5300                  * 1 tindirect block
5301                  */
5302                 indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb);
5303                 return indirects + 3;
5304         }
5305         /*
5306          * if nrblocks are not contiguous, worse case, each block touch
5307          * a indirect block, and each indirect block touch a double indirect
5308          * block, plus a triple indirect block
5309          */
5310         indirects = nrblocks * 2 + 1;
5311         return indirects;
5312 }
5313
5314 static int ext4_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
5315 {
5316         if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
5317                 return ext4_indirect_trans_blocks(inode, nrblocks, chunk);
5318         return ext4_ext_index_trans_blocks(inode, nrblocks, chunk);
5319 }
5320
5321 /*
5322  * Account for index blocks, block groups bitmaps and block group
5323  * descriptor blocks if modify datablocks and index blocks
5324  * worse case, the indexs blocks spread over different block groups
5325  *
5326  * If datablocks are discontiguous, they are possible to spread over
5327  * different block groups too. If they are contiugous, with flexbg,
5328  * they could still across block group boundary.
5329  *
5330  * Also account for superblock, inode, quota and xattr blocks
5331  */
5332 int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
5333 {
5334         ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
5335         int gdpblocks;
5336         int idxblocks;
5337         int ret = 0;
5338
5339         /*
5340          * How many index blocks need to touch to modify nrblocks?
5341          * The "Chunk" flag indicating whether the nrblocks is
5342          * physically contiguous on disk
5343          *
5344          * For Direct IO and fallocate, they calls get_block to allocate
5345          * one single extent at a time, so they could set the "Chunk" flag
5346          */
5347         idxblocks = ext4_index_trans_blocks(inode, nrblocks, chunk);
5348
5349         ret = idxblocks;
5350
5351         /*
5352          * Now let's see how many group bitmaps and group descriptors need
5353          * to account
5354          */
5355         groups = idxblocks;
5356         if (chunk)
5357                 groups += 1;
5358         else
5359                 groups += nrblocks;
5360
5361         gdpblocks = groups;
5362         if (groups > ngroups)
5363                 groups = ngroups;
5364         if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
5365                 gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
5366
5367         /* bitmaps and block group descriptor blocks */
5368         ret += groups + gdpblocks;
5369
5370         /* Blocks for super block, inode, quota and xattr blocks */
5371         ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
5372
5373         return ret;
5374 }
5375
5376 /*
5377  * Calulate the total number of credits to reserve to fit
5378  * the modification of a single pages into a single transaction,
5379  * which may include multiple chunks of block allocations.
5380  *
5381  * This could be called via ext4_write_begin()
5382  *
5383  * We need to consider the worse case, when
5384  * one new block per extent.
5385  */
5386 int ext4_writepage_trans_blocks(struct inode *inode)
5387 {
5388         int bpp = ext4_journal_blocks_per_page(inode);
5389         int ret;
5390
5391         ret = ext4_meta_trans_blocks(inode, bpp, 0);
5392
5393         /* Account for data blocks for journalled mode */
5394         if (ext4_should_journal_data(inode))
5395                 ret += bpp;
5396         return ret;
5397 }
5398
5399 /*
5400  * Calculate the journal credits for a chunk of data modification.
5401  *
5402  * This is called from DIO, fallocate or whoever calling
5403  * ext4_get_blocks() to map/allocate a chunk of contigous disk blocks.
5404  *
5405  * journal buffers for data blocks are not included here, as DIO
5406  * and fallocate do no need to journal data buffers.
5407  */
5408 int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
5409 {
5410         return ext4_meta_trans_blocks(inode, nrblocks, 1);
5411 }
5412
5413 /*
5414  * The caller must have previously called ext4_reserve_inode_write().
5415  * Give this, we know that the caller already has write access to iloc->bh.
5416  */
5417 int ext4_mark_iloc_dirty(handle_t *handle,
5418                          struct inode *inode, struct ext4_iloc *iloc)
5419 {
5420         int err = 0;
5421
5422         if (test_opt(inode->i_sb, I_VERSION))
5423                 inode_inc_iversion(inode);
5424
5425         /* the do_update_inode consumes one bh->b_count */
5426         get_bh(iloc->bh);
5427
5428         /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
5429         err = ext4_do_update_inode(handle, inode, iloc);
5430         put_bh(iloc->bh);
5431         return err;
5432 }
5433
5434 /*
5435  * On success, We end up with an outstanding reference count against
5436  * iloc->bh.  This _must_ be cleaned up later.
5437  */
5438
5439 int
5440 ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
5441                          struct ext4_iloc *iloc)
5442 {
5443         int err;
5444
5445         err = ext4_get_inode_loc(inode, iloc);
5446         if (!err) {
5447                 BUFFER_TRACE(iloc->bh, "get_write_access");
5448                 err = ext4_journal_get_write_access(handle, iloc->bh);
5449                 if (err) {
5450                         brelse(iloc->bh);
5451                         iloc->bh = NULL;
5452                 }
5453         }
5454         ext4_std_error(inode->i_sb, err);
5455         return err;
5456 }
5457
5458 /*
5459  * Expand an inode by new_extra_isize bytes.
5460  * Returns 0 on success or negative error number on failure.
5461  */
5462 static int ext4_expand_extra_isize(struct inode *inode,
5463                                    unsigned int new_extra_isize,
5464                                    struct ext4_iloc iloc,
5465                                    handle_t *handle)
5466 {
5467         struct ext4_inode *raw_inode;
5468         struct ext4_xattr_ibody_header *header;
5469         struct ext4_xattr_entry *entry;
5470
5471         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
5472                 return 0;
5473
5474         raw_inode = ext4_raw_inode(&iloc);
5475
5476         header = IHDR(inode, raw_inode);
5477         entry = IFIRST(header);
5478
5479         /* No extended attributes present */
5480         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR) ||
5481                 header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
5482                 memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
5483                         new_extra_isize);
5484                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
5485                 return 0;
5486         }
5487
5488         /* try to expand with EAs present */
5489         return ext4_expand_extra_isize_ea(inode, new_extra_isize,
5490                                           raw_inode, handle);
5491 }
5492
5493 /*
5494  * What we do here is to mark the in-core inode as clean with respect to inode
5495  * dirtiness (it may still be data-dirty).
5496  * This means that the in-core inode may be reaped by prune_icache
5497  * without having to perform any I/O.  This is a very good thing,
5498  * because *any* task may call prune_icache - even ones which
5499  * have a transaction open against a different journal.
5500  *
5501  * Is this cheating?  Not really.  Sure, we haven't written the
5502  * inode out, but prune_icache isn't a user-visible syncing function.
5503  * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
5504  * we start and wait on commits.
5505  *
5506  * Is this efficient/effective?  Well, we're being nice to the system
5507  * by cleaning up our inodes proactively so they can be reaped
5508  * without I/O.  But we are potentially leaving up to five seconds'
5509  * worth of inodes floating about which prune_icache wants us to
5510  * write out.  One way to fix that would be to get prune_icache()
5511  * to do a write_super() to free up some memory.  It has the desired
5512  * effect.
5513  */
5514 int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
5515 {
5516         struct ext4_iloc iloc;
5517         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5518         static unsigned int mnt_count;
5519         int err, ret;
5520
5521         might_sleep();
5522         err = ext4_reserve_inode_write(handle, inode, &iloc);
5523         if (ext4_handle_valid(handle) &&
5524             EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
5525             !(EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND)) {
5526                 /*
5527                  * We need extra buffer credits since we may write into EA block
5528                  * with this same handle. If journal_extend fails, then it will
5529                  * only result in a minor loss of functionality for that inode.
5530                  * If this is felt to be critical, then e2fsck should be run to
5531                  * force a large enough s_min_extra_isize.
5532                  */
5533                 if ((jbd2_journal_extend(handle,
5534                              EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) {
5535                         ret = ext4_expand_extra_isize(inode,
5536                                                       sbi->s_want_extra_isize,
5537                                                       iloc, handle);
5538                         if (ret) {
5539                                 EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND;
5540                                 if (mnt_count !=
5541                                         le16_to_cpu(sbi->s_es->s_mnt_count)) {
5542                                         ext4_warning(inode->i_sb, __func__,
5543                                         "Unable to expand inode %lu. Delete"
5544                                         " some EAs or run e2fsck.",
5545                                         inode->i_ino);
5546                                         mnt_count =
5547                                           le16_to_cpu(sbi->s_es->s_mnt_count);
5548                                 }
5549                         }
5550                 }
5551         }
5552         if (!err)
5553                 err = ext4_mark_iloc_dirty(handle, inode, &iloc);
5554         return err;
5555 }
5556
5557 /*
5558  * ext4_dirty_inode() is called from __mark_inode_dirty()
5559  *
5560  * We're really interested in the case where a file is being extended.
5561  * i_size has been changed by generic_commit_write() and we thus need
5562  * to include the updated inode in the current transaction.
5563  *
5564  * Also, vfs_dq_alloc_block() will always dirty the inode when blocks
5565  * are allocated to the file.
5566  *
5567  * If the inode is marked synchronous, we don't honour that here - doing
5568  * so would cause a commit on atime updates, which we don't bother doing.
5569  * We handle synchronous inodes at the highest possible level.
5570  */
5571 void ext4_dirty_inode(struct inode *inode)
5572 {
5573         handle_t *handle;
5574
5575         handle = ext4_journal_start(inode, 2);
5576         if (IS_ERR(handle))
5577                 goto out;
5578
5579         ext4_mark_inode_dirty(handle, inode);
5580
5581         ext4_journal_stop(handle);
5582 out:
5583         return;
5584 }
5585
5586 #if 0
5587 /*
5588  * Bind an inode's backing buffer_head into this transaction, to prevent
5589  * it from being flushed to disk early.  Unlike
5590  * ext4_reserve_inode_write, this leaves behind no bh reference and
5591  * returns no iloc structure, so the caller needs to repeat the iloc
5592  * lookup to mark the inode dirty later.
5593  */
5594 static int ext4_pin_inode(handle_t *handle, struct inode *inode)
5595 {
5596         struct ext4_iloc iloc;
5597
5598         int err = 0;
5599         if (handle) {
5600                 err = ext4_get_inode_loc(inode, &iloc);
5601                 if (!err) {
5602                         BUFFER_TRACE(iloc.bh, "get_write_access");