ext4: Pass line numbers to ext4_error() and friends
[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 #include <linux/kernel.h>
42 #include <linux/slab.h>
43
44 #include "ext4_jbd2.h"
45 #include "xattr.h"
46 #include "acl.h"
47 #include "ext4_extents.h"
48
49 #include <trace/events/ext4.h>
50
51 #define MPAGE_DA_EXTENT_TAIL 0x01
52
53 static inline int ext4_begin_ordered_truncate(struct inode *inode,
54                                               loff_t new_size)
55 {
56         return jbd2_journal_begin_ordered_truncate(
57                                         EXT4_SB(inode->i_sb)->s_journal,
58                                         &EXT4_I(inode)->jinode,
59                                         new_size);
60 }
61
62 static void ext4_invalidatepage(struct page *page, unsigned long offset);
63
64 /*
65  * Test whether an inode is a fast symlink.
66  */
67 static int ext4_inode_is_fast_symlink(struct inode *inode)
68 {
69         int ea_blocks = EXT4_I(inode)->i_file_acl ?
70                 (inode->i_sb->s_blocksize >> 9) : 0;
71
72         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
73 }
74
75 /*
76  * Work out how many blocks we need to proceed with the next chunk of a
77  * truncate transaction.
78  */
79 static unsigned long blocks_for_truncate(struct inode *inode)
80 {
81         ext4_lblk_t needed;
82
83         needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
84
85         /* Give ourselves just enough room to cope with inodes in which
86          * i_blocks is corrupt: we've seen disk corruptions in the past
87          * which resulted in random data in an inode which looked enough
88          * like a regular file for ext4 to try to delete it.  Things
89          * will go a bit crazy if that happens, but at least we should
90          * try not to panic the whole kernel. */
91         if (needed < 2)
92                 needed = 2;
93
94         /* But we need to bound the transaction so we don't overflow the
95          * journal. */
96         if (needed > EXT4_MAX_TRANS_DATA)
97                 needed = EXT4_MAX_TRANS_DATA;
98
99         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
100 }
101
102 /*
103  * Truncate transactions can be complex and absolutely huge.  So we need to
104  * be able to restart the transaction at a conventient checkpoint to make
105  * sure we don't overflow the journal.
106  *
107  * start_transaction gets us a new handle for a truncate transaction,
108  * and extend_transaction tries to extend the existing one a bit.  If
109  * extend fails, we need to propagate the failure up and restart the
110  * transaction in the top-level truncate loop. --sct
111  */
112 static handle_t *start_transaction(struct inode *inode)
113 {
114         handle_t *result;
115
116         result = ext4_journal_start(inode, blocks_for_truncate(inode));
117         if (!IS_ERR(result))
118                 return result;
119
120         ext4_std_error(inode->i_sb, PTR_ERR(result));
121         return result;
122 }
123
124 /*
125  * Try to extend this transaction for the purposes of truncation.
126  *
127  * Returns 0 if we managed to create more room.  If we can't create more
128  * room, and the transaction must be restarted we return 1.
129  */
130 static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
131 {
132         if (!ext4_handle_valid(handle))
133                 return 0;
134         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
135                 return 0;
136         if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
137                 return 0;
138         return 1;
139 }
140
141 /*
142  * Restart the transaction associated with *handle.  This does a commit,
143  * so before we call here everything must be consistently dirtied against
144  * this transaction.
145  */
146 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
147                                  int nblocks)
148 {
149         int ret;
150
151         /*
152          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
153          * moment, get_block can be called only for blocks inside i_size since
154          * page cache has been already dropped and writes are blocked by
155          * i_mutex. So we can safely drop the i_data_sem here.
156          */
157         BUG_ON(EXT4_JOURNAL(inode) == NULL);
158         jbd_debug(2, "restarting handle %p\n", handle);
159         up_write(&EXT4_I(inode)->i_data_sem);
160         ret = ext4_journal_restart(handle, blocks_for_truncate(inode));
161         down_write(&EXT4_I(inode)->i_data_sem);
162         ext4_discard_preallocations(inode);
163
164         return ret;
165 }
166
167 /*
168  * Called at the last iput() if i_nlink is zero.
169  */
170 void ext4_delete_inode(struct inode *inode)
171 {
172         handle_t *handle;
173         int err;
174
175         if (!is_bad_inode(inode))
176                 dquot_initialize(inode);
177
178         if (ext4_should_order_data(inode))
179                 ext4_begin_ordered_truncate(inode, 0);
180         truncate_inode_pages(&inode->i_data, 0);
181
182         if (is_bad_inode(inode))
183                 goto no_delete;
184
185         handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
186         if (IS_ERR(handle)) {
187                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
188                 /*
189                  * If we're going to skip the normal cleanup, we still need to
190                  * make sure that the in-core orphan linked list is properly
191                  * cleaned up.
192                  */
193                 ext4_orphan_del(NULL, inode);
194                 goto no_delete;
195         }
196
197         if (IS_SYNC(inode))
198                 ext4_handle_sync(handle);
199         inode->i_size = 0;
200         err = ext4_mark_inode_dirty(handle, inode);
201         if (err) {
202                 ext4_warning(inode->i_sb,
203                              "couldn't mark inode dirty (err %d)", err);
204                 goto stop_handle;
205         }
206         if (inode->i_blocks)
207                 ext4_truncate(inode);
208
209         /*
210          * ext4_ext_truncate() doesn't reserve any slop when it
211          * restarts journal transactions; therefore there may not be
212          * enough credits left in the handle to remove the inode from
213          * the orphan list and set the dtime field.
214          */
215         if (!ext4_handle_has_enough_credits(handle, 3)) {
216                 err = ext4_journal_extend(handle, 3);
217                 if (err > 0)
218                         err = ext4_journal_restart(handle, 3);
219                 if (err != 0) {
220                         ext4_warning(inode->i_sb,
221                                      "couldn't extend journal (err %d)", err);
222                 stop_handle:
223                         ext4_journal_stop(handle);
224                         goto no_delete;
225                 }
226         }
227
228         /*
229          * Kill off the orphan record which ext4_truncate created.
230          * AKPM: I think this can be inside the above `if'.
231          * Note that ext4_orphan_del() has to be able to cope with the
232          * deletion of a non-existent orphan - this is because we don't
233          * know if ext4_truncate() actually created an orphan record.
234          * (Well, we could do this if we need to, but heck - it works)
235          */
236         ext4_orphan_del(handle, inode);
237         EXT4_I(inode)->i_dtime  = get_seconds();
238
239         /*
240          * One subtle ordering requirement: if anything has gone wrong
241          * (transaction abort, IO errors, whatever), then we can still
242          * do these next steps (the fs will already have been marked as
243          * having errors), but we can't free the inode if the mark_dirty
244          * fails.
245          */
246         if (ext4_mark_inode_dirty(handle, inode))
247                 /* If that failed, just do the required in-core inode clear. */
248                 clear_inode(inode);
249         else
250                 ext4_free_inode(handle, inode);
251         ext4_journal_stop(handle);
252         return;
253 no_delete:
254         clear_inode(inode);     /* We must guarantee clearing of inode... */
255 }
256
257 typedef struct {
258         __le32  *p;
259         __le32  key;
260         struct buffer_head *bh;
261 } Indirect;
262
263 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
264 {
265         p->key = *(p->p = v);
266         p->bh = bh;
267 }
268
269 /**
270  *      ext4_block_to_path - parse the block number into array of offsets
271  *      @inode: inode in question (we are only interested in its superblock)
272  *      @i_block: block number to be parsed
273  *      @offsets: array to store the offsets in
274  *      @boundary: set this non-zero if the referred-to block is likely to be
275  *             followed (on disk) by an indirect block.
276  *
277  *      To store the locations of file's data ext4 uses a data structure common
278  *      for UNIX filesystems - tree of pointers anchored in the inode, with
279  *      data blocks at leaves and indirect blocks in intermediate nodes.
280  *      This function translates the block number into path in that tree -
281  *      return value is the path length and @offsets[n] is the offset of
282  *      pointer to (n+1)th node in the nth one. If @block is out of range
283  *      (negative or too large) warning is printed and zero returned.
284  *
285  *      Note: function doesn't find node addresses, so no IO is needed. All
286  *      we need to know is the capacity of indirect blocks (taken from the
287  *      inode->i_sb).
288  */
289
290 /*
291  * Portability note: the last comparison (check that we fit into triple
292  * indirect block) is spelled differently, because otherwise on an
293  * architecture with 32-bit longs and 8Kb pages we might get into trouble
294  * if our filesystem had 8Kb blocks. We might use long long, but that would
295  * kill us on x86. Oh, well, at least the sign propagation does not matter -
296  * i_block would have to be negative in the very beginning, so we would not
297  * get there at all.
298  */
299
300 static int ext4_block_to_path(struct inode *inode,
301                               ext4_lblk_t i_block,
302                               ext4_lblk_t offsets[4], int *boundary)
303 {
304         int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
305         int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
306         const long direct_blocks = EXT4_NDIR_BLOCKS,
307                 indirect_blocks = ptrs,
308                 double_blocks = (1 << (ptrs_bits * 2));
309         int n = 0;
310         int final = 0;
311
312         if (i_block < direct_blocks) {
313                 offsets[n++] = i_block;
314                 final = direct_blocks;
315         } else if ((i_block -= direct_blocks) < indirect_blocks) {
316                 offsets[n++] = EXT4_IND_BLOCK;
317                 offsets[n++] = i_block;
318                 final = ptrs;
319         } else if ((i_block -= indirect_blocks) < double_blocks) {
320                 offsets[n++] = EXT4_DIND_BLOCK;
321                 offsets[n++] = i_block >> ptrs_bits;
322                 offsets[n++] = i_block & (ptrs - 1);
323                 final = ptrs;
324         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
325                 offsets[n++] = EXT4_TIND_BLOCK;
326                 offsets[n++] = i_block >> (ptrs_bits * 2);
327                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
328                 offsets[n++] = i_block & (ptrs - 1);
329                 final = ptrs;
330         } else {
331                 ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
332                              i_block + direct_blocks +
333                              indirect_blocks + double_blocks, inode->i_ino);
334         }
335         if (boundary)
336                 *boundary = final - 1 - (i_block & (ptrs - 1));
337         return n;
338 }
339
340 static int __ext4_check_blockref(const char *function, unsigned int line,
341                                  struct inode *inode,
342                                  __le32 *p, unsigned int max)
343 {
344         __le32 *bref = p;
345         unsigned int blk;
346
347         while (bref < p+max) {
348                 blk = le32_to_cpu(*bref++);
349                 if (blk &&
350                     unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
351                                                     blk, 1))) {
352                         ext4_error_inode(inode, function, line, blk,
353                                          "invalid block");
354                         return -EIO;
355                 }
356         }
357         return 0;
358 }
359
360
361 #define ext4_check_indirect_blockref(inode, bh)                         \
362         __ext4_check_blockref(__func__, __LINE__, inode,                \
363                               (__le32 *)(bh)->b_data,                   \
364                               EXT4_ADDR_PER_BLOCK((inode)->i_sb))
365
366 #define ext4_check_inode_blockref(inode)                                \
367         __ext4_check_blockref(__func__, __LINE__, inode,                \
368                               EXT4_I(inode)->i_data,                    \
369                               EXT4_NDIR_BLOCKS)
370
371 /**
372  *      ext4_get_branch - read the chain of indirect blocks leading to data
373  *      @inode: inode in question
374  *      @depth: depth of the chain (1 - direct pointer, etc.)
375  *      @offsets: offsets of pointers in inode/indirect blocks
376  *      @chain: place to store the result
377  *      @err: here we store the error value
378  *
379  *      Function fills the array of triples <key, p, bh> and returns %NULL
380  *      if everything went OK or the pointer to the last filled triple
381  *      (incomplete one) otherwise. Upon the return chain[i].key contains
382  *      the number of (i+1)-th block in the chain (as it is stored in memory,
383  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
384  *      number (it points into struct inode for i==0 and into the bh->b_data
385  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
386  *      block for i>0 and NULL for i==0. In other words, it holds the block
387  *      numbers of the chain, addresses they were taken from (and where we can
388  *      verify that chain did not change) and buffer_heads hosting these
389  *      numbers.
390  *
391  *      Function stops when it stumbles upon zero pointer (absent block)
392  *              (pointer to last triple returned, *@err == 0)
393  *      or when it gets an IO error reading an indirect block
394  *              (ditto, *@err == -EIO)
395  *      or when it reads all @depth-1 indirect blocks successfully and finds
396  *      the whole chain, all way to the data (returns %NULL, *err == 0).
397  *
398  *      Need to be called with
399  *      down_read(&EXT4_I(inode)->i_data_sem)
400  */
401 static Indirect *ext4_get_branch(struct inode *inode, int depth,
402                                  ext4_lblk_t  *offsets,
403                                  Indirect chain[4], int *err)
404 {
405         struct super_block *sb = inode->i_sb;
406         Indirect *p = chain;
407         struct buffer_head *bh;
408
409         *err = 0;
410         /* i_data is not going away, no lock needed */
411         add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
412         if (!p->key)
413                 goto no_block;
414         while (--depth) {
415                 bh = sb_getblk(sb, le32_to_cpu(p->key));
416                 if (unlikely(!bh))
417                         goto failure;
418
419                 if (!bh_uptodate_or_lock(bh)) {
420                         if (bh_submit_read(bh) < 0) {
421                                 put_bh(bh);
422                                 goto failure;
423                         }
424                         /* validate block references */
425                         if (ext4_check_indirect_blockref(inode, bh)) {
426                                 put_bh(bh);
427                                 goto failure;
428                         }
429                 }
430
431                 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
432                 /* Reader: end */
433                 if (!p->key)
434                         goto no_block;
435         }
436         return NULL;
437
438 failure:
439         *err = -EIO;
440 no_block:
441         return p;
442 }
443
444 /**
445  *      ext4_find_near - find a place for allocation with sufficient locality
446  *      @inode: owner
447  *      @ind: descriptor of indirect block.
448  *
449  *      This function returns the preferred place for block allocation.
450  *      It is used when heuristic for sequential allocation fails.
451  *      Rules are:
452  *        + if there is a block to the left of our position - allocate near it.
453  *        + if pointer will live in indirect block - allocate near that block.
454  *        + if pointer will live in inode - allocate in the same
455  *          cylinder group.
456  *
457  * In the latter case we colour the starting block by the callers PID to
458  * prevent it from clashing with concurrent allocations for a different inode
459  * in the same block group.   The PID is used here so that functionally related
460  * files will be close-by on-disk.
461  *
462  *      Caller must make sure that @ind is valid and will stay that way.
463  */
464 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
465 {
466         struct ext4_inode_info *ei = EXT4_I(inode);
467         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
468         __le32 *p;
469         ext4_fsblk_t bg_start;
470         ext4_fsblk_t last_block;
471         ext4_grpblk_t colour;
472         ext4_group_t block_group;
473         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
474
475         /* Try to find previous block */
476         for (p = ind->p - 1; p >= start; p--) {
477                 if (*p)
478                         return le32_to_cpu(*p);
479         }
480
481         /* No such thing, so let's try location of indirect block */
482         if (ind->bh)
483                 return ind->bh->b_blocknr;
484
485         /*
486          * It is going to be referred to from the inode itself? OK, just put it
487          * into the same cylinder group then.
488          */
489         block_group = ei->i_block_group;
490         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
491                 block_group &= ~(flex_size-1);
492                 if (S_ISREG(inode->i_mode))
493                         block_group++;
494         }
495         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
496         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
497
498         /*
499          * If we are doing delayed allocation, we don't need take
500          * colour into account.
501          */
502         if (test_opt(inode->i_sb, DELALLOC))
503                 return bg_start;
504
505         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
506                 colour = (current->pid % 16) *
507                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
508         else
509                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
510         return bg_start + colour;
511 }
512
513 /**
514  *      ext4_find_goal - find a preferred place for allocation.
515  *      @inode: owner
516  *      @block:  block we want
517  *      @partial: pointer to the last triple within a chain
518  *
519  *      Normally this function find the preferred place for block allocation,
520  *      returns it.
521  *      Because this is only used for non-extent files, we limit the block nr
522  *      to 32 bits.
523  */
524 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
525                                    Indirect *partial)
526 {
527         ext4_fsblk_t goal;
528
529         /*
530          * XXX need to get goal block from mballoc's data structures
531          */
532
533         goal = ext4_find_near(inode, partial);
534         goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
535         return goal;
536 }
537
538 /**
539  *      ext4_blks_to_allocate: Look up the block map and count the number
540  *      of direct blocks need to be allocated for the given branch.
541  *
542  *      @branch: chain of indirect blocks
543  *      @k: number of blocks need for indirect blocks
544  *      @blks: number of data blocks to be mapped.
545  *      @blocks_to_boundary:  the offset in the indirect block
546  *
547  *      return the total number of blocks to be allocate, including the
548  *      direct and indirect blocks.
549  */
550 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
551                                  int blocks_to_boundary)
552 {
553         unsigned int count = 0;
554
555         /*
556          * Simple case, [t,d]Indirect block(s) has not allocated yet
557          * then it's clear blocks on that path have not allocated
558          */
559         if (k > 0) {
560                 /* right now we don't handle cross boundary allocation */
561                 if (blks < blocks_to_boundary + 1)
562                         count += blks;
563                 else
564                         count += blocks_to_boundary + 1;
565                 return count;
566         }
567
568         count++;
569         while (count < blks && count <= blocks_to_boundary &&
570                 le32_to_cpu(*(branch[0].p + count)) == 0) {
571                 count++;
572         }
573         return count;
574 }
575
576 /**
577  *      ext4_alloc_blocks: multiple allocate blocks needed for a branch
578  *      @indirect_blks: the number of blocks need to allocate for indirect
579  *                      blocks
580  *
581  *      @new_blocks: on return it will store the new block numbers for
582  *      the indirect blocks(if needed) and the first direct block,
583  *      @blks:  on return it will store the total number of allocated
584  *              direct blocks
585  */
586 static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
587                              ext4_lblk_t iblock, ext4_fsblk_t goal,
588                              int indirect_blks, int blks,
589                              ext4_fsblk_t new_blocks[4], int *err)
590 {
591         struct ext4_allocation_request ar;
592         int target, i;
593         unsigned long count = 0, blk_allocated = 0;
594         int index = 0;
595         ext4_fsblk_t current_block = 0;
596         int ret = 0;
597
598         /*
599          * Here we try to allocate the requested multiple blocks at once,
600          * on a best-effort basis.
601          * To build a branch, we should allocate blocks for
602          * the indirect blocks(if not allocated yet), and at least
603          * the first direct block of this branch.  That's the
604          * minimum number of blocks need to allocate(required)
605          */
606         /* first we try to allocate the indirect blocks */
607         target = indirect_blks;
608         while (target > 0) {
609                 count = target;
610                 /* allocating blocks for indirect blocks and direct blocks */
611                 current_block = ext4_new_meta_blocks(handle, inode,
612                                                         goal, &count, err);
613                 if (*err)
614                         goto failed_out;
615
616                 if (unlikely(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS)) {
617                         EXT4_ERROR_INODE(inode,
618                                          "current_block %llu + count %lu > %d!",
619                                          current_block, count,
620                                          EXT4_MAX_BLOCK_FILE_PHYS);
621                         *err = -EIO;
622                         goto failed_out;
623                 }
624
625                 target -= count;
626                 /* allocate blocks for indirect blocks */
627                 while (index < indirect_blks && count) {
628                         new_blocks[index++] = current_block++;
629                         count--;
630                 }
631                 if (count > 0) {
632                         /*
633                          * save the new block number
634                          * for the first direct block
635                          */
636                         new_blocks[index] = current_block;
637                         printk(KERN_INFO "%s returned more blocks than "
638                                                 "requested\n", __func__);
639                         WARN_ON(1);
640                         break;
641                 }
642         }
643
644         target = blks - count ;
645         blk_allocated = count;
646         if (!target)
647                 goto allocated;
648         /* Now allocate data blocks */
649         memset(&ar, 0, sizeof(ar));
650         ar.inode = inode;
651         ar.goal = goal;
652         ar.len = target;
653         ar.logical = iblock;
654         if (S_ISREG(inode->i_mode))
655                 /* enable in-core preallocation only for regular files */
656                 ar.flags = EXT4_MB_HINT_DATA;
657
658         current_block = ext4_mb_new_blocks(handle, &ar, err);
659         if (unlikely(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS)) {
660                 EXT4_ERROR_INODE(inode,
661                                  "current_block %llu + ar.len %d > %d!",
662                                  current_block, ar.len,
663                                  EXT4_MAX_BLOCK_FILE_PHYS);
664                 *err = -EIO;
665                 goto failed_out;
666         }
667
668         if (*err && (target == blks)) {
669                 /*
670                  * if the allocation failed and we didn't allocate
671                  * any blocks before
672                  */
673                 goto failed_out;
674         }
675         if (!*err) {
676                 if (target == blks) {
677                         /*
678                          * save the new block number
679                          * for the first direct block
680                          */
681                         new_blocks[index] = current_block;
682                 }
683                 blk_allocated += ar.len;
684         }
685 allocated:
686         /* total number of blocks allocated for direct blocks */
687         ret = blk_allocated;
688         *err = 0;
689         return ret;
690 failed_out:
691         for (i = 0; i < index; i++)
692                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0);
693         return ret;
694 }
695
696 /**
697  *      ext4_alloc_branch - allocate and set up a chain of blocks.
698  *      @inode: owner
699  *      @indirect_blks: number of allocated indirect blocks
700  *      @blks: number of allocated direct blocks
701  *      @offsets: offsets (in the blocks) to store the pointers to next.
702  *      @branch: place to store the chain in.
703  *
704  *      This function allocates blocks, zeroes out all but the last one,
705  *      links them into chain and (if we are synchronous) writes them to disk.
706  *      In other words, it prepares a branch that can be spliced onto the
707  *      inode. It stores the information about that chain in the branch[], in
708  *      the same format as ext4_get_branch() would do. We are calling it after
709  *      we had read the existing part of chain and partial points to the last
710  *      triple of that (one with zero ->key). Upon the exit we have the same
711  *      picture as after the successful ext4_get_block(), except that in one
712  *      place chain is disconnected - *branch->p is still zero (we did not
713  *      set the last link), but branch->key contains the number that should
714  *      be placed into *branch->p to fill that gap.
715  *
716  *      If allocation fails we free all blocks we've allocated (and forget
717  *      their buffer_heads) and return the error value the from failed
718  *      ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
719  *      as described above and return 0.
720  */
721 static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
722                              ext4_lblk_t iblock, int indirect_blks,
723                              int *blks, ext4_fsblk_t goal,
724                              ext4_lblk_t *offsets, Indirect *branch)
725 {
726         int blocksize = inode->i_sb->s_blocksize;
727         int i, n = 0;
728         int err = 0;
729         struct buffer_head *bh;
730         int num;
731         ext4_fsblk_t new_blocks[4];
732         ext4_fsblk_t current_block;
733
734         num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
735                                 *blks, new_blocks, &err);
736         if (err)
737                 return err;
738
739         branch[0].key = cpu_to_le32(new_blocks[0]);
740         /*
741          * metadata blocks and data blocks are allocated.
742          */
743         for (n = 1; n <= indirect_blks;  n++) {
744                 /*
745                  * Get buffer_head for parent block, zero it out
746                  * and set the pointer to new one, then send
747                  * parent to disk.
748                  */
749                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
750                 branch[n].bh = bh;
751                 lock_buffer(bh);
752                 BUFFER_TRACE(bh, "call get_create_access");
753                 err = ext4_journal_get_create_access(handle, bh);
754                 if (err) {
755                         /* Don't brelse(bh) here; it's done in
756                          * ext4_journal_forget() below */
757                         unlock_buffer(bh);
758                         goto failed;
759                 }
760
761                 memset(bh->b_data, 0, blocksize);
762                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
763                 branch[n].key = cpu_to_le32(new_blocks[n]);
764                 *branch[n].p = branch[n].key;
765                 if (n == indirect_blks) {
766                         current_block = new_blocks[n];
767                         /*
768                          * End of chain, update the last new metablock of
769                          * the chain to point to the new allocated
770                          * data blocks numbers
771                          */
772                         for (i = 1; i < num; i++)
773                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
774                 }
775                 BUFFER_TRACE(bh, "marking uptodate");
776                 set_buffer_uptodate(bh);
777                 unlock_buffer(bh);
778
779                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
780                 err = ext4_handle_dirty_metadata(handle, inode, bh);
781                 if (err)
782                         goto failed;
783         }
784         *blks = num;
785         return err;
786 failed:
787         /* Allocation failed, free what we already allocated */
788         ext4_free_blocks(handle, inode, 0, new_blocks[0], 1, 0);
789         for (i = 1; i <= n ; i++) {
790                 /*
791                  * branch[i].bh is newly allocated, so there is no
792                  * need to revoke the block, which is why we don't
793                  * need to set EXT4_FREE_BLOCKS_METADATA.
794                  */
795                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1,
796                                  EXT4_FREE_BLOCKS_FORGET);
797         }
798         for (i = n+1; i < indirect_blks; i++)
799                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0);
800
801         ext4_free_blocks(handle, inode, 0, new_blocks[i], num, 0);
802
803         return err;
804 }
805
806 /**
807  * ext4_splice_branch - splice the allocated branch onto inode.
808  * @inode: owner
809  * @block: (logical) number of block we are adding
810  * @chain: chain of indirect blocks (with a missing link - see
811  *      ext4_alloc_branch)
812  * @where: location of missing link
813  * @num:   number of indirect blocks we are adding
814  * @blks:  number of direct blocks we are adding
815  *
816  * This function fills the missing link and does all housekeeping needed in
817  * inode (->i_blocks, etc.). In case of success we end up with the full
818  * chain to new block and return 0.
819  */
820 static int ext4_splice_branch(handle_t *handle, struct inode *inode,
821                               ext4_lblk_t block, Indirect *where, int num,
822                               int blks)
823 {
824         int i;
825         int err = 0;
826         ext4_fsblk_t current_block;
827
828         /*
829          * If we're splicing into a [td]indirect block (as opposed to the
830          * inode) then we need to get write access to the [td]indirect block
831          * before the splice.
832          */
833         if (where->bh) {
834                 BUFFER_TRACE(where->bh, "get_write_access");
835                 err = ext4_journal_get_write_access(handle, where->bh);
836                 if (err)
837                         goto err_out;
838         }
839         /* That's it */
840
841         *where->p = where->key;
842
843         /*
844          * Update the host buffer_head or inode to point to more just allocated
845          * direct blocks blocks
846          */
847         if (num == 0 && blks > 1) {
848                 current_block = le32_to_cpu(where->key) + 1;
849                 for (i = 1; i < blks; i++)
850                         *(where->p + i) = cpu_to_le32(current_block++);
851         }
852
853         /* We are done with atomic stuff, now do the rest of housekeeping */
854         /* had we spliced it onto indirect block? */
855         if (where->bh) {
856                 /*
857                  * If we spliced it onto an indirect block, we haven't
858                  * altered the inode.  Note however that if it is being spliced
859                  * onto an indirect block at the very end of the file (the
860                  * file is growing) then we *will* alter the inode to reflect
861                  * the new i_size.  But that is not done here - it is done in
862                  * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
863                  */
864                 jbd_debug(5, "splicing indirect only\n");
865                 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
866                 err = ext4_handle_dirty_metadata(handle, inode, where->bh);
867                 if (err)
868                         goto err_out;
869         } else {
870                 /*
871                  * OK, we spliced it into the inode itself on a direct block.
872                  */
873                 ext4_mark_inode_dirty(handle, inode);
874                 jbd_debug(5, "splicing direct\n");
875         }
876         return err;
877
878 err_out:
879         for (i = 1; i <= num; i++) {
880                 /*
881                  * branch[i].bh is newly allocated, so there is no
882                  * need to revoke the block, which is why we don't
883                  * need to set EXT4_FREE_BLOCKS_METADATA.
884                  */
885                 ext4_free_blocks(handle, inode, where[i].bh, 0, 1,
886                                  EXT4_FREE_BLOCKS_FORGET);
887         }
888         ext4_free_blocks(handle, inode, 0, le32_to_cpu(where[num].key),
889                          blks, 0);
890
891         return err;
892 }
893
894 /*
895  * The ext4_ind_map_blocks() function handles non-extents inodes
896  * (i.e., using the traditional indirect/double-indirect i_blocks
897  * scheme) for ext4_map_blocks().
898  *
899  * Allocation strategy is simple: if we have to allocate something, we will
900  * have to go the whole way to leaf. So let's do it before attaching anything
901  * to tree, set linkage between the newborn blocks, write them if sync is
902  * required, recheck the path, free and repeat if check fails, otherwise
903  * set the last missing link (that will protect us from any truncate-generated
904  * removals - all blocks on the path are immune now) and possibly force the
905  * write on the parent block.
906  * That has a nice additional property: no special recovery from the failed
907  * allocations is needed - we simply release blocks and do not touch anything
908  * reachable from inode.
909  *
910  * `handle' can be NULL if create == 0.
911  *
912  * return > 0, # of blocks mapped or allocated.
913  * return = 0, if plain lookup failed.
914  * return < 0, error case.
915  *
916  * The ext4_ind_get_blocks() function should be called with
917  * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
918  * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
919  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
920  * blocks.
921  */
922 static int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
923                                struct ext4_map_blocks *map,
924                                int flags)
925 {
926         int err = -EIO;
927         ext4_lblk_t offsets[4];
928         Indirect chain[4];
929         Indirect *partial;
930         ext4_fsblk_t goal;
931         int indirect_blks;
932         int blocks_to_boundary = 0;
933         int depth;
934         int count = 0;
935         ext4_fsblk_t first_block = 0;
936
937         J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
938         J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
939         depth = ext4_block_to_path(inode, map->m_lblk, offsets,
940                                    &blocks_to_boundary);
941
942         if (depth == 0)
943                 goto out;
944
945         partial = ext4_get_branch(inode, depth, offsets, chain, &err);
946
947         /* Simplest case - block found, no allocation needed */
948         if (!partial) {
949                 first_block = le32_to_cpu(chain[depth - 1].key);
950                 count++;
951                 /*map more blocks*/
952                 while (count < map->m_len && count <= blocks_to_boundary) {
953                         ext4_fsblk_t blk;
954
955                         blk = le32_to_cpu(*(chain[depth-1].p + count));
956
957                         if (blk == first_block + count)
958                                 count++;
959                         else
960                                 break;
961                 }
962                 goto got_it;
963         }
964
965         /* Next simple case - plain lookup or failed read of indirect block */
966         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
967                 goto cleanup;
968
969         /*
970          * Okay, we need to do block allocation.
971         */
972         goal = ext4_find_goal(inode, map->m_lblk, partial);
973
974         /* the number of blocks need to allocate for [d,t]indirect blocks */
975         indirect_blks = (chain + depth) - partial - 1;
976
977         /*
978          * Next look up the indirect map to count the totoal number of
979          * direct blocks to allocate for this branch.
980          */
981         count = ext4_blks_to_allocate(partial, indirect_blks,
982                                       map->m_len, blocks_to_boundary);
983         /*
984          * Block out ext4_truncate while we alter the tree
985          */
986         err = ext4_alloc_branch(handle, inode, map->m_lblk, indirect_blks,
987                                 &count, goal,
988                                 offsets + (partial - chain), partial);
989
990         /*
991          * The ext4_splice_branch call will free and forget any buffers
992          * on the new chain if there is a failure, but that risks using
993          * up transaction credits, especially for bitmaps where the
994          * credits cannot be returned.  Can we handle this somehow?  We
995          * may need to return -EAGAIN upwards in the worst case.  --sct
996          */
997         if (!err)
998                 err = ext4_splice_branch(handle, inode, map->m_lblk,
999                                          partial, indirect_blks, count);
1000         if (err)
1001                 goto cleanup;
1002
1003         map->m_flags |= EXT4_MAP_NEW;
1004
1005         ext4_update_inode_fsync_trans(handle, inode, 1);
1006 got_it:
1007         map->m_flags |= EXT4_MAP_MAPPED;
1008         map->m_pblk = le32_to_cpu(chain[depth-1].key);
1009         map->m_len = count;
1010         if (count > blocks_to_boundary)
1011                 map->m_flags |= EXT4_MAP_BOUNDARY;
1012         err = count;
1013         /* Clean up and exit */
1014         partial = chain + depth - 1;    /* the whole chain */
1015 cleanup:
1016         while (partial > chain) {
1017                 BUFFER_TRACE(partial->bh, "call brelse");
1018                 brelse(partial->bh);
1019                 partial--;
1020         }
1021 out:
1022         return err;
1023 }
1024
1025 #ifdef CONFIG_QUOTA
1026 qsize_t *ext4_get_reserved_space(struct inode *inode)
1027 {
1028         return &EXT4_I(inode)->i_reserved_quota;
1029 }
1030 #endif
1031
1032 /*
1033  * Calculate the number of metadata blocks need to reserve
1034  * to allocate a new block at @lblocks for non extent file based file
1035  */
1036 static int ext4_indirect_calc_metadata_amount(struct inode *inode,
1037                                               sector_t lblock)
1038 {
1039         struct ext4_inode_info *ei = EXT4_I(inode);
1040         sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
1041         int blk_bits;
1042
1043         if (lblock < EXT4_NDIR_BLOCKS)
1044                 return 0;
1045
1046         lblock -= EXT4_NDIR_BLOCKS;
1047
1048         if (ei->i_da_metadata_calc_len &&
1049             (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
1050                 ei->i_da_metadata_calc_len++;
1051                 return 0;
1052         }
1053         ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
1054         ei->i_da_metadata_calc_len = 1;
1055         blk_bits = order_base_2(lblock);
1056         return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
1057 }
1058
1059 /*
1060  * Calculate the number of metadata blocks need to reserve
1061  * to allocate a block located at @lblock
1062  */
1063 static int ext4_calc_metadata_amount(struct inode *inode, sector_t lblock)
1064 {
1065         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1066                 return ext4_ext_calc_metadata_amount(inode, lblock);
1067
1068         return ext4_indirect_calc_metadata_amount(inode, lblock);
1069 }
1070
1071 /*
1072  * Called with i_data_sem down, which is important since we can call
1073  * ext4_discard_preallocations() from here.
1074  */
1075 void ext4_da_update_reserve_space(struct inode *inode,
1076                                         int used, int quota_claim)
1077 {
1078         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1079         struct ext4_inode_info *ei = EXT4_I(inode);
1080
1081         spin_lock(&ei->i_block_reservation_lock);
1082         trace_ext4_da_update_reserve_space(inode, used);
1083         if (unlikely(used > ei->i_reserved_data_blocks)) {
1084                 ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, used %d "
1085                          "with only %d reserved data blocks\n",
1086                          __func__, inode->i_ino, used,
1087                          ei->i_reserved_data_blocks);
1088                 WARN_ON(1);
1089                 used = ei->i_reserved_data_blocks;
1090         }
1091
1092         /* Update per-inode reservations */
1093         ei->i_reserved_data_blocks -= used;
1094         ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
1095         percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1096                            used + ei->i_allocated_meta_blocks);
1097         ei->i_allocated_meta_blocks = 0;
1098
1099         if (ei->i_reserved_data_blocks == 0) {
1100                 /*
1101                  * We can release all of the reserved metadata blocks
1102                  * only when we have written all of the delayed
1103                  * allocation blocks.
1104                  */
1105                 percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1106                                    ei->i_reserved_meta_blocks);
1107                 ei->i_reserved_meta_blocks = 0;
1108                 ei->i_da_metadata_calc_len = 0;
1109         }
1110         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1111
1112         /* Update quota subsystem for data blocks */
1113         if (quota_claim)
1114                 dquot_claim_block(inode, used);
1115         else {
1116                 /*
1117                  * We did fallocate with an offset that is already delayed
1118                  * allocated. So on delayed allocated writeback we should
1119                  * not re-claim the quota for fallocated blocks.
1120                  */
1121                 dquot_release_reservation_block(inode, used);
1122         }
1123
1124         /*
1125          * If we have done all the pending block allocations and if
1126          * there aren't any writers on the inode, we can discard the
1127          * inode's preallocations.
1128          */
1129         if ((ei->i_reserved_data_blocks == 0) &&
1130             (atomic_read(&inode->i_writecount) == 0))
1131                 ext4_discard_preallocations(inode);
1132 }
1133
1134 static int __check_block_validity(struct inode *inode, const char *func,
1135                                 unsigned int line,
1136                                 struct ext4_map_blocks *map)
1137 {
1138         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
1139                                    map->m_len)) {
1140                 ext4_error_inode(inode, func, line, map->m_pblk,
1141                                  "lblock %lu mapped to illegal pblock "
1142                                  "(length %d)", (unsigned long) map->m_lblk,
1143                                  map->m_len);
1144                 return -EIO;
1145         }
1146         return 0;
1147 }
1148
1149 #define check_block_validity(inode, map)        \
1150         __check_block_validity((inode), __func__, __LINE__, (map))
1151
1152 /*
1153  * Return the number of contiguous dirty pages in a given inode
1154  * starting at page frame idx.
1155  */
1156 static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
1157                                     unsigned int max_pages)
1158 {
1159         struct address_space *mapping = inode->i_mapping;
1160         pgoff_t index;
1161         struct pagevec pvec;
1162         pgoff_t num = 0;
1163         int i, nr_pages, done = 0;
1164
1165         if (max_pages == 0)
1166                 return 0;
1167         pagevec_init(&pvec, 0);
1168         while (!done) {
1169                 index = idx;
1170                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
1171                                               PAGECACHE_TAG_DIRTY,
1172                                               (pgoff_t)PAGEVEC_SIZE);
1173                 if (nr_pages == 0)
1174                         break;
1175                 for (i = 0; i < nr_pages; i++) {
1176                         struct page *page = pvec.pages[i];
1177                         struct buffer_head *bh, *head;
1178
1179                         lock_page(page);
1180                         if (unlikely(page->mapping != mapping) ||
1181                             !PageDirty(page) ||
1182                             PageWriteback(page) ||
1183                             page->index != idx) {
1184                                 done = 1;
1185                                 unlock_page(page);
1186                                 break;
1187                         }
1188                         if (page_has_buffers(page)) {
1189                                 bh = head = page_buffers(page);
1190                                 do {
1191                                         if (!buffer_delay(bh) &&
1192                                             !buffer_unwritten(bh))
1193                                                 done = 1;
1194                                         bh = bh->b_this_page;
1195                                 } while (!done && (bh != head));
1196                         }
1197                         unlock_page(page);
1198                         if (done)
1199                                 break;
1200                         idx++;
1201                         num++;
1202                         if (num >= max_pages)
1203                                 break;
1204                 }
1205                 pagevec_release(&pvec);
1206         }
1207         return num;
1208 }
1209
1210 /*
1211  * The ext4_map_blocks() function tries to look up the requested blocks,
1212  * and returns if the blocks are already mapped.
1213  *
1214  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
1215  * and store the allocated blocks in the result buffer head and mark it
1216  * mapped.
1217  *
1218  * If file type is extents based, it will call ext4_ext_map_blocks(),
1219  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
1220  * based files
1221  *
1222  * On success, it returns the number of blocks being mapped or allocate.
1223  * if create==0 and the blocks are pre-allocated and uninitialized block,
1224  * the result buffer head is unmapped. If the create ==1, it will make sure
1225  * the buffer head is mapped.
1226  *
1227  * It returns 0 if plain look up failed (blocks have not been allocated), in
1228  * that casem, buffer head is unmapped
1229  *
1230  * It returns the error in case of allocation failure.
1231  */
1232 int ext4_map_blocks(handle_t *handle, struct inode *inode,
1233                     struct ext4_map_blocks *map, int flags)
1234 {
1235         int retval;
1236
1237         map->m_flags = 0;
1238         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
1239                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
1240                   (unsigned long) map->m_lblk);
1241         /*
1242          * Try to see if we can get the block without requesting a new
1243          * file system block.
1244          */
1245         down_read((&EXT4_I(inode)->i_data_sem));
1246         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
1247                 retval = ext4_ext_map_blocks(handle, inode, map, 0);
1248         } else {
1249                 retval = ext4_ind_map_blocks(handle, inode, map, 0);
1250         }
1251         up_read((&EXT4_I(inode)->i_data_sem));
1252
1253         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
1254                 int ret = check_block_validity(inode, map);
1255                 if (ret != 0)
1256                         return ret;
1257         }
1258
1259         /* If it is only a block(s) look up */
1260         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
1261                 return retval;
1262
1263         /*
1264          * Returns if the blocks have already allocated
1265          *
1266          * Note that if blocks have been preallocated
1267          * ext4_ext_get_block() returns th create = 0
1268          * with buffer head unmapped.
1269          */
1270         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
1271                 return retval;
1272
1273         /*
1274          * When we call get_blocks without the create flag, the
1275          * BH_Unwritten flag could have gotten set if the blocks
1276          * requested were part of a uninitialized extent.  We need to
1277          * clear this flag now that we are committed to convert all or
1278          * part of the uninitialized extent to be an initialized
1279          * extent.  This is because we need to avoid the combination
1280          * of BH_Unwritten and BH_Mapped flags being simultaneously
1281          * set on the buffer_head.
1282          */
1283         map->m_flags &= ~EXT4_MAP_UNWRITTEN;
1284
1285         /*
1286          * New blocks allocate and/or writing to uninitialized extent
1287          * will possibly result in updating i_data, so we take
1288          * the write lock of i_data_sem, and call get_blocks()
1289          * with create == 1 flag.
1290          */
1291         down_write((&EXT4_I(inode)->i_data_sem));
1292
1293         /*
1294          * if the caller is from delayed allocation writeout path
1295          * we have already reserved fs blocks for allocation
1296          * let the underlying get_block() function know to
1297          * avoid double accounting
1298          */
1299         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1300                 EXT4_I(inode)->i_delalloc_reserved_flag = 1;
1301         /*
1302          * We need to check for EXT4 here because migrate
1303          * could have changed the inode type in between
1304          */
1305         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
1306                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
1307         } else {
1308                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
1309
1310                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
1311                         /*
1312                          * We allocated new blocks which will result in
1313                          * i_data's format changing.  Force the migrate
1314                          * to fail by clearing migrate flags
1315                          */
1316                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
1317                 }
1318
1319                 /*
1320                  * Update reserved blocks/metadata blocks after successful
1321                  * block allocation which had been deferred till now. We don't
1322                  * support fallocate for non extent files. So we can update
1323                  * reserve space here.
1324                  */
1325                 if ((retval > 0) &&
1326                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
1327                         ext4_da_update_reserve_space(inode, retval, 1);
1328         }
1329         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1330                 EXT4_I(inode)->i_delalloc_reserved_flag = 0;
1331
1332         up_write((&EXT4_I(inode)->i_data_sem));
1333         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
1334                 int ret = check_block_validity(inode, map);
1335                 if (ret != 0)
1336                         return ret;
1337         }
1338         return retval;
1339 }
1340
1341 /* Maximum number of blocks we map for direct IO at once. */
1342 #define DIO_MAX_BLOCKS 4096
1343
1344 static int _ext4_get_block(struct inode *inode, sector_t iblock,
1345                            struct buffer_head *bh, int flags)
1346 {
1347         handle_t *handle = ext4_journal_current_handle();
1348         struct ext4_map_blocks map;
1349         int ret = 0, started = 0;
1350         int dio_credits;
1351
1352         map.m_lblk = iblock;
1353         map.m_len = bh->b_size >> inode->i_blkbits;
1354
1355         if (flags && !handle) {
1356                 /* Direct IO write... */
1357                 if (map.m_len > DIO_MAX_BLOCKS)
1358                         map.m_len = DIO_MAX_BLOCKS;
1359                 dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
1360                 handle = ext4_journal_start(inode, dio_credits);
1361                 if (IS_ERR(handle)) {
1362                         ret = PTR_ERR(handle);
1363                         return ret;
1364                 }
1365                 started = 1;
1366         }
1367
1368         ret = ext4_map_blocks(handle, inode, &map, flags);
1369         if (ret > 0) {
1370                 map_bh(bh, inode->i_sb, map.m_pblk);
1371                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
1372                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
1373                 ret = 0;
1374         }
1375         if (started)
1376                 ext4_journal_stop(handle);
1377         return ret;
1378 }
1379
1380 int ext4_get_block(struct inode *inode, sector_t iblock,
1381                    struct buffer_head *bh, int create)
1382 {
1383         return _ext4_get_block(inode, iblock, bh,
1384                                create ? EXT4_GET_BLOCKS_CREATE : 0);
1385 }
1386
1387 /*
1388  * `handle' can be NULL if create is zero
1389  */
1390 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
1391                                 ext4_lblk_t block, int create, int *errp)
1392 {
1393         struct ext4_map_blocks map;
1394         struct buffer_head *bh;
1395         int fatal = 0, err;
1396
1397         J_ASSERT(handle != NULL || create == 0);
1398
1399         map.m_lblk = block;
1400         map.m_len = 1;
1401         err = ext4_map_blocks(handle, inode, &map,
1402                               create ? EXT4_GET_BLOCKS_CREATE : 0);
1403
1404         if (err < 0)
1405                 *errp = err;
1406         if (err <= 0)
1407                 return NULL;
1408         *errp = 0;
1409
1410         bh = sb_getblk(inode->i_sb, map.m_pblk);
1411         if (!bh) {
1412                 *errp = -EIO;
1413                 return NULL;
1414         }
1415         if (map.m_flags & EXT4_MAP_NEW) {
1416                 J_ASSERT(create != 0);
1417                 J_ASSERT(handle != NULL);
1418
1419                 /*
1420                  * Now that we do not always journal data, we should
1421                  * keep in mind whether this should always journal the
1422                  * new buffer as metadata.  For now, regular file
1423                  * writes use ext4_get_block instead, so it's not a
1424                  * problem.
1425                  */
1426                 lock_buffer(bh);
1427                 BUFFER_TRACE(bh, "call get_create_access");
1428                 fatal = ext4_journal_get_create_access(handle, bh);
1429                 if (!fatal && !buffer_uptodate(bh)) {
1430                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
1431                         set_buffer_uptodate(bh);
1432                 }
1433                 unlock_buffer(bh);
1434                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
1435                 err = ext4_handle_dirty_metadata(handle, inode, bh);
1436                 if (!fatal)
1437                         fatal = err;
1438         } else {
1439                 BUFFER_TRACE(bh, "not a new buffer");
1440         }
1441         if (fatal) {
1442                 *errp = fatal;
1443                 brelse(bh);
1444                 bh = NULL;
1445         }
1446         return bh;
1447 }
1448
1449 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1450                                ext4_lblk_t block, int create, int *err)
1451 {
1452         struct buffer_head *bh;
1453
1454         bh = ext4_getblk(handle, inode, block, create, err);
1455         if (!bh)
1456                 return bh;
1457         if (buffer_uptodate(bh))
1458                 return bh;
1459         ll_rw_block(READ_META, 1, &bh);
1460         wait_on_buffer(bh);
1461         if (buffer_uptodate(bh))
1462                 return bh;
1463         put_bh(bh);
1464         *err = -EIO;
1465         return NULL;
1466 }
1467
1468 static int walk_page_buffers(handle_t *handle,
1469                              struct buffer_head *head,
1470                              unsigned from,
1471                              unsigned to,
1472                              int *partial,
1473                              int (*fn)(handle_t *handle,
1474                                        struct buffer_head *bh))
1475 {
1476         struct buffer_head *bh;
1477         unsigned block_start, block_end;
1478         unsigned blocksize = head->b_size;
1479         int err, ret = 0;
1480         struct buffer_head *next;
1481
1482         for (bh = head, block_start = 0;
1483              ret == 0 && (bh != head || !block_start);
1484              block_start = block_end, bh = next) {
1485                 next = bh->b_this_page;
1486                 block_end = block_start + blocksize;
1487                 if (block_end <= from || block_start >= to) {
1488                         if (partial && !buffer_uptodate(bh))
1489                                 *partial = 1;
1490                         continue;
1491                 }
1492                 err = (*fn)(handle, bh);
1493                 if (!ret)
1494                         ret = err;
1495         }
1496         return ret;
1497 }
1498
1499 /*
1500  * To preserve ordering, it is essential that the hole instantiation and
1501  * the data write be encapsulated in a single transaction.  We cannot
1502  * close off a transaction and start a new one between the ext4_get_block()
1503  * and the commit_write().  So doing the jbd2_journal_start at the start of
1504  * prepare_write() is the right place.
1505  *
1506  * Also, this function can nest inside ext4_writepage() ->
1507  * block_write_full_page(). In that case, we *know* that ext4_writepage()
1508  * has generated enough buffer credits to do the whole page.  So we won't
1509  * block on the journal in that case, which is good, because the caller may
1510  * be PF_MEMALLOC.
1511  *
1512  * By accident, ext4 can be reentered when a transaction is open via
1513  * quota file writes.  If we were to commit the transaction while thus
1514  * reentered, there can be a deadlock - we would be holding a quota
1515  * lock, and the commit would never complete if another thread had a
1516  * transaction open and was blocking on the quota lock - a ranking
1517  * violation.
1518  *
1519  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1520  * will _not_ run commit under these circumstances because handle->h_ref
1521  * is elevated.  We'll still have enough credits for the tiny quotafile
1522  * write.
1523  */
1524 static int do_journal_get_write_access(handle_t *handle,
1525                                        struct buffer_head *bh)
1526 {
1527         if (!buffer_mapped(bh) || buffer_freed(bh))
1528                 return 0;
1529         return ext4_journal_get_write_access(handle, bh);
1530 }
1531
1532 /*
1533  * Truncate blocks that were not used by write. We have to truncate the
1534  * pagecache as well so that corresponding buffers get properly unmapped.
1535  */
1536 static void ext4_truncate_failed_write(struct inode *inode)
1537 {
1538         truncate_inode_pages(inode->i_mapping, inode->i_size);
1539         ext4_truncate(inode);
1540 }
1541
1542 static int ext4_get_block_write(struct inode *inode, sector_t iblock,
1543                    struct buffer_head *bh_result, int create);
1544 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1545                             loff_t pos, unsigned len, unsigned flags,
1546                             struct page **pagep, void **fsdata)
1547 {
1548         struct inode *inode = mapping->host;
1549         int ret, needed_blocks;
1550         handle_t *handle;
1551         int retries = 0;
1552         struct page *page;
1553         pgoff_t index;
1554         unsigned from, to;
1555
1556         trace_ext4_write_begin(inode, pos, len, flags);
1557         /*
1558          * Reserve one block more for addition to orphan list in case
1559          * we allocate blocks but write fails for some reason
1560          */
1561         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1562         index = pos >> PAGE_CACHE_SHIFT;
1563         from = pos & (PAGE_CACHE_SIZE - 1);
1564         to = from + len;
1565
1566 retry:
1567         handle = ext4_journal_start(inode, needed_blocks);
1568         if (IS_ERR(handle)) {
1569                 ret = PTR_ERR(handle);
1570                 goto out;
1571         }
1572
1573         /* We cannot recurse into the filesystem as the transaction is already
1574          * started */
1575         flags |= AOP_FLAG_NOFS;
1576
1577         page = grab_cache_page_write_begin(mapping, index, flags);
1578         if (!page) {
1579                 ext4_journal_stop(handle);
1580                 ret = -ENOMEM;
1581                 goto out;
1582         }
1583         *pagep = page;
1584
1585         if (ext4_should_dioread_nolock(inode))
1586                 ret = block_write_begin(file, mapping, pos, len, flags, pagep,
1587                                 fsdata, ext4_get_block_write);
1588         else
1589                 ret = block_write_begin(file, mapping, pos, len, flags, pagep,
1590                                 fsdata, ext4_get_block);
1591
1592         if (!ret && ext4_should_journal_data(inode)) {
1593                 ret = walk_page_buffers(handle, page_buffers(page),
1594                                 from, to, NULL, do_journal_get_write_access);
1595         }
1596
1597         if (ret) {
1598                 unlock_page(page);
1599                 page_cache_release(page);
1600                 /*
1601                  * block_write_begin may have instantiated a few blocks
1602                  * outside i_size.  Trim these off again. Don't need
1603                  * i_size_read because we hold i_mutex.
1604                  *
1605                  * Add inode to orphan list in case we crash before
1606                  * truncate finishes
1607                  */
1608                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1609                         ext4_orphan_add(handle, inode);
1610
1611                 ext4_journal_stop(handle);
1612                 if (pos + len > inode->i_size) {
1613                         ext4_truncate_failed_write(inode);
1614                         /*
1615                          * If truncate failed early the inode might
1616                          * still be on the orphan list; we need to
1617                          * make sure the inode is removed from the
1618                          * orphan list in that case.
1619                          */
1620                         if (inode->i_nlink)
1621                                 ext4_orphan_del(NULL, inode);
1622                 }
1623         }
1624
1625         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1626                 goto retry;
1627 out:
1628         return ret;
1629 }
1630
1631 /* For write_end() in data=journal mode */
1632 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1633 {
1634         if (!buffer_mapped(bh) || buffer_freed(bh))
1635                 return 0;
1636         set_buffer_uptodate(bh);
1637         return ext4_handle_dirty_metadata(handle, NULL, bh);
1638 }
1639
1640 static int ext4_generic_write_end(struct file *file,
1641                                   struct address_space *mapping,
1642                                   loff_t pos, unsigned len, unsigned copied,
1643                                   struct page *page, void *fsdata)
1644 {
1645         int i_size_changed = 0;
1646         struct inode *inode = mapping->host;
1647         handle_t *handle = ext4_journal_current_handle();
1648
1649         copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1650
1651         /*
1652          * No need to use i_size_read() here, the i_size
1653          * cannot change under us because we hold i_mutex.
1654          *
1655          * But it's important to update i_size while still holding page lock:
1656          * page writeout could otherwise come in and zero beyond i_size.
1657          */
1658         if (pos + copied > inode->i_size) {
1659                 i_size_write(inode, pos + copied);
1660                 i_size_changed = 1;
1661         }
1662
1663         if (pos + copied >  EXT4_I(inode)->i_disksize) {
1664                 /* We need to mark inode dirty even if
1665                  * new_i_size is less that inode->i_size
1666                  * bu greater than i_disksize.(hint delalloc)
1667                  */
1668                 ext4_update_i_disksize(inode, (pos + copied));
1669                 i_size_changed = 1;
1670         }
1671         unlock_page(page);
1672         page_cache_release(page);
1673
1674         /*
1675          * Don't mark the inode dirty under page lock. First, it unnecessarily
1676          * makes the holding time of page lock longer. Second, it forces lock
1677          * ordering of page lock and transaction start for journaling
1678          * filesystems.
1679          */
1680         if (i_size_changed)
1681                 ext4_mark_inode_dirty(handle, inode);
1682
1683         return copied;
1684 }
1685
1686 /*
1687  * We need to pick up the new inode size which generic_commit_write gave us
1688  * `file' can be NULL - eg, when called from page_symlink().
1689  *
1690  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1691  * buffers are managed internally.
1692  */
1693 static int ext4_ordered_write_end(struct file *file,
1694                                   struct address_space *mapping,
1695                                   loff_t pos, unsigned len, unsigned copied,
1696                                   struct page *page, void *fsdata)
1697 {
1698         handle_t *handle = ext4_journal_current_handle();
1699         struct inode *inode = mapping->host;
1700         int ret = 0, ret2;
1701
1702         trace_ext4_ordered_write_end(inode, pos, len, copied);
1703         ret = ext4_jbd2_file_inode(handle, inode);
1704
1705         if (ret == 0) {
1706                 ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1707                                                         page, fsdata);
1708                 copied = ret2;
1709                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1710                         /* if we have allocated more blocks and copied
1711                          * less. We will have blocks allocated outside
1712                          * inode->i_size. So truncate them
1713                          */
1714                         ext4_orphan_add(handle, inode);
1715                 if (ret2 < 0)
1716                         ret = ret2;
1717         }
1718         ret2 = ext4_journal_stop(handle);
1719         if (!ret)
1720                 ret = ret2;
1721
1722         if (pos + len > inode->i_size) {
1723                 ext4_truncate_failed_write(inode);
1724                 /*
1725                  * If truncate failed early the inode might still be
1726                  * on the orphan list; we need to make sure the inode
1727                  * is removed from the orphan list in that case.
1728                  */
1729                 if (inode->i_nlink)
1730                         ext4_orphan_del(NULL, inode);
1731         }
1732
1733
1734         return ret ? ret : copied;
1735 }
1736
1737 static int ext4_writeback_write_end(struct file *file,
1738                                     struct address_space *mapping,
1739                                     loff_t pos, unsigned len, unsigned copied,
1740                                     struct page *page, void *fsdata)
1741 {
1742         handle_t *handle = ext4_journal_current_handle();
1743         struct inode *inode = mapping->host;
1744         int ret = 0, ret2;
1745
1746         trace_ext4_writeback_write_end(inode, pos, len, copied);
1747         ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1748                                                         page, fsdata);
1749         copied = ret2;
1750         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1751                 /* if we have allocated more blocks and copied
1752                  * less. We will have blocks allocated outside
1753                  * inode->i_size. So truncate them
1754                  */
1755                 ext4_orphan_add(handle, inode);
1756
1757         if (ret2 < 0)
1758                 ret = ret2;
1759
1760         ret2 = ext4_journal_stop(handle);
1761         if (!ret)
1762                 ret = ret2;
1763
1764         if (pos + len > inode->i_size) {
1765                 ext4_truncate_failed_write(inode);
1766                 /*
1767                  * If truncate failed early the inode might still be
1768                  * on the orphan list; we need to make sure the inode
1769                  * is removed from the orphan list in that case.
1770                  */
1771                 if (inode->i_nlink)
1772                         ext4_orphan_del(NULL, inode);
1773         }
1774
1775         return ret ? ret : copied;
1776 }
1777
1778 static int ext4_journalled_write_end(struct file *file,
1779                                      struct address_space *mapping,
1780                                      loff_t pos, unsigned len, unsigned copied,
1781                                      struct page *page, void *fsdata)
1782 {
1783         handle_t *handle = ext4_journal_current_handle();
1784         struct inode *inode = mapping->host;
1785         int ret = 0, ret2;
1786         int partial = 0;
1787         unsigned from, to;
1788         loff_t new_i_size;
1789
1790         trace_ext4_journalled_write_end(inode, pos, len, copied);
1791         from = pos & (PAGE_CACHE_SIZE - 1);
1792         to = from + len;
1793
1794         if (copied < len) {
1795                 if (!PageUptodate(page))
1796                         copied = 0;
1797                 page_zero_new_buffers(page, from+copied, to);
1798         }
1799
1800         ret = walk_page_buffers(handle, page_buffers(page), from,
1801                                 to, &partial, write_end_fn);
1802         if (!partial)
1803                 SetPageUptodate(page);
1804         new_i_size = pos + copied;
1805         if (new_i_size > inode->i_size)
1806                 i_size_write(inode, pos+copied);
1807         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1808         if (new_i_size > EXT4_I(inode)->i_disksize) {
1809                 ext4_update_i_disksize(inode, new_i_size);
1810                 ret2 = ext4_mark_inode_dirty(handle, inode);
1811                 if (!ret)
1812                         ret = ret2;
1813         }
1814
1815         unlock_page(page);
1816         page_cache_release(page);
1817         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1818                 /* if we have allocated more blocks and copied
1819                  * less. We will have blocks allocated outside
1820                  * inode->i_size. So truncate them
1821                  */
1822                 ext4_orphan_add(handle, inode);
1823
1824         ret2 = ext4_journal_stop(handle);
1825         if (!ret)
1826                 ret = ret2;
1827         if (pos + len > inode->i_size) {
1828                 ext4_truncate_failed_write(inode);
1829                 /*
1830                  * If truncate failed early the inode might still be
1831                  * on the orphan list; we need to make sure the inode
1832                  * is removed from the orphan list in that case.
1833                  */
1834                 if (inode->i_nlink)
1835                         ext4_orphan_del(NULL, inode);
1836         }
1837
1838         return ret ? ret : copied;
1839 }
1840
1841 /*
1842  * Reserve a single block located at lblock
1843  */
1844 static int ext4_da_reserve_space(struct inode *inode, sector_t lblock)
1845 {
1846         int retries = 0;
1847         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1848         struct ext4_inode_info *ei = EXT4_I(inode);
1849         unsigned long md_needed;
1850         int ret;
1851
1852         /*
1853          * recalculate the amount of metadata blocks to reserve
1854          * in order to allocate nrblocks
1855          * worse case is one extent per block
1856          */
1857 repeat:
1858         spin_lock(&ei->i_block_reservation_lock);
1859         md_needed = ext4_calc_metadata_amount(inode, lblock);
1860         trace_ext4_da_reserve_space(inode, md_needed);
1861         spin_unlock(&ei->i_block_reservation_lock);
1862
1863         /*
1864          * We will charge metadata quota at writeout time; this saves
1865          * us from metadata over-estimation, though we may go over by
1866          * a small amount in the end.  Here we just reserve for data.
1867          */
1868         ret = dquot_reserve_block(inode, 1);
1869         if (ret)
1870                 return ret;
1871         /*
1872          * We do still charge estimated metadata to the sb though;
1873          * we cannot afford to run out of free blocks.
1874          */
1875         if (ext4_claim_free_blocks(sbi, md_needed + 1)) {
1876                 dquot_release_reservation_block(inode, 1);
1877                 if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1878                         yield();
1879                         goto repeat;
1880                 }
1881                 return -ENOSPC;
1882         }
1883         spin_lock(&ei->i_block_reservation_lock);
1884         ei->i_reserved_data_blocks++;
1885         ei->i_reserved_meta_blocks += md_needed;
1886         spin_unlock(&ei->i_block_reservation_lock);
1887
1888         return 0;       /* success */
1889 }
1890
1891 static void ext4_da_release_space(struct inode *inode, int to_free)
1892 {
1893         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1894         struct ext4_inode_info *ei = EXT4_I(inode);
1895
1896         if (!to_free)
1897                 return;         /* Nothing to release, exit */
1898
1899         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1900
1901         trace_ext4_da_release_space(inode, to_free);
1902         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1903                 /*
1904                  * if there aren't enough reserved blocks, then the
1905                  * counter is messed up somewhere.  Since this
1906                  * function is called from invalidate page, it's
1907                  * harmless to return without any action.
1908                  */
1909                 ext4_msg(inode->i_sb, KERN_NOTICE, "ext4_da_release_space: "
1910                          "ino %lu, to_free %d with only %d reserved "
1911                          "data blocks\n", inode->i_ino, to_free,
1912                          ei->i_reserved_data_blocks);
1913                 WARN_ON(1);
1914                 to_free = ei->i_reserved_data_blocks;
1915         }
1916         ei->i_reserved_data_blocks -= to_free;
1917
1918         if (ei->i_reserved_data_blocks == 0) {
1919                 /*
1920                  * We can release all of the reserved metadata blocks
1921                  * only when we have written all of the delayed
1922                  * allocation blocks.
1923                  */
1924                 percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1925                                    ei->i_reserved_meta_blocks);
1926                 ei->i_reserved_meta_blocks = 0;
1927                 ei->i_da_metadata_calc_len = 0;
1928         }
1929
1930         /* update fs dirty data blocks counter */
1931         percpu_counter_sub(&sbi->s_dirtyblocks_counter, to_free);
1932
1933         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1934
1935         dquot_release_reservation_block(inode, to_free);
1936 }
1937
1938 static void ext4_da_page_release_reservation(struct page *page,
1939                                              unsigned long offset)
1940 {
1941         int to_release = 0;
1942         struct buffer_head *head, *bh;
1943         unsigned int curr_off = 0;
1944
1945         head = page_buffers(page);
1946         bh = head;
1947         do {
1948                 unsigned int next_off = curr_off + bh->b_size;
1949
1950                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1951                         to_release++;
1952                         clear_buffer_delay(bh);
1953                 }
1954                 curr_off = next_off;
1955         } while ((bh = bh->b_this_page) != head);
1956         ext4_da_release_space(page->mapping->host, to_release);
1957 }
1958
1959 /*
1960  * Delayed allocation stuff
1961  */
1962
1963 /*
1964  * mpage_da_submit_io - walks through extent of pages and try to write
1965  * them with writepage() call back
1966  *
1967  * @mpd->inode: inode
1968  * @mpd->first_page: first page of the extent
1969  * @mpd->next_page: page after the last page of the extent
1970  *
1971  * By the time mpage_da_submit_io() is called we expect all blocks
1972  * to be allocated. this may be wrong if allocation failed.
1973  *
1974  * As pages are already locked by write_cache_pages(), we can't use it
1975  */
1976 static int mpage_da_submit_io(struct mpage_da_data *mpd)
1977 {
1978         long pages_skipped;
1979         struct pagevec pvec;
1980         unsigned long index, end;
1981         int ret = 0, err, nr_pages, i;
1982         struct inode *inode = mpd->inode;
1983         struct address_space *mapping = inode->i_mapping;
1984
1985         BUG_ON(mpd->next_page <= mpd->first_page);
1986         /*
1987          * We need to start from the first_page to the next_page - 1
1988          * to make sure we also write the mapped dirty buffer_heads.
1989          * If we look at mpd->b_blocknr we would only be looking
1990          * at the currently mapped buffer_heads.
1991          */
1992         index = mpd->first_page;
1993         end = mpd->next_page - 1;
1994
1995         pagevec_init(&pvec, 0);
1996         while (index <= end) {
1997                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1998                 if (nr_pages == 0)
1999                         break;
2000                 for (i = 0; i < nr_pages; i++) {
2001                         struct page *page = pvec.pages[i];
2002
2003                         index = page->index;
2004                         if (index > end)
2005                                 break;
2006                         index++;
2007
2008                         BUG_ON(!PageLocked(page));
2009                         BUG_ON(PageWriteback(page));
2010
2011                         pages_skipped = mpd->wbc->pages_skipped;
2012                         err = mapping->a_ops->writepage(page, mpd->wbc);
2013                         if (!err && (pages_skipped == mpd->wbc->pages_skipped))
2014                                 /*
2015                                  * have successfully written the page
2016                                  * without skipping the same
2017                                  */
2018                                 mpd->pages_written++;
2019                         /*
2020                          * In error case, we have to continue because
2021                          * remaining pages are still locked
2022                          * XXX: unlock and re-dirty them?
2023                          */
2024                         if (ret == 0)
2025                                 ret = err;
2026                 }
2027                 pagevec_release(&pvec);
2028         }
2029         return ret;
2030 }
2031
2032 /*
2033  * mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
2034  *
2035  * the function goes through all passed space and put actual disk
2036  * block numbers into buffer heads, dropping BH_Delay and BH_Unwritten
2037  */
2038 static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd,
2039                                  struct ext4_map_blocks *map)
2040 {
2041         struct inode *inode = mpd->inode;
2042         struct address_space *mapping = inode->i_mapping;
2043         int blocks = map->m_len;
2044         sector_t pblock = map->m_pblk, cur_logical;
2045         struct buffer_head *head, *bh;
2046         pgoff_t index, end;
2047         struct pagevec pvec;
2048         int nr_pages, i;
2049
2050         index = map->m_lblk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2051         end = (map->m_lblk + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2052         cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2053
2054         pagevec_init(&pvec, 0);
2055
2056         while (index <= end) {
2057                 /* XXX: optimize tail */
2058                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
2059                 if (nr_pages == 0)
2060                         break;
2061                 for (i = 0; i < nr_pages; i++) {
2062                         struct page *page = pvec.pages[i];
2063
2064                         index = page->index;
2065                         if (index > end)
2066                                 break;
2067                         index++;
2068
2069                         BUG_ON(!PageLocked(page));
2070                         BUG_ON(PageWriteback(page));
2071                         BUG_ON(!page_has_buffers(page));
2072
2073                         bh = page_buffers(page);
2074                         head = bh;
2075
2076                         /* skip blocks out of the range */
2077                         do {
2078                                 if (cur_logical >= map->m_lblk)
2079                                         break;
2080                                 cur_logical++;
2081                         } while ((bh = bh->b_this_page) != head);
2082
2083                         do {
2084                                 if (cur_logical >= map->m_lblk + blocks)
2085                                         break;
2086
2087                                 if (buffer_delay(bh) || buffer_unwritten(bh)) {
2088
2089                                         BUG_ON(bh->b_bdev != inode->i_sb->s_bdev);
2090
2091                                         if (buffer_delay(bh)) {
2092                                                 clear_buffer_delay(bh);
2093                                                 bh->b_blocknr = pblock;
2094                                         } else {
2095                                                 /*
2096                                                  * unwritten already should have
2097                                                  * blocknr assigned. Verify that
2098                                                  */
2099                                                 clear_buffer_unwritten(bh);
2100                                                 BUG_ON(bh->b_blocknr != pblock);
2101                                         }
2102
2103                                 } else if (buffer_mapped(bh))
2104                                         BUG_ON(bh->b_blocknr != pblock);
2105
2106                                 if (map->m_flags & EXT4_MAP_UNINIT)
2107                                         set_buffer_uninit(bh);
2108                                 cur_logical++;
2109                                 pblock++;
2110                         } while ((bh = bh->b_this_page) != head);
2111                 }
2112                 pagevec_release(&pvec);
2113         }
2114 }
2115
2116
2117 static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
2118                                         sector_t logical, long blk_cnt)
2119 {
2120         int nr_pages, i;
2121         pgoff_t index, end;
2122         struct pagevec pvec;
2123         struct inode *inode = mpd->inode;
2124         struct address_space *mapping = inode->i_mapping;
2125
2126         index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2127         end   = (logical + blk_cnt - 1) >>
2128                                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
2129         while (index <= end) {
2130                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
2131                 if (nr_pages == 0)
2132                         break;
2133                 for (i = 0; i < nr_pages; i++) {
2134                         struct page *page = pvec.pages[i];
2135                         if (page->index > end)
2136                                 break;
2137                         BUG_ON(!PageLocked(page));
2138                         BUG_ON(PageWriteback(page));
2139                         block_invalidatepage(page, 0);
2140                         ClearPageUptodate(page);
2141                         unlock_page(page);
2142                 }
2143                 index = pvec.pages[nr_pages - 1]->index + 1;
2144                 pagevec_release(&pvec);
2145         }
2146         return;
2147 }
2148
2149 static void ext4_print_free_blocks(struct inode *inode)
2150 {
2151         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2152         printk(KERN_CRIT "Total free blocks count %lld\n",
2153                ext4_count_free_blocks(inode->i_sb));
2154         printk(KERN_CRIT "Free/Dirty block details\n");
2155         printk(KERN_CRIT "free_blocks=%lld\n",
2156                (long long) percpu_counter_sum(&sbi->s_freeblocks_counter));
2157         printk(KERN_CRIT "dirty_blocks=%lld\n",
2158                (long long) percpu_counter_sum(&sbi->s_dirtyblocks_counter));
2159         printk(KERN_CRIT "Block reservation details\n");
2160         printk(KERN_CRIT "i_reserved_data_blocks=%u\n",
2161                EXT4_I(inode)->i_reserved_data_blocks);
2162         printk(KERN_CRIT "i_reserved_meta_blocks=%u\n",
2163                EXT4_I(inode)->i_reserved_meta_blocks);
2164         return;
2165 }
2166
2167 /*
2168  * mpage_da_map_blocks - go through given space
2169  *
2170  * @mpd - bh describing space
2171  *
2172  * The function skips space we know is already mapped to disk blocks.
2173  *
2174  */
2175 static int mpage_da_map_blocks(struct mpage_da_data *mpd)
2176 {
2177         int err, blks, get_blocks_flags;
2178         struct ext4_map_blocks map;
2179         sector_t next = mpd->b_blocknr;
2180         unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
2181         loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
2182         handle_t *handle = NULL;
2183
2184         /*
2185          * We consider only non-mapped and non-allocated blocks
2186          */
2187         if ((mpd->b_state  & (1 << BH_Mapped)) &&
2188                 !(mpd->b_state & (1 << BH_Delay)) &&
2189                 !(mpd->b_state & (1 << BH_Unwritten)))
2190                 return 0;
2191
2192         /*
2193          * If we didn't accumulate anything to write simply return
2194          */
2195         if (!mpd->b_size)
2196                 return 0;
2197
2198         handle = ext4_journal_current_handle();
2199         BUG_ON(!handle);
2200
2201         /*
2202          * Call ext4_get_blocks() to allocate any delayed allocation
2203          * blocks, or to convert an uninitialized extent to be
2204          * initialized (in the case where we have written into
2205          * one or more preallocated blocks).
2206          *
2207          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
2208          * indicate that we are on the delayed allocation path.  This
2209          * affects functions in many different parts of the allocation
2210          * call path.  This flag exists primarily because we don't
2211          * want to change *many* call functions, so ext4_get_blocks()
2212          * will set the magic i_delalloc_reserved_flag once the
2213          * inode's allocation semaphore is taken.
2214          *
2215          * If the blocks in questions were delalloc blocks, set
2216          * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
2217          * variables are updated after the blocks have been allocated.
2218          */
2219         map.m_lblk = next;
2220         map.m_len = max_blocks;
2221         get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
2222         if (ext4_should_dioread_nolock(mpd->inode))
2223                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
2224         if (mpd->b_state & (1 << BH_Delay))
2225                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
2226
2227         blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
2228         if (blks < 0) {
2229                 err = blks;
2230                 /*
2231                  * If get block returns with error we simply
2232                  * return. Later writepage will redirty the page and
2233                  * writepages will find the dirty page again
2234                  */
2235                 if (err == -EAGAIN)
2236                         return 0;
2237
2238                 if (err == -ENOSPC &&
2239                     ext4_count_free_blocks(mpd->inode->i_sb)) {
2240                         mpd->retval = err;
2241                         return 0;
2242                 }
2243
2244                 /*
2245                  * get block failure will cause us to loop in
2246                  * writepages, because a_ops->writepage won't be able
2247                  * to make progress. The page will be redirtied by
2248                  * writepage and writepages will again try to write
2249                  * the same.
2250                  */
2251                 ext4_msg(mpd->inode->i_sb, KERN_CRIT,
2252                          "delayed block allocation failed for inode %lu at "
2253                          "logical offset %llu with max blocks %zd with "
2254                          "error %d", mpd->inode->i_ino,
2255                          (unsigned long long) next,
2256                          mpd->b_size >> mpd->inode->i_blkbits, err);
2257                 printk(KERN_CRIT "This should not happen!!  "
2258                        "Data will be lost\n");
2259                 if (err == -ENOSPC) {
2260                         ext4_print_free_blocks(mpd->inode);
2261                 }
2262                 /* invalidate all the pages */
2263                 ext4_da_block_invalidatepages(mpd, next,
2264                                 mpd->b_size >> mpd->inode->i_blkbits);
2265                 return err;
2266         }
2267         BUG_ON(blks == 0);
2268
2269         if (map.m_flags & EXT4_MAP_NEW) {
2270                 struct block_device *bdev = mpd->inode->i_sb->s_bdev;
2271                 int i;
2272
2273                 for (i = 0; i < map.m_len; i++)
2274                         unmap_underlying_metadata(bdev, map.m_pblk + i);
2275         }
2276
2277         /*
2278          * If blocks are delayed marked, we need to
2279          * put actual blocknr and drop delayed bit
2280          */
2281         if ((mpd->b_state & (1 << BH_Delay)) ||
2282             (mpd->b_state & (1 << BH_Unwritten)))
2283                 mpage_put_bnr_to_bhs(mpd, &map);
2284
2285         if (ext4_should_order_data(mpd->inode)) {
2286                 err = ext4_jbd2_file_inode(handle, mpd->inode);
2287                 if (err)
2288                         return err;
2289         }
2290
2291         /*
2292          * Update on-disk size along with block allocation.
2293          */
2294         disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
2295         if (disksize > i_size_read(mpd->inode))
2296                 disksize = i_size_read(mpd->inode);
2297         if (disksize > EXT4_I(mpd->inode)->i_disksize) {
2298                 ext4_update_i_disksize(mpd->inode, disksize);
2299                 return ext4_mark_inode_dirty(handle, mpd->inode);
2300         }
2301
2302         return 0;
2303 }
2304
2305 #define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
2306                 (1 << BH_Delay) | (1 << BH_Unwritten))
2307
2308 /*
2309  * mpage_add_bh_to_extent - try to add one more block to extent of blocks
2310  *
2311  * @mpd->lbh - extent of blocks
2312  * @logical - logical number of the block in the file
2313  * @bh - bh of the block (used to access block's state)
2314  *
2315  * the function is used to collect contig. blocks in same state
2316  */
2317 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
2318                                    sector_t logical, size_t b_size,
2319                                    unsigned long b_state)
2320 {
2321         sector_t next;
2322         int nrblocks = mpd->b_size >> mpd->inode->i_blkbits;
2323
2324         /*
2325          * XXX Don't go larger than mballoc is willing to allocate
2326          * This is a stopgap solution.  We eventually need to fold
2327          * mpage_da_submit_io() into this function and then call
2328          * ext4_get_blocks() multiple times in a loop
2329          */
2330         if (nrblocks >= 8*1024*1024/mpd->inode->i_sb->s_blocksize)
2331                 goto flush_it;
2332
2333         /* check if thereserved journal credits might overflow */
2334         if (!(ext4_test_inode_flag(mpd->inode, EXT4_INODE_EXTENTS))) {
2335                 if (nrblocks >= EXT4_MAX_TRANS_DATA) {
2336                         /*
2337                          * With non-extent format we are limited by the journal
2338                          * credit available.  Total credit needed to insert
2339                          * nrblocks contiguous blocks is dependent on the
2340                          * nrblocks.  So limit nrblocks.
2341                          */
2342                         goto flush_it;
2343                 } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
2344                                 EXT4_MAX_TRANS_DATA) {
2345                         /*
2346                          * Adding the new buffer_head would make it cross the
2347                          * allowed limit for which we have journal credit
2348                          * reserved. So limit the new bh->b_size
2349                          */
2350                         b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
2351                                                 mpd->inode->i_blkbits;
2352                         /* we will do mpage_da_submit_io in the next loop */
2353                 }
2354         }
2355         /*
2356          * First block in the extent
2357          */
2358         if (mpd->b_size == 0) {
2359                 mpd->b_blocknr = logical;
2360                 mpd->b_size = b_size;
2361                 mpd->b_state = b_state & BH_FLAGS;
2362                 return;
2363         }
2364
2365         next = mpd->b_blocknr + nrblocks;
2366         /*
2367          * Can we merge the block to our big extent?
2368          */
2369         if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
2370                 mpd->b_size += b_size;
2371                 return;
2372         }
2373
2374 flush_it:
2375         /*
2376          * We couldn't merge the block to our extent, so we
2377          * need to flush current  extent and start new one
2378          */
2379         if (mpage_da_map_blocks(mpd) == 0)
2380                 mpage_da_submit_io(mpd);
2381         mpd->io_done = 1;
2382         return;
2383 }
2384
2385 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
2386 {
2387         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
2388 }
2389
2390 /*
2391  * __mpage_da_writepage - finds extent of pages and blocks
2392  *
2393  * @page: page to consider
2394  * @wbc: not used, we just follow rules
2395  * @data: context
2396  *
2397  * The function finds extents of pages and scan them for all blocks.
2398  */
2399 static int __mpage_da_writepage(struct page *page,
2400                                 struct writeback_control *wbc, void *data)
2401 {
2402         struct mpage_da_data *mpd = data;
2403         struct inode *inode = mpd->inode;
2404         struct buffer_head *bh, *head;
2405         sector_t logical;
2406
2407         /*
2408          * Can we merge this page to current extent?
2409          */
2410         if (mpd->next_page != page->index) {
2411                 /*
2412                  * Nope, we can't. So, we map non-allocated blocks
2413                  * and start IO on them using writepage()
2414                  */
2415                 if (mpd->next_page != mpd->first_page) {
2416                         if (mpage_da_map_blocks(mpd) == 0)
2417                                 mpage_da_submit_io(mpd);
2418                         /*
2419                          * skip rest of the page in the page_vec
2420                          */
2421                         mpd->io_done = 1;
2422                         redirty_page_for_writepage(wbc, page);
2423                         unlock_page(page);
2424                         return MPAGE_DA_EXTENT_TAIL;
2425                 }
2426
2427                 /*
2428                  * Start next extent of pages ...
2429                  */
2430                 mpd->first_page = page->index;
2431
2432                 /*
2433                  * ... and blocks
2434                  */
2435                 mpd->b_size = 0;
2436                 mpd->b_state = 0;
2437                 mpd->b_blocknr = 0;
2438         }
2439
2440         mpd->next_page = page->index + 1;
2441         logical = (sector_t) page->index <<
2442                   (PAGE_CACHE_SHIFT - inode->i_blkbits);
2443
2444         if (!page_has_buffers(page)) {
2445                 mpage_add_bh_to_extent(mpd, logical, PAGE_CACHE_SIZE,
2446                                        (1 << BH_Dirty) | (1 << BH_Uptodate));
2447                 if (mpd->io_done)
2448                         return MPAGE_DA_EXTENT_TAIL;
2449         } else {
2450                 /*
2451                  * Page with regular buffer heads, just add all dirty ones
2452                  */
2453                 head = page_buffers(page);
2454                 bh = head;
2455                 do {
2456                         BUG_ON(buffer_locked(bh));
2457                         /*
2458                          * We need to try to allocate
2459                          * unmapped blocks in the same page.
2460                          * Otherwise we won't make progress
2461                          * with the page in ext4_writepage
2462                          */
2463                         if (ext4_bh_delay_or_unwritten(NULL, bh)) {
2464                                 mpage_add_bh_to_extent(mpd, logical,
2465                                                        bh->b_size,
2466                                                        bh->b_state);
2467                                 if (mpd->io_done)
2468                                         return MPAGE_DA_EXTENT_TAIL;
2469                         } else if (buffer_dirty(bh) && (buffer_mapped(bh))) {
2470                                 /*
2471                                  * mapped dirty buffer. We need to update
2472                                  * the b_state because we look at
2473                                  * b_state in mpage_da_map_blocks. We don't
2474                                  * update b_size because if we find an
2475                                  * unmapped buffer_head later we need to
2476                                  * use the b_state flag of that buffer_head.
2477                                  */
2478                                 if (mpd->b_size == 0)
2479                                         mpd->b_state = bh->b_state & BH_FLAGS;
2480                         }
2481                         logical++;
2482                 } while ((bh = bh->b_this_page) != head);
2483         }
2484
2485         return 0;
2486 }
2487
2488 /*
2489  * This is a special get_blocks_t callback which is used by
2490  * ext4_da_write_begin().  It will either return mapped block or
2491  * reserve space for a single block.
2492  *
2493  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
2494  * We also have b_blocknr = -1 and b_bdev initialized properly
2495  *
2496  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
2497  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
2498  * initialized properly.
2499  */
2500 static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
2501                                   struct buffer_head *bh, int create)
2502 {
2503         struct ext4_map_blocks map;
2504         int ret = 0;
2505         sector_t invalid_block = ~((sector_t) 0xffff);
2506
2507         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
2508                 invalid_block = ~0;
2509
2510         BUG_ON(create == 0);
2511         BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
2512
2513         map.m_lblk = iblock;
2514         map.m_len = 1;
2515
2516         /*
2517          * first, we need to know whether the block is allocated already
2518          * preallocated blocks are unmapped but should treated
2519          * the same as allocated blocks.
2520          */
2521         ret = ext4_map_blocks(NULL, inode, &map, 0);
2522         if (ret < 0)
2523                 return ret;
2524         if (ret == 0) {
2525                 if (buffer_delay(bh))
2526                         return 0; /* Not sure this could or should happen */
2527                 /*
2528                  * XXX: __block_prepare_write() unmaps passed block,
2529                  * is it OK?
2530                  */
2531                 ret = ext4_da_reserve_space(inode, iblock);
2532                 if (ret)
2533                         /* not enough space to reserve */
2534                         return ret;
2535
2536                 map_bh(bh, inode->i_sb, invalid_block);
2537                 set_buffer_new(bh);
2538                 set_buffer_delay(bh);
2539                 return 0;
2540         }
2541
2542         map_bh(bh, inode->i_sb, map.m_pblk);
2543         bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
2544
2545         if (buffer_unwritten(bh)) {
2546                 /* A delayed write to unwritten bh should be marked
2547                  * new and mapped.  Mapped ensures that we don't do
2548                  * get_block multiple times when we write to the same
2549                  * offset and new ensures that we do proper zero out
2550                  * for partial write.
2551                  */
2552                 set_buffer_new(bh);
2553                 set_buffer_mapped(bh);
2554         }
2555         return 0;
2556 }
2557
2558 /*
2559  * This function is used as a standard get_block_t calback function
2560  * when there is no desire to allocate any blocks.  It is used as a
2561  * callback function for block_prepare_write() and block_write_full_page().
2562  * These functions should only try to map a single block at a time.
2563  *
2564  * Since this function doesn't do block allocations even if the caller
2565  * requests it by passing in create=1, it is critically important that
2566  * any caller checks to make sure that any buffer heads are returned
2567  * by this function are either all already mapped or marked for
2568  * delayed allocation before calling  block_write_full_page().  Otherwise,
2569  * b_blocknr could be left unitialized, and the page write functions will
2570  * be taken by surprise.
2571  */
2572 static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
2573                                    struct buffer_head *bh_result, int create)
2574 {
2575         BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
2576         return _ext4_get_block(inode, iblock, bh_result, 0);
2577 }
2578
2579 static int bget_one(handle_t *handle, struct buffer_head *bh)
2580 {
2581         get_bh(bh);
2582         return 0;
2583 }
2584
2585 static int bput_one(handle_t *handle, struct buffer_head *bh)
2586 {
2587         put_bh(bh);
2588         return 0;
2589 }
2590
2591 static int __ext4_journalled_writepage(struct page *page,
2592                                        unsigned int len)
2593 {
2594         struct address_space *mapping = page->mapping;
2595         struct inode *inode = mapping->host;
2596         struct buffer_head *page_bufs;
2597         handle_t *handle = NULL;
2598         int ret = 0;
2599         int err;
2600
2601         page_bufs = page_buffers(page);
2602         BUG_ON(!page_bufs);
2603         walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
2604         /* As soon as we unlock the page, it can go away, but we have
2605          * references to buffers so we are safe */
2606         unlock_page(page);
2607
2608         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
2609         if (IS_ERR(handle)) {
2610                 ret = PTR_ERR(handle);
2611                 goto out;
2612         }
2613
2614         ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2615                                 do_journal_get_write_access);
2616
2617         err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2618                                 write_end_fn);
2619         if (ret == 0)
2620                 ret = err;
2621         err = ext4_journal_stop(handle);
2622         if (!ret)
2623                 ret = err;
2624
2625         walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
2626         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
2627 out:
2628         return ret;
2629 }
2630
2631 static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
2632 static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
2633
2634 /*
2635  * Note that we don't need to start a transaction unless we're journaling data
2636  * because we should have holes filled from ext4_page_mkwrite(). We even don't
2637  * need to file the inode to the transaction's list in ordered mode because if
2638  * we are writing back data added by write(), the inode is already there and if
2639  * we are writing back data modified via mmap(), noone guarantees in which
2640  * transaction the data will hit the disk. In case we are journaling data, we
2641  * cannot start transaction directly because transaction start ranks above page
2642  * lock so we have to do some magic.
2643  *
2644  * This function can get called via...
2645  *   - ext4_da_writepages after taking page lock (have journal handle)
2646  *   - journal_submit_inode_data_buffers (no journal handle)
2647  *   - shrink_page_list via pdflush (no journal handle)
2648  *   - grab_page_cache when doing write_begin (have journal handle)
2649  *
2650  * We don't do any block allocation in this function. If we have page with
2651  * multiple blocks we need to write those buffer_heads that are mapped. This
2652  * is important for mmaped based write. So if we do with blocksize 1K
2653  * truncate(f, 1024);
2654  * a = mmap(f, 0, 4096);
2655  * a[0] = 'a';
2656  * truncate(f, 4096);
2657  * we have in the page first buffer_head mapped via page_mkwrite call back
2658  * but other bufer_heads would be unmapped but dirty(dirty done via the
2659  * do_wp_page). So writepage should write the first block. If we modify
2660  * the mmap area beyond 1024 we will again get a page_fault and the
2661  * page_mkwrite callback will do the block allocation and mark the
2662  * buffer_heads mapped.
2663  *
2664  * We redirty the page if we have any buffer_heads that is either delay or
2665  * unwritten in the page.
2666  *
2667  * We can get recursively called as show below.
2668  *
2669  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2670  *              ext4_writepage()
2671  *
2672  * But since we don't do any block allocation we should not deadlock.
2673  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2674  */
2675 static int ext4_writepage(struct page *page,
2676                           struct writeback_control *wbc)
2677 {
2678         int ret = 0;
2679         loff_t size;
2680         unsigned int len;
2681         struct buffer_head *page_bufs = NULL;
2682         struct inode *inode = page->mapping->host;
2683
2684         trace_ext4_writepage(inode, page);
2685         size = i_size_read(inode);
2686         if (page->index == size >> PAGE_CACHE_SHIFT)
2687                 len = size & ~PAGE_CACHE_MASK;
2688         else
2689                 len = PAGE_CACHE_SIZE;
2690
2691         if (page_has_buffers(page)) {
2692                 page_bufs = page_buffers(page);
2693                 if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2694                                         ext4_bh_delay_or_unwritten)) {
2695                         /*
2696                          * We don't want to do  block allocation
2697                          * So redirty the page and return
2698                          * We may reach here when we do a journal commit
2699                          * via journal_submit_inode_data_buffers.
2700                          * If we don't have mapping block we just ignore
2701                          * them. We can also reach here via shrink_page_list
2702                          */
2703                         redirty_page_for_writepage(wbc, page);
2704                         unlock_page(page);
2705                         return 0;
2706                 }
2707         } else {
2708                 /*
2709                  * The test for page_has_buffers() is subtle:
2710                  * We know the page is dirty but it lost buffers. That means
2711                  * that at some moment in time after write_begin()/write_end()
2712                  * has been called all buffers have been clean and thus they
2713                  * must have been written at least once. So they are all
2714                  * mapped and we can happily proceed with mapping them
2715                  * and writing the page.
2716                  *
2717                  * Try to initialize the buffer_heads and check whether
2718                  * all are mapped and non delay. We don't want to
2719                  * do block allocation here.
2720                  */
2721                 ret = block_prepare_write(page, 0, len,
2722                                           noalloc_get_block_write);
2723                 if (!ret) {
2724                         page_bufs = page_buffers(page);
2725                         /* check whether all are mapped and non delay */
2726                         if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2727                                                 ext4_bh_delay_or_unwritten)) {
2728                                 redirty_page_for_writepage(wbc, page);
2729                                 unlock_page(page);
2730                                 return 0;
2731                         }
2732                 } else {
2733                         /*
2734                          * We can't do block allocation here
2735                          * so just redity the page and unlock
2736                          * and return
2737                          */
2738                         redirty_page_for_writepage(wbc, page);
2739                         unlock_page(page);
2740                         return 0;
2741                 }
2742                 /* now mark the buffer_heads as dirty and uptodate */
2743                 block_commit_write(page, 0, len);
2744         }
2745
2746         if (PageChecked(page) && ext4_should_journal_data(inode)) {
2747                 /*
2748                  * It's mmapped pagecache.  Add buffers and journal it.  There
2749                  * doesn't seem much point in redirtying the page here.
2750                  */
2751                 ClearPageChecked(page);
2752                 return __ext4_journalled_writepage(page, len);
2753         }
2754
2755         if (page_bufs && buffer_uninit(page_bufs)) {
2756                 ext4_set_bh_endio(page_bufs, inode);
2757                 ret = block_write_full_page_endio(page, noalloc_get_block_write,
2758                                             wbc, ext4_end_io_buffer_write);
2759         } else
2760                 ret = block_write_full_page(page, noalloc_get_block_write,
2761                                             wbc);
2762
2763         return ret;
2764 }
2765
2766 /*
2767  * This is called via ext4_da_writepages() to
2768  * calulate the total number of credits to reserve to fit
2769  * a single extent allocation into a single transaction,
2770  * ext4_da_writpeages() will loop calling this before
2771  * the block allocation.
2772  */
2773
2774 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2775 {
2776         int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
2777
2778         /*
2779          * With non-extent format the journal credit needed to
2780          * insert nrblocks contiguous block is dependent on
2781          * number of contiguous block. So we will limit
2782          * number of contiguous block to a sane value
2783          */
2784         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
2785             (max_blocks > EXT4_MAX_TRANS_DATA))
2786                 max_blocks = EXT4_MAX_TRANS_DATA;
2787
2788         return ext4_chunk_trans_blocks(inode, max_blocks);
2789 }
2790
2791 /*
2792  * write_cache_pages_da - walk the list of dirty pages of the given
2793  * address space and call the callback function (which usually writes
2794  * the pages).
2795  *
2796  * This is a forked version of write_cache_pages().  Differences:
2797  *      Range cyclic is ignored.
2798  *      no_nrwrite_index_update is always presumed true
2799  */
2800 static int write_cache_pages_da(struct address_space *mapping,
2801                                 struct writeback_control *wbc,
2802                                 struct mpage_da_data *mpd)
2803 {
2804         int ret = 0;
2805         int done = 0;
2806         struct pagevec pvec;
2807         int nr_pages;
2808         pgoff_t index;
2809         pgoff_t end;            /* Inclusive */
2810         long nr_to_write = wbc->nr_to_write;
2811
2812         pagevec_init(&pvec, 0);
2813         index = wbc->range_start >> PAGE_CACHE_SHIFT;
2814         end = wbc->range_end >> PAGE_CACHE_SHIFT;
2815
2816         while (!done && (index <= end)) {
2817                 int i;
2818
2819                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
2820                               PAGECACHE_TAG_DIRTY,
2821                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2822                 if (nr_pages == 0)
2823                         break;
2824
2825                 for (i = 0; i < nr_pages; i++) {
2826                         struct page *page = pvec.pages[i];
2827
2828                         /*
2829                          * At this point, the page may be truncated or
2830                          * invalidated (changing page->mapping to NULL), or
2831                          * even swizzled back from swapper_space to tmpfs file
2832                          * mapping. However, page->index will not change
2833                          * because we have a reference on the page.
2834                          */
2835                         if (page->index > end) {
2836                                 done = 1;
2837                                 break;
2838                         }
2839
2840                         lock_page(page);
2841
2842                         /*
2843                          * Page truncated or invalidated. We can freely skip it
2844                          * then, even for data integrity operations: the page
2845                          * has disappeared concurrently, so there could be no
2846                          * real expectation of this data interity operation
2847                          * even if there is now a new, dirty page at the same
2848                          * pagecache address.
2849                          */
2850                         if (unlikely(page->mapping != mapping)) {
2851 continue_unlock:
2852                                 unlock_page(page);
2853                                 continue;
2854                         }
2855
2856                         if (!PageDirty(page)) {
2857                                 /* someone wrote it for us */
2858                                 goto continue_unlock;
2859                         }
2860
2861                         if (PageWriteback(page)) {
2862                                 if (wbc->sync_mode != WB_SYNC_NONE)
2863                                         wait_on_page_writeback(page);
2864                                 else
2865                                         goto continue_unlock;
2866                         }
2867
2868                         BUG_ON(PageWriteback(page));
2869                         if (!clear_page_dirty_for_io(page))
2870                                 goto continue_unlock;
2871
2872                         ret = __mpage_da_writepage(page, wbc, mpd);
2873                         if (unlikely(ret)) {
2874                                 if (ret == AOP_WRITEPAGE_ACTIVATE) {
2875                                         unlock_page(page);
2876                                         ret = 0;
2877                                 } else {
2878                                         done = 1;
2879                                         break;
2880                                 }
2881                         }
2882
2883                         if (nr_to_write > 0) {
2884                                 nr_to_write--;
2885                                 if (nr_to_write == 0 &&
2886                                     wbc->sync_mode == WB_SYNC_NONE) {
2887                                         /*
2888                                          * We stop writing back only if we are
2889                                          * not doing integrity sync. In case of
2890                                          * integrity sync we have to keep going
2891                                          * because someone may be concurrently
2892                                          * dirtying pages, and we might have
2893                                          * synced a lot of newly appeared dirty
2894                                          * pages, but have not synced all of the
2895                                          * old dirty pages.
2896                                          */
2897                                         done = 1;
2898                                         break;
2899                                 }
2900                         }
2901                 }
2902                 pagevec_release(&pvec);
2903                 cond_resched();
2904         }
2905         return ret;
2906 }
2907
2908
2909 static int ext4_da_writepages(struct address_space *mapping,
2910                               struct writeback_control *wbc)
2911 {
2912         pgoff_t index;
2913         int range_whole = 0;
2914         handle_t *handle = NULL;
2915         struct mpage_da_data mpd;
2916         struct inode *inode = mapping->host;
2917         int pages_written = 0;
2918         long pages_skipped;
2919         unsigned int max_pages;
2920         int range_cyclic, cycled = 1, io_done = 0;
2921         int needed_blocks, ret = 0;
2922         long desired_nr_to_write, nr_to_writebump = 0;
2923         loff_t range_start = wbc->range_start;
2924         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2925
2926         trace_ext4_da_writepages(inode, wbc);
2927
2928         /*
2929          * No pages to write? This is mainly a kludge to avoid starting
2930          * a transaction for special inodes like journal inode on last iput()
2931          * because that could violate lock ordering on umount
2932          */
2933         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2934                 return 0;
2935
2936         /*
2937          * If the filesystem has aborted, it is read-only, so return
2938          * right away instead of dumping stack traces later on that
2939          * will obscure the real source of the problem.  We test
2940          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2941          * the latter could be true if the filesystem is mounted
2942          * read-only, and in that case, ext4_da_writepages should
2943          * *never* be called, so if that ever happens, we would want
2944          * the stack trace.
2945          */
2946         if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2947                 return -EROFS;
2948
2949         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2950                 range_whole = 1;
2951
2952         range_cyclic = wbc->range_cyclic;
2953         if (wbc->range_cyclic) {
2954                 index = mapping->writeback_index;
2955                 if (index)
2956                         cycled = 0;
2957                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2958                 wbc->range_end  = LLONG_MAX;
2959                 wbc->range_cyclic = 0;
2960         } else
2961                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2962
2963         /*
2964          * This works around two forms of stupidity.  The first is in
2965          * the writeback code, which caps the maximum number of pages
2966          * written to be 1024 pages.  This is wrong on multiple
2967          * levels; different architectues have a different page size,
2968          * which changes the maximum amount of data which gets
2969          * written.  Secondly, 4 megabytes is way too small.  XFS
2970          * forces this value to be 16 megabytes by multiplying
2971          * nr_to_write parameter by four, and then relies on its
2972          * allocator to allocate larger extents to make them
2973          * contiguous.  Unfortunately this brings us to the second
2974          * stupidity, which is that ext4's mballoc code only allocates
2975          * at most 2048 blocks.  So we force contiguous writes up to
2976          * the number of dirty blocks in the inode, or
2977          * sbi->max_writeback_mb_bump whichever is smaller.
2978          */
2979         max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT);
2980         if (!range_cyclic && range_whole)
2981                 desired_nr_to_write = wbc->nr_to_write * 8;
2982         else
2983                 desired_nr_to_write = ext4_num_dirty_pages(inode, index,
2984                                                            max_pages);
2985         if (desired_nr_to_write > max_pages)
2986                 desired_nr_to_write = max_pages;
2987
2988         if (wbc->nr_to_write < desired_nr_to_write) {
2989                 nr_to_writebump = desired_nr_to_write - wbc->nr_to_write;
2990                 wbc->nr_to_write = desired_nr_to_write;
2991         }
2992
2993         mpd.wbc = wbc;
2994         mpd.inode = mapping->host;
2995
2996         pages_skipped = wbc->pages_skipped;
2997
2998 retry:
2999         while (!ret && wbc->nr_to_write > 0) {
3000
3001                 /*
3002                  * we  insert one extent at a time. So we need
3003                  * credit needed for single extent allocation.
3004                  * journalled mode is currently not supported
3005                  * by delalloc
3006                  */
3007                 BUG_ON(ext4_should_journal_data(inode));
3008                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
3009
3010                 /* start a new transaction*/
3011                 handle = ext4_journal_start(inode, needed_blocks);
3012                 if (IS_ERR(handle)) {
3013                         ret = PTR_ERR(handle);
3014                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
3015                                "%ld pages, ino %lu; err %d", __func__,
3016                                 wbc->nr_to_write, inode->i_ino, ret);
3017                         goto out_writepages;
3018                 }
3019
3020                 /*
3021                  * Now call __mpage_da_writepage to find the next
3022                  * contiguous region of logical blocks that need
3023                  * blocks to be allocated by ext4.  We don't actually
3024                  * submit the blocks for I/O here, even though
3025                  * write_cache_pages thinks it will, and will set the
3026                  * pages as clean for write before calling
3027                  * __mpage_da_writepage().
3028                  */
3029                 mpd.b_size = 0;
3030                 mpd.b_state = 0;
3031                 mpd.b_blocknr = 0;
3032                 mpd.first_page = 0;
3033                 mpd.next_page = 0;
3034                 mpd.io_done = 0;
3035                 mpd.pages_written = 0;
3036                 mpd.retval = 0;
3037                 ret = write_cache_pages_da(mapping, wbc, &mpd);
3038                 /*
3039                  * If we have a contiguous extent of pages and we
3040                  * haven't done the I/O yet, map the blocks and submit
3041                  * them for I/O.
3042                  */
3043                 if (!mpd.io_done && mpd.next_page != mpd.first_page) {
3044                         if (mpage_da_map_blocks(&mpd) == 0)
3045                                 mpage_da_submit_io(&mpd);
3046                         mpd.io_done = 1;
3047                         ret = MPAGE_DA_EXTENT_TAIL;
3048                 }
3049                 trace_ext4_da_write_pages(inode, &mpd);
3050                 wbc->nr_to_write -= mpd.pages_written;
3051
3052                 ext4_journal_stop(handle);
3053
3054                 if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
3055                         /* commit the transaction which would
3056                          * free blocks released in the transaction
3057                          * and try again
3058                          */
3059                         jbd2_journal_force_commit_nested(sbi->s_journal);
3060                         wbc->pages_skipped = pages_skipped;
3061                         ret = 0;
3062                 } else if (ret == MPAGE_DA_EXTENT_TAIL) {
3063                         /*
3064                          * got one extent now try with
3065                          * rest of the pages
3066                          */
3067                         pages_written += mpd.pages_written;
3068                         wbc->pages_skipped = pages_skipped;
3069                         ret = 0;
3070                         io_done = 1;
3071                 } else if (wbc->nr_to_write)
3072                         /*
3073                          * There is no more writeout needed
3074                          * or we requested for a noblocking writeout
3075                          * and we found the device congested
3076                          */
3077                         break;
3078         }
3079         if (!io_done && !cycled) {
3080                 cycled = 1;
3081                 index = 0;
3082                 wbc->range_start = index << PAGE_CACHE_SHIFT;
3083                 wbc->range_end  = mapping->writeback_index - 1;
3084                 goto retry;
3085         }
3086         if (pages_skipped != wbc->pages_skipped)
3087                 ext4_msg(inode->i_sb, KERN_CRIT,
3088                          "This should not happen leaving %s "
3089                          "with nr_to_write = %ld ret = %d",
3090                          __func__, wbc->nr_to_write, ret);
3091
3092         /* Update index */
3093         index += pages_written;
3094         wbc->range_cyclic = range_cyclic;
3095         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
3096                 /*
3097                  * set the writeback_index so that range_cyclic
3098                  * mode will write it back later
3099                  */
3100                 mapping->writeback_index = index;
3101
3102 out_writepages:
3103         wbc->nr_to_write -= nr_to_writebump;
3104         wbc->range_start = range_start;
3105         trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
3106         return ret;
3107 }
3108
3109 #define FALL_BACK_TO_NONDELALLOC 1
3110 static int ext4_nonda_switch(struct super_block *sb)
3111 {
3112         s64 free_blocks, dirty_blocks;
3113         struct ext4_sb_info *sbi = EXT4_SB(sb);
3114
3115         /*
3116          * switch to non delalloc mode if we are running low
3117          * on free block. The free block accounting via percpu
3118          * counters can get slightly wrong with percpu_counter_batch getting
3119          * accumulated on each CPU without updating global counters
3120          * Delalloc need an accurate free block accounting. So switch
3121          * to non delalloc when we are near to error range.
3122          */
3123         free_blocks  = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
3124         dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyblocks_counter);
3125         if (2 * free_blocks < 3 * dirty_blocks ||
3126                 free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
3127                 /*
3128                  * free block count is less than 150% of dirty blocks
3129                  * or free blocks is less than watermark
3130                  */
3131                 return 1;
3132         }
3133         /*
3134          * Even if we don't switch but are nearing capacity,
3135          * start pushing delalloc when 1/2 of free blocks are dirty.
3136          */
3137         if (free_blocks < 2 * dirty_blocks)
3138                 writeback_inodes_sb_if_idle(sb);
3139
3140         return 0;
3141 }
3142
3143 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
3144                                loff_t pos, unsigned len, unsigned flags,
3145                                struct page **pagep, void **fsdata)
3146 {
3147         int ret, retries = 0;
3148         struct page *page;
3149         pgoff_t index;
3150         struct inode *inode = mapping->host;
3151         handle_t *handle;
3152
3153         index = pos >> PAGE_CACHE_SHIFT;
3154
3155         if (ext4_nonda_switch(inode->i_sb)) {
3156                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
3157                 return ext4_write_begin(file, mapping, pos,
3158                                         len, flags, pagep, fsdata);
3159         }
3160         *fsdata = (void *)0;
3161         trace_ext4_da_write_begin(inode, pos, len, flags);
3162 retry:
3163         /*
3164          * With delayed allocation, we don't log the i_disksize update
3165          * if there is delayed block allocation. But we still need
3166          * to journalling the i_disksize update if writes to the end
3167          * of file which has an already mapped buffer.
3168          */
3169         handle = ext4_journal_start(inode, 1);
3170         if (IS_ERR(handle)) {
3171                 ret = PTR_ERR(handle);
3172                 goto out;
3173         }
3174         /* We cannot recurse into the filesystem as the transaction is already
3175          * started */
3176         flags |= AOP_FLAG_NOFS;
3177
3178         page = grab_cache_page_write_begin(mapping, index, flags);
3179         if (!page) {
3180                 ext4_journal_stop(handle);
3181                 ret = -ENOMEM;
3182                 goto out;
3183         }
3184         *pagep = page;
3185
3186         ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
3187                                 ext4_da_get_block_prep);
3188         if (ret < 0) {
3189                 unlock_page(page);
3190                 ext4_journal_stop(handle);
3191                 page_cache_release(page);
3192                 /*
3193                  * block_write_begin may have instantiated a few blocks
3194                  * outside i_size.  Trim these off again. Don't need
3195                  * i_size_read because we hold i_mutex.
3196                  */
3197                 if (pos + len > inode->i_size)
3198                         ext4_truncate_failed_write(inode);
3199         }
3200
3201         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
3202                 goto retry;
3203 out:
3204         return ret;
3205 }
3206
3207 /*
3208  * Check if we should update i_disksize
3209  * when write to the end of file but not require block allocation
3210  */
3211 static int ext4_da_should_update_i_disksize(struct page *page,
3212                                             unsigned long offset)
3213 {
3214         struct buffer_head *bh;
3215         struct inode *inode = page->mapping->host;
3216         unsigned int idx;
3217         int i;
3218
3219         bh = page_buffers(page);
3220         idx = offset >> inode->i_blkbits;
3221
3222         for (i = 0; i < idx; i++)
3223                 bh = bh->b_this_page;
3224
3225         if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
3226                 return 0;
3227         return 1;
3228 }
3229
3230 static int ext4_da_write_end(struct file *file,
3231                              struct address_space *mapping,
3232                              loff_t pos, unsigned len, unsigned copied,
3233                              struct page *page, void *fsdata)
3234 {
3235         struct inode *inode = mapping->host;
3236         int ret = 0, ret2;
3237         handle_t *handle = ext4_journal_current_handle();
3238         loff_t new_i_size;
3239         unsigned long start, end;
3240         int write_mode = (int)(unsigned long)fsdata;
3241
3242         if (write_mode == FALL_BACK_TO_NONDELALLOC) {
3243                 if (ext4_should_order_data(inode)) {
3244                         return ext4_ordered_write_end(file, mapping, pos,
3245                                         len, copied, page, fsdata);
3246                 } else if (ext4_should_writeback_data(inode)) {
3247                         return ext4_writeback_write_end(file, mapping, pos,
3248                                         len, copied, page, fsdata);
3249                 } else {
3250                         BUG();
3251                 }
3252         }
3253
3254         trace_ext4_da_write_end(inode, pos, len, copied);
3255         start = pos & (PAGE_CACHE_SIZE - 1);
3256         end = start + copied - 1;
3257
3258         /*
3259          * generic_write_end() will run mark_inode_dirty() if i_size
3260          * changes.  So let's piggyback the i_disksize mark_inode_dirty
3261          * into that.
3262          */
3263
3264         new_i_size = pos + copied;
3265         if (new_i_size > EXT4_I(inode)->i_disksize) {
3266                 if (ext4_da_should_update_i_disksize(page, end)) {
3267                         down_write(&EXT4_I(inode)->i_data_sem);
3268                         if (new_i_size > EXT4_I(inode)->i_disksize) {
3269                                 /*
3270                                  * Updating i_disksize when extending file
3271                                  * without needing block allocation
3272                                  */
3273                                 if (ext4_should_order_data(inode))
3274                                         ret = ext4_jbd2_file_inode(handle,
3275                                                                    inode);
3276
3277                                 EXT4_I(inode)->i_disksize = new_i_size;
3278                         }
3279                         up_write(&EXT4_I(inode)->i_data_sem);
3280                         /* We need to mark inode dirty even if
3281                          * new_i_size is less that inode->i_size
3282                          * bu greater than i_disksize.(hint delalloc)
3283                          */
3284                         ext4_mark_inode_dirty(handle, inode);
3285                 }
3286         }
3287         ret2 = generic_write_end(file, mapping, pos, len, copied,
3288                                                         page, fsdata);
3289         copied = ret2;
3290         if (ret2 < 0)
3291                 ret = ret2;
3292         ret2 = ext4_journal_stop(handle);
3293         if (!ret)
3294                 ret = ret2;
3295
3296         return ret ? ret : copied;
3297 }
3298
3299 static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
3300 {
3301         /*
3302          * Drop reserved blocks
3303          */
3304         BUG_ON(!PageLocked(page));
3305         if (!page_has_buffers(page))
3306                 goto out;
3307
3308         ext4_da_page_release_reservation(page, offset);
3309
3310 out:
3311         ext4_invalidatepage(page, offset);
3312
3313         return;
3314 }
3315
3316 /*
3317  * Force all delayed allocation blocks to be allocated for a given inode.
3318  */
3319 int ext4_alloc_da_blocks(struct inode *inode)
3320 {
3321         trace_ext4_alloc_da_blocks(inode);
3322
3323         if (!EXT4_I(inode)->i_reserved_data_blocks &&
3324             !EXT4_I(inode)->i_reserved_meta_blocks)
3325                 return 0;
3326
3327         /*
3328          * We do something simple for now.  The filemap_flush() will
3329          * also start triggering a write of the data blocks, which is
3330          * not strictly speaking necessary (and for users of
3331          * laptop_mode, not even desirable).  However, to do otherwise
3332          * would require replicating code paths in:
3333          *
3334          * ext4_da_writepages() ->
3335          *    write_cache_pages() ---> (via passed in callback function)
3336          *        __mpage_da_writepage() -->
3337          *           mpage_add_bh_to_extent()
3338          *           mpage_da_map_blocks()
3339          *
3340          * The problem is that write_cache_pages(), located in
3341          * mm/page-writeback.c, marks pages clean in preparation for
3342          * doing I/O, which is not desirable if we're not planning on
3343          * doing I/O at all.
3344          *
3345          * We could call write_cache_pages(), and then redirty all of
3346          * the pages by calling redirty_page_for_writeback() but that
3347          * would be ugly in the extreme.  So instead we would need to
3348          * replicate parts of the code in the above functions,
3349          * simplifying them becuase we wouldn't actually intend to
3350          * write out the pages, but rather only collect contiguous
3351          * logical block extents, call the multi-block allocator, and
3352          * then update the buffer heads with the block allocations.
3353          *
3354          * For now, though, we'll cheat by calling filemap_flush(),
3355          * which will map the blocks, and start the I/O, but not
3356          * actually wait for the I/O to complete.
3357          */
3358         return filemap_flush(inode->i_mapping);
3359 }
3360
3361 /*
3362  * bmap() is special.  It gets used by applications such as lilo and by
3363  * the swapper to find the on-disk block of a specific piece of data.
3364  *
3365  * Naturally, this is dangerous if the block concerned is still in the
3366  * journal.  If somebody makes a swapfile on an ext4 data-journaling
3367  * filesystem and enables swap, then they may get a nasty shock when the
3368  * data getting swapped to that swapfile suddenly gets overwritten by
3369  * the original zero's written out previously to the journal and
3370  * awaiting writeback in the kernel's buffer cache.
3371  *
3372  * So, if we see any bmap calls here on a modified, data-journaled file,
3373  * take extra steps to flush any blocks which might be in the cache.
3374  */
3375 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
3376 {
3377         struct inode *inode = mapping->host;
3378         journal_t *journal;
3379         int err;
3380
3381         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
3382                         test_opt(inode->i_sb, DELALLOC)) {
3383                 /*
3384                  * With delalloc we want to sync the file
3385                  * so that we can make sure we allocate
3386                  * blocks for file
3387                  */
3388                 filemap_write_and_wait(mapping);
3389         }
3390
3391         if (EXT4_JOURNAL(inode) &&
3392             ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
3393                 /*
3394                  * This is a REALLY heavyweight approach, but the use of
3395                  * bmap on dirty files is expected to be extremely rare:
3396                  * only if we run lilo or swapon on a freshly made file
3397                  * do we expect this to happen.
3398                  *
3399                  * (bmap requires CAP_SYS_RAWIO so this does not
3400                  * represent an unprivileged user DOS attack --- we'd be
3401                  * in trouble if mortal users could trigger this path at
3402                  * will.)
3403                  *
3404                  * NB. EXT4_STATE_JDATA is not set on files other than
3405                  * regular files.  If somebody wants to bmap a directory
3406                  * or symlink and gets confused because the buffer
3407                  * hasn't yet been flushed to disk, they deserve
3408                  * everything they get.
3409                  */
3410
3411                 ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
3412                 journal = EXT4_JOURNAL(inode);
3413                 jbd2_journal_lock_updates(journal);
3414                 err = jbd2_journal_flush(journal);
3415                 jbd2_journal_unlock_updates(journal);
3416
3417                 if (err)
3418                         return 0;
3419         }
3420
3421         return generic_block_bmap(mapping, block, ext4_get_block);
3422 }
3423
3424 static int ext4_readpage(struct file *file, struct page *page)
3425 {
3426         return mpage_readpage(page, ext4_get_block);
3427 }
3428
3429 static int
3430 ext4_readpages(struct file *file, struct address_space *mapping,
3431                 struct list_head *pages, unsigned nr_pages)
3432 {
3433         return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
3434 }
3435
3436 static void ext4_free_io_end(ext4_io_end_t *io)
3437 {
3438         BUG_ON(!io);
3439         if (io->page)
3440                 put_page(io->page);
3441         iput(io->inode);
3442         kfree(io);
3443 }
3444
3445 static void ext4_invalidatepage_free_endio(struct page *page, unsigned long offset)
3446 {
3447         struct buffer_head *head, *bh;
3448         unsigned int curr_off = 0;
3449
3450         if (!page_has_buffers(page))
3451                 return;
3452         head = bh = page_buffers(page);
3453         do {
3454                 if (offset <= curr_off && test_clear_buffer_uninit(bh)
3455                                         && bh->b_private) {
3456                         ext4_free_io_end(bh->b_private);
3457                         bh->b_private = NULL;
3458                         bh->b_end_io = NULL;
3459                 }
3460                 curr_off = curr_off + bh->b_size;
3461                 bh = bh->b_this_page;
3462         } while (bh != head);
3463 }
3464
3465 static void ext4_invalidatepage(struct page *page, unsigned long offset)
3466 {
3467         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3468
3469         /*
3470          * free any io_end structure allocated for buffers to be discarded
3471          */
3472         if (ext4_should_dioread_nolock(page->mapping->host))
3473                 ext4_invalidatepage_free_endio(page, offset);
3474         /*
3475          * If it's a full truncate we just forget about the pending dirtying
3476          */
3477         if (offset == 0)
3478                 ClearPageChecked(page);
3479
3480         if (journal)
3481                 jbd2_journal_invalidatepage(journal, page, offset);
3482         else
3483                 block_invalidatepage(page, offset);
3484 }
3485
3486 static int ext4_releasepage(struct page *page, gfp_t wait)
3487 {
3488         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3489
3490         WARN_ON(PageChecked(page));
3491         if (!page_has_buffers(page))
3492                 return 0;
3493         if (journal)
3494                 return jbd2_journal_try_to_free_buffers(journal, page, wait);
3495         else
3496                 return try_to_free_buffers(page);
3497 }
3498
3499 /*
3500  * O_DIRECT for ext3 (or indirect map) based files
3501  *
3502  * If the O_DIRECT write will extend the file then add this inode to the
3503  * orphan list.  So recovery will truncate it back to the original size
3504  * if the machine crashes during the write.
3505  *
3506  * If the O_DIRECT write is intantiating holes inside i_size and the machine
3507  * crashes then stale disk data _may_ be exposed inside the file. But current
3508  * VFS code falls back into buffered path in that case so we are safe.
3509  */
3510 static ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
3511                               const struct iovec *iov, loff_t offset,
3512                               unsigned long nr_segs)
3513 {
3514         struct file *file = iocb->ki_filp;
3515         struct inode *inode = file->f_mapping->host;
3516         struct ext4_inode_info *ei = EXT4_I(inode);
3517         handle_t *handle;
3518         ssize_t ret;
3519         int orphan = 0;
3520         size_t count = iov_length(iov, nr_segs);
3521         int retries = 0;
3522
3523         if (rw == WRITE) {
3524                 loff_t final_size = offset + count;
3525
3526                 if (final_size > inode->i_size) {
3527                         /* Credits for sb + inode write */
3528                         handle = ext4_journal_start(inode, 2);
3529                         if (IS_ERR(handle)) {
3530                                 ret = PTR_ERR(handle);
3531                                 goto out;
3532                         }
3533                         ret = ext4_orphan_add(handle, inode);
3534                         if (ret) {
3535                                 ext4_journal_stop(handle);
3536                                 goto out;
3537                         }
3538                         orphan = 1;
3539                         ei->i_disksize = inode->i_size;
3540                         ext4_journal_stop(handle);
3541                 }
3542         }
3543
3544 retry:
3545         if (rw == READ && ext4_should_dioread_nolock(inode))
3546                 ret = blockdev_direct_IO_no_locking(rw, iocb, inode,
3547                                  inode->i_sb->s_bdev, iov,
3548                                  offset, nr_segs,
3549                                  ext4_get_block, NULL);
3550         else
3551                 ret = blockdev_direct_IO(rw, iocb, inode,
3552                                  inode->i_sb->s_bdev, iov,
3553                                  offset, nr_segs,
3554                                  ext4_get_block, NULL);
3555         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
3556                 goto retry;
3557
3558         if (orphan) {
3559                 int err;
3560
3561                 /* Credits for sb + inode write */
3562                 handle = ext4_journal_start(inode, 2);
3563                 if (IS_ERR(handle)) {
3564                         /* This is really bad luck. We've written the data
3565                          * but cannot extend i_size. Bail out and pretend
3566                          * the write failed... */
3567                         ret = PTR_ERR(handle);
3568                         if (inode->i_nlink)
3569                                 ext4_orphan_del(NULL, inode);
3570
3571                         goto out;
3572                 }
3573                 if (inode->i_nlink)
3574                         ext4_orphan_del(handle, inode);
3575                 if (ret > 0) {
3576                         loff_t end = offset + ret;
3577                         if (end > inode->i_size) {
3578                                 ei->i_disksize = end;
3579                                 i_size_write(inode, end);
3580                                 /*
3581                                  * We're going to return a positive `ret'
3582                                  * here due to non-zero-length I/O, so there's
3583                                  * no way of reporting error returns from
3584                                  * ext4_mark_inode_dirty() to userspace.  So
3585                                  * ignore it.
3586                                  */
3587                                 ext4_mark_inode_dirty(handle, inode);
3588                         }
3589                 }
3590                 err = ext4_journal_stop(handle);
3591                 if (ret == 0)
3592                         ret = err;
3593         }
3594 out:
3595         return ret;
3596 }
3597
3598 /*
3599  * ext4_get_block used when preparing for a DIO write or buffer write.
3600  * We allocate an uinitialized extent if blocks haven't been allocated.
3601  * The extent will be converted to initialized after the IO is complete.
3602  */
3603 static int ext4_get_block_write(struct inode *inode, sector_t iblock,
3604                    struct buffer_head *bh_result, int create)
3605 {
3606         ext4_debug("ext4_get_block_write: inode %lu, create flag %d\n",
3607                    inode->i_ino, create);
3608         return _ext4_get_block(inode, iblock, bh_result,
3609                                EXT4_GET_BLOCKS_IO_CREATE_EXT);
3610 }
3611
3612 static void dump_completed_IO(struct inode * inode)
3613 {
3614 #ifdef  EXT4_DEBUG
3615         struct list_head *cur, *before, *after;
3616         ext4_io_end_t *io, *io0, *io1;
3617         unsigned long flags;
3618
3619         if (list_empty(&EXT4_I(inode)->i_completed_io_list)){
3620                 ext4_debug("inode %lu completed_io list is empty\n", inode->i_ino);
3621                 return;
3622         }
3623
3624         ext4_debug("Dump inode %lu completed_io list \n", inode->i_ino);
3625         spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
3626         list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list){
3627                 cur = &io->list;
3628                 before = cur->prev;
3629                 io0 = container_of(before, ext4_io_end_t, list);
3630                 after = cur->next;
3631                 io1 = container_of(after, ext4_io_end_t, list);
3632
3633                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
3634                             io, inode->i_ino, io0, io1);
3635         }
3636         spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
3637 #endif
3638 }
3639
3640 /*
3641  * check a range of space and convert unwritten extents to written.
3642  */
3643 static int ext4_end_io_nolock(ext4_io_end_t *io)
3644 {
3645         struct inode *inode = io->inode;
3646         loff_t offset = io->offset;
3647         ssize_t size = io->size;
3648         int ret = 0;
3649
3650         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
3651                    "list->prev 0x%p\n",
3652                    io, inode->i_ino, io->list.next, io->list.prev);
3653
3654         if (list_empty(&io->list))
3655                 return ret;
3656
3657         if (io->flag != EXT4_IO_UNWRITTEN)
3658                 return ret;
3659
3660         ret = ext4_convert_unwritten_extents(inode, offset, size);
3661         if (ret < 0) {
3662                 printk(KERN_EMERG "%s: failed to convert unwritten"
3663                         "extents to written extents, error is %d"
3664                         " io is still on inode %lu aio dio list\n",
3665                        __func__, ret, inode->i_ino);
3666                 return ret;
3667         }
3668
3669         /* clear the DIO AIO unwritten flag */
3670         io->flag = 0;
3671         return ret;
3672 }
3673
3674 /*
3675  * work on completed aio dio IO, to convert unwritten extents to extents
3676  */
3677 static void ext4_end_io_work(struct work_struct *work)
3678 {
3679         ext4_io_end_t           *io = container_of(work, ext4_io_end_t, work);
3680         struct inode            *inode = io->inode;
3681         struct ext4_inode_info  *ei = EXT4_I(inode);
3682         unsigned long           flags;
3683         int                     ret;
3684
3685         mutex_lock(&inode->i_mutex);
3686         ret = ext4_end_io_nolock(io);
3687         if (ret < 0) {
3688                 mutex_unlock(&inode->i_mutex);
3689                 return;
3690         }
3691
3692         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
3693         if (!list_empty(&io->list))
3694                 list_del_init(&io->list);
3695         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
3696         mutex_unlock(&inode->i_mutex);
3697         ext4_free_io_end(io);
3698 }
3699
3700 /*
3701  * This function is called from ext4_sync_file().
3702  *
3703  * When IO is completed, the work to convert unwritten extents to
3704  * written is queued on workqueue but may not get immediately
3705  * scheduled. When fsync is called, we need to ensure the
3706  * conversion is complete before fsync returns.
3707  * The inode keeps track of a list of pending/completed IO that
3708  * might needs to do the conversion. This function walks through
3709  * the list and convert the related unwritten extents for completed IO
3710  * to written.
3711  * The function return the number of pending IOs on success.
3712  */
3713 int flush_completed_IO(struct inode *inode)
3714 {
3715         ext4_io_end_t *io;
3716         struct ext4_inode_info *ei = EXT4_I(inode);
3717         unsigned long flags;
3718         int ret = 0;
3719         int ret2 = 0;
3720
3721         if (list_empty(&ei->i_completed_io_list))
3722                 return ret;
3723
3724         dump_completed_IO(inode);
3725         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
3726         while (!list_empty(&ei->i_completed_io_list)){
3727                 io = list_entry(ei->i_completed_io_list.next,
3728                                 ext4_io_end_t, list);
3729                 /*
3730                  * Calling ext4_end_io_nolock() to convert completed
3731                  * IO to written.
3732                  *
3733                  * When ext4_sync_file() is called, run_queue() may already
3734                  * about to flush the work corresponding to this io structure.
3735                  * It will be upset if it founds the io structure related
3736                  * to the work-to-be schedule is freed.
3737                  *
3738                  * Thus we need to keep the io structure still valid here after
3739                  * convertion finished. The io structure has a flag to
3740                  * avoid double converting from both fsync and background work
3741                  * queue work.
3742                  */
3743                 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
3744                 ret = ext4_end_io_nolock(io);
3745                 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
3746                 if (ret < 0)
3747                         ret2 = ret;
3748                 else
3749                         list_del_init(&io->list);
3750         }
3751         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
3752         return (ret2 < 0) ? ret2 : 0;
3753 }
3754
3755 static ext4_io_end_t *ext4_init_io_end (struct inode *inode, gfp_t flags)
3756 {
3757         ext4_io_end_t *io = NULL;
3758
3759         io = kmalloc(sizeof(*io), flags);
3760
3761         if (io) {
3762                 igrab(inode);
3763                 io->inode = inode;
3764                 io->flag = 0;
3765                 io->offset = 0;
3766                 io->size = 0;
3767                 io->page = NULL;
3768                 INIT_WORK(&io->work, ext4_end_io_work);
3769                 INIT_LIST_HEAD(&io->list);
3770         }
3771
3772         return io;
3773 }
3774
3775 static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
3776                             ssize_t size, void *private)
3777 {
3778         ext4_io_end_t *io_end = iocb->private;
3779         struct workqueue_struct *wq;
3780         unsigned long flags;
3781         struct ext4_inode_info *ei;
3782
3783         /* if not async direct IO or dio with 0 bytes write, just return */
3784         if (!io_end || !size)
3785                 return;
3786
3787         ext_debug("ext4_end_io_dio(): io_end 0x%p"
3788                   "for inode %lu, iocb 0x%p, offset %llu, size %llu\n",
3789                   iocb->private, io_end->inode->i_ino, iocb, offset,
3790                   size);
3791
3792         /* if not aio dio with unwritten extents, just free io and return */
3793         if (io_end->flag != EXT4_IO_UNWRITTEN){
3794                 ext4_free_io_end(io_end);
3795                 iocb->private = NULL;
3796                 return;
3797         }
3798
3799         io_end->offset = offset;
3800         io_end->size = size;
3801         io_end->flag = EXT4_IO_UNWRITTEN;
3802         wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
3803
3804         /* queue the work to convert unwritten extents to written */
3805         queue_work(wq, &io_end->work);
3806
3807         /* Add the io_end to per-inode completed aio dio list*/
3808         ei = EXT4_I(io_end->inode);
3809         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
3810         list_add_tail(&io_end->list, &ei->i_completed_io_list);
3811         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
3812         iocb->private = NULL;
3813 }
3814
3815 static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
3816 {
3817         ext4_io_end_t *io_end = bh->b_private;
3818         struct workqueue_struct *wq;
3819         struct inode *inode;
3820         unsigned long flags;
3821
3822         if (!test_clear_buffer_uninit(bh) || !io_end)
3823                 goto out;
3824
3825         if (!(io_end->inode->i_sb->s_flags & MS_ACTIVE)) {
3826                 printk("sb umounted, discard end_io request for inode %lu\n",
3827                         io_end->inode->i_ino);
3828                 ext4_free_io_end(io_end);
3829                 goto out;
3830         }
3831
3832         io_end->flag = EXT4_IO_UNWRITTEN;
3833         inode = io_end->inode;
3834
3835         /* Add the io_end to per-inode completed io list*/
3836         spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
3837         list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
3838         spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
3839
3840         wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
3841         /* queue the work to convert unwritten extents to written */
3842         queue_work(wq, &io_end->work);
3843 out:
3844         bh->b_private = NULL;
3845         bh->b_end_io = NULL;
3846         clear_buffer_uninit(bh);
3847         end_buffer_async_write(bh, uptodate);
3848 }
3849
3850 static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode)
3851 {
3852         ext4_io_end_t *io_end;
3853         struct page *page = bh->b_page;
3854         loff_t offset = (sector_t)page->index << PAGE_CACHE_SHIFT;
3855         size_t size = bh->b_size;
3856
3857 retry:
3858         io_end = ext4_init_io_end(inode, GFP_ATOMIC);
3859         if (!io_end) {
3860                 if (printk_ratelimit())
3861                         printk(KERN_WARNING "%s: allocation fail\n", __func__);
3862                 schedule();
3863                 goto retry;
3864         }
3865         io_end->offset = offset;
3866         io_end->size = size;
3867         /*
3868          * We need to hold a reference to the page to make sure it
3869          * doesn't get evicted before ext4_end_io_work() has a chance
3870          * to convert the extent from written to unwritten.
3871          */
3872         io_end->page = page;
3873         get_page(io_end->page);
3874
3875         bh->b_private = io_end;
3876         bh->b_end_io = ext4_end_io_buffer_write;
3877         return 0;
3878 }
3879
3880 /*
3881  * For ext4 extent files, ext4 will do direct-io write to holes,
3882  * preallocated extents, and those write extend the file, no need to
3883  * fall back to buffered IO.
3884  *
3885  * For holes, we fallocate those blocks, mark them as unintialized
3886  * If those blocks were preallocated, we mark sure they are splited, but
3887  * still keep the range to write as unintialized.
3888  *
3889  * The unwrritten extents will be converted to written when DIO is completed.
3890  * For async direct IO, since the IO may still pending when return, we
3891  * set up an end_io call back function, which will do the convertion
3892  * when async direct IO completed.
3893  *
3894  * If the O_DIRECT write will extend the file then add this inode to the
3895  * orphan list.  So recovery will truncate it back to the original size
3896  * if the machine crashes during the write.
3897  *
3898  */
3899 static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
3900                               const struct iovec *iov, loff_t offset,
3901                               unsigned long nr_segs)
3902 {
3903         struct file *file = iocb->ki_filp;
3904         struct inode *inode = file->f_mapping->host;
3905         ssize_t ret;
3906         size_t count = iov_length(iov, nr_segs);
3907
3908         loff_t final_size = offset + count;
3909         if (rw == WRITE && final_size <= inode->i_size) {
3910                 /*
3911                  * We could direct write to holes and fallocate.
3912                  *
3913                  * Allocated blocks to fill the hole are marked as uninitialized
3914                  * to prevent paralel buffered read to expose the stale data
3915                  * before DIO complete the data IO.
3916                  *
3917                  * As to previously fallocated extents, ext4 get_block
3918                  * will just simply mark the buffer mapped but still
3919                  * keep the extents uninitialized.
3920                  *
3921                  * for non AIO case, we will convert those unwritten extents
3922                  * to written after return back from blockdev_direct_IO.
3923                  *
3924                  * for async DIO, the conversion needs to be defered when
3925                  * the IO is completed. The ext4 end_io callback function
3926                  * will be called to take care of the conversion work.
3927                  * Here for async case, we allocate an io_end structure to
3928                  * hook to the iocb.
3929                  */
3930                 iocb->private = NULL;
3931                 EXT4_I(inode)->cur_aio_dio = NULL;
3932                 if (!is_sync_kiocb(iocb)) {
3933                         iocb->private = ext4_init_io_end(inode, GFP_NOFS);
3934                         if (!iocb->private)
3935                                 return -ENOMEM;
3936                         /*
3937                          * we save the io structure for current async
3938                          * direct IO, so that later ext4_get_blocks()
3939                          * could flag the io structure whether there
3940                          * is a unwritten extents needs to be converted
3941                          * when IO is completed.
3942                          */
3943                         EXT4_I(inode)->cur_aio_dio = iocb->private;
3944                 }
3945
3946                 ret = blockdev_direct_IO(rw, iocb, inode,
3947                                          inode->i_sb->s_bdev, iov,
3948                                          offset, nr_segs,
3949                                          ext4_get_block_write,
3950                                          ext4_end_io_dio);
3951                 if (iocb->private)
3952                         EXT4_I(inode)->cur_aio_dio = NULL;
3953                 /*
3954                  * The io_end structure takes a reference to the inode,
3955                  * that structure needs to be destroyed and the
3956                  * reference to the inode need to be dropped, when IO is
3957                  * complete, even with 0 byte write, or failed.
3958                  *
3959                  * In the successful AIO DIO case, the io_end structure will be
3960                  * desctroyed and the reference to the inode will be dropped
3961                  * after the end_io call back function is called.
3962                  *
3963                  * In the case there is 0 byte write, or error case, since
3964                  * VFS direct IO won't invoke the end_io call back function,
3965                  * we need to free the end_io structure here.
3966                  */
3967                 if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
3968                         ext4_free_io_end(iocb->private);
3969                         iocb->private = NULL;
3970                 } else if (ret > 0 && ext4_test_inode_state(inode,
3971                                                 EXT4_STATE_DIO_UNWRITTEN)) {
3972                         int err;
3973                         /*
3974                          * for non AIO case, since the IO is already
3975                          * completed, we could do the convertion right here
3976                          */
3977                         err = ext4_convert_unwritten_extents(inode,
3978                                                              offset, ret);
3979                         if (err < 0)
3980                                 ret = err;
3981                         ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3982                 }
3983                 return ret;
3984         }
3985
3986         /* for write the the end of file case, we fall back to old way */
3987         return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
3988 }
3989
3990 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
3991                               const struct iovec *iov, loff_t offset,
3992                               unsigned long nr_segs)
3993 {
3994         struct file *file = iocb->ki_filp;
3995         struct inode *inode = file->f_mapping->host;
3996
3997         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3998                 return ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
3999
4000         return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
4001 }
4002
4003 /*
4004  * Pages can be marked dirty completely asynchronously from ext4's journalling
4005  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
4006  * much here because ->set_page_dirty is called under VFS locks.  The page is
4007  * not necessarily locked.
4008  *
4009  * We cannot just dirty the page and leave attached buffers clean, because the
4010  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
4011  * or jbddirty because all the journalling code will explode.
4012  *
4013  * So what we do is to mark the page "pending dirty" and next time writepage
4014  * is called, propagate that into the buffers appropriately.
4015  */
4016 static int ext4_journalled_set_page_dirty(struct page *page)
4017 {
4018         SetPageChecked(page);
4019         return __set_page_dirty_nobuffers(page);
4020 }
4021
4022 static const struct address_space_operations ext4_ordered_aops = {
4023         .readpage               = ext4_readpage,
4024         .readpages              = ext4_readpages,
4025         .writepage              = ext4_writepage,
4026         .sync_page              = block_sync_page,
4027         .write_begin            = ext4_write_begin,
4028         .write_end              = ext4_ordered_write_end,
4029         .bmap                   = ext4_bmap,
4030         .invalidatepage         = ext4_invalidatepage,
4031         .releasepage            = ext4_releasepage,
4032         .direct_IO              = ext4_direct_IO,
4033         .migratepage            = buffer_migrate_page,
4034         .is_partially_uptodate  = block_is_partially_uptodate,
4035         .error_remove_page      = generic_error_remove_page,
4036 };
4037
4038 static const struct address_space_operations ext4_writeback_aops = {
4039         .readpage               = ext4_readpage,
4040         .readpages              = ext4_readpages,
4041         .writepage              = ext4_writepage,
4042         .sync_page              = block_sync_page,
4043         .write_begin            = ext4_write_begin,
4044         .write_end              = ext4_writeback_write_end,
4045         .bmap                   = ext4_bmap,
4046         .invalidatepage         = ext4_invalidatepage,
4047         .releasepage            = ext4_releasepage,
4048         .direct_IO              = ext4_direct_IO,
4049         .migratepage            = buffer_migrate_page,
4050         .is_partially_uptodate  = block_is_partially_uptodate,
4051         .error_remove_page      = generic_error_remove_page,
4052 };
4053
4054 static const struct address_space_operations ext4_journalled_aops = {
4055         .readpage               = ext4_readpage,
4056         .readpages              = ext4_readpages,
4057         .writepage              = ext4_writepage,
4058         .sync_page              = block_sync_page,
4059         .write_begin            = ext4_write_begin,
4060         .write_end              = ext4_journalled_write_end,
4061         .set_page_dirty         = ext4_journalled_set_page_dirty,
4062         .bmap                   = ext4_bmap,
4063         .invalidatepage         = ext4_invalidatepage,
4064         .releasepage            = ext4_releasepage,
4065         .is_partially_uptodate  = block_is_partially_uptodate,
4066         .error_remove_page      = generic_error_remove_page,
4067 };
4068
4069 static const struct address_space_operations ext4_da_aops = {
4070         .readpage               = ext4_readpage,
4071         .readpages              = ext4_readpages,
4072         .writepage              = ext4_writepage,
4073         .writepages             = ext4_da_writepages,
4074         .sync_page              = block_sync_page,
4075         .write_begin            = ext4_da_write_begin,
4076         .write_end              = ext4_da_write_end,
4077         .bmap                   = ext4_bmap,
4078         .invalidatepage         = ext4_da_invalidatepage,
4079         .releasepage            = ext4_releasepage,
4080         .direct_IO              = ext4_direct_IO,
4081         .migratepage            = buffer_migrate_page,
4082         .is_partially_uptodate  = block_is_partially_uptodate,
4083         .error_remove_page      = generic_error_remove_page,
4084 };
4085
4086 void ext4_set_aops(struct inode *inode)
4087 {
4088         if (ext4_should_order_data(inode) &&
4089                 test_opt(inode->i_sb, DELALLOC))
4090                 inode->i_mapping->a_ops = &ext4_da_aops;
4091         else if (ext4_should_order_data(inode))
4092                 inode->i_mapping->a_ops = &ext4_ordered_aops;
4093         else if (ext4_should_writeback_data(inode) &&
4094                  test_opt(inode->i_sb, DELALLOC))
4095                 inode->i_mapping->a_ops = &ext4_da_aops;
4096         else if (ext4_should_writeback_data(inode))
4097                 inode->i_mapping->a_ops = &ext4_writeback_aops;
4098         else
4099                 inode->i_mapping->a_ops = &ext4_journalled_aops;
4100 }
4101
4102 /*
4103  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
4104  * up to the end of the block which corresponds to `from'.
4105  * This required during truncate. We need to physically zero the tail end
4106  * of that block so it doesn't yield old data if the file is later grown.
4107  */
4108 int ext4_block_truncate_page(handle_t *handle,
4109                 struct address_space *mapping, loff_t from)
4110 {
4111         ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
4112         unsigned offset = from & (PAGE_CACHE_SIZE-1);
4113         unsigned blocksize, length, pos;
4114         ext4_lblk_t iblock;
4115         struct inode *inode = mapping->host;
4116         struct buffer_head *bh;
4117         struct page *page;
4118         int err = 0;
4119
4120         page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
4121                                    mapping_gfp_mask(mapping) & ~__GFP_FS);
4122         if (!page)
4123                 return -EINVAL;
4124
4125         blocksize = inode->i_sb->s_blocksize;
4126         length = blocksize - (offset & (blocksize - 1));
4127         iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
4128
4129         if (!page_has_buffers(page))
4130                 create_empty_buffers(page, blocksize, 0);
4131
4132         /* Find the buffer that contains "offset" */
4133         bh = page_buffers(page);
4134         pos = blocksize;
4135         while (offset >= pos) {
4136                 bh = bh->b_this_page;
4137                 iblock++;
4138                 pos += blocksize;
4139         }
4140
4141         err = 0;
4142         if (buffer_freed(bh)) {
4143                 BUFFER_TRACE(bh, "freed: skip");
4144                 goto unlock;
4145         }
4146
4147         if (!buffer_mapped(bh)) {
4148                 BUFFER_TRACE(bh, "unmapped");
4149                 ext4_get_block(inode, iblock, bh, 0);
4150                 /* unmapped? It's a hole - nothing to do */
4151                 if (!buffer_mapped(bh)) {
4152                         BUFFER_TRACE(bh, "still unmapped");
4153                         goto unlock;
4154                 }
4155         }
4156
4157         /* Ok, it's mapped. Make sure it's up-to-date */
4158         if (PageUptodate(page))
4159                 set_buffer_uptodate(bh);
4160
4161         if (!buffer_uptodate(bh)) {
4162                 err = -EIO;
4163                 ll_rw_block(READ, 1, &bh);
4164                 wait_on_buffer(bh);
4165                 /* Uhhuh. Read error. Complain and punt. */
4166                 if (!buffer_uptodate(bh))
4167                         goto unlock;
4168         }
4169
4170         if (ext4_should_journal_data(inode)) {
4171                 BUFFER_TRACE(bh, "get write access");
4172                 err = ext4_journal_get_write_access(handle, bh);
4173                 if (err)
4174                         goto unlock;
4175         }
4176
4177         zero_user(page, offset, length);
4178
4179         BUFFER_TRACE(bh, "zeroed end of block");
4180
4181         err = 0;
4182         if (ext4_should_journal_data(inode)) {
4183                 err = ext4_handle_dirty_metadata(handle, inode, bh);
4184         } else {
4185                 if (ext4_should_order_data(inode))
4186                         err = ext4_jbd2_file_inode(handle, inode);
4187                 mark_buffer_dirty(bh);
4188         }
4189
4190 unlock:
4191         unlock_page(page);
4192         page_cache_release(page);
4193         return err;
4194 }
4195
4196 /*
4197  * Probably it should be a library function... search for first non-zero word
4198  * or memcmp with zero_page, whatever is better for particular architecture.
4199  * Linus?
4200  */
4201 static inline int all_zeroes(__le32 *p, __le32 *q)
4202 {
4203         while (p < q)
4204                 if (*p++)
4205                         return 0;
4206         return 1;
4207 }
4208
4209 /**
4210  *      ext4_find_shared - find the indirect blocks for partial truncation.
4211  *      @inode:   inode in question
4212  *      @depth:   depth of the affected branch
4213  *      @offsets: offsets of pointers in that branch (see ext4_block_to_path)
4214  *      @chain:   place to store the pointers to partial indirect blocks
4215  *      @top:     place to the (detached) top of branch
4216  *
4217  *      This is a helper function used by ext4_truncate().
4218  *
4219  *      When we do truncate() we may have to clean the ends of several
4220  *      indirect blocks but leave the blocks themselves alive. Block is
4221  *      partially truncated if some data below the new i_size is refered
4222  *      from it (and it is on the path to the first completely truncated
4223  *      data block, indeed).  We have to free the top of that path along
4224  *      with everything to the right of the path. Since no allocation
4225  *      past the truncation point is possible until ext4_truncate()
4226  *      finishes, we may safely do the latter, but top of branch may
4227  *      require special attention - pageout below the truncation point
4228  *      might try to populate it.
4229  *
4230  *      We atomically detach the top of branch from the tree, store the
4231  *      block number of its root in *@top, pointers to buffer_heads of
4232  *      partially truncated blocks - in @chain[].bh and pointers to
4233  *      their last elements that should not be removed - in
4234  *      @chain[].p. Return value is the pointer to last filled element
4235  *      of @chain.
4236  *
4237  *      The work left to caller to do the actual freeing of subtrees:
4238  *              a) free the subtree starting from *@top
4239  *              b) free the subtrees whose roots are stored in
4240  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
4241  *              c) free the subtrees growing from the inode past the @chain[0].
4242  *                      (no partially truncated stuff there).  */
4243
4244 static Indirect *ext4_find_shared(struct inode *inode, int depth,
4245                                   ext4_lblk_t offsets[4], Indirect chain[4],
4246                                   __le32 *top)
4247 {
4248         Indirect *partial, *p;
4249         int k, err;
4250
4251         *top = 0;
4252         /* Make k index the deepest non-null offset + 1 */
4253         for (k = depth; k > 1 && !offsets[k-1]; k--)
4254                 ;
4255         partial = ext4_get_branch(inode, k, offsets, chain, &err);
4256         /* Writer: pointers */
4257         if (!partial)
4258                 partial = chain + k-1;
4259         /*
4260          * If the branch acquired continuation since we've looked at it -
4261          * fine, it should all survive and (new) top doesn't belong to us.
4262          */
4263         if (!partial->key && *partial->p)
4264                 /* Writer: end */
4265                 goto no_top;
4266         for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
4267                 ;
4268         /*
4269          * OK, we've found the last block that must survive. The rest of our
4270          * branch should be detached before unlocking. However, if that rest
4271          * of branch is all ours and does not grow immediately from the inode
4272          * it's easier to cheat and just decrement partial->p.
4273          */
4274         if (p == chain + k - 1 && p > chain) {
4275                 p->p--;
4276         } else {
4277                 *top = *p->p;
4278                 /* Nope, don't do this in ext4.  Must leave the tree intact */
4279 #if 0
4280                 *p->p = 0;
4281 #endif
4282         }
4283         /* Writer: end */
4284
4285         while (partial > p) {
4286                 brelse(partial->bh);
4287                 partial--;
4288         }
4289 no_top:
4290         return partial;
4291 }
4292
4293 /*
4294  * Zero a number of block pointers in either an inode or an indirect block.
4295  * If we restart the transaction we must again get write access to the
4296  * indirect block for further modification.
4297  *
4298  * We release `count' blocks on disk, but (last - first) may be greater
4299  * than `count' because there can be holes in there.
4300  */
4301 static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
4302                              struct buffer_head *bh,
4303                              ext4_fsblk_t block_to_free,
4304                              unsigned long count, __le32 *first,
4305                              __le32 *last)
4306 {
4307         __le32 *p;
4308         int     flags = EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_VALIDATED;
4309
4310         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
4311                 flags |= EXT4_FREE_BLOCKS_METADATA;
4312
4313         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), block_to_free,
4314                                    count)) {
4315                 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
4316                                  "blocks %llu len %lu",
4317                                  (unsigned long long) block_to_free, count);
4318                 return 1;
4319         }
4320
4321         if (try_to_extend_transaction(handle, inode)) {
4322                 if (bh) {
4323                         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
4324                         ext4_handle_dirty_metadata(handle, inode, bh);
4325                 }
4326                 ext4_mark_inode_dirty(handle, inode);
4327                 ext4_truncate_restart_trans(handle, inode,
4328                                             blocks_for_truncate(inode));
4329                 if (bh) {
4330                         BUFFER_TRACE(bh, "retaking write access");
4331                         ext4_journal_get_write_access(handle, bh);
4332                 }
4333         }
4334
4335         for (p = first; p < last; p++)
4336                 *p = 0;
4337
4338         ext4_free_blocks(handle, inode, 0, block_to_free, count, flags);
4339         return 0;
4340 }
4341
4342 /**
4343  * ext4_free_data - free a list of data blocks
4344  * @handle:     handle for this transaction
4345  * @inode:      inode we are dealing with
4346  * @this_bh:    indirect buffer_head which contains *@first and *@last
4347  * @first:      array of block numbers
4348  * @last:       points immediately past the end of array
4349  *
4350  * We are freeing all blocks refered from that array (numbers are stored as
4351  * little-endian 32-bit) and updating @inode->i_blocks appropriately.
4352  *
4353  * We accumulate contiguous runs of blocks to free.  Conveniently, if these
4354  * blocks are contiguous then releasing them at one time will only affect one
4355  * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
4356  * actually use a lot of journal space.
4357  *
4358  * @this_bh will be %NULL if @first and @last point into the inode's direct
4359  * block pointers.
4360  */
4361 static void ext4_free_data(handle_t *handle, struct inode *inode,
4362                            struct buffer_head *this_bh,
4363                            __le32 *first, __le32 *last)
4364 {
4365         ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
4366         unsigned long count = 0;            /* Number of blocks in the run */
4367         __le32 *block_to_free_p = NULL;     /* Pointer into inode/ind
4368                                                corresponding to
4369                                                block_to_free */
4370         ext4_fsblk_t nr;                    /* Current block # */
4371         __le32 *p;                          /* Pointer into inode/ind
4372                                                for current block */
4373         int err;
4374
4375         if (this_bh) {                          /* For indirect block */
4376                 BUFFER_TRACE(this_bh, "get_write_access");
4377                 err = ext4_journal_get_write_access(handle, this_bh);
4378                 /* Important: if we can't update the indirect pointers
4379                  * to the blocks, we can't free them. */
4380                 if (err)
4381                         return;
4382         }
4383
4384         for (p = first; p < last; p++) {
4385                 nr = le32_to_cpu(*p);
4386                 if (nr) {
4387                         /* accumulate blocks to free if they're contiguous */
4388                         if (count == 0) {
4389                                 block_to_free = nr;
4390                                 block_to_free_p = p;
4391                                 count = 1;
4392                         } else if (nr == block_to_free + count) {
4393                                 count++;
4394                         } else {
4395                                 if (ext4_clear_blocks(handle, inode, this_bh,
4396                                                       block_to_free, count,
4397                                                       block_to_free_p, p))
4398                                         break;
4399                                 block_to_free = nr;
4400                                 block_to_free_p = p;
4401                                 count = 1;
4402                         }
4403                 }
4404         }
4405
4406         if (count > 0)
4407                 ext4_clear_blocks(handle, inode, this_bh, block_to_free,
4408                                   count, block_to_free_p, p);
4409
4410         if (this_bh) {
4411                 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
4412
4413                 /*
4414                  * The buffer head should have an attached journal head at this
4415                  * point. However, if the data is corrupted and an indirect
4416                  * block pointed to itself, it would have been detached when
4417                  * the block was cleared. Check for this instead of OOPSing.
4418                  */
4419                 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
4420                         ext4_handle_dirty_metadata(handle, inode, this_bh);
4421                 else
4422                         EXT4_ERROR_INODE(inode,
4423                                          "circular indirect block detected at "
4424                                          "block %llu",
4425                                 (unsigned long long) this_bh->b_blocknr);
4426         }
4427 }
4428
4429 /**
4430  *      ext4_free_branches - free an array of branches
4431  *      @handle: JBD handle for this transaction
4432  *      @inode: inode we are dealing with
4433  *      @parent_bh: the buffer_head which contains *@first and *@last
4434  *      @first: array of block numbers
4435  *      @last:  pointer immediately past the end of array
4436  *      @depth: depth of the branches to free
4437  *
4438  *      We are freeing all blocks refered from these branches (numbers are
4439  *      stored as little-endian 32-bit) and updating @inode->i_blocks
4440  *      appropriately.
4441  */
4442 static void ext4_free_branches(handle_t *handle, struct inode *inode,
4443                                struct buffer_head *parent_bh,
4444                                __le32 *first, __le32 *last, int depth)
4445 {
4446         ext4_fsblk_t nr;
4447         __le32 *p;
4448
4449         if (ext4_handle_is_aborted(handle))
4450                 return;
4451
4452         if (depth--) {
4453                 struct buffer_head *bh;
4454                 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
4455                 p = last;
4456                 while (--p >= first) {
4457                         nr = le32_to_cpu(*p);
4458                         if (!nr)
4459                                 continue;               /* A hole */
4460
4461                         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb),
4462                                                    nr, 1)) {
4463                                 EXT4_ERROR_INODE(inode,
4464                                                  "invalid indirect mapped "
4465                                                  "block %lu (level %d)",
4466                                                  (unsigned long) nr, depth);
4467                                 break;
4468                         }
4469
4470                         /* Go read the buffer for the next level down */
4471                         bh = sb_bread(inode->i_sb, nr);
4472
4473                         /*
4474                          * A read failure? Report error and clear slot
4475                          * (should be rare).
4476                          */
4477                         if (!bh) {
4478                                 EXT4_ERROR_INODE_BLOCK(inode, nr,
4479                                                        "Read failure");
4480                                 continue;
4481                         }
4482
4483                         /* This zaps the entire block.  Bottom up. */
4484                         BUFFER_TRACE(bh, "free child branches");
4485                         ext4_free_branches(handle, inode, bh,
4486                                         (__le32 *) bh->b_data,
4487                                         (__le32 *) bh->b_data + addr_per_block,
4488                                         depth);
4489
4490                         /*
4491                          * We've probably journalled the indirect block several
4492                          * times during the truncate.  But it's no longer
4493                          * needed and we now drop it from the transaction via
4494                          * jbd2_journal_revoke().
4495                          *
4496                          * That's easy if it's exclusively part of this
4497                          * transaction.  But if it's part of the committing
4498                          * transaction then jbd2_journal_forget() will simply
4499                          * brelse() it.  That means that if the underlying
4500                          * block is reallocated in ext4_get_block(),
4501                          * unmap_underlying_metadata() will find this block
4502                          * and will try to get rid of it.  damn, damn.
4503                          *
4504                          * If this block has already been committed to the
4505                          * journal, a revoke record will be written.  And
4506                          * revoke records must be emitted *before* clearing
4507                          * this block's bit in the bitmaps.
4508                          */
4509                         ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
4510
4511                         /*
4512                          * Everything below this this pointer has been
4513                          * released.  Now let this top-of-subtree go.
4514                          *
4515                          * We want the freeing of this indirect block to be
4516                          * atomic in the journal with the updating of the
4517                          * bitmap block which owns it.  So make some room in
4518                          * the journal.
4519                          *
4520                          * We zero the parent pointer *after* freeing its
4521                          * pointee in the bitmaps, so if extend_transaction()
4522                          * for some reason fails to put the bitmap changes and
4523                          * the release into the same transaction, recovery
4524                          * will merely complain about releasing a free block,
4525                          * rather than leaking blocks.
4526                          */
4527                         if (ext4_handle_is_aborted(handle))
4528                                 return;
4529                         if (try_to_extend_transaction(handle, inode)) {
4530                                 ext4_mark_inode_dirty(handle, inode);
4531                                 ext4_truncate_restart_trans(handle, inode,
4532                                             blocks_for_truncate(inode));
4533                         }
4534
4535                         ext4_free_blocks(handle, inode, 0, nr, 1,
4536                                          EXT4_FREE_BLOCKS_METADATA);
4537
4538                         if (parent_bh) {
4539                                 /*
4540                                  * The block which we have just freed is
4541                                  * pointed to by an indirect block: journal it
4542                                  */
4543                                 BUFFER_TRACE(parent_bh, "get_write_access");
4544                                 if (!ext4_journal_get_write_access(handle,
4545                                                                    parent_bh)){
4546                                         *p = 0;
4547                                         BUFFER_TRACE(parent_bh,
4548                                         "call ext4_handle_dirty_metadata");
4549                                         ext4_handle_dirty_metadata(handle,
4550                                                                    inode,
4551                                                                    parent_bh);
4552                                 }
4553                         }
4554                 }
4555         } else {
4556                 /* We have reached the bottom of the tree. */
4557                 BUFFER_TRACE(parent_bh, "free data blocks");
4558                 ext4_free_data(handle, inode, parent_bh, first, last);
4559         }
4560 }
4561
4562 int ext4_can_truncate(struct inode *inode)
4563 {
4564         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
4565                 return 0;
4566         if (S_ISREG(inode->i_mode))
4567                 return 1;
4568         if (S_ISDIR(inode->i_mode))
4569                 return 1;
4570         if (S_ISLNK(inode->i_mode))
4571                 return !ext4_inode_is_fast_symlink(inode);
4572         return 0;
4573 }
4574
4575 /*
4576  * ext4_truncate()
4577  *
4578  * We block out ext4_get_block() block instantiations across the entire
4579  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
4580  * simultaneously on behalf of the same inode.
4581  *
4582  * As we work through the truncate and commmit bits of it to the journal there
4583  * is one core, guiding principle: the file's tree must always be consistent on
4584  * disk.  We must be able to restart the truncate after a crash.
4585  *
4586  * The file's tree may be transiently inconsistent in memory (although it
4587  * probably isn't), but whenever we close off and commit a journal transaction,
4588  * the contents of (the filesystem + the journal) must be consistent and
4589  * restartable.  It's pretty simple, really: bottom up, right to left (although
4590  * left-to-right works OK too).
4591  *
4592  * Note that at recovery time, journal replay occurs *before* the restart of
4593  * truncate against the orphan inode list.
4594  *
4595  * The committed inode has the new, desired i_size (which is the same as
4596  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
4597  * that this inode's truncate did not complete and it will again call
4598  * ext4_truncate() to have another go.  So there will be instantiated blocks
4599  * to the right of the truncation point in a crashed ext4 filesystem.  But
4600  * that's fine - as long as they are linked from the inode, the post-crash
4601  * ext4_truncate() run will find them and release them.
4602  */
4603 void ext4_truncate(struct inode *inode)
4604 {
4605         handle_t *handle;
4606         struct ext4_inode_info *ei = EXT4_I(inode);
4607         __le32 *i_data = ei->i_data;
4608         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
4609         struct address_space *mapping = inode->i_mapping;
4610         ext4_lblk_t offsets[4];
4611         Indirect chain[4];
4612         Indirect *partial;
4613         __le32 nr = 0;
4614         int n;
4615         ext4_lblk_t last_block;
4616         unsigned blocksize = inode->i_sb->s_blocksize;
4617
4618         if (!ext4_can_truncate(inode))
4619                 return;
4620
4621         ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
4622
4623         if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
4624                 ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
4625
4626         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
4627                 ext4_ext_truncate(inode);
4628                 return;
4629         }
4630
4631         handle = start_transaction(inode);
4632         if (IS_ERR(handle))
4633                 return;         /* AKPM: return what? */
4634
4635         last_block = (inode->i_size + blocksize-1)
4636                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
4637
4638         if (inode->i_size & (blocksize - 1))
4639                 if (ext4_block_truncate_page(handle, mapping, inode->i_size))
4640                         goto out_stop;
4641
4642         n = ext4_block_to_path(inode, last_block, offsets, NULL);
4643         if (n == 0)
4644                 goto out_stop;  /* error */
4645
4646         /*
4647          * OK.  This truncate is going to happen.  We add the inode to the
4648          * orphan list, so that if this truncate spans multiple transactions,
4649          * and we crash, we will resume the truncate when the filesystem
4650          * recovers.  It also marks the inode dirty, to catch the new size.
4651          *
4652          * Implication: the file must always be in a sane, consistent
4653          * truncatable state while each transaction commits.
4654          */
4655         if (ext4_orphan_add(handle, inode))
4656                 goto out_stop;
4657
4658         /*
4659          * From here we block out all ext4_get_block() callers who want to
4660          * modify the block allocation tree.
4661          */
4662         down_write(&ei->i_data_sem);
4663
4664         ext4_discard_preallocations(inode);
4665
4666         /*
4667          * The orphan list entry will now protect us from any crash which
4668          * occurs before the truncate completes, so it is now safe to propagate
4669          * the new, shorter inode size (held for now in i_size) into the
4670          * on-disk inode. We do this via i_disksize, which is the value which
4671          * ext4 *really* writes onto the disk inode.
4672          */
4673         ei->i_disksize = inode->i_size;
4674
4675         if (n == 1) {           /* direct blocks */
4676                 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
4677                                i_data + EXT4_NDIR_BLOCKS);
4678                 goto do_indirects;
4679         }
4680
4681         partial = ext4_find_shared(inode, n, offsets, chain, &nr);
4682         /* Kill the top of shared branch (not detached) */
4683         if (nr) {
4684                 if (partial == chain) {
4685                         /* Shared branch grows from the inode */
4686                         ext4_free_branches(handle, inode, NULL,
4687                                            &nr, &nr+1, (chain+n-1) - partial);
4688                         *partial->p = 0;
4689                         /*
4690                          * We mark the inode dirty prior to restart,
4691                          * and prior to stop.  No need for it here.
4692                          */
4693                 } else {
4694                         /* Shared branch grows from an indirect block */
4695                         BUFFER_TRACE(partial->bh, "get_write_access");
4696                         ext4_free_branches(handle, inode, partial->bh,
4697                                         partial->p,
4698                                         partial->p+1, (chain+n-1) - partial);
4699                 }
4700         }
4701         /* Clear the ends of indirect blocks on the shared branch */
4702         while (partial > chain) {
4703                 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
4704                                    (__le32*)partial->bh->b_data+addr_per_block,
4705                                    (chain+n-1) - partial);
4706                 BUFFER_TRACE(partial->bh, "call brelse");
4707                 brelse(partial->bh);
4708                 partial--;
4709         }
4710 do_indirects:
4711         /* Kill the remaining (whole) subtrees */
4712         switch (offsets[0]) {
4713         default:
4714                 nr = i_data[EXT4_IND_BLOCK];
4715                 if (nr) {
4716                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
4717                         i_data[EXT4_IND_BLOCK] = 0;
4718                 }
4719         case EXT4_IND_BLOCK:
4720                 nr = i_data[EXT4_DIND_BLOCK];
4721                 if (nr) {
4722                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
4723                         i_data[EXT4_DIND_BLOCK] = 0;
4724                 }
4725         case EXT4_DIND_BLOCK:
4726                 nr = i_data[EXT4_TIND_BLOCK];
4727                 if (nr) {
4728                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
4729                         i_data[EXT4_TIND_BLOCK] = 0;
4730                 }
4731         case EXT4_TIND_BLOCK:
4732                 ;
4733         }
4734
4735         up_write(&ei->i_data_sem);
4736         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
4737         ext4_mark_inode_dirty(handle, inode);
4738
4739         /*
4740          * In a multi-transaction truncate, we only make the final transaction
4741          * synchronous
4742          */
4743         if (IS_SYNC(inode))
4744                 ext4_handle_sync(handle);
4745 out_stop:
4746         /*
4747          * If this was a simple ftruncate(), and the file will remain alive
4748          * then we need to clear up the orphan record which we created above.
4749          * However, if this was a real unlink then we were called by
4750          * ext4_delete_inode(), and we allow that function to clean up the
4751          * orphan info for us.
4752          */
4753         if (inode->i_nlink)
4754                 ext4_orphan_del(handle, inode);
4755
4756         ext4_journal_stop(handle);
4757 }
4758
4759 /*
4760  * ext4_get_inode_loc returns with an extra refcount against the inode's
4761  * underlying buffer_head on success. If 'in_mem' is true, we have all
4762  * data in memory that is needed to recreate the on-disk version of this
4763  * inode.
4764  */
4765 static int __ext4_get_inode_loc(struct inode *inode,
4766                                 struct ext4_iloc *iloc, int in_mem)
4767 {
4768         struct ext4_group_desc  *gdp;
4769         struct buffer_head      *bh;
4770         struct super_block      *sb = inode->i_sb;
4771         ext4_fsblk_t            block;
4772         int                     inodes_per_block, inode_offset;
4773
4774         iloc->bh = NULL;
4775         if (!ext4_valid_inum(sb, inode->i_ino))
4776                 return -EIO;
4777
4778         iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
4779         gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
4780         if (!gdp)
4781                 return -EIO;
4782
4783         /*
4784          * Figure out the offset within the block group inode table
4785          */
4786         inodes_per_block = (EXT4_BLOCK_SIZE(sb) / EXT4_INODE_SIZE(sb));
4787         inode_offset = ((inode->i_ino - 1) %
4788                         EXT4_INODES_PER_GROUP(sb));
4789         block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
4790         iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
4791
4792         bh = sb_getblk(sb, block);
4793         if (!bh) {
4794                 EXT4_ERROR_INODE_BLOCK(inode, block,
4795                                        "unable to read itable block");
4796                 return -EIO;
4797         }
4798         if (!buffer_uptodate(bh)) {
4799                 lock_buffer(bh);
4800
4801                 /*
4802                  * If the buffer has the write error flag, we have failed
4803                  * to write out another inode in the same block.  In this
4804                  * case, we don't have to read the block because we may
4805                  * read the old inode data successfully.
4806                  */
4807                 if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
4808                         set_buffer_uptodate(bh);
4809
4810                 if (buffer_uptodate(bh)) {
4811                         /* someone brought it uptodate while we waited */
4812                         unlock_buffer(bh);
4813                         goto has_buffer;
4814                 }
4815
4816                 /*
4817                  * If we have all information of the inode in memory and this
4818                  * is the only valid inode in the block, we need not read the
4819                  * block.
4820                  */
4821                 if (in_mem) {
4822                         struct buffer_head *bitmap_bh;
4823                         int i, start;
4824
4825                         start = inode_offset & ~(inodes_per_block - 1);
4826
4827                         /* Is the inode bitmap in cache? */
4828                         bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
4829                         if (!bitmap_bh)
4830                                 goto make_io;
4831
4832                         /*
4833                          * If the inode bitmap isn't in cache then the
4834                          * optimisation may end up performing two reads instead
4835                          * of one, so skip it.
4836                          */
4837                         if (!buffer_uptodate(bitmap_bh)) {
4838                                 brelse(bitmap_bh);
4839                                 goto make_io;
4840                         }
4841                         for (i = start; i < start + inodes_per_block; i++) {
4842                                 if (i == inode_offset)
4843                                         continue;
4844                                 if (ext4_test_bit(i, bitmap_bh->b_data))
4845                                         break;
4846                         }
4847                         brelse(bitmap_bh);
4848                         if (i == start + inodes_per_block) {
4849                                 /* all other inodes are free, so skip I/O */
4850                                 memset(bh->b_data, 0, bh->b_size);
4851                                 set_buffer_uptodate(bh);
4852                                 unlock_buffer(bh);
4853                                 goto has_buffer;
4854                         }
4855                 }
4856
4857 make_io:
4858                 /*
4859                  * If we need to do any I/O, try to pre-readahead extra
4860                  * blocks from the inode table.
4861                  */
4862                 if (EXT4_SB(sb)->s_inode_readahead_blks) {
4863                         ext4_fsblk_t b, end, table;
4864                         unsigned num;
4865
4866                         table = ext4_inode_table(sb, gdp);
4867                         /* s_inode_readahead_blks is always a power of 2 */
4868                         b = block & ~(EXT4_SB(sb)->s_inode_readahead_blks-1);
4869                         if (table > b)
4870                                 b = table;
4871                         end = b + EXT4_SB(sb)->s_inode_readahead_blks;
4872                         num = EXT4_INODES_PER_GROUP(sb);
4873                         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
4874                                        EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
4875                                 num -= ext4_itable_unused_count(sb, gdp);
4876                         table += num / inodes_per_block;
4877                         if (end > table)
4878                                 end = table;
4879                         while (b <= end)
4880                                 sb_breadahead(sb, b++);
4881                 }
4882
4883                 /*
4884                  * There are other valid inodes in the buffer, this inode
4885                  * has in-inode xattrs, or we don't have this inode in memory.
4886                  * Read the block from disk.
4887                  */
4888                 get_bh(bh);
4889                 bh->b_end_io = end_buffer_read_sync;
4890                 submit_bh(READ_META, bh);
4891                 wait_on_buffer(bh);
4892                 if (!buffer_uptodate(bh)) {
4893                         EXT4_ERROR_INODE_BLOCK(inode, block,
4894                                                "unable to read itable block");
4895                         brelse(bh);
4896                         return -EIO;
4897                 }
4898         }
4899 has_buffer:
4900         iloc->bh = bh;
4901         return 0;
4902 }
4903
4904 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
4905 {
4906         /* We have all inode data except xattrs in memory here. */
4907         return __ext4_get_inode_loc(inode, iloc,
4908                 !ext4_test_inode_state(inode, EXT4_STATE_XATTR));
4909 }
4910
4911 void ext4_set_inode_flags(struct inode *inode)
4912 {
4913         unsigned int flags = EXT4_I(inode)->i_flags;
4914
4915         inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
4916         if (flags & EXT4_SYNC_FL)
4917                 inode->i_flags |= S_SYNC;
4918         if (flags & EXT4_APPEND_FL)
4919                 inode->i_flags |= S_APPEND;
4920         if (flags & EXT4_IMMUTABLE_FL)
4921                 inode->i_flags |= S_IMMUTABLE;
4922         if (flags & EXT4_NOATIME_FL)
4923                 inode->i_flags |= S_NOATIME;
4924         if (flags & EXT4_DIRSYNC_FL)
4925                 inode->i_flags |= S_DIRSYNC;
4926 }
4927
4928 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
4929 void ext4_get_inode_flags(struct ext4_inode_info *ei)
4930 {
4931         unsigned int vfs_fl;
4932         unsigned long old_fl, new_fl;
4933
4934         do {
4935                 vfs_fl = ei->vfs_inode.i_flags;
4936                 old_fl = ei->i_flags;
4937                 new_fl = old_fl & ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
4938                                 EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|
4939                                 EXT4_DIRSYNC_FL);
4940                 if (vfs_fl & S_SYNC)
4941                         new_fl |= EXT4_SYNC_FL;
4942                 if (vfs_fl & S_APPEND)
4943                         new_fl |= EXT4_APPEND_FL;
4944                 if (vfs_fl & S_IMMUTABLE)
4945                         new_fl |= EXT4_IMMUTABLE_FL;
4946                 if (vfs_fl & S_NOATIME)
4947                         new_fl |= EXT4_NOATIME_FL;
4948                 if (vfs_fl & S_DIRSYNC)
4949                         new_fl |= EXT4_DIRSYNC_FL;
4950         } while (cmpxchg(&ei->i_flags, old_fl, new_fl) != old_fl);
4951 }
4952
4953 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
4954                                   struct ext4_inode_info *ei)
4955 {
4956         blkcnt_t i_blocks ;
4957         struct inode *inode = &(ei->vfs_inode);
4958         struct super_block *sb = inode->i_sb;
4959
4960         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
4961                                 EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
4962                 /* we are using combined 48 bit field */
4963                 i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
4964                                         le32_to_cpu(raw_inode->i_blocks_lo);
4965                 if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
4966                         /* i_blocks represent file system block size */
4967                         return i_blocks  << (inode->i_blkbits - 9);
4968                 } else {
4969                         return i_blocks;
4970                 }
4971         } else {
4972                 return le32_to_cpu(raw_inode->i_blocks_lo);
4973         }
4974 }
4975
4976 struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
4977 {
4978         struct ext4_iloc iloc;
4979         struct ext4_inode *raw_inode;
4980         struct ext4_inode_info *ei;
4981         struct inode *inode;
4982         journal_t *journal = EXT4_SB(sb)->s_journal;
4983         long ret;
4984         int block;
4985
4986         inode = iget_locked(sb, ino);
4987         if (!inode)
4988                 return ERR_PTR(-ENOMEM);
4989         if (!(inode->i_state & I_NEW))
4990                 return inode;
4991
4992         ei = EXT4_I(inode);
4993         iloc.bh = 0;
4994
4995         ret = __ext4_get_inode_loc(inode, &iloc, 0);
4996         if (ret < 0)
4997                 goto bad_inode;
4998         raw_inode = ext4_raw_inode(&iloc);
4999         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
5000         inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
5001         inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
5002         if (!(test_opt(inode->i_sb, NO_UID32))) {
5003                 inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
5004                 inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
5005         }
5006         inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
5007
5008         ei->i_state_flags = 0;
5009         ei->i_dir_start_lookup = 0;
5010         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
5011         /* We now have enough fields to check if the inode was active or not.
5012          * This is needed because nfsd might try to access dead inodes
5013          * the test is that same one that e2fsck uses
5014          * NeilBrown 1999oct15
5015          */
5016         if (inode->i_nlink == 0) {
5017                 if (inode->i_mode == 0 ||
5018                     !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
5019                         /* this inode is deleted */
5020                         ret = -ESTALE;
5021                         goto bad_inode;
5022                 }
5023                 /* The only unlinked inodes we let through here have
5024                  * valid i_mode and are being read by the orphan
5025                  * recovery code: that's fine, we're about to complete
5026                  * the process of deleting those. */
5027         }
5028         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
5029         inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
5030         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
5031         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT))
5032                 ei->i_file_acl |=
5033                         ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
5034         inode->i_size = ext4_isize(raw_inode);
5035         ei->i_disksize = inode->i_size;
5036 #ifdef CONFIG_QUOTA
5037         ei->i_reserved_quota = 0;
5038 #endif
5039         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
5040         ei->i_block_group = iloc.block_group;
5041         ei->i_last_alloc_group = ~0;
5042         /*
5043          * NOTE! The in-memory inode i_data array is in little-endian order
5044          * even on big-endian machines: we do NOT byteswap the block numbers!
5045          */
5046         for (block = 0; block < EXT4_N_BLOCKS; block++)
5047                 ei->i_data[block] = raw_inode->i_block[block];
5048         INIT_LIST_HEAD(&ei->i_orphan);
5049
5050         /*
5051          * Set transaction id's of transactions that have to be committed
5052          * to finish f[data]sync. We set them to currently running transaction
5053          * as we cannot be sure that the inode or some of its metadata isn't
5054          * part of the transaction - the inode could have been reclaimed and
5055          * now it is reread from disk.
5056          */
5057         if (journal) {
5058                 transaction_t *transaction;
5059                 tid_t tid;
5060
5061                 spin_lock(&journal->j_state_lock);
5062                 if (journal->j_running_transaction)
5063                         transaction = journal->j_running_transaction;
5064                 else
5065                         transaction = journal->j_committing_transaction;
5066                 if (transaction)
5067                         tid = transaction->t_tid;
5068                 else
5069                         tid = journal->j_commit_sequence;
5070                 spin_unlock(&journal->j_state_lock);
5071                 ei->i_sync_tid = tid;
5072                 ei->i_datasync_tid = tid;
5073         }
5074
5075         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
5076                 ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
5077                 if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
5078                     EXT4_INODE_SIZE(inode->i_sb)) {
5079                         ret = -EIO;
5080                         goto bad_inode;
5081                 }
5082                 if (ei->i_extra_isize == 0) {
5083                         /* The extra space is currently unused. Use it. */
5084                         ei->i_extra_isize = sizeof(struct ext4_inode) -
5085                                             EXT4_GOOD_OLD_INODE_SIZE;
5086                 } else {
5087                         __le32 *magic = (void *)raw_inode +
5088                                         EXT4_GOOD_OLD_INODE_SIZE +
5089                                         ei->i_extra_isize;
5090                         if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
5091                                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
5092                 }
5093         } else
5094                 ei->i_extra_isize = 0;
5095
5096         EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
5097         EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
5098         EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
5099         EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
5100
5101         inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
5102         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
5103                 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
5104                         inode->i_version |=
5105                         (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
5106         }
5107
5108         ret = 0;
5109         if (ei->i_file_acl &&
5110             !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
5111                 EXT4_ERROR_INODE(inode, "bad extended attribute block %llu",
5112                                  ei->i_file_acl);
5113                 ret = -EIO;
5114                 goto bad_inode;
5115         } else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
5116                 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
5117                     (S_ISLNK(inode->i_mode) &&
5118                      !ext4_inode_is_fast_symlink(inode)))
5119                         /* Validate extent which is part of inode */
5120                         ret = ext4_ext_check_inode(inode);
5121         } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
5122                    (S_ISLNK(inode->i_mode) &&
5123                     !ext4_inode_is_fast_symlink(inode))) {
5124                 /* Validate block references which are part of inode */
5125                 ret = ext4_check_inode_blockref(inode);
5126         }
5127         if (ret)
5128                 goto bad_inode;
5129
5130         if (S_ISREG(inode->i_mode)) {
5131                 inode->i_op = &ext4_file_inode_operations;
5132                 inode->i_fop = &ext4_file_operations;
5133                 ext4_set_aops(inode);
5134         } else if (S_ISDIR(inode->i_mode)) {
5135                 inode->i_op = &ext4_dir_inode_operations;
5136                 inode->i_fop = &ext4_dir_operations;
5137         } else if (S_ISLNK(inode->i_mode)) {
5138                 if (ext4_inode_is_fast_symlink(inode)) {
5139                         inode->i_op = &ext4_fast_symlink_inode_operations;
5140                         nd_terminate_link(ei->i_data, inode->i_size,
5141                                 sizeof(ei->i_data) - 1);
5142                 } else {
5143                         inode->i_op = &ext4_symlink_inode_operations;
5144                         ext4_set_aops(inode);
5145                 }
5146         } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
5147               S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
5148                 inode->i_op = &ext4_special_inode_operations;
5149                 if (raw_inode->i_block[0])
5150                         init_special_inode(inode, inode->i_mode,
5151                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
5152                 else
5153                         init_special_inode(inode, inode->i_mode,
5154                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
5155         } else {
5156                 ret = -EIO;
5157                 EXT4_ERROR_INODE(inode, "bogus i_mode (%o)", inode->i_mode);
5158                 goto bad_inode;
5159         }
5160         brelse(iloc.bh);
5161         ext4_set_inode_flags(inode);
5162         unlock_new_inode(inode);
5163         return inode;
5164
5165 bad_inode:
5166         brelse(iloc.bh);
5167         iget_failed(inode);
5168         return ERR_PTR(ret);
5169 }
5170
5171 static int ext4_inode_blocks_set(handle_t *handle,
5172                                 struct ext4_inode *raw_inode,
5173                                 struct ext4_inode_info *ei)
5174 {
5175         struct inode *inode = &(ei->vfs_inode);
5176         u64 i_blocks = inode->i_blocks;
5177         struct super_block *sb = inode->i_sb;
5178
5179         if (i_blocks <= ~0U) {
5180                 /*
5181                  * i_blocks can be represnted in a 32 bit variable
5182                  * as multiple of 512 bytes
5183                  */
5184                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
5185                 raw_inode->i_blocks_high = 0;
5186                 ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
5187                 return 0;
5188         }
5189         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE))
5190                 return -EFBIG;
5191
5192         if (i_blocks <= 0xffffffffffffULL) {
5193                 /*
5194                  * i_blocks can be represented in a 48 bit variable
5195                  * as multiple of 512 bytes
5196                  */
5197                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
5198                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
5199                 ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
5200         } else {
5201                 ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
5202                 /* i_block is stored in file system block size */
5203                 i_blocks = i_blocks >> (inode->i_blkbits - 9);
5204                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
5205                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
5206         }
5207         return 0;
5208 }
5209
5210 /*
5211  * Post the struct inode info into an on-disk inode location in the
5212  * buffer-cache.  This gobbles the caller's reference to the
5213  * buffer_head in the inode location struct.
5214  *
5215  * The caller must have write access to iloc->bh.
5216  */
5217 static int ext4_do_update_inode(handle_t *handle,
5218                                 struct inode *inode,
5219                                 struct ext4_iloc *iloc)
5220 {
5221         struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
5222         struct ext4_inode_info *ei = EXT4_I(inode);
5223         struct buffer_head *bh = iloc->bh;
5224         int err = 0, rc, block;
5225
5226         /* For fields not not tracking in the in-memory inode,
5227          * initialise them to zero for new inodes. */
5228         if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
5229                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
5230
5231         ext4_get_inode_flags(ei);
5232         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
5233         if (!(test_opt(inode->i_sb, NO_UID32))) {
5234                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
5235                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
5236 /*
5237  * Fix up interoperability with old kernels. Otherwise, old inodes get
5238  * re-used with the upper 16 bits of the uid/gid intact
5239  */
5240                 if (!ei->i_dtime) {
5241                         raw_inode->i_uid_high =
5242                                 cpu_to_le16(high_16_bits(inode->i_uid));
5243                         raw_inode->i_gid_high =
5244                                 cpu_to_le16(high_16_bits(inode->i_gid));
5245                 } else {
5246                         raw_inode->i_uid_high = 0;
5247                         raw_inode->i_gid_high = 0;
5248                 }
5249         } else {
5250                 raw_inode->i_uid_low =
5251                         cpu_to_le16(fs_high2lowuid(inode->i_uid));
5252                 raw_inode->i_gid_low =
5253                         cpu_to_le16(fs_high2lowgid(inode->i_gid));
5254                 raw_inode->i_uid_high = 0;
5255                 raw_inode->i_gid_high = 0;
5256         }
5257         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
5258
5259         EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
5260         EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
5261         EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
5262         EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
5263
5264         if (ext4_inode_blocks_set(handle, raw_inode, ei))
5265                 goto out_brelse;
5266         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
5267         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
5268         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
5269             cpu_to_le32(EXT4_OS_HURD))
5270                 raw_inode->i_file_acl_high =
5271                         cpu_to_le16(ei->i_file_acl >> 32);
5272         raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
5273         ext4_isize_set(raw_inode, ei->i_disksize);
5274         if (ei->i_disksize > 0x7fffffffULL) {
5275                 struct super_block *sb = inode->i_sb;
5276                 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
5277                                 EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
5278                                 EXT4_SB(sb)->s_es->s_rev_level ==
5279                                 cpu_to_le32(EXT4_GOOD_OLD_REV)) {
5280                         /* If this is the first large file
5281                          * created, add a flag to the superblock.
5282                          */
5283                         err = ext4_journal_get_write_access(handle,
5284                                         EXT4_SB(sb)->s_sbh);
5285                         if (err)
5286                                 goto out_brelse;
5287                         ext4_update_dynamic_rev(sb);
5288                         EXT4_SET_RO_COMPAT_FEATURE(sb,
5289                                         EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
5290                         sb->s_dirt = 1;
5291                         ext4_handle_sync(handle);
5292                         err = ext4_handle_dirty_metadata(handle, NULL,
5293                                         EXT4_SB(sb)->s_sbh);
5294                 }
5295         }
5296         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
5297         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
5298                 if (old_valid_dev(inode->i_rdev)) {
5299                         raw_inode->i_block[0] =
5300                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
5301                         raw_inode->i_block[1] = 0;
5302                 } else {
5303                         raw_inode->i_block[0] = 0;
5304                         raw_inode->i_block[1] =
5305                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
5306                         raw_inode->i_block[2] = 0;
5307                 }
5308         } else
5309                 for (block = 0; block < EXT4_N_BLOCKS; block++)
5310                         raw_inode->i_block[block] = ei->i_data[block];
5311
5312         raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
5313         if (ei->i_extra_isize) {
5314                 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
5315                         raw_inode->i_version_hi =
5316                         cpu_to_le32(inode->i_version >> 32);
5317                 raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
5318         }
5319
5320         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
5321         rc = ext4_handle_dirty_metadata(handle, NULL, bh);
5322         if (!err)
5323                 err = rc;
5324         ext4_clear_inode_state(inode, EXT4_STATE_NEW);
5325
5326         ext4_update_inode_fsync_trans(handle, inode, 0);
5327 out_brelse:
5328         brelse(bh);
5329         ext4_std_error(inode->i_sb, err);
5330         return err;
5331 }
5332
5333 /*
5334  * ext4_write_inode()
5335  *
5336  * We are called from a few places:
5337  *
5338  * - Within generic_file_write() for O_SYNC files.
5339  *   Here, there will be no transaction running. We wait for any running
5340  *   trasnaction to commit.
5341  *
5342  * - Within sys_sync(), kupdate and such.
5343  *   We wait on commit, if tol to.
5344  *
5345  * - Within prune_icache() (PF_MEMALLOC == true)
5346  *   Here we simply return.  We can't afford to block kswapd on the
5347  *   journal commit.
5348  *
5349  * In all cases it is actually safe for us to return without doing anything,
5350  * because the inode has been copied into a raw inode buffer in
5351  * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
5352  * knfsd.
5353  *
5354  * Note that we are absolutely dependent upon all inode dirtiers doing the
5355  * right thing: they *must* call mark_inode_dirty() after dirtying info in
5356  * which we are interested.
5357  *
5358  * It would be a bug for them to not do this.  The code:
5359  *
5360  *      mark_inode_dirty(inode)
5361  *      stuff();
5362  *      inode->i_size = expr;
5363  *
5364  * is in error because a kswapd-driven write_inode() could occur while
5365  * `stuff()' is running, and the new i_size will be lost.  Plus the inode
5366  * will no longer be on the superblock's dirty inode list.
5367  */
5368 int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
5369 {
5370         int err;
5371
5372         if (current->flags & PF_MEMALLOC)
5373                 return 0;
5374
5375         if (EXT4_SB(inode->i_sb)->s_journal) {
5376                 if (ext4_journal_current_handle()) {
5377                         jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
5378                         dump_stack();
5379                         return -EIO;
5380                 }
5381
5382                 if (wbc->sync_mode != WB_SYNC_ALL)
5383                         return 0;
5384
5385                 err = ext4_force_commit(inode->i_sb);
5386         } else {
5387                 struct ext4_iloc iloc;
5388
5389                 err = __ext4_get_inode_loc(inode, &iloc, 0);
5390                 if (err)
5391                         return err;
5392                 if (wbc->sync_mode == WB_SYNC_ALL)
5393                         sync_dirty_buffer(iloc.bh);
5394                 if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
5395                         EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
5396                                          "IO error syncing inode");
5397                         err = -EIO;
5398                 }
5399                 brelse(iloc.bh);
5400         }
5401         return err;
5402 }
5403
5404 /*
5405  * ext4_setattr()
5406  *
5407  * Called from notify_change.
5408  *
5409  * We want to trap VFS attempts to truncate the file as soon as
5410  * possible.  In particular, we want to make sure that when the VFS
5411  * shrinks i_size, we put the inode on the orphan list and modify
5412  * i_disksize immediately, so that during the subsequent flushing of
5413  * dirty pages and freeing of disk blocks, we can guarantee that any
5414  * commit will leave the blocks being flushed in an unused state on
5415  * disk.  (On recovery, the inode will get truncated and the blocks will
5416  * be freed, so we have a strong guarantee that no future commit will
5417  * leave these blocks visible to the user.)
5418  *
5419  * Another thing we have to assure is that if we are in ordered mode
5420  * and inode is still attached to the committing transaction, we must
5421  * we start writeout of all the dirty pages which are being truncated.
5422  * This way we are sure that all the data written in the previous
5423  * transaction are already on disk (truncate waits for pages under
5424  * writeback).
5425  *
5426  * Called with inode->i_mutex down.
5427  */
5428 int ext4_setattr(struct dentry *dentry, struct iattr *attr)
5429 {
5430         struct inode *inode = dentry->d_inode;
5431         int error, rc = 0;
5432         const unsigned int ia_valid = attr->ia_valid;
5433
5434         error = inode_change_ok(inode, attr);
5435         if (error)
5436                 return error;
5437
5438         if (is_quota_modification(inode, attr))
5439                 dquot_initialize(inode);
5440         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
5441                 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
5442                 handle_t *handle;
5443
5444                 /* (user+group)*(old+new) structure, inode write (sb,
5445                  * inode block, ? - but truncate inode update has it) */
5446                 handle = ext4_journal_start(inode, (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)+
5447                                         EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb))+3);
5448                 if (IS_ERR(handle)) {
5449                         error = PTR_ERR(handle);
5450                         goto err_out;
5451                 }
5452                 error = dquot_transfer(inode, attr);
5453                 if (error) {
5454                         ext4_journal_stop(handle);
5455                         return error;
5456                 }
5457                 /* Update corresponding info in inode so that everything is in
5458                  * one transaction */
5459                 if (attr->ia_valid & ATTR_UID)
5460                         inode->i_uid = attr->ia_uid;
5461                 if (attr->ia_valid & ATTR_GID)
5462                         inode->i_gid = attr->ia_gid;
5463                 error = ext4_mark_inode_dirty(handle, inode);
5464                 ext4_journal_stop(handle);
5465         }
5466
5467         if (attr->ia_valid & ATTR_SIZE) {
5468                 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
5469                         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5470
5471                         if (attr->ia_size > sbi->s_bitmap_maxbytes) {
5472                                 error = -EFBIG;
5473                                 goto err_out;
5474                         }
5475                 }
5476         }
5477
5478         if (S_ISREG(inode->i_mode) &&
5479             attr->ia_valid & ATTR_SIZE &&
5480             (attr->ia_size < inode->i_size ||
5481              (ext4_test_inode_flag(inode, EXT4_INODE_EOFBLOCKS)))) {
5482                 handle_t *handle;
5483
5484                 handle = ext4_journal_start(inode, 3);
5485                 if (IS_ERR(handle)) {
5486                         error = PTR_ERR(handle);
5487                         goto err_out;
5488                 }
5489
5490                 error = ext4_orphan_add(handle, inode);
5491                 EXT4_I(inode)->i_disksize = attr->ia_size;
5492                 rc = ext4_mark_inode_dirty(handle, inode);
5493                 if (!error)
5494                         error = rc;
5495                 ext4_journal_stop(handle);
5496
5497                 if (ext4_should_order_data(inode)) {
5498                         error = ext4_begin_ordered_truncate(inode,
5499                                                             attr->ia_size);
5500                         if (error) {
5501                                 /* Do as much error cleanup as possible */
5502                                 handle = ext4_journal_start(inode, 3);
5503                                 if (IS_ERR(handle)) {
5504                                         ext4_orphan_del(NULL, inode);
5505                                         goto err_out;
5506                                 }
5507                                 ext4_orphan_del(handle, inode);
5508                                 ext4_journal_stop(handle);
5509                                 goto err_out;
5510                         }
5511                 }
5512                 /* ext4_truncate will clear the flag */
5513                 if ((ext4_test_inode_flag(inode, EXT4_INODE_EOFBLOCKS)))
5514                         ext4_truncate(inode);
5515         }
5516
5517         rc = inode_setattr(inode, attr);
5518
5519         /* If inode_setattr's call to ext4_truncate failed to get a
5520          * transaction handle at all, we need to clean up the in-core
5521          * orphan list manually. */
5522         if (inode->i_nlink)
5523                 ext4_orphan_del(NULL, inode);
5524
5525         if (!rc && (ia_valid & ATTR_MODE))
5526                 rc = ext4_acl_chmod(inode);
5527
5528 err_out:
5529         ext4_std_error(inode->i_sb, error);
5530         if (!error)
5531                 error = rc;
5532         return error;
5533 }
5534
5535 int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
5536            &n