ext4: let ext4_group_add_blocks() return an error code
[linux-2.6.git] / fs / ext4 / indirect.c
1 /*
2  *  linux/fs/ext4/indirect.c
3  *
4  *  from
5  *
6  *  linux/fs/ext4/inode.c
7  *
8  * Copyright (C) 1992, 1993, 1994, 1995
9  * Remy Card (card@masi.ibp.fr)
10  * Laboratoire MASI - Institut Blaise Pascal
11  * Universite Pierre et Marie Curie (Paris VI)
12  *
13  *  from
14  *
15  *  linux/fs/minix/inode.c
16  *
17  *  Copyright (C) 1991, 1992  Linus Torvalds
18  *
19  *  Goal-directed block allocation by Stephen Tweedie
20  *      (sct@redhat.com), 1993, 1998
21  */
22
23 #include <linux/module.h>
24 #include "ext4_jbd2.h"
25 #include "truncate.h"
26
27 #include <trace/events/ext4.h>
28
29 typedef struct {
30         __le32  *p;
31         __le32  key;
32         struct buffer_head *bh;
33 } Indirect;
34
35 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
36 {
37         p->key = *(p->p = v);
38         p->bh = bh;
39 }
40
41 /**
42  *      ext4_block_to_path - parse the block number into array of offsets
43  *      @inode: inode in question (we are only interested in its superblock)
44  *      @i_block: block number to be parsed
45  *      @offsets: array to store the offsets in
46  *      @boundary: set this non-zero if the referred-to block is likely to be
47  *             followed (on disk) by an indirect block.
48  *
49  *      To store the locations of file's data ext4 uses a data structure common
50  *      for UNIX filesystems - tree of pointers anchored in the inode, with
51  *      data blocks at leaves and indirect blocks in intermediate nodes.
52  *      This function translates the block number into path in that tree -
53  *      return value is the path length and @offsets[n] is the offset of
54  *      pointer to (n+1)th node in the nth one. If @block is out of range
55  *      (negative or too large) warning is printed and zero returned.
56  *
57  *      Note: function doesn't find node addresses, so no IO is needed. All
58  *      we need to know is the capacity of indirect blocks (taken from the
59  *      inode->i_sb).
60  */
61
62 /*
63  * Portability note: the last comparison (check that we fit into triple
64  * indirect block) is spelled differently, because otherwise on an
65  * architecture with 32-bit longs and 8Kb pages we might get into trouble
66  * if our filesystem had 8Kb blocks. We might use long long, but that would
67  * kill us on x86. Oh, well, at least the sign propagation does not matter -
68  * i_block would have to be negative in the very beginning, so we would not
69  * get there at all.
70  */
71
72 static int ext4_block_to_path(struct inode *inode,
73                               ext4_lblk_t i_block,
74                               ext4_lblk_t offsets[4], int *boundary)
75 {
76         int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
77         int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
78         const long direct_blocks = EXT4_NDIR_BLOCKS,
79                 indirect_blocks = ptrs,
80                 double_blocks = (1 << (ptrs_bits * 2));
81         int n = 0;
82         int final = 0;
83
84         if (i_block < direct_blocks) {
85                 offsets[n++] = i_block;
86                 final = direct_blocks;
87         } else if ((i_block -= direct_blocks) < indirect_blocks) {
88                 offsets[n++] = EXT4_IND_BLOCK;
89                 offsets[n++] = i_block;
90                 final = ptrs;
91         } else if ((i_block -= indirect_blocks) < double_blocks) {
92                 offsets[n++] = EXT4_DIND_BLOCK;
93                 offsets[n++] = i_block >> ptrs_bits;
94                 offsets[n++] = i_block & (ptrs - 1);
95                 final = ptrs;
96         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
97                 offsets[n++] = EXT4_TIND_BLOCK;
98                 offsets[n++] = i_block >> (ptrs_bits * 2);
99                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
100                 offsets[n++] = i_block & (ptrs - 1);
101                 final = ptrs;
102         } else {
103                 ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
104                              i_block + direct_blocks +
105                              indirect_blocks + double_blocks, inode->i_ino);
106         }
107         if (boundary)
108                 *boundary = final - 1 - (i_block & (ptrs - 1));
109         return n;
110 }
111
112 /**
113  *      ext4_get_branch - read the chain of indirect blocks leading to data
114  *      @inode: inode in question
115  *      @depth: depth of the chain (1 - direct pointer, etc.)
116  *      @offsets: offsets of pointers in inode/indirect blocks
117  *      @chain: place to store the result
118  *      @err: here we store the error value
119  *
120  *      Function fills the array of triples <key, p, bh> and returns %NULL
121  *      if everything went OK or the pointer to the last filled triple
122  *      (incomplete one) otherwise. Upon the return chain[i].key contains
123  *      the number of (i+1)-th block in the chain (as it is stored in memory,
124  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
125  *      number (it points into struct inode for i==0 and into the bh->b_data
126  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
127  *      block for i>0 and NULL for i==0. In other words, it holds the block
128  *      numbers of the chain, addresses they were taken from (and where we can
129  *      verify that chain did not change) and buffer_heads hosting these
130  *      numbers.
131  *
132  *      Function stops when it stumbles upon zero pointer (absent block)
133  *              (pointer to last triple returned, *@err == 0)
134  *      or when it gets an IO error reading an indirect block
135  *              (ditto, *@err == -EIO)
136  *      or when it reads all @depth-1 indirect blocks successfully and finds
137  *      the whole chain, all way to the data (returns %NULL, *err == 0).
138  *
139  *      Need to be called with
140  *      down_read(&EXT4_I(inode)->i_data_sem)
141  */
142 static Indirect *ext4_get_branch(struct inode *inode, int depth,
143                                  ext4_lblk_t  *offsets,
144                                  Indirect chain[4], int *err)
145 {
146         struct super_block *sb = inode->i_sb;
147         Indirect *p = chain;
148         struct buffer_head *bh;
149
150         *err = 0;
151         /* i_data is not going away, no lock needed */
152         add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
153         if (!p->key)
154                 goto no_block;
155         while (--depth) {
156                 bh = sb_getblk(sb, le32_to_cpu(p->key));
157                 if (unlikely(!bh))
158                         goto failure;
159
160                 if (!bh_uptodate_or_lock(bh)) {
161                         if (bh_submit_read(bh) < 0) {
162                                 put_bh(bh);
163                                 goto failure;
164                         }
165                         /* validate block references */
166                         if (ext4_check_indirect_blockref(inode, bh)) {
167                                 put_bh(bh);
168                                 goto failure;
169                         }
170                 }
171
172                 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
173                 /* Reader: end */
174                 if (!p->key)
175                         goto no_block;
176         }
177         return NULL;
178
179 failure:
180         *err = -EIO;
181 no_block:
182         return p;
183 }
184
185 /**
186  *      ext4_find_near - find a place for allocation with sufficient locality
187  *      @inode: owner
188  *      @ind: descriptor of indirect block.
189  *
190  *      This function returns the preferred place for block allocation.
191  *      It is used when heuristic for sequential allocation fails.
192  *      Rules are:
193  *        + if there is a block to the left of our position - allocate near it.
194  *        + if pointer will live in indirect block - allocate near that block.
195  *        + if pointer will live in inode - allocate in the same
196  *          cylinder group.
197  *
198  * In the latter case we colour the starting block by the callers PID to
199  * prevent it from clashing with concurrent allocations for a different inode
200  * in the same block group.   The PID is used here so that functionally related
201  * files will be close-by on-disk.
202  *
203  *      Caller must make sure that @ind is valid and will stay that way.
204  */
205 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
206 {
207         struct ext4_inode_info *ei = EXT4_I(inode);
208         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
209         __le32 *p;
210
211         /* Try to find previous block */
212         for (p = ind->p - 1; p >= start; p--) {
213                 if (*p)
214                         return le32_to_cpu(*p);
215         }
216
217         /* No such thing, so let's try location of indirect block */
218         if (ind->bh)
219                 return ind->bh->b_blocknr;
220
221         /*
222          * It is going to be referred to from the inode itself? OK, just put it
223          * into the same cylinder group then.
224          */
225         return ext4_inode_to_goal_block(inode);
226 }
227
228 /**
229  *      ext4_find_goal - find a preferred place for allocation.
230  *      @inode: owner
231  *      @block:  block we want
232  *      @partial: pointer to the last triple within a chain
233  *
234  *      Normally this function find the preferred place for block allocation,
235  *      returns it.
236  *      Because this is only used for non-extent files, we limit the block nr
237  *      to 32 bits.
238  */
239 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
240                                    Indirect *partial)
241 {
242         ext4_fsblk_t goal;
243
244         /*
245          * XXX need to get goal block from mballoc's data structures
246          */
247
248         goal = ext4_find_near(inode, partial);
249         goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
250         return goal;
251 }
252
253 /**
254  *      ext4_blks_to_allocate - Look up the block map and count the number
255  *      of direct blocks need to be allocated for the given branch.
256  *
257  *      @branch: chain of indirect blocks
258  *      @k: number of blocks need for indirect blocks
259  *      @blks: number of data blocks to be mapped.
260  *      @blocks_to_boundary:  the offset in the indirect block
261  *
262  *      return the total number of blocks to be allocate, including the
263  *      direct and indirect blocks.
264  */
265 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
266                                  int blocks_to_boundary)
267 {
268         unsigned int count = 0;
269
270         /*
271          * Simple case, [t,d]Indirect block(s) has not allocated yet
272          * then it's clear blocks on that path have not allocated
273          */
274         if (k > 0) {
275                 /* right now we don't handle cross boundary allocation */
276                 if (blks < blocks_to_boundary + 1)
277                         count += blks;
278                 else
279                         count += blocks_to_boundary + 1;
280                 return count;
281         }
282
283         count++;
284         while (count < blks && count <= blocks_to_boundary &&
285                 le32_to_cpu(*(branch[0].p + count)) == 0) {
286                 count++;
287         }
288         return count;
289 }
290
291 /**
292  *      ext4_alloc_blocks: multiple allocate blocks needed for a branch
293  *      @handle: handle for this transaction
294  *      @inode: inode which needs allocated blocks
295  *      @iblock: the logical block to start allocated at
296  *      @goal: preferred physical block of allocation
297  *      @indirect_blks: the number of blocks need to allocate for indirect
298  *                      blocks
299  *      @blks: number of desired blocks
300  *      @new_blocks: on return it will store the new block numbers for
301  *      the indirect blocks(if needed) and the first direct block,
302  *      @err: on return it will store the error code
303  *
304  *      This function will return the number of blocks allocated as
305  *      requested by the passed-in parameters.
306  */
307 static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
308                              ext4_lblk_t iblock, ext4_fsblk_t goal,
309                              int indirect_blks, int blks,
310                              ext4_fsblk_t new_blocks[4], int *err)
311 {
312         struct ext4_allocation_request ar;
313         int target, i;
314         unsigned long count = 0, blk_allocated = 0;
315         int index = 0;
316         ext4_fsblk_t current_block = 0;
317         int ret = 0;
318
319         /*
320          * Here we try to allocate the requested multiple blocks at once,
321          * on a best-effort basis.
322          * To build a branch, we should allocate blocks for
323          * the indirect blocks(if not allocated yet), and at least
324          * the first direct block of this branch.  That's the
325          * minimum number of blocks need to allocate(required)
326          */
327         /* first we try to allocate the indirect blocks */
328         target = indirect_blks;
329         while (target > 0) {
330                 count = target;
331                 /* allocating blocks for indirect blocks and direct blocks */
332                 current_block = ext4_new_meta_blocks(handle, inode, goal,
333                                                      0, &count, err);
334                 if (*err)
335                         goto failed_out;
336
337                 if (unlikely(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS)) {
338                         EXT4_ERROR_INODE(inode,
339                                          "current_block %llu + count %lu > %d!",
340                                          current_block, count,
341                                          EXT4_MAX_BLOCK_FILE_PHYS);
342                         *err = -EIO;
343                         goto failed_out;
344                 }
345
346                 target -= count;
347                 /* allocate blocks for indirect blocks */
348                 while (index < indirect_blks && count) {
349                         new_blocks[index++] = current_block++;
350                         count--;
351                 }
352                 if (count > 0) {
353                         /*
354                          * save the new block number
355                          * for the first direct block
356                          */
357                         new_blocks[index] = current_block;
358                         printk(KERN_INFO "%s returned more blocks than "
359                                                 "requested\n", __func__);
360                         WARN_ON(1);
361                         break;
362                 }
363         }
364
365         target = blks - count ;
366         blk_allocated = count;
367         if (!target)
368                 goto allocated;
369         /* Now allocate data blocks */
370         memset(&ar, 0, sizeof(ar));
371         ar.inode = inode;
372         ar.goal = goal;
373         ar.len = target;
374         ar.logical = iblock;
375         if (S_ISREG(inode->i_mode))
376                 /* enable in-core preallocation only for regular files */
377                 ar.flags = EXT4_MB_HINT_DATA;
378
379         current_block = ext4_mb_new_blocks(handle, &ar, err);
380         if (unlikely(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS)) {
381                 EXT4_ERROR_INODE(inode,
382                                  "current_block %llu + ar.len %d > %d!",
383                                  current_block, ar.len,
384                                  EXT4_MAX_BLOCK_FILE_PHYS);
385                 *err = -EIO;
386                 goto failed_out;
387         }
388
389         if (*err && (target == blks)) {
390                 /*
391                  * if the allocation failed and we didn't allocate
392                  * any blocks before
393                  */
394                 goto failed_out;
395         }
396         if (!*err) {
397                 if (target == blks) {
398                         /*
399                          * save the new block number
400                          * for the first direct block
401                          */
402                         new_blocks[index] = current_block;
403                 }
404                 blk_allocated += ar.len;
405         }
406 allocated:
407         /* total number of blocks allocated for direct blocks */
408         ret = blk_allocated;
409         *err = 0;
410         return ret;
411 failed_out:
412         for (i = 0; i < index; i++)
413                 ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1, 0);
414         return ret;
415 }
416
417 /**
418  *      ext4_alloc_branch - allocate and set up a chain of blocks.
419  *      @handle: handle for this transaction
420  *      @inode: owner
421  *      @indirect_blks: number of allocated indirect blocks
422  *      @blks: number of allocated direct blocks
423  *      @goal: preferred place for allocation
424  *      @offsets: offsets (in the blocks) to store the pointers to next.
425  *      @branch: place to store the chain in.
426  *
427  *      This function allocates blocks, zeroes out all but the last one,
428  *      links them into chain and (if we are synchronous) writes them to disk.
429  *      In other words, it prepares a branch that can be spliced onto the
430  *      inode. It stores the information about that chain in the branch[], in
431  *      the same format as ext4_get_branch() would do. We are calling it after
432  *      we had read the existing part of chain and partial points to the last
433  *      triple of that (one with zero ->key). Upon the exit we have the same
434  *      picture as after the successful ext4_get_block(), except that in one
435  *      place chain is disconnected - *branch->p is still zero (we did not
436  *      set the last link), but branch->key contains the number that should
437  *      be placed into *branch->p to fill that gap.
438  *
439  *      If allocation fails we free all blocks we've allocated (and forget
440  *      their buffer_heads) and return the error value the from failed
441  *      ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
442  *      as described above and return 0.
443  */
444 static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
445                              ext4_lblk_t iblock, int indirect_blks,
446                              int *blks, ext4_fsblk_t goal,
447                              ext4_lblk_t *offsets, Indirect *branch)
448 {
449         int blocksize = inode->i_sb->s_blocksize;
450         int i, n = 0;
451         int err = 0;
452         struct buffer_head *bh;
453         int num;
454         ext4_fsblk_t new_blocks[4];
455         ext4_fsblk_t current_block;
456
457         num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
458                                 *blks, new_blocks, &err);
459         if (err)
460                 return err;
461
462         branch[0].key = cpu_to_le32(new_blocks[0]);
463         /*
464          * metadata blocks and data blocks are allocated.
465          */
466         for (n = 1; n <= indirect_blks;  n++) {
467                 /*
468                  * Get buffer_head for parent block, zero it out
469                  * and set the pointer to new one, then send
470                  * parent to disk.
471                  */
472                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
473                 if (unlikely(!bh)) {
474                         err = -EIO;
475                         goto failed;
476                 }
477
478                 branch[n].bh = bh;
479                 lock_buffer(bh);
480                 BUFFER_TRACE(bh, "call get_create_access");
481                 err = ext4_journal_get_create_access(handle, bh);
482                 if (err) {
483                         /* Don't brelse(bh) here; it's done in
484                          * ext4_journal_forget() below */
485                         unlock_buffer(bh);
486                         goto failed;
487                 }
488
489                 memset(bh->b_data, 0, blocksize);
490                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
491                 branch[n].key = cpu_to_le32(new_blocks[n]);
492                 *branch[n].p = branch[n].key;
493                 if (n == indirect_blks) {
494                         current_block = new_blocks[n];
495                         /*
496                          * End of chain, update the last new metablock of
497                          * the chain to point to the new allocated
498                          * data blocks numbers
499                          */
500                         for (i = 1; i < num; i++)
501                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
502                 }
503                 BUFFER_TRACE(bh, "marking uptodate");
504                 set_buffer_uptodate(bh);
505                 unlock_buffer(bh);
506
507                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
508                 err = ext4_handle_dirty_metadata(handle, inode, bh);
509                 if (err)
510                         goto failed;
511         }
512         *blks = num;
513         return err;
514 failed:
515         /* Allocation failed, free what we already allocated */
516         ext4_free_blocks(handle, inode, NULL, new_blocks[0], 1, 0);
517         for (i = 1; i <= n ; i++) {
518                 /*
519                  * branch[i].bh is newly allocated, so there is no
520                  * need to revoke the block, which is why we don't
521                  * need to set EXT4_FREE_BLOCKS_METADATA.
522                  */
523                 ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1,
524                                  EXT4_FREE_BLOCKS_FORGET);
525         }
526         for (i = n+1; i < indirect_blks; i++)
527                 ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1, 0);
528
529         ext4_free_blocks(handle, inode, NULL, new_blocks[i], num, 0);
530
531         return err;
532 }
533
534 /**
535  * ext4_splice_branch - splice the allocated branch onto inode.
536  * @handle: handle for this transaction
537  * @inode: owner
538  * @block: (logical) number of block we are adding
539  * @chain: chain of indirect blocks (with a missing link - see
540  *      ext4_alloc_branch)
541  * @where: location of missing link
542  * @num:   number of indirect blocks we are adding
543  * @blks:  number of direct blocks we are adding
544  *
545  * This function fills the missing link and does all housekeeping needed in
546  * inode (->i_blocks, etc.). In case of success we end up with the full
547  * chain to new block and return 0.
548  */
549 static int ext4_splice_branch(handle_t *handle, struct inode *inode,
550                               ext4_lblk_t block, Indirect *where, int num,
551                               int blks)
552 {
553         int i;
554         int err = 0;
555         ext4_fsblk_t current_block;
556
557         /*
558          * If we're splicing into a [td]indirect block (as opposed to the
559          * inode) then we need to get write access to the [td]indirect block
560          * before the splice.
561          */
562         if (where->bh) {
563                 BUFFER_TRACE(where->bh, "get_write_access");
564                 err = ext4_journal_get_write_access(handle, where->bh);
565                 if (err)
566                         goto err_out;
567         }
568         /* That's it */
569
570         *where->p = where->key;
571
572         /*
573          * Update the host buffer_head or inode to point to more just allocated
574          * direct blocks blocks
575          */
576         if (num == 0 && blks > 1) {
577                 current_block = le32_to_cpu(where->key) + 1;
578                 for (i = 1; i < blks; i++)
579                         *(where->p + i) = cpu_to_le32(current_block++);
580         }
581
582         /* We are done with atomic stuff, now do the rest of housekeeping */
583         /* had we spliced it onto indirect block? */
584         if (where->bh) {
585                 /*
586                  * If we spliced it onto an indirect block, we haven't
587                  * altered the inode.  Note however that if it is being spliced
588                  * onto an indirect block at the very end of the file (the
589                  * file is growing) then we *will* alter the inode to reflect
590                  * the new i_size.  But that is not done here - it is done in
591                  * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
592                  */
593                 jbd_debug(5, "splicing indirect only\n");
594                 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
595                 err = ext4_handle_dirty_metadata(handle, inode, where->bh);
596                 if (err)
597                         goto err_out;
598         } else {
599                 /*
600                  * OK, we spliced it into the inode itself on a direct block.
601                  */
602                 ext4_mark_inode_dirty(handle, inode);
603                 jbd_debug(5, "splicing direct\n");
604         }
605         return err;
606
607 err_out:
608         for (i = 1; i <= num; i++) {
609                 /*
610                  * branch[i].bh is newly allocated, so there is no
611                  * need to revoke the block, which is why we don't
612                  * need to set EXT4_FREE_BLOCKS_METADATA.
613                  */
614                 ext4_free_blocks(handle, inode, where[i].bh, 0, 1,
615                                  EXT4_FREE_BLOCKS_FORGET);
616         }
617         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(where[num].key),
618                          blks, 0);
619
620         return err;
621 }
622
623 /*
624  * The ext4_ind_map_blocks() function handles non-extents inodes
625  * (i.e., using the traditional indirect/double-indirect i_blocks
626  * scheme) for ext4_map_blocks().
627  *
628  * Allocation strategy is simple: if we have to allocate something, we will
629  * have to go the whole way to leaf. So let's do it before attaching anything
630  * to tree, set linkage between the newborn blocks, write them if sync is
631  * required, recheck the path, free and repeat if check fails, otherwise
632  * set the last missing link (that will protect us from any truncate-generated
633  * removals - all blocks on the path are immune now) and possibly force the
634  * write on the parent block.
635  * That has a nice additional property: no special recovery from the failed
636  * allocations is needed - we simply release blocks and do not touch anything
637  * reachable from inode.
638  *
639  * `handle' can be NULL if create == 0.
640  *
641  * return > 0, # of blocks mapped or allocated.
642  * return = 0, if plain lookup failed.
643  * return < 0, error case.
644  *
645  * The ext4_ind_get_blocks() function should be called with
646  * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
647  * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
648  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
649  * blocks.
650  */
651 int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
652                         struct ext4_map_blocks *map,
653                         int flags)
654 {
655         int err = -EIO;
656         ext4_lblk_t offsets[4];
657         Indirect chain[4];
658         Indirect *partial;
659         ext4_fsblk_t goal;
660         int indirect_blks;
661         int blocks_to_boundary = 0;
662         int depth;
663         int count = 0;
664         ext4_fsblk_t first_block = 0;
665
666         trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
667         J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
668         J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
669         depth = ext4_block_to_path(inode, map->m_lblk, offsets,
670                                    &blocks_to_boundary);
671
672         if (depth == 0)
673                 goto out;
674
675         partial = ext4_get_branch(inode, depth, offsets, chain, &err);
676
677         /* Simplest case - block found, no allocation needed */
678         if (!partial) {
679                 first_block = le32_to_cpu(chain[depth - 1].key);
680                 count++;
681                 /*map more blocks*/
682                 while (count < map->m_len && count <= blocks_to_boundary) {
683                         ext4_fsblk_t blk;
684
685                         blk = le32_to_cpu(*(chain[depth-1].p + count));
686
687                         if (blk == first_block + count)
688                                 count++;
689                         else
690                                 break;
691                 }
692                 goto got_it;
693         }
694
695         /* Next simple case - plain lookup or failed read of indirect block */
696         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
697                 goto cleanup;
698
699         /*
700          * Okay, we need to do block allocation.
701         */
702         goal = ext4_find_goal(inode, map->m_lblk, partial);
703
704         /* the number of blocks need to allocate for [d,t]indirect blocks */
705         indirect_blks = (chain + depth) - partial - 1;
706
707         /*
708          * Next look up the indirect map to count the totoal number of
709          * direct blocks to allocate for this branch.
710          */
711         count = ext4_blks_to_allocate(partial, indirect_blks,
712                                       map->m_len, blocks_to_boundary);
713         /*
714          * Block out ext4_truncate while we alter the tree
715          */
716         err = ext4_alloc_branch(handle, inode, map->m_lblk, indirect_blks,
717                                 &count, goal,
718                                 offsets + (partial - chain), partial);
719
720         /*
721          * The ext4_splice_branch call will free and forget any buffers
722          * on the new chain if there is a failure, but that risks using
723          * up transaction credits, especially for bitmaps where the
724          * credits cannot be returned.  Can we handle this somehow?  We
725          * may need to return -EAGAIN upwards in the worst case.  --sct
726          */
727         if (!err)
728                 err = ext4_splice_branch(handle, inode, map->m_lblk,
729                                          partial, indirect_blks, count);
730         if (err)
731                 goto cleanup;
732
733         map->m_flags |= EXT4_MAP_NEW;
734
735         ext4_update_inode_fsync_trans(handle, inode, 1);
736 got_it:
737         map->m_flags |= EXT4_MAP_MAPPED;
738         map->m_pblk = le32_to_cpu(chain[depth-1].key);
739         map->m_len = count;
740         if (count > blocks_to_boundary)
741                 map->m_flags |= EXT4_MAP_BOUNDARY;
742         err = count;
743         /* Clean up and exit */
744         partial = chain + depth - 1;    /* the whole chain */
745 cleanup:
746         while (partial > chain) {
747                 BUFFER_TRACE(partial->bh, "call brelse");
748                 brelse(partial->bh);
749                 partial--;
750         }
751 out:
752         trace_ext4_ind_map_blocks_exit(inode, map->m_lblk,
753                                 map->m_pblk, map->m_len, err);
754         return err;
755 }
756
757 /*
758  * O_DIRECT for ext3 (or indirect map) based files
759  *
760  * If the O_DIRECT write will extend the file then add this inode to the
761  * orphan list.  So recovery will truncate it back to the original size
762  * if the machine crashes during the write.
763  *
764  * If the O_DIRECT write is intantiating holes inside i_size and the machine
765  * crashes then stale disk data _may_ be exposed inside the file. But current
766  * VFS code falls back into buffered path in that case so we are safe.
767  */
768 ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
769                            const struct iovec *iov, loff_t offset,
770                            unsigned long nr_segs)
771 {
772         struct file *file = iocb->ki_filp;
773         struct inode *inode = file->f_mapping->host;
774         struct ext4_inode_info *ei = EXT4_I(inode);
775         handle_t *handle;
776         ssize_t ret;
777         int orphan = 0;
778         size_t count = iov_length(iov, nr_segs);
779         int retries = 0;
780
781         if (rw == WRITE) {
782                 loff_t final_size = offset + count;
783
784                 if (final_size > inode->i_size) {
785                         /* Credits for sb + inode write */
786                         handle = ext4_journal_start(inode, 2);
787                         if (IS_ERR(handle)) {
788                                 ret = PTR_ERR(handle);
789                                 goto out;
790                         }
791                         ret = ext4_orphan_add(handle, inode);
792                         if (ret) {
793                                 ext4_journal_stop(handle);
794                                 goto out;
795                         }
796                         orphan = 1;
797                         ei->i_disksize = inode->i_size;
798                         ext4_journal_stop(handle);
799                 }
800         }
801
802 retry:
803         if (rw == READ && ext4_should_dioread_nolock(inode))
804                 ret = __blockdev_direct_IO(rw, iocb, inode,
805                                  inode->i_sb->s_bdev, iov,
806                                  offset, nr_segs,
807                                  ext4_get_block, NULL, NULL, 0);
808         else {
809                 ret = blockdev_direct_IO(rw, iocb, inode,
810                                  inode->i_sb->s_bdev, iov,
811                                  offset, nr_segs,
812                                  ext4_get_block, NULL);
813
814                 if (unlikely((rw & WRITE) && ret < 0)) {
815                         loff_t isize = i_size_read(inode);
816                         loff_t end = offset + iov_length(iov, nr_segs);
817
818                         if (end > isize)
819                                 ext4_truncate_failed_write(inode);
820                 }
821         }
822         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
823                 goto retry;
824
825         if (orphan) {
826                 int err;
827
828                 /* Credits for sb + inode write */
829                 handle = ext4_journal_start(inode, 2);
830                 if (IS_ERR(handle)) {
831                         /* This is really bad luck. We've written the data
832                          * but cannot extend i_size. Bail out and pretend
833                          * the write failed... */
834                         ret = PTR_ERR(handle);
835                         if (inode->i_nlink)
836                                 ext4_orphan_del(NULL, inode);
837
838                         goto out;
839                 }
840                 if (inode->i_nlink)
841                         ext4_orphan_del(handle, inode);
842                 if (ret > 0) {
843                         loff_t end = offset + ret;
844                         if (end > inode->i_size) {
845                                 ei->i_disksize = end;
846                                 i_size_write(inode, end);
847                                 /*
848                                  * We're going to return a positive `ret'
849                                  * here due to non-zero-length I/O, so there's
850                                  * no way of reporting error returns from
851                                  * ext4_mark_inode_dirty() to userspace.  So
852                                  * ignore it.
853                                  */
854                                 ext4_mark_inode_dirty(handle, inode);
855                         }
856                 }
857                 err = ext4_journal_stop(handle);
858                 if (ret == 0)
859                         ret = err;
860         }
861 out:
862         return ret;
863 }
864
865 /*
866  * Calculate the number of metadata blocks need to reserve
867  * to allocate a new block at @lblocks for non extent file based file
868  */
869 int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock)
870 {
871         struct ext4_inode_info *ei = EXT4_I(inode);
872         sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
873         int blk_bits;
874
875         if (lblock < EXT4_NDIR_BLOCKS)
876                 return 0;
877
878         lblock -= EXT4_NDIR_BLOCKS;
879
880         if (ei->i_da_metadata_calc_len &&
881             (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
882                 ei->i_da_metadata_calc_len++;
883                 return 0;
884         }
885         ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
886         ei->i_da_metadata_calc_len = 1;
887         blk_bits = order_base_2(lblock);
888         return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
889 }
890
891 int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk)
892 {
893         int indirects;
894
895         /* if nrblocks are contiguous */
896         if (chunk) {
897                 /*
898                  * With N contiguous data blocks, we need at most
899                  * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
900                  * 2 dindirect blocks, and 1 tindirect block
901                  */
902                 return DIV_ROUND_UP(nrblocks,
903                                     EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
904         }
905         /*
906          * if nrblocks are not contiguous, worse case, each block touch
907          * a indirect block, and each indirect block touch a double indirect
908          * block, plus a triple indirect block
909          */
910         indirects = nrblocks * 2 + 1;
911         return indirects;
912 }
913
914 /*
915  * Truncate transactions can be complex and absolutely huge.  So we need to
916  * be able to restart the transaction at a conventient checkpoint to make
917  * sure we don't overflow the journal.
918  *
919  * start_transaction gets us a new handle for a truncate transaction,
920  * and extend_transaction tries to extend the existing one a bit.  If
921  * extend fails, we need to propagate the failure up and restart the
922  * transaction in the top-level truncate loop. --sct
923  */
924 static handle_t *start_transaction(struct inode *inode)
925 {
926         handle_t *result;
927
928         result = ext4_journal_start(inode, ext4_blocks_for_truncate(inode));
929         if (!IS_ERR(result))
930                 return result;
931
932         ext4_std_error(inode->i_sb, PTR_ERR(result));
933         return result;
934 }
935
936 /*
937  * Try to extend this transaction for the purposes of truncation.
938  *
939  * Returns 0 if we managed to create more room.  If we can't create more
940  * room, and the transaction must be restarted we return 1.
941  */
942 static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
943 {
944         if (!ext4_handle_valid(handle))
945                 return 0;
946         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
947                 return 0;
948         if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
949                 return 0;
950         return 1;
951 }
952
953 /*
954  * Probably it should be a library function... search for first non-zero word
955  * or memcmp with zero_page, whatever is better for particular architecture.
956  * Linus?
957  */
958 static inline int all_zeroes(__le32 *p, __le32 *q)
959 {
960         while (p < q)
961                 if (*p++)
962                         return 0;
963         return 1;
964 }
965
966 /**
967  *      ext4_find_shared - find the indirect blocks for partial truncation.
968  *      @inode:   inode in question
969  *      @depth:   depth of the affected branch
970  *      @offsets: offsets of pointers in that branch (see ext4_block_to_path)
971  *      @chain:   place to store the pointers to partial indirect blocks
972  *      @top:     place to the (detached) top of branch
973  *
974  *      This is a helper function used by ext4_truncate().
975  *
976  *      When we do truncate() we may have to clean the ends of several
977  *      indirect blocks but leave the blocks themselves alive. Block is
978  *      partially truncated if some data below the new i_size is referred
979  *      from it (and it is on the path to the first completely truncated
980  *      data block, indeed).  We have to free the top of that path along
981  *      with everything to the right of the path. Since no allocation
982  *      past the truncation point is possible until ext4_truncate()
983  *      finishes, we may safely do the latter, but top of branch may
984  *      require special attention - pageout below the truncation point
985  *      might try to populate it.
986  *
987  *      We atomically detach the top of branch from the tree, store the
988  *      block number of its root in *@top, pointers to buffer_heads of
989  *      partially truncated blocks - in @chain[].bh and pointers to
990  *      their last elements that should not be removed - in
991  *      @chain[].p. Return value is the pointer to last filled element
992  *      of @chain.
993  *
994  *      The work left to caller to do the actual freeing of subtrees:
995  *              a) free the subtree starting from *@top
996  *              b) free the subtrees whose roots are stored in
997  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
998  *              c) free the subtrees growing from the inode past the @chain[0].
999  *                      (no partially truncated stuff there).  */
1000
1001 static Indirect *ext4_find_shared(struct inode *inode, int depth,
1002                                   ext4_lblk_t offsets[4], Indirect chain[4],
1003                                   __le32 *top)
1004 {
1005         Indirect *partial, *p;
1006         int k, err;
1007
1008         *top = 0;
1009         /* Make k index the deepest non-null offset + 1 */
1010         for (k = depth; k > 1 && !offsets[k-1]; k--)
1011                 ;
1012         partial = ext4_get_branch(inode, k, offsets, chain, &err);
1013         /* Writer: pointers */
1014         if (!partial)
1015                 partial = chain + k-1;
1016         /*
1017          * If the branch acquired continuation since we've looked at it -
1018          * fine, it should all survive and (new) top doesn't belong to us.
1019          */
1020         if (!partial->key && *partial->p)
1021                 /* Writer: end */
1022                 goto no_top;
1023         for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
1024                 ;
1025         /*
1026          * OK, we've found the last block that must survive. The rest of our
1027          * branch should be detached before unlocking. However, if that rest
1028          * of branch is all ours and does not grow immediately from the inode
1029          * it's easier to cheat and just decrement partial->p.
1030          */
1031         if (p == chain + k - 1 && p > chain) {
1032                 p->p--;
1033         } else {
1034                 *top = *p->p;
1035                 /* Nope, don't do this in ext4.  Must leave the tree intact */
1036 #if 0
1037                 *p->p = 0;
1038 #endif
1039         }
1040         /* Writer: end */
1041
1042         while (partial > p) {
1043                 brelse(partial->bh);
1044                 partial--;
1045         }
1046 no_top:
1047         return partial;
1048 }
1049
1050 /*
1051  * Zero a number of block pointers in either an inode or an indirect block.
1052  * If we restart the transaction we must again get write access to the
1053  * indirect block for further modification.
1054  *
1055  * We release `count' blocks on disk, but (last - first) may be greater
1056  * than `count' because there can be holes in there.
1057  *
1058  * Return 0 on success, 1 on invalid block range
1059  * and < 0 on fatal error.
1060  */
1061 static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
1062                              struct buffer_head *bh,
1063                              ext4_fsblk_t block_to_free,
1064                              unsigned long count, __le32 *first,
1065                              __le32 *last)
1066 {
1067         __le32 *p;
1068         int     flags = EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_VALIDATED;
1069         int     err;
1070
1071         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
1072                 flags |= EXT4_FREE_BLOCKS_METADATA;
1073
1074         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), block_to_free,
1075                                    count)) {
1076                 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
1077                                  "blocks %llu len %lu",
1078                                  (unsigned long long) block_to_free, count);
1079                 return 1;
1080         }
1081
1082         if (try_to_extend_transaction(handle, inode)) {
1083                 if (bh) {
1084                         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
1085                         err = ext4_handle_dirty_metadata(handle, inode, bh);
1086                         if (unlikely(err))
1087                                 goto out_err;
1088                 }
1089                 err = ext4_mark_inode_dirty(handle, inode);
1090                 if (unlikely(err))
1091                         goto out_err;
1092                 err = ext4_truncate_restart_trans(handle, inode,
1093                                         ext4_blocks_for_truncate(inode));
1094                 if (unlikely(err))
1095                         goto out_err;
1096                 if (bh) {
1097                         BUFFER_TRACE(bh, "retaking write access");
1098                         err = ext4_journal_get_write_access(handle, bh);
1099                         if (unlikely(err))
1100                                 goto out_err;
1101                 }
1102         }
1103
1104         for (p = first; p < last; p++)
1105                 *p = 0;
1106
1107         ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
1108         return 0;
1109 out_err:
1110         ext4_std_error(inode->i_sb, err);
1111         return err;
1112 }
1113
1114 /**
1115  * ext4_free_data - free a list of data blocks
1116  * @handle:     handle for this transaction
1117  * @inode:      inode we are dealing with
1118  * @this_bh:    indirect buffer_head which contains *@first and *@last
1119  * @first:      array of block numbers
1120  * @last:       points immediately past the end of array
1121  *
1122  * We are freeing all blocks referred from that array (numbers are stored as
1123  * little-endian 32-bit) and updating @inode->i_blocks appropriately.
1124  *
1125  * We accumulate contiguous runs of blocks to free.  Conveniently, if these
1126  * blocks are contiguous then releasing them at one time will only affect one
1127  * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
1128  * actually use a lot of journal space.
1129  *
1130  * @this_bh will be %NULL if @first and @last point into the inode's direct
1131  * block pointers.
1132  */
1133 static void ext4_free_data(handle_t *handle, struct inode *inode,
1134                            struct buffer_head *this_bh,
1135                            __le32 *first, __le32 *last)
1136 {
1137         ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
1138         unsigned long count = 0;            /* Number of blocks in the run */
1139         __le32 *block_to_free_p = NULL;     /* Pointer into inode/ind
1140                                                corresponding to
1141                                                block_to_free */
1142         ext4_fsblk_t nr;                    /* Current block # */
1143         __le32 *p;                          /* Pointer into inode/ind
1144                                                for current block */
1145         int err = 0;
1146
1147         if (this_bh) {                          /* For indirect block */
1148                 BUFFER_TRACE(this_bh, "get_write_access");
1149                 err = ext4_journal_get_write_access(handle, this_bh);
1150                 /* Important: if we can't update the indirect pointers
1151                  * to the blocks, we can't free them. */
1152                 if (err)
1153                         return;
1154         }
1155
1156         for (p = first; p < last; p++) {
1157                 nr = le32_to_cpu(*p);
1158                 if (nr) {
1159                         /* accumulate blocks to free if they're contiguous */
1160                         if (count == 0) {
1161                                 block_to_free = nr;
1162                                 block_to_free_p = p;
1163                                 count = 1;
1164                         } else if (nr == block_to_free + count) {
1165                                 count++;
1166                         } else {
1167                                 err = ext4_clear_blocks(handle, inode, this_bh,
1168                                                         block_to_free, count,
1169                                                         block_to_free_p, p);
1170                                 if (err)
1171                                         break;
1172                                 block_to_free = nr;
1173                                 block_to_free_p = p;
1174                                 count = 1;
1175                         }
1176                 }
1177         }
1178
1179         if (!err && count > 0)
1180                 err = ext4_clear_blocks(handle, inode, this_bh, block_to_free,
1181                                         count, block_to_free_p, p);
1182         if (err < 0)
1183                 /* fatal error */
1184                 return;
1185
1186         if (this_bh) {
1187                 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
1188
1189                 /*
1190                  * The buffer head should have an attached journal head at this
1191                  * point. However, if the data is corrupted and an indirect
1192                  * block pointed to itself, it would have been detached when
1193                  * the block was cleared. Check for this instead of OOPSing.
1194                  */
1195                 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
1196                         ext4_handle_dirty_metadata(handle, inode, this_bh);
1197                 else
1198                         EXT4_ERROR_INODE(inode,
1199                                          "circular indirect block detected at "
1200                                          "block %llu",
1201                                 (unsigned long long) this_bh->b_blocknr);
1202         }
1203 }
1204
1205 /**
1206  *      ext4_free_branches - free an array of branches
1207  *      @handle: JBD handle for this transaction
1208  *      @inode: inode we are dealing with
1209  *      @parent_bh: the buffer_head which contains *@first and *@last
1210  *      @first: array of block numbers
1211  *      @last:  pointer immediately past the end of array
1212  *      @depth: depth of the branches to free
1213  *
1214  *      We are freeing all blocks referred from these branches (numbers are
1215  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1216  *      appropriately.
1217  */
1218 static void ext4_free_branches(handle_t *handle, struct inode *inode,
1219                                struct buffer_head *parent_bh,
1220                                __le32 *first, __le32 *last, int depth)
1221 {
1222         ext4_fsblk_t nr;
1223         __le32 *p;
1224
1225         if (ext4_handle_is_aborted(handle))
1226                 return;
1227
1228         if (depth--) {
1229                 struct buffer_head *bh;
1230                 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1231                 p = last;
1232                 while (--p >= first) {
1233                         nr = le32_to_cpu(*p);
1234                         if (!nr)
1235                                 continue;               /* A hole */
1236
1237                         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb),
1238                                                    nr, 1)) {
1239                                 EXT4_ERROR_INODE(inode,
1240                                                  "invalid indirect mapped "
1241                                                  "block %lu (level %d)",
1242                                                  (unsigned long) nr, depth);
1243                                 break;
1244                         }
1245
1246                         /* Go read the buffer for the next level down */
1247                         bh = sb_bread(inode->i_sb, nr);
1248
1249                         /*
1250                          * A read failure? Report error and clear slot
1251                          * (should be rare).
1252                          */
1253                         if (!bh) {
1254                                 EXT4_ERROR_INODE_BLOCK(inode, nr,
1255                                                        "Read failure");
1256                                 continue;
1257                         }
1258
1259                         /* This zaps the entire block.  Bottom up. */
1260                         BUFFER_TRACE(bh, "free child branches");
1261                         ext4_free_branches(handle, inode, bh,
1262                                         (__le32 *) bh->b_data,
1263                                         (__le32 *) bh->b_data + addr_per_block,
1264                                         depth);
1265                         brelse(bh);
1266
1267                         /*
1268                          * Everything below this this pointer has been
1269                          * released.  Now let this top-of-subtree go.
1270                          *
1271                          * We want the freeing of this indirect block to be
1272                          * atomic in the journal with the updating of the
1273                          * bitmap block which owns it.  So make some room in
1274                          * the journal.
1275                          *
1276                          * We zero the parent pointer *after* freeing its
1277                          * pointee in the bitmaps, so if extend_transaction()
1278                          * for some reason fails to put the bitmap changes and
1279                          * the release into the same transaction, recovery
1280                          * will merely complain about releasing a free block,
1281                          * rather than leaking blocks.
1282                          */
1283                         if (ext4_handle_is_aborted(handle))
1284                                 return;
1285                         if (try_to_extend_transaction(handle, inode)) {
1286                                 ext4_mark_inode_dirty(handle, inode);
1287                                 ext4_truncate_restart_trans(handle, inode,
1288                                             ext4_blocks_for_truncate(inode));
1289                         }
1290
1291                         /*
1292                          * The forget flag here is critical because if
1293                          * we are journaling (and not doing data
1294                          * journaling), we have to make sure a revoke
1295                          * record is written to prevent the journal
1296                          * replay from overwriting the (former)
1297                          * indirect block if it gets reallocated as a
1298                          * data block.  This must happen in the same
1299                          * transaction where the data blocks are
1300                          * actually freed.
1301                          */
1302                         ext4_free_blocks(handle, inode, NULL, nr, 1,
1303                                          EXT4_FREE_BLOCKS_METADATA|
1304                                          EXT4_FREE_BLOCKS_FORGET);
1305
1306                         if (parent_bh) {
1307                                 /*
1308                                  * The block which we have just freed is
1309                                  * pointed to by an indirect block: journal it
1310                                  */
1311                                 BUFFER_TRACE(parent_bh, "get_write_access");
1312                                 if (!ext4_journal_get_write_access(handle,
1313                                                                    parent_bh)){
1314                                         *p = 0;
1315                                         BUFFER_TRACE(parent_bh,
1316                                         "call ext4_handle_dirty_metadata");
1317                                         ext4_handle_dirty_metadata(handle,
1318                                                                    inode,
1319                                                                    parent_bh);
1320                                 }
1321                         }
1322                 }
1323         } else {
1324                 /* We have reached the bottom of the tree. */
1325                 BUFFER_TRACE(parent_bh, "free data blocks");
1326                 ext4_free_data(handle, inode, parent_bh, first, last);
1327         }
1328 }
1329
1330 void ext4_ind_truncate(struct inode *inode)
1331 {
1332         handle_t *handle;
1333         struct ext4_inode_info *ei = EXT4_I(inode);
1334         __le32 *i_data = ei->i_data;
1335         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1336         struct address_space *mapping = inode->i_mapping;
1337         ext4_lblk_t offsets[4];
1338         Indirect chain[4];
1339         Indirect *partial;
1340         __le32 nr = 0;
1341         int n = 0;
1342         ext4_lblk_t last_block, max_block;
1343         unsigned blocksize = inode->i_sb->s_blocksize;
1344
1345         handle = start_transaction(inode);
1346         if (IS_ERR(handle))
1347                 return;         /* AKPM: return what? */
1348
1349         last_block = (inode->i_size + blocksize-1)
1350                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1351         max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1352                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1353
1354         if (inode->i_size & (blocksize - 1))
1355                 if (ext4_block_truncate_page(handle, mapping, inode->i_size))
1356                         goto out_stop;
1357
1358         if (last_block != max_block) {
1359                 n = ext4_block_to_path(inode, last_block, offsets, NULL);
1360                 if (n == 0)
1361                         goto out_stop;  /* error */
1362         }
1363
1364         /*
1365          * OK.  This truncate is going to happen.  We add the inode to the
1366          * orphan list, so that if this truncate spans multiple transactions,
1367          * and we crash, we will resume the truncate when the filesystem
1368          * recovers.  It also marks the inode dirty, to catch the new size.
1369          *
1370          * Implication: the file must always be in a sane, consistent
1371          * truncatable state while each transaction commits.
1372          */
1373         if (ext4_orphan_add(handle, inode))
1374                 goto out_stop;
1375
1376         /*
1377          * From here we block out all ext4_get_block() callers who want to
1378          * modify the block allocation tree.
1379          */
1380         down_write(&ei->i_data_sem);
1381
1382         ext4_discard_preallocations(inode);
1383
1384         /*
1385          * The orphan list entry will now protect us from any crash which
1386          * occurs before the truncate completes, so it is now safe to propagate
1387          * the new, shorter inode size (held for now in i_size) into the
1388          * on-disk inode. We do this via i_disksize, which is the value which
1389          * ext4 *really* writes onto the disk inode.
1390          */
1391         ei->i_disksize = inode->i_size;
1392
1393         if (last_block == max_block) {
1394                 /*
1395                  * It is unnecessary to free any data blocks if last_block is
1396                  * equal to the indirect block limit.
1397                  */
1398                 goto out_unlock;
1399         } else if (n == 1) {            /* direct blocks */
1400                 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
1401                                i_data + EXT4_NDIR_BLOCKS);
1402                 goto do_indirects;
1403         }
1404
1405         partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1406         /* Kill the top of shared branch (not detached) */
1407         if (nr) {
1408                 if (partial == chain) {
1409                         /* Shared branch grows from the inode */
1410                         ext4_free_branches(handle, inode, NULL,
1411                                            &nr, &nr+1, (chain+n-1) - partial);
1412                         *partial->p = 0;
1413                         /*
1414                          * We mark the inode dirty prior to restart,
1415                          * and prior to stop.  No need for it here.
1416                          */
1417                 } else {
1418                         /* Shared branch grows from an indirect block */
1419                         BUFFER_TRACE(partial->bh, "get_write_access");
1420                         ext4_free_branches(handle, inode, partial->bh,
1421                                         partial->p,
1422                                         partial->p+1, (chain+n-1) - partial);
1423                 }
1424         }
1425         /* Clear the ends of indirect blocks on the shared branch */
1426         while (partial > chain) {
1427                 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
1428                                    (__le32*)partial->bh->b_data+addr_per_block,
1429                                    (chain+n-1) - partial);
1430                 BUFFER_TRACE(partial->bh, "call brelse");
1431                 brelse(partial->bh);
1432                 partial--;
1433         }
1434 do_indirects:
1435         /* Kill the remaining (whole) subtrees */
1436         switch (offsets[0]) {
1437         default:
1438                 nr = i_data[EXT4_IND_BLOCK];
1439                 if (nr) {
1440                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1441                         i_data[EXT4_IND_BLOCK] = 0;
1442                 }
1443         case EXT4_IND_BLOCK:
1444                 nr = i_data[EXT4_DIND_BLOCK];
1445                 if (nr) {
1446                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1447                         i_data[EXT4_DIND_BLOCK] = 0;
1448                 }
1449         case EXT4_DIND_BLOCK:
1450                 nr = i_data[EXT4_TIND_BLOCK];
1451                 if (nr) {
1452                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1453                         i_data[EXT4_TIND_BLOCK] = 0;
1454                 }
1455         case EXT4_TIND_BLOCK:
1456                 ;
1457         }
1458
1459 out_unlock:
1460         up_write(&ei->i_data_sem);
1461         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
1462         ext4_mark_inode_dirty(handle, inode);
1463
1464         /*
1465          * In a multi-transaction truncate, we only make the final transaction
1466          * synchronous
1467          */
1468         if (IS_SYNC(inode))
1469                 ext4_handle_sync(handle);
1470 out_stop:
1471         /*
1472          * If this was a simple ftruncate(), and the file will remain alive
1473          * then we need to clear up the orphan record which we created above.
1474          * However, if this was a real unlink then we were called by
1475          * ext4_delete_inode(), and we allow that function to clean up the
1476          * orphan info for us.
1477          */
1478         if (inode->i_nlink)
1479                 ext4_orphan_del(handle, inode);
1480
1481         ext4_journal_stop(handle);
1482         trace_ext4_truncate_exit(inode);
1483 }
1484