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Amir Goldsteindae1e522011-06-27 19:40:50 -04001/*
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
Amir Goldsteindae1e522011-06-27 19:40:50 -040023#include "ext4_jbd2.h"
24#include "truncate.h"
25
26#include <trace/events/ext4.h>
27
28typedef struct {
29 __le32 *p;
30 __le32 key;
31 struct buffer_head *bh;
32} Indirect;
33
34static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
35{
36 p->key = *(p->p = v);
37 p->bh = bh;
38}
39
40/**
41 * ext4_block_to_path - parse the block number into array of offsets
42 * @inode: inode in question (we are only interested in its superblock)
43 * @i_block: block number to be parsed
44 * @offsets: array to store the offsets in
45 * @boundary: set this non-zero if the referred-to block is likely to be
46 * followed (on disk) by an indirect block.
47 *
48 * To store the locations of file's data ext4 uses a data structure common
49 * for UNIX filesystems - tree of pointers anchored in the inode, with
50 * data blocks at leaves and indirect blocks in intermediate nodes.
51 * This function translates the block number into path in that tree -
52 * return value is the path length and @offsets[n] is the offset of
53 * pointer to (n+1)th node in the nth one. If @block is out of range
54 * (negative or too large) warning is printed and zero returned.
55 *
56 * Note: function doesn't find node addresses, so no IO is needed. All
57 * we need to know is the capacity of indirect blocks (taken from the
58 * inode->i_sb).
59 */
60
61/*
62 * Portability note: the last comparison (check that we fit into triple
63 * indirect block) is spelled differently, because otherwise on an
64 * architecture with 32-bit longs and 8Kb pages we might get into trouble
65 * if our filesystem had 8Kb blocks. We might use long long, but that would
66 * kill us on x86. Oh, well, at least the sign propagation does not matter -
67 * i_block would have to be negative in the very beginning, so we would not
68 * get there at all.
69 */
70
71static int ext4_block_to_path(struct inode *inode,
72 ext4_lblk_t i_block,
73 ext4_lblk_t offsets[4], int *boundary)
74{
75 int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
76 int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
77 const long direct_blocks = EXT4_NDIR_BLOCKS,
78 indirect_blocks = ptrs,
79 double_blocks = (1 << (ptrs_bits * 2));
80 int n = 0;
81 int final = 0;
82
83 if (i_block < direct_blocks) {
84 offsets[n++] = i_block;
85 final = direct_blocks;
86 } else if ((i_block -= direct_blocks) < indirect_blocks) {
87 offsets[n++] = EXT4_IND_BLOCK;
88 offsets[n++] = i_block;
89 final = ptrs;
90 } else if ((i_block -= indirect_blocks) < double_blocks) {
91 offsets[n++] = EXT4_DIND_BLOCK;
92 offsets[n++] = i_block >> ptrs_bits;
93 offsets[n++] = i_block & (ptrs - 1);
94 final = ptrs;
95 } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
96 offsets[n++] = EXT4_TIND_BLOCK;
97 offsets[n++] = i_block >> (ptrs_bits * 2);
98 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
99 offsets[n++] = i_block & (ptrs - 1);
100 final = ptrs;
101 } else {
102 ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
103 i_block + direct_blocks +
104 indirect_blocks + double_blocks, inode->i_ino);
105 }
106 if (boundary)
107 *boundary = final - 1 - (i_block & (ptrs - 1));
108 return n;
109}
110
111/**
112 * ext4_get_branch - read the chain of indirect blocks leading to data
113 * @inode: inode in question
114 * @depth: depth of the chain (1 - direct pointer, etc.)
115 * @offsets: offsets of pointers in inode/indirect blocks
116 * @chain: place to store the result
117 * @err: here we store the error value
118 *
119 * Function fills the array of triples <key, p, bh> and returns %NULL
120 * if everything went OK or the pointer to the last filled triple
121 * (incomplete one) otherwise. Upon the return chain[i].key contains
122 * the number of (i+1)-th block in the chain (as it is stored in memory,
123 * i.e. little-endian 32-bit), chain[i].p contains the address of that
124 * number (it points into struct inode for i==0 and into the bh->b_data
125 * for i>0) and chain[i].bh points to the buffer_head of i-th indirect
126 * block for i>0 and NULL for i==0. In other words, it holds the block
127 * numbers of the chain, addresses they were taken from (and where we can
128 * verify that chain did not change) and buffer_heads hosting these
129 * numbers.
130 *
131 * Function stops when it stumbles upon zero pointer (absent block)
132 * (pointer to last triple returned, *@err == 0)
133 * or when it gets an IO error reading an indirect block
134 * (ditto, *@err == -EIO)
135 * or when it reads all @depth-1 indirect blocks successfully and finds
136 * the whole chain, all way to the data (returns %NULL, *err == 0).
137 *
138 * Need to be called with
139 * down_read(&EXT4_I(inode)->i_data_sem)
140 */
141static Indirect *ext4_get_branch(struct inode *inode, int depth,
142 ext4_lblk_t *offsets,
143 Indirect chain[4], int *err)
144{
145 struct super_block *sb = inode->i_sb;
146 Indirect *p = chain;
147 struct buffer_head *bh;
148
149 *err = 0;
150 /* i_data is not going away, no lock needed */
151 add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
152 if (!p->key)
153 goto no_block;
154 while (--depth) {
155 bh = sb_getblk(sb, le32_to_cpu(p->key));
156 if (unlikely(!bh))
157 goto failure;
158
159 if (!bh_uptodate_or_lock(bh)) {
160 if (bh_submit_read(bh) < 0) {
161 put_bh(bh);
162 goto failure;
163 }
164 /* validate block references */
165 if (ext4_check_indirect_blockref(inode, bh)) {
166 put_bh(bh);
167 goto failure;
168 }
169 }
170
171 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
172 /* Reader: end */
173 if (!p->key)
174 goto no_block;
175 }
176 return NULL;
177
178failure:
179 *err = -EIO;
180no_block:
181 return p;
182}
183
184/**
185 * ext4_find_near - find a place for allocation with sufficient locality
186 * @inode: owner
187 * @ind: descriptor of indirect block.
188 *
189 * This function returns the preferred place for block allocation.
190 * It is used when heuristic for sequential allocation fails.
191 * Rules are:
192 * + if there is a block to the left of our position - allocate near it.
193 * + if pointer will live in indirect block - allocate near that block.
194 * + if pointer will live in inode - allocate in the same
195 * cylinder group.
196 *
197 * In the latter case we colour the starting block by the callers PID to
198 * prevent it from clashing with concurrent allocations for a different inode
199 * in the same block group. The PID is used here so that functionally related
200 * files will be close-by on-disk.
201 *
202 * Caller must make sure that @ind is valid and will stay that way.
203 */
204static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
205{
206 struct ext4_inode_info *ei = EXT4_I(inode);
207 __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
208 __le32 *p;
Amir Goldsteindae1e522011-06-27 19:40:50 -0400209
210 /* Try to find previous block */
211 for (p = ind->p - 1; p >= start; p--) {
212 if (*p)
213 return le32_to_cpu(*p);
214 }
215
216 /* No such thing, so let's try location of indirect block */
217 if (ind->bh)
218 return ind->bh->b_blocknr;
219
220 /*
221 * It is going to be referred to from the inode itself? OK, just put it
222 * into the same cylinder group then.
223 */
Eric Sandeenf86186b2011-06-28 10:01:31 -0400224 return ext4_inode_to_goal_block(inode);
Amir Goldsteindae1e522011-06-27 19:40:50 -0400225}
226
227/**
228 * ext4_find_goal - find a preferred place for allocation.
229 * @inode: owner
230 * @block: block we want
231 * @partial: pointer to the last triple within a chain
232 *
233 * Normally this function find the preferred place for block allocation,
234 * returns it.
235 * Because this is only used for non-extent files, we limit the block nr
236 * to 32 bits.
237 */
238static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
239 Indirect *partial)
240{
241 ext4_fsblk_t goal;
242
243 /*
244 * XXX need to get goal block from mballoc's data structures
245 */
246
247 goal = ext4_find_near(inode, partial);
248 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
249 return goal;
250}
251
252/**
253 * ext4_blks_to_allocate - Look up the block map and count the number
254 * of direct blocks need to be allocated for the given branch.
255 *
256 * @branch: chain of indirect blocks
257 * @k: number of blocks need for indirect blocks
258 * @blks: number of data blocks to be mapped.
259 * @blocks_to_boundary: the offset in the indirect block
260 *
261 * return the total number of blocks to be allocate, including the
262 * direct and indirect blocks.
263 */
264static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
265 int blocks_to_boundary)
266{
267 unsigned int count = 0;
268
269 /*
270 * Simple case, [t,d]Indirect block(s) has not allocated yet
271 * then it's clear blocks on that path have not allocated
272 */
273 if (k > 0) {
274 /* right now we don't handle cross boundary allocation */
275 if (blks < blocks_to_boundary + 1)
276 count += blks;
277 else
278 count += blocks_to_boundary + 1;
279 return count;
280 }
281
282 count++;
283 while (count < blks && count <= blocks_to_boundary &&
284 le32_to_cpu(*(branch[0].p + count)) == 0) {
285 count++;
286 }
287 return count;
288}
289
290/**
291 * ext4_alloc_blocks: multiple allocate blocks needed for a branch
292 * @handle: handle for this transaction
293 * @inode: inode which needs allocated blocks
294 * @iblock: the logical block to start allocated at
295 * @goal: preferred physical block of allocation
296 * @indirect_blks: the number of blocks need to allocate for indirect
297 * blocks
298 * @blks: number of desired blocks
299 * @new_blocks: on return it will store the new block numbers for
300 * the indirect blocks(if needed) and the first direct block,
301 * @err: on return it will store the error code
302 *
303 * This function will return the number of blocks allocated as
304 * requested by the passed-in parameters.
305 */
306static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
307 ext4_lblk_t iblock, ext4_fsblk_t goal,
308 int indirect_blks, int blks,
309 ext4_fsblk_t new_blocks[4], int *err)
310{
311 struct ext4_allocation_request ar;
312 int target, i;
313 unsigned long count = 0, blk_allocated = 0;
314 int index = 0;
315 ext4_fsblk_t current_block = 0;
316 int ret = 0;
317
318 /*
319 * Here we try to allocate the requested multiple blocks at once,
320 * on a best-effort basis.
321 * To build a branch, we should allocate blocks for
322 * the indirect blocks(if not allocated yet), and at least
323 * the first direct block of this branch. That's the
324 * minimum number of blocks need to allocate(required)
325 */
326 /* first we try to allocate the indirect blocks */
327 target = indirect_blks;
328 while (target > 0) {
329 count = target;
330 /* allocating blocks for indirect blocks and direct blocks */
331 current_block = ext4_new_meta_blocks(handle, inode, goal,
332 0, &count, err);
333 if (*err)
334 goto failed_out;
335
336 if (unlikely(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS)) {
337 EXT4_ERROR_INODE(inode,
338 "current_block %llu + count %lu > %d!",
339 current_block, count,
340 EXT4_MAX_BLOCK_FILE_PHYS);
341 *err = -EIO;
342 goto failed_out;
343 }
344
345 target -= count;
346 /* allocate blocks for indirect blocks */
347 while (index < indirect_blks && count) {
348 new_blocks[index++] = current_block++;
349 count--;
350 }
351 if (count > 0) {
352 /*
353 * save the new block number
354 * for the first direct block
355 */
356 new_blocks[index] = current_block;
357 printk(KERN_INFO "%s returned more blocks than "
358 "requested\n", __func__);
359 WARN_ON(1);
360 break;
361 }
362 }
363
364 target = blks - count ;
365 blk_allocated = count;
366 if (!target)
367 goto allocated;
368 /* Now allocate data blocks */
369 memset(&ar, 0, sizeof(ar));
370 ar.inode = inode;
371 ar.goal = goal;
372 ar.len = target;
373 ar.logical = iblock;
374 if (S_ISREG(inode->i_mode))
375 /* enable in-core preallocation only for regular files */
376 ar.flags = EXT4_MB_HINT_DATA;
377
378 current_block = ext4_mb_new_blocks(handle, &ar, err);
379 if (unlikely(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS)) {
380 EXT4_ERROR_INODE(inode,
381 "current_block %llu + ar.len %d > %d!",
382 current_block, ar.len,
383 EXT4_MAX_BLOCK_FILE_PHYS);
384 *err = -EIO;
385 goto failed_out;
386 }
387
388 if (*err && (target == blks)) {
389 /*
390 * if the allocation failed and we didn't allocate
391 * any blocks before
392 */
393 goto failed_out;
394 }
395 if (!*err) {
396 if (target == blks) {
397 /*
398 * save the new block number
399 * for the first direct block
400 */
401 new_blocks[index] = current_block;
402 }
403 blk_allocated += ar.len;
404 }
405allocated:
406 /* total number of blocks allocated for direct blocks */
407 ret = blk_allocated;
408 *err = 0;
409 return ret;
410failed_out:
411 for (i = 0; i < index; i++)
412 ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1, 0);
413 return ret;
414}
415
416/**
417 * ext4_alloc_branch - allocate and set up a chain of blocks.
418 * @handle: handle for this transaction
419 * @inode: owner
420 * @indirect_blks: number of allocated indirect blocks
421 * @blks: number of allocated direct blocks
422 * @goal: preferred place for allocation
423 * @offsets: offsets (in the blocks) to store the pointers to next.
424 * @branch: place to store the chain in.
425 *
426 * This function allocates blocks, zeroes out all but the last one,
427 * links them into chain and (if we are synchronous) writes them to disk.
428 * In other words, it prepares a branch that can be spliced onto the
429 * inode. It stores the information about that chain in the branch[], in
430 * the same format as ext4_get_branch() would do. We are calling it after
431 * we had read the existing part of chain and partial points to the last
432 * triple of that (one with zero ->key). Upon the exit we have the same
433 * picture as after the successful ext4_get_block(), except that in one
434 * place chain is disconnected - *branch->p is still zero (we did not
435 * set the last link), but branch->key contains the number that should
436 * be placed into *branch->p to fill that gap.
437 *
438 * If allocation fails we free all blocks we've allocated (and forget
439 * their buffer_heads) and return the error value the from failed
440 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
441 * as described above and return 0.
442 */
443static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
444 ext4_lblk_t iblock, int indirect_blks,
445 int *blks, ext4_fsblk_t goal,
446 ext4_lblk_t *offsets, Indirect *branch)
447{
448 int blocksize = inode->i_sb->s_blocksize;
449 int i, n = 0;
450 int err = 0;
451 struct buffer_head *bh;
452 int num;
453 ext4_fsblk_t new_blocks[4];
454 ext4_fsblk_t current_block;
455
456 num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
457 *blks, new_blocks, &err);
458 if (err)
459 return err;
460
461 branch[0].key = cpu_to_le32(new_blocks[0]);
462 /*
463 * metadata blocks and data blocks are allocated.
464 */
465 for (n = 1; n <= indirect_blks; n++) {
466 /*
467 * Get buffer_head for parent block, zero it out
468 * and set the pointer to new one, then send
469 * parent to disk.
470 */
471 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
472 if (unlikely(!bh)) {
473 err = -EIO;
474 goto failed;
475 }
476
477 branch[n].bh = bh;
478 lock_buffer(bh);
479 BUFFER_TRACE(bh, "call get_create_access");
480 err = ext4_journal_get_create_access(handle, bh);
481 if (err) {
482 /* Don't brelse(bh) here; it's done in
483 * ext4_journal_forget() below */
484 unlock_buffer(bh);
485 goto failed;
486 }
487
488 memset(bh->b_data, 0, blocksize);
489 branch[n].p = (__le32 *) bh->b_data + offsets[n];
490 branch[n].key = cpu_to_le32(new_blocks[n]);
491 *branch[n].p = branch[n].key;
492 if (n == indirect_blks) {
493 current_block = new_blocks[n];
494 /*
495 * End of chain, update the last new metablock of
496 * the chain to point to the new allocated
497 * data blocks numbers
498 */
499 for (i = 1; i < num; i++)
500 *(branch[n].p + i) = cpu_to_le32(++current_block);
501 }
502 BUFFER_TRACE(bh, "marking uptodate");
503 set_buffer_uptodate(bh);
504 unlock_buffer(bh);
505
506 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
507 err = ext4_handle_dirty_metadata(handle, inode, bh);
508 if (err)
509 goto failed;
510 }
511 *blks = num;
512 return err;
513failed:
514 /* Allocation failed, free what we already allocated */
515 ext4_free_blocks(handle, inode, NULL, new_blocks[0], 1, 0);
516 for (i = 1; i <= n ; i++) {
517 /*
518 * branch[i].bh is newly allocated, so there is no
519 * need to revoke the block, which is why we don't
520 * need to set EXT4_FREE_BLOCKS_METADATA.
521 */
522 ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1,
523 EXT4_FREE_BLOCKS_FORGET);
524 }
525 for (i = n+1; i < indirect_blks; i++)
526 ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1, 0);
527
528 ext4_free_blocks(handle, inode, NULL, new_blocks[i], num, 0);
529
530 return err;
531}
532
533/**
534 * ext4_splice_branch - splice the allocated branch onto inode.
535 * @handle: handle for this transaction
536 * @inode: owner
537 * @block: (logical) number of block we are adding
538 * @chain: chain of indirect blocks (with a missing link - see
539 * ext4_alloc_branch)
540 * @where: location of missing link
541 * @num: number of indirect blocks we are adding
542 * @blks: number of direct blocks we are adding
543 *
544 * This function fills the missing link and does all housekeeping needed in
545 * inode (->i_blocks, etc.). In case of success we end up with the full
546 * chain to new block and return 0.
547 */
548static int ext4_splice_branch(handle_t *handle, struct inode *inode,
549 ext4_lblk_t block, Indirect *where, int num,
550 int blks)
551{
552 int i;
553 int err = 0;
554 ext4_fsblk_t current_block;
555
556 /*
557 * If we're splicing into a [td]indirect block (as opposed to the
558 * inode) then we need to get write access to the [td]indirect block
559 * before the splice.
560 */
561 if (where->bh) {
562 BUFFER_TRACE(where->bh, "get_write_access");
563 err = ext4_journal_get_write_access(handle, where->bh);
564 if (err)
565 goto err_out;
566 }
567 /* That's it */
568
569 *where->p = where->key;
570
571 /*
572 * Update the host buffer_head or inode to point to more just allocated
573 * direct blocks blocks
574 */
575 if (num == 0 && blks > 1) {
576 current_block = le32_to_cpu(where->key) + 1;
577 for (i = 1; i < blks; i++)
578 *(where->p + i) = cpu_to_le32(current_block++);
579 }
580
581 /* We are done with atomic stuff, now do the rest of housekeeping */
582 /* had we spliced it onto indirect block? */
583 if (where->bh) {
584 /*
585 * If we spliced it onto an indirect block, we haven't
586 * altered the inode. Note however that if it is being spliced
587 * onto an indirect block at the very end of the file (the
588 * file is growing) then we *will* alter the inode to reflect
589 * the new i_size. But that is not done here - it is done in
590 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
591 */
592 jbd_debug(5, "splicing indirect only\n");
593 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
594 err = ext4_handle_dirty_metadata(handle, inode, where->bh);
595 if (err)
596 goto err_out;
597 } else {
598 /*
599 * OK, we spliced it into the inode itself on a direct block.
600 */
601 ext4_mark_inode_dirty(handle, inode);
602 jbd_debug(5, "splicing direct\n");
603 }
604 return err;
605
606err_out:
607 for (i = 1; i <= num; i++) {
608 /*
609 * branch[i].bh is newly allocated, so there is no
610 * need to revoke the block, which is why we don't
611 * need to set EXT4_FREE_BLOCKS_METADATA.
612 */
613 ext4_free_blocks(handle, inode, where[i].bh, 0, 1,
614 EXT4_FREE_BLOCKS_FORGET);
615 }
616 ext4_free_blocks(handle, inode, NULL, le32_to_cpu(where[num].key),
617 blks, 0);
618
619 return err;
620}
621
622/*
623 * The ext4_ind_map_blocks() function handles non-extents inodes
624 * (i.e., using the traditional indirect/double-indirect i_blocks
625 * scheme) for ext4_map_blocks().
626 *
627 * Allocation strategy is simple: if we have to allocate something, we will
628 * have to go the whole way to leaf. So let's do it before attaching anything
629 * to tree, set linkage between the newborn blocks, write them if sync is
630 * required, recheck the path, free and repeat if check fails, otherwise
631 * set the last missing link (that will protect us from any truncate-generated
632 * removals - all blocks on the path are immune now) and possibly force the
633 * write on the parent block.
634 * That has a nice additional property: no special recovery from the failed
635 * allocations is needed - we simply release blocks and do not touch anything
636 * reachable from inode.
637 *
638 * `handle' can be NULL if create == 0.
639 *
640 * return > 0, # of blocks mapped or allocated.
641 * return = 0, if plain lookup failed.
642 * return < 0, error case.
643 *
644 * The ext4_ind_get_blocks() function should be called with
645 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
646 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
647 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
648 * blocks.
649 */
650int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
651 struct ext4_map_blocks *map,
652 int flags)
653{
654 int err = -EIO;
655 ext4_lblk_t offsets[4];
656 Indirect chain[4];
657 Indirect *partial;
658 ext4_fsblk_t goal;
659 int indirect_blks;
660 int blocks_to_boundary = 0;
661 int depth;
662 int count = 0;
663 ext4_fsblk_t first_block = 0;
664
665 trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
666 J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
667 J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
668 depth = ext4_block_to_path(inode, map->m_lblk, offsets,
669 &blocks_to_boundary);
670
671 if (depth == 0)
672 goto out;
673
674 partial = ext4_get_branch(inode, depth, offsets, chain, &err);
675
676 /* Simplest case - block found, no allocation needed */
677 if (!partial) {
678 first_block = le32_to_cpu(chain[depth - 1].key);
679 count++;
680 /*map more blocks*/
681 while (count < map->m_len && count <= blocks_to_boundary) {
682 ext4_fsblk_t blk;
683
684 blk = le32_to_cpu(*(chain[depth-1].p + count));
685
686 if (blk == first_block + count)
687 count++;
688 else
689 break;
690 }
691 goto got_it;
692 }
693
694 /* Next simple case - plain lookup or failed read of indirect block */
695 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
696 goto cleanup;
697
698 /*
699 * Okay, we need to do block allocation.
700 */
Theodore Ts'obab08ab2011-09-09 18:36:51 -0400701 if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
702 EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
703 EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
704 "non-extent mapped inodes with bigalloc");
705 return -ENOSPC;
706 }
707
Amir Goldsteindae1e522011-06-27 19:40:50 -0400708 goal = ext4_find_goal(inode, map->m_lblk, partial);
709
710 /* the number of blocks need to allocate for [d,t]indirect blocks */
711 indirect_blks = (chain + depth) - partial - 1;
712
713 /*
714 * Next look up the indirect map to count the totoal number of
715 * direct blocks to allocate for this branch.
716 */
717 count = ext4_blks_to_allocate(partial, indirect_blks,
718 map->m_len, blocks_to_boundary);
719 /*
720 * Block out ext4_truncate while we alter the tree
721 */
722 err = ext4_alloc_branch(handle, inode, map->m_lblk, indirect_blks,
723 &count, goal,
724 offsets + (partial - chain), partial);
725
726 /*
727 * The ext4_splice_branch call will free and forget any buffers
728 * on the new chain if there is a failure, but that risks using
729 * up transaction credits, especially for bitmaps where the
730 * credits cannot be returned. Can we handle this somehow? We
731 * may need to return -EAGAIN upwards in the worst case. --sct
732 */
733 if (!err)
734 err = ext4_splice_branch(handle, inode, map->m_lblk,
735 partial, indirect_blks, count);
736 if (err)
737 goto cleanup;
738
739 map->m_flags |= EXT4_MAP_NEW;
740
741 ext4_update_inode_fsync_trans(handle, inode, 1);
742got_it:
743 map->m_flags |= EXT4_MAP_MAPPED;
744 map->m_pblk = le32_to_cpu(chain[depth-1].key);
745 map->m_len = count;
746 if (count > blocks_to_boundary)
747 map->m_flags |= EXT4_MAP_BOUNDARY;
748 err = count;
749 /* Clean up and exit */
750 partial = chain + depth - 1; /* the whole chain */
751cleanup:
752 while (partial > chain) {
753 BUFFER_TRACE(partial->bh, "call brelse");
754 brelse(partial->bh);
755 partial--;
756 }
757out:
758 trace_ext4_ind_map_blocks_exit(inode, map->m_lblk,
759 map->m_pblk, map->m_len, err);
760 return err;
761}
762
763/*
764 * O_DIRECT for ext3 (or indirect map) based files
765 *
766 * If the O_DIRECT write will extend the file then add this inode to the
767 * orphan list. So recovery will truncate it back to the original size
768 * if the machine crashes during the write.
769 *
770 * If the O_DIRECT write is intantiating holes inside i_size and the machine
771 * crashes then stale disk data _may_ be exposed inside the file. But current
772 * VFS code falls back into buffered path in that case so we are safe.
773 */
774ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
775 const struct iovec *iov, loff_t offset,
776 unsigned long nr_segs)
777{
778 struct file *file = iocb->ki_filp;
779 struct inode *inode = file->f_mapping->host;
780 struct ext4_inode_info *ei = EXT4_I(inode);
781 handle_t *handle;
782 ssize_t ret;
783 int orphan = 0;
784 size_t count = iov_length(iov, nr_segs);
785 int retries = 0;
786
787 if (rw == WRITE) {
788 loff_t final_size = offset + count;
789
790 if (final_size > inode->i_size) {
791 /* Credits for sb + inode write */
792 handle = ext4_journal_start(inode, 2);
793 if (IS_ERR(handle)) {
794 ret = PTR_ERR(handle);
795 goto out;
796 }
797 ret = ext4_orphan_add(handle, inode);
798 if (ret) {
799 ext4_journal_stop(handle);
800 goto out;
801 }
802 orphan = 1;
803 ei->i_disksize = inode->i_size;
804 ext4_journal_stop(handle);
805 }
806 }
807
808retry:
Jiaying Zhangdccaf332011-08-19 19:13:32 -0400809 if (rw == READ && ext4_should_dioread_nolock(inode)) {
810 if (unlikely(!list_empty(&ei->i_completed_io_list))) {
811 mutex_lock(&inode->i_mutex);
812 ext4_flush_completed_IO(inode);
813 mutex_unlock(&inode->i_mutex);
814 }
Amir Goldsteindae1e522011-06-27 19:40:50 -0400815 ret = __blockdev_direct_IO(rw, iocb, inode,
816 inode->i_sb->s_bdev, iov,
817 offset, nr_segs,
818 ext4_get_block, NULL, NULL, 0);
Jiaying Zhangdccaf332011-08-19 19:13:32 -0400819 } else {
Linus Torvalds60ad4462011-08-01 13:56:03 -1000820 ret = blockdev_direct_IO(rw, iocb, inode, iov,
821 offset, nr_segs, ext4_get_block);
Amir Goldsteindae1e522011-06-27 19:40:50 -0400822
823 if (unlikely((rw & WRITE) && ret < 0)) {
824 loff_t isize = i_size_read(inode);
825 loff_t end = offset + iov_length(iov, nr_segs);
826
827 if (end > isize)
828 ext4_truncate_failed_write(inode);
829 }
830 }
831 if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
832 goto retry;
833
834 if (orphan) {
835 int err;
836
837 /* Credits for sb + inode write */
838 handle = ext4_journal_start(inode, 2);
839 if (IS_ERR(handle)) {
840 /* This is really bad luck. We've written the data
841 * but cannot extend i_size. Bail out and pretend
842 * the write failed... */
843 ret = PTR_ERR(handle);
844 if (inode->i_nlink)
845 ext4_orphan_del(NULL, inode);
846
847 goto out;
848 }
849 if (inode->i_nlink)
850 ext4_orphan_del(handle, inode);
851 if (ret > 0) {
852 loff_t end = offset + ret;
853 if (end > inode->i_size) {
854 ei->i_disksize = end;
855 i_size_write(inode, end);
856 /*
857 * We're going to return a positive `ret'
858 * here due to non-zero-length I/O, so there's
859 * no way of reporting error returns from
860 * ext4_mark_inode_dirty() to userspace. So
861 * ignore it.
862 */
863 ext4_mark_inode_dirty(handle, inode);
864 }
865 }
866 err = ext4_journal_stop(handle);
867 if (ret == 0)
868 ret = err;
869 }
870out:
871 return ret;
872}
873
874/*
875 * Calculate the number of metadata blocks need to reserve
876 * to allocate a new block at @lblocks for non extent file based file
877 */
878int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock)
879{
880 struct ext4_inode_info *ei = EXT4_I(inode);
881 sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
882 int blk_bits;
883
884 if (lblock < EXT4_NDIR_BLOCKS)
885 return 0;
886
887 lblock -= EXT4_NDIR_BLOCKS;
888
889 if (ei->i_da_metadata_calc_len &&
890 (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
891 ei->i_da_metadata_calc_len++;
892 return 0;
893 }
894 ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
895 ei->i_da_metadata_calc_len = 1;
896 blk_bits = order_base_2(lblock);
897 return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
898}
899
900int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk)
901{
902 int indirects;
903
904 /* if nrblocks are contiguous */
905 if (chunk) {
906 /*
907 * With N contiguous data blocks, we need at most
908 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
909 * 2 dindirect blocks, and 1 tindirect block
910 */
911 return DIV_ROUND_UP(nrblocks,
912 EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
913 }
914 /*
915 * if nrblocks are not contiguous, worse case, each block touch
916 * a indirect block, and each indirect block touch a double indirect
917 * block, plus a triple indirect block
918 */
919 indirects = nrblocks * 2 + 1;
920 return indirects;
921}
922
923/*
924 * Truncate transactions can be complex and absolutely huge. So we need to
925 * be able to restart the transaction at a conventient checkpoint to make
926 * sure we don't overflow the journal.
927 *
928 * start_transaction gets us a new handle for a truncate transaction,
929 * and extend_transaction tries to extend the existing one a bit. If
930 * extend fails, we need to propagate the failure up and restart the
931 * transaction in the top-level truncate loop. --sct
932 */
933static handle_t *start_transaction(struct inode *inode)
934{
935 handle_t *result;
936
937 result = ext4_journal_start(inode, ext4_blocks_for_truncate(inode));
938 if (!IS_ERR(result))
939 return result;
940
941 ext4_std_error(inode->i_sb, PTR_ERR(result));
942 return result;
943}
944
945/*
946 * Try to extend this transaction for the purposes of truncation.
947 *
948 * Returns 0 if we managed to create more room. If we can't create more
949 * room, and the transaction must be restarted we return 1.
950 */
951static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
952{
953 if (!ext4_handle_valid(handle))
954 return 0;
955 if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
956 return 0;
957 if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
958 return 0;
959 return 1;
960}
961
962/*
963 * Probably it should be a library function... search for first non-zero word
964 * or memcmp with zero_page, whatever is better for particular architecture.
965 * Linus?
966 */
967static inline int all_zeroes(__le32 *p, __le32 *q)
968{
969 while (p < q)
970 if (*p++)
971 return 0;
972 return 1;
973}
974
975/**
976 * ext4_find_shared - find the indirect blocks for partial truncation.
977 * @inode: inode in question
978 * @depth: depth of the affected branch
979 * @offsets: offsets of pointers in that branch (see ext4_block_to_path)
980 * @chain: place to store the pointers to partial indirect blocks
981 * @top: place to the (detached) top of branch
982 *
983 * This is a helper function used by ext4_truncate().
984 *
985 * When we do truncate() we may have to clean the ends of several
986 * indirect blocks but leave the blocks themselves alive. Block is
987 * partially truncated if some data below the new i_size is referred
988 * from it (and it is on the path to the first completely truncated
989 * data block, indeed). We have to free the top of that path along
990 * with everything to the right of the path. Since no allocation
991 * past the truncation point is possible until ext4_truncate()
992 * finishes, we may safely do the latter, but top of branch may
993 * require special attention - pageout below the truncation point
994 * might try to populate it.
995 *
996 * We atomically detach the top of branch from the tree, store the
997 * block number of its root in *@top, pointers to buffer_heads of
998 * partially truncated blocks - in @chain[].bh and pointers to
999 * their last elements that should not be removed - in
1000 * @chain[].p. Return value is the pointer to last filled element
1001 * of @chain.
1002 *
1003 * The work left to caller to do the actual freeing of subtrees:
1004 * a) free the subtree starting from *@top
1005 * b) free the subtrees whose roots are stored in
1006 * (@chain[i].p+1 .. end of @chain[i].bh->b_data)
1007 * c) free the subtrees growing from the inode past the @chain[0].
1008 * (no partially truncated stuff there). */
1009
1010static Indirect *ext4_find_shared(struct inode *inode, int depth,
1011 ext4_lblk_t offsets[4], Indirect chain[4],
1012 __le32 *top)
1013{
1014 Indirect *partial, *p;
1015 int k, err;
1016
1017 *top = 0;
1018 /* Make k index the deepest non-null offset + 1 */
1019 for (k = depth; k > 1 && !offsets[k-1]; k--)
1020 ;
1021 partial = ext4_get_branch(inode, k, offsets, chain, &err);
1022 /* Writer: pointers */
1023 if (!partial)
1024 partial = chain + k-1;
1025 /*
1026 * If the branch acquired continuation since we've looked at it -
1027 * fine, it should all survive and (new) top doesn't belong to us.
1028 */
1029 if (!partial->key && *partial->p)
1030 /* Writer: end */
1031 goto no_top;
1032 for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
1033 ;
1034 /*
1035 * OK, we've found the last block that must survive. The rest of our
1036 * branch should be detached before unlocking. However, if that rest
1037 * of branch is all ours and does not grow immediately from the inode
1038 * it's easier to cheat and just decrement partial->p.
1039 */
1040 if (p == chain + k - 1 && p > chain) {
1041 p->p--;
1042 } else {
1043 *top = *p->p;
1044 /* Nope, don't do this in ext4. Must leave the tree intact */
1045#if 0
1046 *p->p = 0;
1047#endif
1048 }
1049 /* Writer: end */
1050
1051 while (partial > p) {
1052 brelse(partial->bh);
1053 partial--;
1054 }
1055no_top:
1056 return partial;
1057}
1058
1059/*
1060 * Zero a number of block pointers in either an inode or an indirect block.
1061 * If we restart the transaction we must again get write access to the
1062 * indirect block for further modification.
1063 *
1064 * We release `count' blocks on disk, but (last - first) may be greater
1065 * than `count' because there can be holes in there.
1066 *
1067 * Return 0 on success, 1 on invalid block range
1068 * and < 0 on fatal error.
1069 */
1070static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
1071 struct buffer_head *bh,
1072 ext4_fsblk_t block_to_free,
1073 unsigned long count, __le32 *first,
1074 __le32 *last)
1075{
1076 __le32 *p;
1077 int flags = EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_VALIDATED;
1078 int err;
1079
1080 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
1081 flags |= EXT4_FREE_BLOCKS_METADATA;
1082
1083 if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), block_to_free,
1084 count)) {
1085 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
1086 "blocks %llu len %lu",
1087 (unsigned long long) block_to_free, count);
1088 return 1;
1089 }
1090
1091 if (try_to_extend_transaction(handle, inode)) {
1092 if (bh) {
1093 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
1094 err = ext4_handle_dirty_metadata(handle, inode, bh);
1095 if (unlikely(err))
1096 goto out_err;
1097 }
1098 err = ext4_mark_inode_dirty(handle, inode);
1099 if (unlikely(err))
1100 goto out_err;
1101 err = ext4_truncate_restart_trans(handle, inode,
1102 ext4_blocks_for_truncate(inode));
1103 if (unlikely(err))
1104 goto out_err;
1105 if (bh) {
1106 BUFFER_TRACE(bh, "retaking write access");
1107 err = ext4_journal_get_write_access(handle, bh);
1108 if (unlikely(err))
1109 goto out_err;
1110 }
1111 }
1112
1113 for (p = first; p < last; p++)
1114 *p = 0;
1115
1116 ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
1117 return 0;
1118out_err:
1119 ext4_std_error(inode->i_sb, err);
1120 return err;
1121}
1122
1123/**
1124 * ext4_free_data - free a list of data blocks
1125 * @handle: handle for this transaction
1126 * @inode: inode we are dealing with
1127 * @this_bh: indirect buffer_head which contains *@first and *@last
1128 * @first: array of block numbers
1129 * @last: points immediately past the end of array
1130 *
1131 * We are freeing all blocks referred from that array (numbers are stored as
1132 * little-endian 32-bit) and updating @inode->i_blocks appropriately.
1133 *
1134 * We accumulate contiguous runs of blocks to free. Conveniently, if these
1135 * blocks are contiguous then releasing them at one time will only affect one
1136 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
1137 * actually use a lot of journal space.
1138 *
1139 * @this_bh will be %NULL if @first and @last point into the inode's direct
1140 * block pointers.
1141 */
1142static void ext4_free_data(handle_t *handle, struct inode *inode,
1143 struct buffer_head *this_bh,
1144 __le32 *first, __le32 *last)
1145{
1146 ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */
1147 unsigned long count = 0; /* Number of blocks in the run */
1148 __le32 *block_to_free_p = NULL; /* Pointer into inode/ind
1149 corresponding to
1150 block_to_free */
1151 ext4_fsblk_t nr; /* Current block # */
1152 __le32 *p; /* Pointer into inode/ind
1153 for current block */
1154 int err = 0;
1155
1156 if (this_bh) { /* For indirect block */
1157 BUFFER_TRACE(this_bh, "get_write_access");
1158 err = ext4_journal_get_write_access(handle, this_bh);
1159 /* Important: if we can't update the indirect pointers
1160 * to the blocks, we can't free them. */
1161 if (err)
1162 return;
1163 }
1164
1165 for (p = first; p < last; p++) {
1166 nr = le32_to_cpu(*p);
1167 if (nr) {
1168 /* accumulate blocks to free if they're contiguous */
1169 if (count == 0) {
1170 block_to_free = nr;
1171 block_to_free_p = p;
1172 count = 1;
1173 } else if (nr == block_to_free + count) {
1174 count++;
1175 } else {
1176 err = ext4_clear_blocks(handle, inode, this_bh,
1177 block_to_free, count,
1178 block_to_free_p, p);
1179 if (err)
1180 break;
1181 block_to_free = nr;
1182 block_to_free_p = p;
1183 count = 1;
1184 }
1185 }
1186 }
1187
1188 if (!err && count > 0)
1189 err = ext4_clear_blocks(handle, inode, this_bh, block_to_free,
1190 count, block_to_free_p, p);
1191 if (err < 0)
1192 /* fatal error */
1193 return;
1194
1195 if (this_bh) {
1196 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
1197
1198 /*
1199 * The buffer head should have an attached journal head at this
1200 * point. However, if the data is corrupted and an indirect
1201 * block pointed to itself, it would have been detached when
1202 * the block was cleared. Check for this instead of OOPSing.
1203 */
1204 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
1205 ext4_handle_dirty_metadata(handle, inode, this_bh);
1206 else
1207 EXT4_ERROR_INODE(inode,
1208 "circular indirect block detected at "
1209 "block %llu",
1210 (unsigned long long) this_bh->b_blocknr);
1211 }
1212}
1213
1214/**
1215 * ext4_free_branches - free an array of branches
1216 * @handle: JBD handle for this transaction
1217 * @inode: inode we are dealing with
1218 * @parent_bh: the buffer_head which contains *@first and *@last
1219 * @first: array of block numbers
1220 * @last: pointer immediately past the end of array
1221 * @depth: depth of the branches to free
1222 *
1223 * We are freeing all blocks referred from these branches (numbers are
1224 * stored as little-endian 32-bit) and updating @inode->i_blocks
1225 * appropriately.
1226 */
1227static void ext4_free_branches(handle_t *handle, struct inode *inode,
1228 struct buffer_head *parent_bh,
1229 __le32 *first, __le32 *last, int depth)
1230{
1231 ext4_fsblk_t nr;
1232 __le32 *p;
1233
1234 if (ext4_handle_is_aborted(handle))
1235 return;
1236
1237 if (depth--) {
1238 struct buffer_head *bh;
1239 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1240 p = last;
1241 while (--p >= first) {
1242 nr = le32_to_cpu(*p);
1243 if (!nr)
1244 continue; /* A hole */
1245
1246 if (!ext4_data_block_valid(EXT4_SB(inode->i_sb),
1247 nr, 1)) {
1248 EXT4_ERROR_INODE(inode,
1249 "invalid indirect mapped "
1250 "block %lu (level %d)",
1251 (unsigned long) nr, depth);
1252 break;
1253 }
1254
1255 /* Go read the buffer for the next level down */
1256 bh = sb_bread(inode->i_sb, nr);
1257
1258 /*
1259 * A read failure? Report error and clear slot
1260 * (should be rare).
1261 */
1262 if (!bh) {
1263 EXT4_ERROR_INODE_BLOCK(inode, nr,
1264 "Read failure");
1265 continue;
1266 }
1267
1268 /* This zaps the entire block. Bottom up. */
1269 BUFFER_TRACE(bh, "free child branches");
1270 ext4_free_branches(handle, inode, bh,
1271 (__le32 *) bh->b_data,
1272 (__le32 *) bh->b_data + addr_per_block,
1273 depth);
1274 brelse(bh);
1275
1276 /*
1277 * Everything below this this pointer has been
1278 * released. Now let this top-of-subtree go.
1279 *
1280 * We want the freeing of this indirect block to be
1281 * atomic in the journal with the updating of the
1282 * bitmap block which owns it. So make some room in
1283 * the journal.
1284 *
1285 * We zero the parent pointer *after* freeing its
1286 * pointee in the bitmaps, so if extend_transaction()
1287 * for some reason fails to put the bitmap changes and
1288 * the release into the same transaction, recovery
1289 * will merely complain about releasing a free block,
1290 * rather than leaking blocks.
1291 */
1292 if (ext4_handle_is_aborted(handle))
1293 return;
1294 if (try_to_extend_transaction(handle, inode)) {
1295 ext4_mark_inode_dirty(handle, inode);
1296 ext4_truncate_restart_trans(handle, inode,
1297 ext4_blocks_for_truncate(inode));
1298 }
1299
1300 /*
1301 * The forget flag here is critical because if
1302 * we are journaling (and not doing data
1303 * journaling), we have to make sure a revoke
1304 * record is written to prevent the journal
1305 * replay from overwriting the (former)
1306 * indirect block if it gets reallocated as a
1307 * data block. This must happen in the same
1308 * transaction where the data blocks are
1309 * actually freed.
1310 */
1311 ext4_free_blocks(handle, inode, NULL, nr, 1,
1312 EXT4_FREE_BLOCKS_METADATA|
1313 EXT4_FREE_BLOCKS_FORGET);
1314
1315 if (parent_bh) {
1316 /*
1317 * The block which we have just freed is
1318 * pointed to by an indirect block: journal it
1319 */
1320 BUFFER_TRACE(parent_bh, "get_write_access");
1321 if (!ext4_journal_get_write_access(handle,
1322 parent_bh)){
1323 *p = 0;
1324 BUFFER_TRACE(parent_bh,
1325 "call ext4_handle_dirty_metadata");
1326 ext4_handle_dirty_metadata(handle,
1327 inode,
1328 parent_bh);
1329 }
1330 }
1331 }
1332 } else {
1333 /* We have reached the bottom of the tree. */
1334 BUFFER_TRACE(parent_bh, "free data blocks");
1335 ext4_free_data(handle, inode, parent_bh, first, last);
1336 }
1337}
1338
1339void ext4_ind_truncate(struct inode *inode)
1340{
1341 handle_t *handle;
1342 struct ext4_inode_info *ei = EXT4_I(inode);
1343 __le32 *i_data = ei->i_data;
1344 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1345 struct address_space *mapping = inode->i_mapping;
1346 ext4_lblk_t offsets[4];
1347 Indirect chain[4];
1348 Indirect *partial;
1349 __le32 nr = 0;
1350 int n = 0;
1351 ext4_lblk_t last_block, max_block;
Allison Henderson189e8682011-09-06 21:49:44 -04001352 loff_t page_len;
Amir Goldsteindae1e522011-06-27 19:40:50 -04001353 unsigned blocksize = inode->i_sb->s_blocksize;
Allison Henderson189e8682011-09-06 21:49:44 -04001354 int err;
Amir Goldsteindae1e522011-06-27 19:40:50 -04001355
1356 handle = start_transaction(inode);
1357 if (IS_ERR(handle))
1358 return; /* AKPM: return what? */
1359
1360 last_block = (inode->i_size + blocksize-1)
1361 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1362 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1363 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1364
Allison Henderson189e8682011-09-06 21:49:44 -04001365 if (inode->i_size % PAGE_CACHE_SIZE != 0) {
1366 page_len = PAGE_CACHE_SIZE -
1367 (inode->i_size & (PAGE_CACHE_SIZE - 1));
1368
1369 err = ext4_discard_partial_page_buffers(handle,
1370 mapping, inode->i_size, page_len, 0);
1371
1372 if (err)
Amir Goldsteindae1e522011-06-27 19:40:50 -04001373 goto out_stop;
Allison Henderson189e8682011-09-06 21:49:44 -04001374 }
Amir Goldsteindae1e522011-06-27 19:40:50 -04001375
1376 if (last_block != max_block) {
1377 n = ext4_block_to_path(inode, last_block, offsets, NULL);
1378 if (n == 0)
1379 goto out_stop; /* error */
1380 }
1381
1382 /*
1383 * OK. This truncate is going to happen. We add the inode to the
1384 * orphan list, so that if this truncate spans multiple transactions,
1385 * and we crash, we will resume the truncate when the filesystem
1386 * recovers. It also marks the inode dirty, to catch the new size.
1387 *
1388 * Implication: the file must always be in a sane, consistent
1389 * truncatable state while each transaction commits.
1390 */
1391 if (ext4_orphan_add(handle, inode))
1392 goto out_stop;
1393
1394 /*
1395 * From here we block out all ext4_get_block() callers who want to
1396 * modify the block allocation tree.
1397 */
1398 down_write(&ei->i_data_sem);
1399
1400 ext4_discard_preallocations(inode);
1401
1402 /*
1403 * The orphan list entry will now protect us from any crash which
1404 * occurs before the truncate completes, so it is now safe to propagate
1405 * the new, shorter inode size (held for now in i_size) into the
1406 * on-disk inode. We do this via i_disksize, which is the value which
1407 * ext4 *really* writes onto the disk inode.
1408 */
1409 ei->i_disksize = inode->i_size;
1410
1411 if (last_block == max_block) {
1412 /*
1413 * It is unnecessary to free any data blocks if last_block is
1414 * equal to the indirect block limit.
1415 */
1416 goto out_unlock;
1417 } else if (n == 1) { /* direct blocks */
1418 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
1419 i_data + EXT4_NDIR_BLOCKS);
1420 goto do_indirects;
1421 }
1422
1423 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1424 /* Kill the top of shared branch (not detached) */
1425 if (nr) {
1426 if (partial == chain) {
1427 /* Shared branch grows from the inode */
1428 ext4_free_branches(handle, inode, NULL,
1429 &nr, &nr+1, (chain+n-1) - partial);
1430 *partial->p = 0;
1431 /*
1432 * We mark the inode dirty prior to restart,
1433 * and prior to stop. No need for it here.
1434 */
1435 } else {
1436 /* Shared branch grows from an indirect block */
1437 BUFFER_TRACE(partial->bh, "get_write_access");
1438 ext4_free_branches(handle, inode, partial->bh,
1439 partial->p,
1440 partial->p+1, (chain+n-1) - partial);
1441 }
1442 }
1443 /* Clear the ends of indirect blocks on the shared branch */
1444 while (partial > chain) {
1445 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
1446 (__le32*)partial->bh->b_data+addr_per_block,
1447 (chain+n-1) - partial);
1448 BUFFER_TRACE(partial->bh, "call brelse");
1449 brelse(partial->bh);
1450 partial--;
1451 }
1452do_indirects:
1453 /* Kill the remaining (whole) subtrees */
1454 switch (offsets[0]) {
1455 default:
1456 nr = i_data[EXT4_IND_BLOCK];
1457 if (nr) {
1458 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1459 i_data[EXT4_IND_BLOCK] = 0;
1460 }
1461 case EXT4_IND_BLOCK:
1462 nr = i_data[EXT4_DIND_BLOCK];
1463 if (nr) {
1464 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1465 i_data[EXT4_DIND_BLOCK] = 0;
1466 }
1467 case EXT4_DIND_BLOCK:
1468 nr = i_data[EXT4_TIND_BLOCK];
1469 if (nr) {
1470 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1471 i_data[EXT4_TIND_BLOCK] = 0;
1472 }
1473 case EXT4_TIND_BLOCK:
1474 ;
1475 }
1476
1477out_unlock:
1478 up_write(&ei->i_data_sem);
1479 inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
1480 ext4_mark_inode_dirty(handle, inode);
1481
1482 /*
1483 * In a multi-transaction truncate, we only make the final transaction
1484 * synchronous
1485 */
1486 if (IS_SYNC(inode))
1487 ext4_handle_sync(handle);
1488out_stop:
1489 /*
1490 * If this was a simple ftruncate(), and the file will remain alive
1491 * then we need to clear up the orphan record which we created above.
1492 * However, if this was a real unlink then we were called by
1493 * ext4_delete_inode(), and we allow that function to clean up the
1494 * orphan info for us.
1495 */
1496 if (inode->i_nlink)
1497 ext4_orphan_del(handle, inode);
1498
1499 ext4_journal_stop(handle);
1500 trace_ext4_truncate_exit(inode);
1501}
1502