1 // SPDX-License-Identifier: GPL-2.0
3 * linux/fs/ext4/indirect.c
7 * linux/fs/ext4/inode.c
9 * Copyright (C) 1992, 1993, 1994, 1995
10 * Remy Card (card@masi.ibp.fr)
11 * Laboratoire MASI - Institut Blaise Pascal
12 * Universite Pierre et Marie Curie (Paris VI)
16 * linux/fs/minix/inode.c
18 * Copyright (C) 1991, 1992 Linus Torvalds
20 * Goal-directed block allocation by Stephen Tweedie
21 * (sct@redhat.com), 1993, 1998
24 #include "ext4_jbd2.h"
26 #include <linux/dax.h>
27 #include <linux/uio.h>
29 #include <trace/events/ext4.h>
34 struct buffer_head *bh;
37 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
44 * ext4_block_to_path - parse the block number into array of offsets
45 * @inode: inode in question (we are only interested in its superblock)
46 * @i_block: block number to be parsed
47 * @offsets: array to store the offsets in
48 * @boundary: set this non-zero if the referred-to block is likely to be
49 * followed (on disk) by an indirect block.
51 * To store the locations of file's data ext4 uses a data structure common
52 * for UNIX filesystems - tree of pointers anchored in the inode, with
53 * data blocks at leaves and indirect blocks in intermediate nodes.
54 * This function translates the block number into path in that tree -
55 * return value is the path length and @offsets[n] is the offset of
56 * pointer to (n+1)th node in the nth one. If @block is out of range
57 * (negative or too large) warning is printed and zero returned.
59 * Note: function doesn't find node addresses, so no IO is needed. All
60 * we need to know is the capacity of indirect blocks (taken from the
65 * Portability note: the last comparison (check that we fit into triple
66 * indirect block) is spelled differently, because otherwise on an
67 * architecture with 32-bit longs and 8Kb pages we might get into trouble
68 * if our filesystem had 8Kb blocks. We might use long long, but that would
69 * kill us on x86. Oh, well, at least the sign propagation does not matter -
70 * i_block would have to be negative in the very beginning, so we would not
74 static int ext4_block_to_path(struct inode *inode,
76 ext4_lblk_t offsets[4], int *boundary)
78 int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
79 int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
80 const long direct_blocks = EXT4_NDIR_BLOCKS,
81 indirect_blocks = ptrs,
82 double_blocks = (1 << (ptrs_bits * 2));
86 if (i_block < direct_blocks) {
87 offsets[n++] = i_block;
88 final = direct_blocks;
89 } else if ((i_block -= direct_blocks) < indirect_blocks) {
90 offsets[n++] = EXT4_IND_BLOCK;
91 offsets[n++] = i_block;
93 } else if ((i_block -= indirect_blocks) < double_blocks) {
94 offsets[n++] = EXT4_DIND_BLOCK;
95 offsets[n++] = i_block >> ptrs_bits;
96 offsets[n++] = i_block & (ptrs - 1);
98 } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
99 offsets[n++] = EXT4_TIND_BLOCK;
100 offsets[n++] = i_block >> (ptrs_bits * 2);
101 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
102 offsets[n++] = i_block & (ptrs - 1);
105 ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
106 i_block + direct_blocks +
107 indirect_blocks + double_blocks, inode->i_ino);
110 *boundary = final - 1 - (i_block & (ptrs - 1));
115 * ext4_get_branch - read the chain of indirect blocks leading to data
116 * @inode: inode in question
117 * @depth: depth of the chain (1 - direct pointer, etc.)
118 * @offsets: offsets of pointers in inode/indirect blocks
119 * @chain: place to store the result
120 * @err: here we store the error value
122 * Function fills the array of triples <key, p, bh> and returns %NULL
123 * if everything went OK or the pointer to the last filled triple
124 * (incomplete one) otherwise. Upon the return chain[i].key contains
125 * the number of (i+1)-th block in the chain (as it is stored in memory,
126 * i.e. little-endian 32-bit), chain[i].p contains the address of that
127 * number (it points into struct inode for i==0 and into the bh->b_data
128 * for i>0) and chain[i].bh points to the buffer_head of i-th indirect
129 * block for i>0 and NULL for i==0. In other words, it holds the block
130 * numbers of the chain, addresses they were taken from (and where we can
131 * verify that chain did not change) and buffer_heads hosting these
134 * Function stops when it stumbles upon zero pointer (absent block)
135 * (pointer to last triple returned, *@err == 0)
136 * or when it gets an IO error reading an indirect block
137 * (ditto, *@err == -EIO)
138 * or when it reads all @depth-1 indirect blocks successfully and finds
139 * the whole chain, all way to the data (returns %NULL, *err == 0).
141 * Need to be called with
142 * down_read(&EXT4_I(inode)->i_data_sem)
144 static Indirect *ext4_get_branch(struct inode *inode, int depth,
145 ext4_lblk_t *offsets,
146 Indirect chain[4], int *err)
148 struct super_block *sb = inode->i_sb;
150 struct buffer_head *bh;
155 /* i_data is not going away, no lock needed */
156 add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
160 key = le32_to_cpu(p->key);
161 if (key > ext4_blocks_count(EXT4_SB(sb)->s_es)) {
162 /* the block was out of range */
166 bh = sb_getblk(sb, key);
172 if (!bh_uptodate_or_lock(bh)) {
173 if (bh_submit_read(bh) < 0) {
177 /* validate block references */
178 if (ext4_check_indirect_blockref(inode, bh)) {
184 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
198 * ext4_find_near - find a place for allocation with sufficient locality
200 * @ind: descriptor of indirect block.
202 * This function returns the preferred place for block allocation.
203 * It is used when heuristic for sequential allocation fails.
205 * + if there is a block to the left of our position - allocate near it.
206 * + if pointer will live in indirect block - allocate near that block.
207 * + if pointer will live in inode - allocate in the same
210 * In the latter case we colour the starting block by the callers PID to
211 * prevent it from clashing with concurrent allocations for a different inode
212 * in the same block group. The PID is used here so that functionally related
213 * files will be close-by on-disk.
215 * Caller must make sure that @ind is valid and will stay that way.
217 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
219 struct ext4_inode_info *ei = EXT4_I(inode);
220 __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
223 /* Try to find previous block */
224 for (p = ind->p - 1; p >= start; p--) {
226 return le32_to_cpu(*p);
229 /* No such thing, so let's try location of indirect block */
231 return ind->bh->b_blocknr;
234 * It is going to be referred to from the inode itself? OK, just put it
235 * into the same cylinder group then.
237 return ext4_inode_to_goal_block(inode);
241 * ext4_find_goal - find a preferred place for allocation.
243 * @block: block we want
244 * @partial: pointer to the last triple within a chain
246 * Normally this function find the preferred place for block allocation,
248 * Because this is only used for non-extent files, we limit the block nr
251 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
257 * XXX need to get goal block from mballoc's data structures
260 goal = ext4_find_near(inode, partial);
261 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
266 * ext4_blks_to_allocate - Look up the block map and count the number
267 * of direct blocks need to be allocated for the given branch.
269 * @branch: chain of indirect blocks
270 * @k: number of blocks need for indirect blocks
271 * @blks: number of data blocks to be mapped.
272 * @blocks_to_boundary: the offset in the indirect block
274 * return the total number of blocks to be allocate, including the
275 * direct and indirect blocks.
277 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
278 int blocks_to_boundary)
280 unsigned int count = 0;
283 * Simple case, [t,d]Indirect block(s) has not allocated yet
284 * then it's clear blocks on that path have not allocated
287 /* right now we don't handle cross boundary allocation */
288 if (blks < blocks_to_boundary + 1)
291 count += blocks_to_boundary + 1;
296 while (count < blks && count <= blocks_to_boundary &&
297 le32_to_cpu(*(branch[0].p + count)) == 0) {
304 * ext4_alloc_branch - allocate and set up a chain of blocks.
305 * @handle: handle for this transaction
307 * @indirect_blks: number of allocated indirect blocks
308 * @blks: number of allocated direct blocks
309 * @goal: preferred place for allocation
310 * @offsets: offsets (in the blocks) to store the pointers to next.
311 * @branch: place to store the chain in.
313 * This function allocates blocks, zeroes out all but the last one,
314 * links them into chain and (if we are synchronous) writes them to disk.
315 * In other words, it prepares a branch that can be spliced onto the
316 * inode. It stores the information about that chain in the branch[], in
317 * the same format as ext4_get_branch() would do. We are calling it after
318 * we had read the existing part of chain and partial points to the last
319 * triple of that (one with zero ->key). Upon the exit we have the same
320 * picture as after the successful ext4_get_block(), except that in one
321 * place chain is disconnected - *branch->p is still zero (we did not
322 * set the last link), but branch->key contains the number that should
323 * be placed into *branch->p to fill that gap.
325 * If allocation fails we free all blocks we've allocated (and forget
326 * their buffer_heads) and return the error value the from failed
327 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
328 * as described above and return 0.
330 static int ext4_alloc_branch(handle_t *handle,
331 struct ext4_allocation_request *ar,
332 int indirect_blks, ext4_lblk_t *offsets,
335 struct buffer_head * bh;
336 ext4_fsblk_t b, new_blocks[4];
338 int i, j, err, len = 1;
340 for (i = 0; i <= indirect_blks; i++) {
341 if (i == indirect_blks) {
342 new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err);
344 ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle,
346 ar->flags & EXT4_MB_DELALLOC_RESERVED,
352 branch[i].key = cpu_to_le32(new_blocks[i]);
356 bh = branch[i].bh = sb_getblk(ar->inode->i_sb, new_blocks[i-1]);
362 BUFFER_TRACE(bh, "call get_create_access");
363 err = ext4_journal_get_create_access(handle, bh);
369 memset(bh->b_data, 0, bh->b_size);
370 p = branch[i].p = (__le32 *) bh->b_data + offsets[i];
373 if (i == indirect_blks)
375 for (j = 0; j < len; j++)
376 *p++ = cpu_to_le32(b++);
378 BUFFER_TRACE(bh, "marking uptodate");
379 set_buffer_uptodate(bh);
382 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
383 err = ext4_handle_dirty_metadata(handle, ar->inode, bh);
389 for (; i >= 0; i--) {
391 * We want to ext4_forget() only freshly allocated indirect
392 * blocks. Buffer for new_blocks[i-1] is at branch[i].bh and
393 * buffer at branch[0].bh is indirect block / inode already
394 * existing before ext4_alloc_branch() was called.
396 if (i > 0 && i != indirect_blks && branch[i].bh)
397 ext4_forget(handle, 1, ar->inode, branch[i].bh,
398 branch[i].bh->b_blocknr);
399 ext4_free_blocks(handle, ar->inode, NULL, new_blocks[i],
400 (i == indirect_blks) ? ar->len : 1, 0);
406 * ext4_splice_branch - splice the allocated branch onto inode.
407 * @handle: handle for this transaction
409 * @block: (logical) number of block we are adding
410 * @chain: chain of indirect blocks (with a missing link - see
412 * @where: location of missing link
413 * @num: number of indirect blocks we are adding
414 * @blks: number of direct blocks we are adding
416 * This function fills the missing link and does all housekeeping needed in
417 * inode (->i_blocks, etc.). In case of success we end up with the full
418 * chain to new block and return 0.
420 static int ext4_splice_branch(handle_t *handle,
421 struct ext4_allocation_request *ar,
422 Indirect *where, int num)
426 ext4_fsblk_t current_block;
429 * If we're splicing into a [td]indirect block (as opposed to the
430 * inode) then we need to get write access to the [td]indirect block
434 BUFFER_TRACE(where->bh, "get_write_access");
435 err = ext4_journal_get_write_access(handle, where->bh);
441 *where->p = where->key;
444 * Update the host buffer_head or inode to point to more just allocated
445 * direct blocks blocks
447 if (num == 0 && ar->len > 1) {
448 current_block = le32_to_cpu(where->key) + 1;
449 for (i = 1; i < ar->len; i++)
450 *(where->p + i) = cpu_to_le32(current_block++);
453 /* We are done with atomic stuff, now do the rest of housekeeping */
454 /* had we spliced it onto indirect block? */
457 * If we spliced it onto an indirect block, we haven't
458 * altered the inode. Note however that if it is being spliced
459 * onto an indirect block at the very end of the file (the
460 * file is growing) then we *will* alter the inode to reflect
461 * the new i_size. But that is not done here - it is done in
462 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
464 jbd_debug(5, "splicing indirect only\n");
465 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
466 err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh);
471 * OK, we spliced it into the inode itself on a direct block.
473 ext4_mark_inode_dirty(handle, ar->inode);
474 jbd_debug(5, "splicing direct\n");
479 for (i = 1; i <= num; i++) {
481 * branch[i].bh is newly allocated, so there is no
482 * need to revoke the block, which is why we don't
483 * need to set EXT4_FREE_BLOCKS_METADATA.
485 ext4_free_blocks(handle, ar->inode, where[i].bh, 0, 1,
486 EXT4_FREE_BLOCKS_FORGET);
488 ext4_free_blocks(handle, ar->inode, NULL, le32_to_cpu(where[num].key),
495 * The ext4_ind_map_blocks() function handles non-extents inodes
496 * (i.e., using the traditional indirect/double-indirect i_blocks
497 * scheme) for ext4_map_blocks().
499 * Allocation strategy is simple: if we have to allocate something, we will
500 * have to go the whole way to leaf. So let's do it before attaching anything
501 * to tree, set linkage between the newborn blocks, write them if sync is
502 * required, recheck the path, free and repeat if check fails, otherwise
503 * set the last missing link (that will protect us from any truncate-generated
504 * removals - all blocks on the path are immune now) and possibly force the
505 * write on the parent block.
506 * That has a nice additional property: no special recovery from the failed
507 * allocations is needed - we simply release blocks and do not touch anything
508 * reachable from inode.
510 * `handle' can be NULL if create == 0.
512 * return > 0, # of blocks mapped or allocated.
513 * return = 0, if plain lookup failed.
514 * return < 0, error case.
516 * The ext4_ind_get_blocks() function should be called with
517 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
518 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
519 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
522 int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
523 struct ext4_map_blocks *map,
526 struct ext4_allocation_request ar;
528 ext4_lblk_t offsets[4];
532 int blocks_to_boundary = 0;
535 ext4_fsblk_t first_block = 0;
537 trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
538 J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
539 J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
540 depth = ext4_block_to_path(inode, map->m_lblk, offsets,
541 &blocks_to_boundary);
546 partial = ext4_get_branch(inode, depth, offsets, chain, &err);
548 /* Simplest case - block found, no allocation needed */
550 first_block = le32_to_cpu(chain[depth - 1].key);
553 while (count < map->m_len && count <= blocks_to_boundary) {
556 blk = le32_to_cpu(*(chain[depth-1].p + count));
558 if (blk == first_block + count)
566 /* Next simple case - plain lookup failed */
567 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
568 unsigned epb = inode->i_sb->s_blocksize / sizeof(u32);
572 * Count number blocks in a subtree under 'partial'. At each
573 * level we count number of complete empty subtrees beyond
574 * current offset and then descend into the subtree only
575 * partially beyond current offset.
578 for (i = partial - chain + 1; i < depth; i++)
579 count = count * epb + (epb - offsets[i] - 1);
581 /* Fill in size of a hole we found */
583 map->m_len = min_t(unsigned int, map->m_len, count);
587 /* Failed read of indirect block */
592 * Okay, we need to do block allocation.
594 if (ext4_has_feature_bigalloc(inode->i_sb)) {
595 EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
596 "non-extent mapped inodes with bigalloc");
597 return -EFSCORRUPTED;
600 /* Set up for the direct block allocation */
601 memset(&ar, 0, sizeof(ar));
603 ar.logical = map->m_lblk;
604 if (S_ISREG(inode->i_mode))
605 ar.flags = EXT4_MB_HINT_DATA;
606 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
607 ar.flags |= EXT4_MB_DELALLOC_RESERVED;
608 if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
609 ar.flags |= EXT4_MB_USE_RESERVED;
611 ar.goal = ext4_find_goal(inode, map->m_lblk, partial);
613 /* the number of blocks need to allocate for [d,t]indirect blocks */
614 indirect_blks = (chain + depth) - partial - 1;
617 * Next look up the indirect map to count the totoal number of
618 * direct blocks to allocate for this branch.
620 ar.len = ext4_blks_to_allocate(partial, indirect_blks,
621 map->m_len, blocks_to_boundary);
624 * Block out ext4_truncate while we alter the tree
626 err = ext4_alloc_branch(handle, &ar, indirect_blks,
627 offsets + (partial - chain), partial);
630 * The ext4_splice_branch call will free and forget any buffers
631 * on the new chain if there is a failure, but that risks using
632 * up transaction credits, especially for bitmaps where the
633 * credits cannot be returned. Can we handle this somehow? We
634 * may need to return -EAGAIN upwards in the worst case. --sct
637 err = ext4_splice_branch(handle, &ar, partial, indirect_blks);
641 map->m_flags |= EXT4_MAP_NEW;
643 ext4_update_inode_fsync_trans(handle, inode, 1);
647 * Update reserved blocks/metadata blocks after successful block
648 * allocation which had been deferred till now.
650 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
651 ext4_da_update_reserve_space(inode, count, 1);
654 map->m_flags |= EXT4_MAP_MAPPED;
655 map->m_pblk = le32_to_cpu(chain[depth-1].key);
657 if (count > blocks_to_boundary)
658 map->m_flags |= EXT4_MAP_BOUNDARY;
660 /* Clean up and exit */
661 partial = chain + depth - 1; /* the whole chain */
663 while (partial > chain) {
664 BUFFER_TRACE(partial->bh, "call brelse");
669 trace_ext4_ind_map_blocks_exit(inode, flags, map, err);
674 * Calculate the number of metadata blocks need to reserve
675 * to allocate a new block at @lblocks for non extent file based file
677 int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock)
679 struct ext4_inode_info *ei = EXT4_I(inode);
680 sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
683 if (lblock < EXT4_NDIR_BLOCKS)
686 lblock -= EXT4_NDIR_BLOCKS;
688 if (ei->i_da_metadata_calc_len &&
689 (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
690 ei->i_da_metadata_calc_len++;
693 ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
694 ei->i_da_metadata_calc_len = 1;
695 blk_bits = order_base_2(lblock);
696 return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
700 * Calculate number of indirect blocks touched by mapping @nrblocks logically
703 int ext4_ind_trans_blocks(struct inode *inode, int nrblocks)
706 * With N contiguous data blocks, we need at most
707 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
708 * 2 dindirect blocks, and 1 tindirect block
710 return DIV_ROUND_UP(nrblocks, EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
714 * Truncate transactions can be complex and absolutely huge. So we need to
715 * be able to restart the transaction at a conventient checkpoint to make
716 * sure we don't overflow the journal.
718 * Try to extend this transaction for the purposes of truncation. If
719 * extend fails, we need to propagate the failure up and restart the
720 * transaction in the top-level truncate loop. --sct
722 * Returns 0 if we managed to create more room. If we can't create more
723 * room, and the transaction must be restarted we return 1.
725 static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
727 if (!ext4_handle_valid(handle))
729 if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
731 if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
737 * Probably it should be a library function... search for first non-zero word
738 * or memcmp with zero_page, whatever is better for particular architecture.
741 static inline int all_zeroes(__le32 *p, __le32 *q)
750 * ext4_find_shared - find the indirect blocks for partial truncation.
751 * @inode: inode in question
752 * @depth: depth of the affected branch
753 * @offsets: offsets of pointers in that branch (see ext4_block_to_path)
754 * @chain: place to store the pointers to partial indirect blocks
755 * @top: place to the (detached) top of branch
757 * This is a helper function used by ext4_truncate().
759 * When we do truncate() we may have to clean the ends of several
760 * indirect blocks but leave the blocks themselves alive. Block is
761 * partially truncated if some data below the new i_size is referred
762 * from it (and it is on the path to the first completely truncated
763 * data block, indeed). We have to free the top of that path along
764 * with everything to the right of the path. Since no allocation
765 * past the truncation point is possible until ext4_truncate()
766 * finishes, we may safely do the latter, but top of branch may
767 * require special attention - pageout below the truncation point
768 * might try to populate it.
770 * We atomically detach the top of branch from the tree, store the
771 * block number of its root in *@top, pointers to buffer_heads of
772 * partially truncated blocks - in @chain[].bh and pointers to
773 * their last elements that should not be removed - in
774 * @chain[].p. Return value is the pointer to last filled element
777 * The work left to caller to do the actual freeing of subtrees:
778 * a) free the subtree starting from *@top
779 * b) free the subtrees whose roots are stored in
780 * (@chain[i].p+1 .. end of @chain[i].bh->b_data)
781 * c) free the subtrees growing from the inode past the @chain[0].
782 * (no partially truncated stuff there). */
784 static Indirect *ext4_find_shared(struct inode *inode, int depth,
785 ext4_lblk_t offsets[4], Indirect chain[4],
788 Indirect *partial, *p;
792 /* Make k index the deepest non-null offset + 1 */
793 for (k = depth; k > 1 && !offsets[k-1]; k--)
795 partial = ext4_get_branch(inode, k, offsets, chain, &err);
796 /* Writer: pointers */
798 partial = chain + k-1;
800 * If the branch acquired continuation since we've looked at it -
801 * fine, it should all survive and (new) top doesn't belong to us.
803 if (!partial->key && *partial->p)
806 for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
809 * OK, we've found the last block that must survive. The rest of our
810 * branch should be detached before unlocking. However, if that rest
811 * of branch is all ours and does not grow immediately from the inode
812 * it's easier to cheat and just decrement partial->p.
814 if (p == chain + k - 1 && p > chain) {
818 /* Nope, don't do this in ext4. Must leave the tree intact */
825 while (partial > p) {
834 * Zero a number of block pointers in either an inode or an indirect block.
835 * If we restart the transaction we must again get write access to the
836 * indirect block for further modification.
838 * We release `count' blocks on disk, but (last - first) may be greater
839 * than `count' because there can be holes in there.
841 * Return 0 on success, 1 on invalid block range
842 * and < 0 on fatal error.
844 static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
845 struct buffer_head *bh,
846 ext4_fsblk_t block_to_free,
847 unsigned long count, __le32 *first,
851 int flags = EXT4_FREE_BLOCKS_VALIDATED;
854 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
855 ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
856 flags |= EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_METADATA;
857 else if (ext4_should_journal_data(inode))
858 flags |= EXT4_FREE_BLOCKS_FORGET;
860 if (!ext4_inode_block_valid(inode, block_to_free, count)) {
861 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
862 "blocks %llu len %lu",
863 (unsigned long long) block_to_free, count);
867 if (try_to_extend_transaction(handle, inode)) {
869 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
870 err = ext4_handle_dirty_metadata(handle, inode, bh);
874 err = ext4_mark_inode_dirty(handle, inode);
877 err = ext4_truncate_restart_trans(handle, inode,
878 ext4_blocks_for_truncate(inode));
882 BUFFER_TRACE(bh, "retaking write access");
883 err = ext4_journal_get_write_access(handle, bh);
889 for (p = first; p < last; p++)
892 ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
895 ext4_std_error(inode->i_sb, err);
900 * ext4_free_data - free a list of data blocks
901 * @handle: handle for this transaction
902 * @inode: inode we are dealing with
903 * @this_bh: indirect buffer_head which contains *@first and *@last
904 * @first: array of block numbers
905 * @last: points immediately past the end of array
907 * We are freeing all blocks referred from that array (numbers are stored as
908 * little-endian 32-bit) and updating @inode->i_blocks appropriately.
910 * We accumulate contiguous runs of blocks to free. Conveniently, if these
911 * blocks are contiguous then releasing them at one time will only affect one
912 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
913 * actually use a lot of journal space.
915 * @this_bh will be %NULL if @first and @last point into the inode's direct
918 static void ext4_free_data(handle_t *handle, struct inode *inode,
919 struct buffer_head *this_bh,
920 __le32 *first, __le32 *last)
922 ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */
923 unsigned long count = 0; /* Number of blocks in the run */
924 __le32 *block_to_free_p = NULL; /* Pointer into inode/ind
927 ext4_fsblk_t nr; /* Current block # */
928 __le32 *p; /* Pointer into inode/ind
932 if (this_bh) { /* For indirect block */
933 BUFFER_TRACE(this_bh, "get_write_access");
934 err = ext4_journal_get_write_access(handle, this_bh);
935 /* Important: if we can't update the indirect pointers
936 * to the blocks, we can't free them. */
941 for (p = first; p < last; p++) {
942 nr = le32_to_cpu(*p);
944 /* accumulate blocks to free if they're contiguous */
949 } else if (nr == block_to_free + count) {
952 err = ext4_clear_blocks(handle, inode, this_bh,
953 block_to_free, count,
964 if (!err && count > 0)
965 err = ext4_clear_blocks(handle, inode, this_bh, block_to_free,
966 count, block_to_free_p, p);
972 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
975 * The buffer head should have an attached journal head at this
976 * point. However, if the data is corrupted and an indirect
977 * block pointed to itself, it would have been detached when
978 * the block was cleared. Check for this instead of OOPSing.
980 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
981 ext4_handle_dirty_metadata(handle, inode, this_bh);
983 EXT4_ERROR_INODE(inode,
984 "circular indirect block detected at "
986 (unsigned long long) this_bh->b_blocknr);
991 * ext4_free_branches - free an array of branches
992 * @handle: JBD handle for this transaction
993 * @inode: inode we are dealing with
994 * @parent_bh: the buffer_head which contains *@first and *@last
995 * @first: array of block numbers
996 * @last: pointer immediately past the end of array
997 * @depth: depth of the branches to free
999 * We are freeing all blocks referred from these branches (numbers are
1000 * stored as little-endian 32-bit) and updating @inode->i_blocks
1003 static void ext4_free_branches(handle_t *handle, struct inode *inode,
1004 struct buffer_head *parent_bh,
1005 __le32 *first, __le32 *last, int depth)
1010 if (ext4_handle_is_aborted(handle))
1014 struct buffer_head *bh;
1015 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1017 while (--p >= first) {
1018 nr = le32_to_cpu(*p);
1020 continue; /* A hole */
1022 if (!ext4_inode_block_valid(inode, nr, 1)) {
1023 EXT4_ERROR_INODE(inode,
1024 "invalid indirect mapped "
1025 "block %lu (level %d)",
1026 (unsigned long) nr, depth);
1030 /* Go read the buffer for the next level down */
1031 bh = sb_bread(inode->i_sb, nr);
1034 * A read failure? Report error and clear slot
1038 EXT4_ERROR_INODE_BLOCK(inode, nr,
1043 /* This zaps the entire block. Bottom up. */
1044 BUFFER_TRACE(bh, "free child branches");
1045 ext4_free_branches(handle, inode, bh,
1046 (__le32 *) bh->b_data,
1047 (__le32 *) bh->b_data + addr_per_block,
1052 * Everything below this this pointer has been
1053 * released. Now let this top-of-subtree go.
1055 * We want the freeing of this indirect block to be
1056 * atomic in the journal with the updating of the
1057 * bitmap block which owns it. So make some room in
1060 * We zero the parent pointer *after* freeing its
1061 * pointee in the bitmaps, so if extend_transaction()
1062 * for some reason fails to put the bitmap changes and
1063 * the release into the same transaction, recovery
1064 * will merely complain about releasing a free block,
1065 * rather than leaking blocks.
1067 if (ext4_handle_is_aborted(handle))
1069 if (try_to_extend_transaction(handle, inode)) {
1070 ext4_mark_inode_dirty(handle, inode);
1071 ext4_truncate_restart_trans(handle, inode,
1072 ext4_blocks_for_truncate(inode));
1076 * The forget flag here is critical because if
1077 * we are journaling (and not doing data
1078 * journaling), we have to make sure a revoke
1079 * record is written to prevent the journal
1080 * replay from overwriting the (former)
1081 * indirect block if it gets reallocated as a
1082 * data block. This must happen in the same
1083 * transaction where the data blocks are
1086 ext4_free_blocks(handle, inode, NULL, nr, 1,
1087 EXT4_FREE_BLOCKS_METADATA|
1088 EXT4_FREE_BLOCKS_FORGET);
1092 * The block which we have just freed is
1093 * pointed to by an indirect block: journal it
1095 BUFFER_TRACE(parent_bh, "get_write_access");
1096 if (!ext4_journal_get_write_access(handle,
1099 BUFFER_TRACE(parent_bh,
1100 "call ext4_handle_dirty_metadata");
1101 ext4_handle_dirty_metadata(handle,
1108 /* We have reached the bottom of the tree. */
1109 BUFFER_TRACE(parent_bh, "free data blocks");
1110 ext4_free_data(handle, inode, parent_bh, first, last);
1114 void ext4_ind_truncate(handle_t *handle, struct inode *inode)
1116 struct ext4_inode_info *ei = EXT4_I(inode);
1117 __le32 *i_data = ei->i_data;
1118 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1119 ext4_lblk_t offsets[4];
1124 ext4_lblk_t last_block, max_block;
1125 unsigned blocksize = inode->i_sb->s_blocksize;
1127 last_block = (inode->i_size + blocksize-1)
1128 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1129 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1130 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1132 if (last_block != max_block) {
1133 n = ext4_block_to_path(inode, last_block, offsets, NULL);
1138 ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block);
1141 * The orphan list entry will now protect us from any crash which
1142 * occurs before the truncate completes, so it is now safe to propagate
1143 * the new, shorter inode size (held for now in i_size) into the
1144 * on-disk inode. We do this via i_disksize, which is the value which
1145 * ext4 *really* writes onto the disk inode.
1147 ei->i_disksize = inode->i_size;
1149 if (last_block == max_block) {
1151 * It is unnecessary to free any data blocks if last_block is
1152 * equal to the indirect block limit.
1155 } else if (n == 1) { /* direct blocks */
1156 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
1157 i_data + EXT4_NDIR_BLOCKS);
1161 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1162 /* Kill the top of shared branch (not detached) */
1164 if (partial == chain) {
1165 /* Shared branch grows from the inode */
1166 ext4_free_branches(handle, inode, NULL,
1167 &nr, &nr+1, (chain+n-1) - partial);
1170 * We mark the inode dirty prior to restart,
1171 * and prior to stop. No need for it here.
1174 /* Shared branch grows from an indirect block */
1175 BUFFER_TRACE(partial->bh, "get_write_access");
1176 ext4_free_branches(handle, inode, partial->bh,
1178 partial->p+1, (chain+n-1) - partial);
1181 /* Clear the ends of indirect blocks on the shared branch */
1182 while (partial > chain) {
1183 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
1184 (__le32*)partial->bh->b_data+addr_per_block,
1185 (chain+n-1) - partial);
1186 BUFFER_TRACE(partial->bh, "call brelse");
1187 brelse(partial->bh);
1191 /* Kill the remaining (whole) subtrees */
1192 switch (offsets[0]) {
1194 nr = i_data[EXT4_IND_BLOCK];
1196 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1197 i_data[EXT4_IND_BLOCK] = 0;
1199 case EXT4_IND_BLOCK:
1200 nr = i_data[EXT4_DIND_BLOCK];
1202 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1203 i_data[EXT4_DIND_BLOCK] = 0;
1205 case EXT4_DIND_BLOCK:
1206 nr = i_data[EXT4_TIND_BLOCK];
1208 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1209 i_data[EXT4_TIND_BLOCK] = 0;
1211 case EXT4_TIND_BLOCK:
1217 * ext4_ind_remove_space - remove space from the range
1218 * @handle: JBD handle for this transaction
1219 * @inode: inode we are dealing with
1220 * @start: First block to remove
1221 * @end: One block after the last block to remove (exclusive)
1223 * Free the blocks in the defined range (end is exclusive endpoint of
1224 * range). This is used by ext4_punch_hole().
1226 int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
1227 ext4_lblk_t start, ext4_lblk_t end)
1229 struct ext4_inode_info *ei = EXT4_I(inode);
1230 __le32 *i_data = ei->i_data;
1231 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1232 ext4_lblk_t offsets[4], offsets2[4];
1233 Indirect chain[4], chain2[4];
1234 Indirect *partial, *partial2;
1235 Indirect *p = NULL, *p2 = NULL;
1236 ext4_lblk_t max_block;
1237 __le32 nr = 0, nr2 = 0;
1239 unsigned blocksize = inode->i_sb->s_blocksize;
1241 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1242 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1243 if (end >= max_block)
1245 if ((start >= end) || (start > max_block))
1248 n = ext4_block_to_path(inode, start, offsets, NULL);
1249 n2 = ext4_block_to_path(inode, end, offsets2, NULL);
1253 if ((n == 1) && (n == n2)) {
1254 /* We're punching only within direct block range */
1255 ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1256 i_data + offsets2[0]);
1258 } else if (n2 > n) {
1260 * Start and end are on a different levels so we're going to
1261 * free partial block at start, and partial block at end of
1262 * the range. If there are some levels in between then
1263 * do_indirects label will take care of that.
1268 * Start is at the direct block level, free
1269 * everything to the end of the level.
1271 ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1272 i_data + EXT4_NDIR_BLOCKS);
1277 partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
1279 if (partial == chain) {
1280 /* Shared branch grows from the inode */
1281 ext4_free_branches(handle, inode, NULL,
1282 &nr, &nr+1, (chain+n-1) - partial);
1285 /* Shared branch grows from an indirect block */
1286 BUFFER_TRACE(partial->bh, "get_write_access");
1287 ext4_free_branches(handle, inode, partial->bh,
1289 partial->p+1, (chain+n-1) - partial);
1294 * Clear the ends of indirect blocks on the shared branch
1295 * at the start of the range
1297 while (partial > chain) {
1298 ext4_free_branches(handle, inode, partial->bh,
1300 (__le32 *)partial->bh->b_data+addr_per_block,
1301 (chain+n-1) - partial);
1306 partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1308 if (partial2 == chain2) {
1310 * Remember, end is exclusive so here we're at
1311 * the start of the next level we're not going
1312 * to free. Everything was covered by the start
1319 * ext4_find_shared returns Indirect structure which
1320 * points to the last element which should not be
1321 * removed by truncate. But this is end of the range
1322 * in punch_hole so we need to point to the next element
1328 * Clear the ends of indirect blocks on the shared branch
1329 * at the end of the range
1331 while (partial2 > chain2) {
1332 ext4_free_branches(handle, inode, partial2->bh,
1333 (__le32 *)partial2->bh->b_data,
1335 (chain2+n2-1) - partial2);
1341 /* Punch happened within the same level (n == n2) */
1342 partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
1343 partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1345 /* Free top, but only if partial2 isn't its subtree. */
1347 int level = min(partial - chain, partial2 - chain2);
1351 for (i = 0; i <= level; i++) {
1352 if (offsets[i] != offsets2[i]) {
1359 if (partial == chain) {
1360 /* Shared branch grows from the inode */
1361 ext4_free_branches(handle, inode, NULL,
1363 (chain+n-1) - partial);
1366 /* Shared branch grows from an indirect block */
1367 BUFFER_TRACE(partial->bh, "get_write_access");
1368 ext4_free_branches(handle, inode, partial->bh,
1371 (chain+n-1) - partial);
1378 * ext4_find_shared returns Indirect structure which
1379 * points to the last element which should not be
1380 * removed by truncate. But this is end of the range
1381 * in punch_hole so we need to point to the next element
1386 while (partial > chain || partial2 > chain2) {
1387 int depth = (chain+n-1) - partial;
1388 int depth2 = (chain2+n2-1) - partial2;
1390 if (partial > chain && partial2 > chain2 &&
1391 partial->bh->b_blocknr == partial2->bh->b_blocknr) {
1393 * We've converged on the same block. Clear the range,
1396 ext4_free_branches(handle, inode, partial->bh,
1399 (chain+n-1) - partial);
1404 * The start and end partial branches may not be at the same
1405 * level even though the punch happened within one level. So, we
1406 * give them a chance to arrive at the same level, then walk
1407 * them in step with each other until we converge on the same
1410 if (partial > chain && depth <= depth2) {
1411 ext4_free_branches(handle, inode, partial->bh,
1413 (__le32 *)partial->bh->b_data+addr_per_block,
1414 (chain+n-1) - partial);
1417 if (partial2 > chain2 && depth2 <= depth) {
1418 ext4_free_branches(handle, inode, partial2->bh,
1419 (__le32 *)partial2->bh->b_data,
1421 (chain2+n2-1) - partial2);
1427 while (p && p > chain) {
1428 BUFFER_TRACE(p->bh, "call brelse");
1432 while (p2 && p2 > chain2) {
1433 BUFFER_TRACE(p2->bh, "call brelse");
1440 /* Kill the remaining (whole) subtrees */
1441 switch (offsets[0]) {
1445 nr = i_data[EXT4_IND_BLOCK];
1447 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1448 i_data[EXT4_IND_BLOCK] = 0;
1450 case EXT4_IND_BLOCK:
1453 nr = i_data[EXT4_DIND_BLOCK];
1455 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1456 i_data[EXT4_DIND_BLOCK] = 0;
1458 case EXT4_DIND_BLOCK:
1461 nr = i_data[EXT4_TIND_BLOCK];
1463 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1464 i_data[EXT4_TIND_BLOCK] = 0;
1466 case EXT4_TIND_BLOCK: