1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext4/indirect.c
4 *
5 * from
6 *
7 * linux/fs/ext4/inode.c
8 *
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)
13 *
14 * from
15 *
16 * linux/fs/minix/inode.c
17 *
18 * Copyright (C) 1991, 1992 Linus Torvalds
19 *
20 * Goal-directed block allocation by Stephen Tweedie
21 * (sct@redhat.com), 1993, 1998
22 */
23
24#include "ext4_jbd2.h"
25#include "truncate.h"
26#include <linux/dax.h>
27#include <linux/uio.h>
28
29#include <trace/events/ext4.h>
30
31typedef struct {
32 __le32 *p;
33 __le32 key;
34 struct buffer_head *bh;
35} Indirect;
36
37static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
38{
39 p->key = *(p->p = v);
40 p->bh = bh;
41}
42
43/**
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.
50 *
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.
58 *
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
61 * inode->i_sb).
62 */
63
64/*
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
71 * get there at all.
72 */
73
74static int ext4_block_to_path(struct inode *inode,
75 ext4_lblk_t i_block,
76 ext4_lblk_t offsets[4], int *boundary)
77{
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));
83 int n = 0;
84 int final = 0;
85
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;
92 final = ptrs;
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);
97 final = ptrs;
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);
103 final = ptrs;
104 } else {
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);
108 }
109 if (boundary)
110 *boundary = final - 1 - (i_block & (ptrs - 1));
111 return n;
112}
113
114/**
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
121 *
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
132 * numbers.
133 *
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).
140 *
141 * Need to be called with
142 * down_read(&EXT4_I(inode)->i_data_sem)
143 */
144static Indirect *ext4_get_branch(struct inode *inode, int depth,
145 ext4_lblk_t *offsets,
146 Indirect chain[4], int *err)
147{
148 struct super_block *sb = inode->i_sb;
149 Indirect *p = chain;
150 struct buffer_head *bh;
151 unsigned int key;
152 int ret = -EIO;
153
154 *err = 0;
155 /* i_data is not going away, no lock needed */
156 add_chain(p: chain, NULL, EXT4_I(inode)->i_data + *offsets);
157 if (!p->key)
158 goto no_block;
159 while (--depth) {
160 key = le32_to_cpu(p->key);
161 if (key > ext4_blocks_count(es: EXT4_SB(sb)->s_es)) {
162 /* the block was out of range */
163 ret = -EFSCORRUPTED;
164 goto failure;
165 }
166 bh = sb_getblk(sb, block: key);
167 if (unlikely(!bh)) {
168 ret = -ENOMEM;
169 goto failure;
170 }
171
172 if (!bh_uptodate_or_lock(bh)) {
173 if (ext4_read_bh(bh, op_flags: 0, NULL, simu_fail: false) < 0) {
174 put_bh(bh);
175 goto failure;
176 }
177 /* validate block references */
178 if (ext4_check_indirect_blockref(inode, bh)) {
179 put_bh(bh);
180 goto failure;
181 }
182 }
183
184 add_chain(p: ++p, bh, v: (__le32 *)bh->b_data + *++offsets);
185 /* Reader: end */
186 if (!p->key)
187 goto no_block;
188 }
189 return NULL;
190
191failure:
192 *err = ret;
193no_block:
194 return p;
195}
196
197/**
198 * ext4_find_near - find a place for allocation with sufficient locality
199 * @inode: owner
200 * @ind: descriptor of indirect block.
201 *
202 * This function returns the preferred place for block allocation.
203 * It is used when heuristic for sequential allocation fails.
204 * Rules are:
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
208 * cylinder group.
209 *
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.
214 *
215 * Caller must make sure that @ind is valid and will stay that way.
216 */
217static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
218{
219 struct ext4_inode_info *ei = EXT4_I(inode);
220 __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
221 __le32 *p;
222
223 /* Try to find previous block */
224 for (p = ind->p - 1; p >= start; p--) {
225 if (*p)
226 return le32_to_cpu(*p);
227 }
228
229 /* No such thing, so let's try location of indirect block */
230 if (ind->bh)
231 return ind->bh->b_blocknr;
232
233 /*
234 * It is going to be referred to from the inode itself? OK, just put it
235 * into the same cylinder group then.
236 */
237 return ext4_inode_to_goal_block(inode);
238}
239
240/**
241 * ext4_find_goal - find a preferred place for allocation.
242 * @inode: owner
243 * @block: block we want
244 * @partial: pointer to the last triple within a chain
245 *
246 * Normally this function find the preferred place for block allocation,
247 * returns it.
248 * Because this is only used for non-extent files, we limit the block nr
249 * to 32 bits.
250 */
251static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
252 Indirect *partial)
253{
254 ext4_fsblk_t goal;
255
256 /*
257 * XXX need to get goal block from mballoc's data structures
258 */
259
260 goal = ext4_find_near(inode, ind: partial);
261 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
262 return goal;
263}
264
265/**
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.
268 *
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
273 *
274 * return the total number of blocks to be allocate, including the
275 * direct and indirect blocks.
276 */
277static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
278 int blocks_to_boundary)
279{
280 unsigned int count = 0;
281
282 /*
283 * Simple case, [t,d]Indirect block(s) has not allocated yet
284 * then it's clear blocks on that path have not allocated
285 */
286 if (k > 0) {
287 /* right now we don't handle cross boundary allocation */
288 if (blks < blocks_to_boundary + 1)
289 count += blks;
290 else
291 count += blocks_to_boundary + 1;
292 return count;
293 }
294
295 count++;
296 while (count < blks && count <= blocks_to_boundary &&
297 le32_to_cpu(*(branch[0].p + count)) == 0) {
298 count++;
299 }
300 return count;
301}
302
303/**
304 * ext4_alloc_branch() - allocate and set up a chain of blocks
305 * @handle: handle for this transaction
306 * @ar: structure describing the allocation request
307 * @indirect_blks: number of allocated indirect blocks
308 * @offsets: offsets (in the blocks) to store the pointers to next.
309 * @branch: place to store the chain in.
310 *
311 * This function allocates blocks, zeroes out all but the last one,
312 * links them into chain and (if we are synchronous) writes them to disk.
313 * In other words, it prepares a branch that can be spliced onto the
314 * inode. It stores the information about that chain in the branch[], in
315 * the same format as ext4_get_branch() would do. We are calling it after
316 * we had read the existing part of chain and partial points to the last
317 * triple of that (one with zero ->key). Upon the exit we have the same
318 * picture as after the successful ext4_get_block(), except that in one
319 * place chain is disconnected - *branch->p is still zero (we did not
320 * set the last link), but branch->key contains the number that should
321 * be placed into *branch->p to fill that gap.
322 *
323 * If allocation fails we free all blocks we've allocated (and forget
324 * their buffer_heads) and return the error value the from failed
325 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
326 * as described above and return 0.
327 */
328static int ext4_alloc_branch(handle_t *handle,
329 struct ext4_allocation_request *ar,
330 int indirect_blks, ext4_lblk_t *offsets,
331 Indirect *branch)
332{
333 struct buffer_head * bh;
334 ext4_fsblk_t b, new_blocks[4];
335 __le32 *p;
336 int i, j, err, len = 1;
337
338 for (i = 0; i <= indirect_blks; i++) {
339 if (i == indirect_blks) {
340 new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err);
341 } else {
342 ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle,
343 inode: ar->inode, goal: ar->goal,
344 flags: ar->flags & EXT4_MB_DELALLOC_RESERVED,
345 NULL, errp: &err);
346 /* Simplify error cleanup... */
347 branch[i+1].bh = NULL;
348 }
349 if (err) {
350 i--;
351 goto failed;
352 }
353 branch[i].key = cpu_to_le32(new_blocks[i]);
354 if (i == 0)
355 continue;
356
357 bh = branch[i].bh = sb_getblk(sb: ar->inode->i_sb, block: new_blocks[i-1]);
358 if (unlikely(!bh)) {
359 err = -ENOMEM;
360 goto failed;
361 }
362 lock_buffer(bh);
363 BUFFER_TRACE(bh, "call get_create_access");
364 err = ext4_journal_get_create_access(handle, ar->inode->i_sb,
365 bh, EXT4_JTR_NONE);
366 if (err) {
367 unlock_buffer(bh);
368 goto failed;
369 }
370
371 memset(s: bh->b_data, c: 0, n: bh->b_size);
372 p = branch[i].p = (__le32 *) bh->b_data + offsets[i];
373 b = new_blocks[i];
374
375 if (i == indirect_blks)
376 len = ar->len;
377 for (j = 0; j < len; j++)
378 *p++ = cpu_to_le32(b++);
379
380 BUFFER_TRACE(bh, "marking uptodate");
381 set_buffer_uptodate(bh);
382 unlock_buffer(bh);
383
384 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
385 err = ext4_handle_dirty_metadata(handle, ar->inode, bh);
386 if (err)
387 goto failed;
388 }
389 return 0;
390failed:
391 if (i == indirect_blks) {
392 /* Free data blocks */
393 ext4_free_blocks(handle, inode: ar->inode, NULL, block: new_blocks[i],
394 count: ar->len, flags: 0);
395 i--;
396 }
397 for (; i >= 0; i--) {
398 /*
399 * We want to ext4_forget() only freshly allocated indirect
400 * blocks. Buffer for new_blocks[i] is at branch[i+1].bh
401 * (buffer at branch[0].bh is indirect block / inode already
402 * existing before ext4_alloc_branch() was called). Also
403 * because blocks are freshly allocated, we don't need to
404 * revoke them which is why we don't set
405 * EXT4_FREE_BLOCKS_METADATA.
406 */
407 ext4_free_blocks(handle, inode: ar->inode, bh: branch[i+1].bh,
408 block: new_blocks[i], count: 1,
409 flags: branch[i+1].bh ? EXT4_FREE_BLOCKS_FORGET : 0);
410 }
411 return err;
412}
413
414/**
415 * ext4_splice_branch() - splice the allocated branch onto inode.
416 * @handle: handle for this transaction
417 * @ar: structure describing the allocation request
418 * @where: location of missing link
419 * @num: number of indirect blocks we are adding
420 *
421 * This function fills the missing link and does all housekeeping needed in
422 * inode (->i_blocks, etc.). In case of success we end up with the full
423 * chain to new block and return 0.
424 */
425static int ext4_splice_branch(handle_t *handle,
426 struct ext4_allocation_request *ar,
427 Indirect *where, int num)
428{
429 int i;
430 int err = 0;
431 ext4_fsblk_t current_block;
432
433 /*
434 * If we're splicing into a [td]indirect block (as opposed to the
435 * inode) then we need to get write access to the [td]indirect block
436 * before the splice.
437 */
438 if (where->bh) {
439 BUFFER_TRACE(where->bh, "get_write_access");
440 err = ext4_journal_get_write_access(handle, ar->inode->i_sb,
441 where->bh, EXT4_JTR_NONE);
442 if (err)
443 goto err_out;
444 }
445 /* That's it */
446
447 *where->p = where->key;
448
449 /*
450 * Update the host buffer_head or inode to point to more just allocated
451 * direct blocks blocks
452 */
453 if (num == 0 && ar->len > 1) {
454 current_block = le32_to_cpu(where->key) + 1;
455 for (i = 1; i < ar->len; i++)
456 *(where->p + i) = cpu_to_le32(current_block++);
457 }
458
459 /* We are done with atomic stuff, now do the rest of housekeeping */
460 /* had we spliced it onto indirect block? */
461 if (where->bh) {
462 /*
463 * If we spliced it onto an indirect block, we haven't
464 * altered the inode. Note however that if it is being spliced
465 * onto an indirect block at the very end of the file (the
466 * file is growing) then we *will* alter the inode to reflect
467 * the new i_size. But that is not done here - it is done in
468 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
469 */
470 ext4_debug("splicing indirect only\n");
471 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
472 err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh);
473 if (err)
474 goto err_out;
475 } else {
476 /*
477 * OK, we spliced it into the inode itself on a direct block.
478 */
479 err = ext4_mark_inode_dirty(handle, ar->inode);
480 if (unlikely(err))
481 goto err_out;
482 ext4_debug("splicing direct\n");
483 }
484 return err;
485
486err_out:
487 for (i = 1; i <= num; i++) {
488 /*
489 * branch[i].bh is newly allocated, so there is no
490 * need to revoke the block, which is why we don't
491 * need to set EXT4_FREE_BLOCKS_METADATA.
492 */
493 ext4_free_blocks(handle, inode: ar->inode, bh: where[i].bh, block: 0, count: 1,
494 EXT4_FREE_BLOCKS_FORGET);
495 }
496 ext4_free_blocks(handle, inode: ar->inode, NULL, le32_to_cpu(where[num].key),
497 count: ar->len, flags: 0);
498
499 return err;
500}
501
502/*
503 * The ext4_ind_map_blocks() function handles non-extents inodes
504 * (i.e., using the traditional indirect/double-indirect i_blocks
505 * scheme) for ext4_map_blocks().
506 *
507 * Allocation strategy is simple: if we have to allocate something, we will
508 * have to go the whole way to leaf. So let's do it before attaching anything
509 * to tree, set linkage between the newborn blocks, write them if sync is
510 * required, recheck the path, free and repeat if check fails, otherwise
511 * set the last missing link (that will protect us from any truncate-generated
512 * removals - all blocks on the path are immune now) and possibly force the
513 * write on the parent block.
514 * That has a nice additional property: no special recovery from the failed
515 * allocations is needed - we simply release blocks and do not touch anything
516 * reachable from inode.
517 *
518 * `handle' can be NULL if create == 0.
519 *
520 * return > 0, # of blocks mapped or allocated.
521 * return = 0, if plain lookup failed.
522 * return < 0, error case.
523 *
524 * The ext4_ind_get_blocks() function should be called with
525 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
526 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
527 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
528 * blocks.
529 */
530int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
531 struct ext4_map_blocks *map,
532 int flags)
533{
534 struct ext4_allocation_request ar;
535 int err = -EIO;
536 ext4_lblk_t offsets[4];
537 Indirect chain[4];
538 Indirect *partial;
539 int indirect_blks;
540 int blocks_to_boundary = 0;
541 int depth;
542 u64 count = 0;
543 ext4_fsblk_t first_block = 0;
544
545 trace_ext4_ind_map_blocks_enter(inode, lblk: map->m_lblk, len: map->m_len, flags);
546 ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
547 ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
548 depth = ext4_block_to_path(inode, i_block: map->m_lblk, offsets,
549 boundary: &blocks_to_boundary);
550
551 if (depth == 0)
552 goto out;
553
554 partial = ext4_get_branch(inode, depth, offsets, chain, err: &err);
555
556 /* Simplest case - block found, no allocation needed */
557 if (!partial) {
558 first_block = le32_to_cpu(chain[depth - 1].key);
559 count++;
560 /*map more blocks*/
561 while (count < map->m_len && count <= blocks_to_boundary) {
562 ext4_fsblk_t blk;
563
564 blk = le32_to_cpu(*(chain[depth-1].p + count));
565
566 if (blk == first_block + count)
567 count++;
568 else
569 break;
570 }
571 goto got_it;
572 }
573
574 /* Next simple case - plain lookup failed */
575 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
576 unsigned epb = inode->i_sb->s_blocksize / sizeof(u32);
577 int i;
578
579 /*
580 * Count number blocks in a subtree under 'partial'. At each
581 * level we count number of complete empty subtrees beyond
582 * current offset and then descend into the subtree only
583 * partially beyond current offset.
584 */
585 count = 0;
586 for (i = partial - chain + 1; i < depth; i++)
587 count = count * epb + (epb - offsets[i] - 1);
588 count++;
589 /* Fill in size of a hole we found */
590 map->m_pblk = 0;
591 map->m_len = umin(map->m_len, count);
592 goto cleanup;
593 }
594
595 /* Failed read of indirect block */
596 if (err == -EIO)
597 goto cleanup;
598
599 /*
600 * Okay, we need to do block allocation.
601 */
602 if (ext4_has_feature_bigalloc(sb: inode->i_sb)) {
603 EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
604 "non-extent mapped inodes with bigalloc");
605 err = -EFSCORRUPTED;
606 goto out;
607 }
608
609 /* Set up for the direct block allocation */
610 memset(s: &ar, c: 0, n: sizeof(ar));
611 ar.inode = inode;
612 ar.logical = map->m_lblk;
613 if (S_ISREG(inode->i_mode))
614 ar.flags = EXT4_MB_HINT_DATA;
615 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
616 ar.flags |= EXT4_MB_DELALLOC_RESERVED;
617 if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
618 ar.flags |= EXT4_MB_USE_RESERVED;
619
620 ar.goal = ext4_find_goal(inode, block: map->m_lblk, partial);
621
622 /* the number of blocks need to allocate for [d,t]indirect blocks */
623 indirect_blks = (chain + depth) - partial - 1;
624
625 /*
626 * Next look up the indirect map to count the totoal number of
627 * direct blocks to allocate for this branch.
628 */
629 ar.len = ext4_blks_to_allocate(branch: partial, k: indirect_blks,
630 blks: map->m_len, blocks_to_boundary);
631
632 /*
633 * Block out ext4_truncate while we alter the tree
634 */
635 err = ext4_alloc_branch(handle, ar: &ar, indirect_blks,
636 offsets: offsets + (partial - chain), branch: partial);
637
638 /*
639 * The ext4_splice_branch call will free and forget any buffers
640 * on the new chain if there is a failure, but that risks using
641 * up transaction credits, especially for bitmaps where the
642 * credits cannot be returned. Can we handle this somehow? We
643 * may need to return -EAGAIN upwards in the worst case. --sct
644 */
645 if (!err)
646 err = ext4_splice_branch(handle, ar: &ar, where: partial, num: indirect_blks);
647 if (err)
648 goto cleanup;
649
650 map->m_flags |= EXT4_MAP_NEW;
651
652 ext4_update_inode_fsync_trans(handle, inode, datasync: 1);
653 count = ar.len;
654
655got_it:
656 map->m_flags |= EXT4_MAP_MAPPED;
657 map->m_pblk = le32_to_cpu(chain[depth-1].key);
658 map->m_len = count;
659 if (count > blocks_to_boundary)
660 map->m_flags |= EXT4_MAP_BOUNDARY;
661 err = count;
662 /* Clean up and exit */
663 partial = chain + depth - 1; /* the whole chain */
664cleanup:
665 while (partial > chain) {
666 BUFFER_TRACE(partial->bh, "call brelse");
667 brelse(bh: partial->bh);
668 partial--;
669 }
670out:
671 trace_ext4_ind_map_blocks_exit(inode, flags, map, ret: err);
672 return err;
673}
674
675/*
676 * Calculate number of indirect blocks touched by mapping @nrblocks logically
677 * contiguous blocks
678 */
679int ext4_ind_trans_blocks(struct inode *inode, int nrblocks)
680{
681 /*
682 * With N contiguous data blocks, we need at most
683 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
684 * 2 dindirect blocks, and 1 tindirect block
685 */
686 return DIV_ROUND_UP(nrblocks, EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
687}
688
689static int ext4_ind_trunc_restart_fn(handle_t *handle, struct inode *inode,
690 struct buffer_head *bh, int *dropped)
691{
692 int err;
693
694 if (bh) {
695 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
696 err = ext4_handle_dirty_metadata(handle, inode, bh);
697 if (unlikely(err))
698 return err;
699 }
700 err = ext4_mark_inode_dirty(handle, inode);
701 if (unlikely(err))
702 return err;
703 /*
704 * Drop i_data_sem to avoid deadlock with ext4_map_blocks. At this
705 * moment, get_block can be called only for blocks inside i_size since
706 * page cache has been already dropped and writes are blocked by
707 * i_rwsem. So we can safely drop the i_data_sem here.
708 */
709 BUG_ON(EXT4_JOURNAL(inode) == NULL);
710 ext4_discard_preallocations(inode);
711 up_write(sem: &EXT4_I(inode)->i_data_sem);
712 *dropped = 1;
713 return 0;
714}
715
716/*
717 * Truncate transactions can be complex and absolutely huge. So we need to
718 * be able to restart the transaction at a convenient checkpoint to make
719 * sure we don't overflow the journal.
720 *
721 * Try to extend this transaction for the purposes of truncation. If
722 * extend fails, we restart transaction.
723 */
724static int ext4_ind_truncate_ensure_credits(handle_t *handle,
725 struct inode *inode,
726 struct buffer_head *bh,
727 int revoke_creds)
728{
729 int ret;
730 int dropped = 0;
731
732 ret = ext4_journal_ensure_credits_fn(handle, EXT4_RESERVE_TRANS_BLOCKS,
733 ext4_blocks_for_truncate(inode), revoke_creds,
734 ext4_ind_trunc_restart_fn(handle, inode, bh, &dropped));
735 if (dropped)
736 down_write(sem: &EXT4_I(inode)->i_data_sem);
737 if (ret <= 0)
738 return ret;
739 if (bh) {
740 BUFFER_TRACE(bh, "retaking write access");
741 ret = ext4_journal_get_write_access(handle, inode->i_sb, bh,
742 EXT4_JTR_NONE);
743 if (unlikely(ret))
744 return ret;
745 }
746 return 0;
747}
748
749/*
750 * Probably it should be a library function... search for first non-zero word
751 * or memcmp with zero_page, whatever is better for particular architecture.
752 * Linus?
753 */
754static inline int all_zeroes(__le32 *p, __le32 *q)
755{
756 while (p < q)
757 if (*p++)
758 return 0;
759 return 1;
760}
761
762/**
763 * ext4_find_shared - find the indirect blocks for partial truncation.
764 * @inode: inode in question
765 * @depth: depth of the affected branch
766 * @offsets: offsets of pointers in that branch (see ext4_block_to_path)
767 * @chain: place to store the pointers to partial indirect blocks
768 * @top: place to the (detached) top of branch
769 *
770 * This is a helper function used by ext4_truncate().
771 *
772 * When we do truncate() we may have to clean the ends of several
773 * indirect blocks but leave the blocks themselves alive. Block is
774 * partially truncated if some data below the new i_size is referred
775 * from it (and it is on the path to the first completely truncated
776 * data block, indeed). We have to free the top of that path along
777 * with everything to the right of the path. Since no allocation
778 * past the truncation point is possible until ext4_truncate()
779 * finishes, we may safely do the latter, but top of branch may
780 * require special attention - pageout below the truncation point
781 * might try to populate it.
782 *
783 * We atomically detach the top of branch from the tree, store the
784 * block number of its root in *@top, pointers to buffer_heads of
785 * partially truncated blocks - in @chain[].bh and pointers to
786 * their last elements that should not be removed - in
787 * @chain[].p. Return value is the pointer to last filled element
788 * of @chain.
789 *
790 * The work left to caller to do the actual freeing of subtrees:
791 * a) free the subtree starting from *@top
792 * b) free the subtrees whose roots are stored in
793 * (@chain[i].p+1 .. end of @chain[i].bh->b_data)
794 * c) free the subtrees growing from the inode past the @chain[0].
795 * (no partially truncated stuff there). */
796
797static Indirect *ext4_find_shared(struct inode *inode, int depth,
798 ext4_lblk_t offsets[4], Indirect chain[4],
799 __le32 *top)
800{
801 Indirect *partial, *p;
802 int k, err;
803
804 *top = 0;
805 /* Make k index the deepest non-null offset + 1 */
806 for (k = depth; k > 1 && !offsets[k-1]; k--)
807 ;
808 partial = ext4_get_branch(inode, depth: k, offsets, chain, err: &err);
809 /* Writer: pointers */
810 if (!partial)
811 partial = chain + k-1;
812 /*
813 * If the branch acquired continuation since we've looked at it -
814 * fine, it should all survive and (new) top doesn't belong to us.
815 */
816 if (!partial->key && *partial->p)
817 /* Writer: end */
818 goto no_top;
819 for (p = partial; (p > chain) && all_zeroes(p: (__le32 *) p->bh->b_data, q: p->p); p--)
820 ;
821 /*
822 * OK, we've found the last block that must survive. The rest of our
823 * branch should be detached before unlocking. However, if that rest
824 * of branch is all ours and does not grow immediately from the inode
825 * it's easier to cheat and just decrement partial->p.
826 */
827 if (p == chain + k - 1 && p > chain) {
828 p->p--;
829 } else {
830 *top = *p->p;
831 /* Nope, don't do this in ext4. Must leave the tree intact */
832#if 0
833 *p->p = 0;
834#endif
835 }
836 /* Writer: end */
837
838 while (partial > p) {
839 brelse(bh: partial->bh);
840 partial--;
841 }
842no_top:
843 return partial;
844}
845
846/*
847 * Zero a number of block pointers in either an inode or an indirect block.
848 * If we restart the transaction we must again get write access to the
849 * indirect block for further modification.
850 *
851 * We release `count' blocks on disk, but (last - first) may be greater
852 * than `count' because there can be holes in there.
853 *
854 * Return 0 on success, 1 on invalid block range
855 * and < 0 on fatal error.
856 */
857static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
858 struct buffer_head *bh,
859 ext4_fsblk_t block_to_free,
860 unsigned long count, __le32 *first,
861 __le32 *last)
862{
863 __le32 *p;
864 int flags = EXT4_FREE_BLOCKS_VALIDATED;
865 int err;
866
867 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
868 ext4_test_inode_flag(inode, bit: EXT4_INODE_EA_INODE))
869 flags |= EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_METADATA;
870 else if (ext4_should_journal_data(inode))
871 flags |= EXT4_FREE_BLOCKS_FORGET;
872
873 if (!ext4_inode_block_valid(inode, start_blk: block_to_free, count)) {
874 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
875 "blocks %llu len %lu",
876 (unsigned long long) block_to_free, count);
877 return 1;
878 }
879
880 err = ext4_ind_truncate_ensure_credits(handle, inode, bh,
881 revoke_creds: ext4_free_data_revoke_credits(inode, blocks: count));
882 if (err < 0)
883 goto out_err;
884
885 for (p = first; p < last; p++)
886 *p = 0;
887
888 ext4_free_blocks(handle, inode, NULL, block: block_to_free, count, flags);
889 return 0;
890out_err:
891 ext4_std_error(inode->i_sb, err);
892 return err;
893}
894
895/**
896 * ext4_free_data - free a list of data blocks
897 * @handle: handle for this transaction
898 * @inode: inode we are dealing with
899 * @this_bh: indirect buffer_head which contains *@first and *@last
900 * @first: array of block numbers
901 * @last: points immediately past the end of array
902 *
903 * We are freeing all blocks referred from that array (numbers are stored as
904 * little-endian 32-bit) and updating @inode->i_blocks appropriately.
905 *
906 * We accumulate contiguous runs of blocks to free. Conveniently, if these
907 * blocks are contiguous then releasing them at one time will only affect one
908 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
909 * actually use a lot of journal space.
910 *
911 * @this_bh will be %NULL if @first and @last point into the inode's direct
912 * block pointers.
913 */
914static void ext4_free_data(handle_t *handle, struct inode *inode,
915 struct buffer_head *this_bh,
916 __le32 *first, __le32 *last)
917{
918 ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */
919 unsigned long count = 0; /* Number of blocks in the run */
920 __le32 *block_to_free_p = NULL; /* Pointer into inode/ind
921 corresponding to
922 block_to_free */
923 ext4_fsblk_t nr; /* Current block # */
924 __le32 *p; /* Pointer into inode/ind
925 for current block */
926 int err = 0;
927
928 if (this_bh) { /* For indirect block */
929 BUFFER_TRACE(this_bh, "get_write_access");
930 err = ext4_journal_get_write_access(handle, inode->i_sb,
931 this_bh, EXT4_JTR_NONE);
932 /* Important: if we can't update the indirect pointers
933 * to the blocks, we can't free them. */
934 if (err)
935 return;
936 }
937
938 for (p = first; p < last; p++) {
939 nr = le32_to_cpu(*p);
940 if (nr) {
941 /* accumulate blocks to free if they're contiguous */
942 if (count == 0) {
943 block_to_free = nr;
944 block_to_free_p = p;
945 count = 1;
946 } else if (nr == block_to_free + count) {
947 count++;
948 } else {
949 err = ext4_clear_blocks(handle, inode, bh: this_bh,
950 block_to_free, count,
951 first: block_to_free_p, last: p);
952 if (err)
953 break;
954 block_to_free = nr;
955 block_to_free_p = p;
956 count = 1;
957 }
958 }
959 }
960
961 if (!err && count > 0)
962 err = ext4_clear_blocks(handle, inode, bh: this_bh, block_to_free,
963 count, first: block_to_free_p, last: p);
964 if (err < 0)
965 /* fatal error */
966 return;
967
968 if (this_bh) {
969 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
970
971 /*
972 * The buffer head should have an attached journal head at this
973 * point. However, if the data is corrupted and an indirect
974 * block pointed to itself, it would have been detached when
975 * the block was cleared. Check for this instead of OOPSing.
976 */
977 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(bh: this_bh))
978 ext4_handle_dirty_metadata(handle, inode, this_bh);
979 else
980 EXT4_ERROR_INODE(inode,
981 "circular indirect block detected at "
982 "block %llu",
983 (unsigned long long) this_bh->b_blocknr);
984 }
985}
986
987/**
988 * ext4_free_branches - free an array of branches
989 * @handle: JBD handle for this transaction
990 * @inode: inode we are dealing with
991 * @parent_bh: the buffer_head which contains *@first and *@last
992 * @first: array of block numbers
993 * @last: pointer immediately past the end of array
994 * @depth: depth of the branches to free
995 *
996 * We are freeing all blocks referred from these branches (numbers are
997 * stored as little-endian 32-bit) and updating @inode->i_blocks
998 * appropriately.
999 */
1000static void ext4_free_branches(handle_t *handle, struct inode *inode,
1001 struct buffer_head *parent_bh,
1002 __le32 *first, __le32 *last, int depth)
1003{
1004 ext4_fsblk_t nr;
1005 __le32 *p;
1006
1007 if (ext4_handle_is_aborted(handle))
1008 return;
1009
1010 if (depth--) {
1011 struct buffer_head *bh;
1012 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1013 p = last;
1014 while (--p >= first) {
1015 nr = le32_to_cpu(*p);
1016 if (!nr)
1017 continue; /* A hole */
1018
1019 if (!ext4_inode_block_valid(inode, start_blk: nr, count: 1)) {
1020 EXT4_ERROR_INODE(inode,
1021 "invalid indirect mapped "
1022 "block %lu (level %d)",
1023 (unsigned long) nr, depth);
1024 break;
1025 }
1026
1027 /* Go read the buffer for the next level down */
1028 bh = ext4_sb_bread_nofail(sb: inode->i_sb, block: nr);
1029
1030 /*
1031 * A read failure? Report error and clear slot
1032 * (should be rare).
1033 */
1034 if (IS_ERR(ptr: bh)) {
1035 ext4_error_inode_block(inode, nr, -PTR_ERR(bh),
1036 "Read failure");
1037 continue;
1038 }
1039
1040 /* This zaps the entire block. Bottom up. */
1041 BUFFER_TRACE(bh, "free child branches");
1042 ext4_free_branches(handle, inode, parent_bh: bh,
1043 first: (__le32 *) bh->b_data,
1044 last: (__le32 *) bh->b_data + addr_per_block,
1045 depth);
1046 brelse(bh);
1047
1048 /*
1049 * Everything below this pointer has been
1050 * released. Now let this top-of-subtree go.
1051 *
1052 * We want the freeing of this indirect block to be
1053 * atomic in the journal with the updating of the
1054 * bitmap block which owns it. So make some room in
1055 * the journal.
1056 *
1057 * We zero the parent pointer *after* freeing its
1058 * pointee in the bitmaps, so if extend_transaction()
1059 * for some reason fails to put the bitmap changes and
1060 * the release into the same transaction, recovery
1061 * will merely complain about releasing a free block,
1062 * rather than leaking blocks.
1063 */
1064 if (ext4_handle_is_aborted(handle))
1065 return;
1066 if (ext4_ind_truncate_ensure_credits(handle, inode,
1067 NULL,
1068 revoke_creds: ext4_free_metadata_revoke_credits(
1069 sb: inode->i_sb, blocks: 1)) < 0)
1070 return;
1071
1072 /*
1073 * The forget flag here is critical because if
1074 * we are journaling (and not doing data
1075 * journaling), we have to make sure a revoke
1076 * record is written to prevent the journal
1077 * replay from overwriting the (former)
1078 * indirect block if it gets reallocated as a
1079 * data block. This must happen in the same
1080 * transaction where the data blocks are
1081 * actually freed.
1082 */
1083 ext4_free_blocks(handle, inode, NULL, block: nr, count: 1,
1084 EXT4_FREE_BLOCKS_METADATA|
1085 EXT4_FREE_BLOCKS_FORGET);
1086
1087 if (parent_bh) {
1088 /*
1089 * The block which we have just freed is
1090 * pointed to by an indirect block: journal it
1091 */
1092 BUFFER_TRACE(parent_bh, "get_write_access");
1093 if (!ext4_journal_get_write_access(handle,
1094 inode->i_sb, parent_bh,
1095 EXT4_JTR_NONE)) {
1096 *p = 0;
1097 BUFFER_TRACE(parent_bh,
1098 "call ext4_handle_dirty_metadata");
1099 ext4_handle_dirty_metadata(handle,
1100 inode,
1101 parent_bh);
1102 }
1103 }
1104 }
1105 } else {
1106 /* We have reached the bottom of the tree. */
1107 BUFFER_TRACE(parent_bh, "free data blocks");
1108 ext4_free_data(handle, inode, this_bh: parent_bh, first, last);
1109 }
1110}
1111
1112void ext4_ind_truncate(handle_t *handle, struct inode *inode)
1113{
1114 struct ext4_inode_info *ei = EXT4_I(inode);
1115 __le32 *i_data = ei->i_data;
1116 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1117 ext4_lblk_t offsets[4];
1118 Indirect chain[4];
1119 Indirect *partial;
1120 __le32 nr = 0;
1121 int n = 0;
1122 ext4_lblk_t last_block, max_block;
1123 unsigned blocksize = inode->i_sb->s_blocksize;
1124
1125 last_block = (inode->i_size + blocksize-1)
1126 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1127 max_block = (EXT4_SB(sb: inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1128 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1129
1130 if (last_block != max_block) {
1131 n = ext4_block_to_path(inode, i_block: last_block, offsets, NULL);
1132 if (n == 0)
1133 return;
1134 }
1135
1136 ext4_es_remove_extent(inode, lblk: last_block, EXT_MAX_BLOCKS - last_block);
1137
1138 /*
1139 * The orphan list entry will now protect us from any crash which
1140 * occurs before the truncate completes, so it is now safe to propagate
1141 * the new, shorter inode size (held for now in i_size) into the
1142 * on-disk inode. We do this via i_disksize, which is the value which
1143 * ext4 *really* writes onto the disk inode.
1144 */
1145 ei->i_disksize = inode->i_size;
1146
1147 if (last_block == max_block) {
1148 /*
1149 * It is unnecessary to free any data blocks if last_block is
1150 * equal to the indirect block limit.
1151 */
1152 return;
1153 } else if (n == 1) { /* direct blocks */
1154 ext4_free_data(handle, inode, NULL, first: i_data+offsets[0],
1155 last: i_data + EXT4_NDIR_BLOCKS);
1156 goto do_indirects;
1157 }
1158
1159 partial = ext4_find_shared(inode, depth: n, offsets, chain, top: &nr);
1160 /* Kill the top of shared branch (not detached) */
1161 if (nr) {
1162 if (partial == chain) {
1163 /* Shared branch grows from the inode */
1164 ext4_free_branches(handle, inode, NULL,
1165 first: &nr, last: &nr+1, depth: (chain+n-1) - partial);
1166 *partial->p = 0;
1167 /*
1168 * We mark the inode dirty prior to restart,
1169 * and prior to stop. No need for it here.
1170 */
1171 } else {
1172 /* Shared branch grows from an indirect block */
1173 BUFFER_TRACE(partial->bh, "get_write_access");
1174 ext4_free_branches(handle, inode, parent_bh: partial->bh,
1175 first: partial->p,
1176 last: partial->p+1, depth: (chain+n-1) - partial);
1177 }
1178 }
1179 /* Clear the ends of indirect blocks on the shared branch */
1180 while (partial > chain) {
1181 ext4_free_branches(handle, inode, parent_bh: partial->bh, first: partial->p + 1,
1182 last: (__le32*)partial->bh->b_data+addr_per_block,
1183 depth: (chain+n-1) - partial);
1184 BUFFER_TRACE(partial->bh, "call brelse");
1185 brelse(bh: partial->bh);
1186 partial--;
1187 }
1188do_indirects:
1189 /* Kill the remaining (whole) subtrees */
1190 switch (offsets[0]) {
1191 default:
1192 nr = i_data[EXT4_IND_BLOCK];
1193 if (nr) {
1194 ext4_free_branches(handle, inode, NULL, first: &nr, last: &nr+1, depth: 1);
1195 i_data[EXT4_IND_BLOCK] = 0;
1196 }
1197 fallthrough;
1198 case EXT4_IND_BLOCK:
1199 nr = i_data[EXT4_DIND_BLOCK];
1200 if (nr) {
1201 ext4_free_branches(handle, inode, NULL, first: &nr, last: &nr+1, depth: 2);
1202 i_data[EXT4_DIND_BLOCK] = 0;
1203 }
1204 fallthrough;
1205 case EXT4_DIND_BLOCK:
1206 nr = i_data[EXT4_TIND_BLOCK];
1207 if (nr) {
1208 ext4_free_branches(handle, inode, NULL, first: &nr, last: &nr+1, depth: 3);
1209 i_data[EXT4_TIND_BLOCK] = 0;
1210 }
1211 fallthrough;
1212 case EXT4_TIND_BLOCK:
1213 ;
1214 }
1215}
1216
1217/**
1218 * ext4_ind_remove_space - remove space from the range
1219 * @handle: JBD handle for this transaction
1220 * @inode: inode we are dealing with
1221 * @start: First block to remove
1222 * @end: One block after the last block to remove (exclusive)
1223 *
1224 * Free the blocks in the defined range (end is exclusive endpoint of
1225 * range). This is used by ext4_punch_hole().
1226 */
1227int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
1228 ext4_lblk_t start, ext4_lblk_t end)
1229{
1230 struct ext4_inode_info *ei = EXT4_I(inode);
1231 __le32 *i_data = ei->i_data;
1232 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1233 ext4_lblk_t offsets[4], offsets2[4];
1234 Indirect chain[4], chain2[4];
1235 Indirect *partial, *partial2;
1236 Indirect *p = NULL, *p2 = NULL;
1237 ext4_lblk_t max_block;
1238 __le32 nr = 0, nr2 = 0;
1239 int n = 0, n2 = 0;
1240 unsigned blocksize = inode->i_sb->s_blocksize;
1241
1242 max_block = (EXT4_SB(sb: inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1243 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1244 if (end >= max_block)
1245 end = max_block;
1246 if ((start >= end) || (start > max_block))
1247 return 0;
1248
1249 n = ext4_block_to_path(inode, i_block: start, offsets, NULL);
1250 n2 = ext4_block_to_path(inode, i_block: end, offsets: offsets2, NULL);
1251
1252 BUG_ON(n > n2);
1253
1254 if ((n == 1) && (n == n2)) {
1255 /* We're punching only within direct block range */
1256 ext4_free_data(handle, inode, NULL, first: i_data + offsets[0],
1257 last: i_data + offsets2[0]);
1258 return 0;
1259 } else if (n2 > n) {
1260 /*
1261 * Start and end are on a different levels so we're going to
1262 * free partial block at start, and partial block at end of
1263 * the range. If there are some levels in between then
1264 * do_indirects label will take care of that.
1265 */
1266
1267 if (n == 1) {
1268 /*
1269 * Start is at the direct block level, free
1270 * everything to the end of the level.
1271 */
1272 ext4_free_data(handle, inode, NULL, first: i_data + offsets[0],
1273 last: i_data + EXT4_NDIR_BLOCKS);
1274 goto end_range;
1275 }
1276
1277
1278 partial = p = ext4_find_shared(inode, depth: n, offsets, chain, top: &nr);
1279 if (nr) {
1280 if (partial == chain) {
1281 /* Shared branch grows from the inode */
1282 ext4_free_branches(handle, inode, NULL,
1283 first: &nr, last: &nr+1, depth: (chain+n-1) - partial);
1284 *partial->p = 0;
1285 } else {
1286 /* Shared branch grows from an indirect block */
1287 BUFFER_TRACE(partial->bh, "get_write_access");
1288 ext4_free_branches(handle, inode, parent_bh: partial->bh,
1289 first: partial->p,
1290 last: partial->p+1, depth: (chain+n-1) - partial);
1291 }
1292 }
1293
1294 /*
1295 * Clear the ends of indirect blocks on the shared branch
1296 * at the start of the range
1297 */
1298 while (partial > chain) {
1299 ext4_free_branches(handle, inode, parent_bh: partial->bh,
1300 first: partial->p + 1,
1301 last: (__le32 *)partial->bh->b_data+addr_per_block,
1302 depth: (chain+n-1) - partial);
1303 partial--;
1304 }
1305
1306end_range:
1307 partial2 = p2 = ext4_find_shared(inode, depth: n2, offsets: offsets2, chain: chain2, top: &nr2);
1308 if (nr2) {
1309 if (partial2 == chain2) {
1310 /*
1311 * Remember, end is exclusive so here we're at
1312 * the start of the next level we're not going
1313 * to free. Everything was covered by the start
1314 * of the range.
1315 */
1316 goto do_indirects;
1317 }
1318 } else {
1319 /*
1320 * ext4_find_shared returns Indirect structure which
1321 * points to the last element which should not be
1322 * removed by truncate. But this is end of the range
1323 * in punch_hole so we need to point to the next element
1324 */
1325 partial2->p++;
1326 }
1327
1328 /*
1329 * Clear the ends of indirect blocks on the shared branch
1330 * at the end of the range
1331 */
1332 while (partial2 > chain2) {
1333 ext4_free_branches(handle, inode, parent_bh: partial2->bh,
1334 first: (__le32 *)partial2->bh->b_data,
1335 last: partial2->p,
1336 depth: (chain2+n2-1) - partial2);
1337 partial2--;
1338 }
1339 goto do_indirects;
1340 }
1341
1342 /* Punch happened within the same level (n == n2) */
1343 partial = p = ext4_find_shared(inode, depth: n, offsets, chain, top: &nr);
1344 partial2 = p2 = ext4_find_shared(inode, depth: n2, offsets: offsets2, chain: chain2, top: &nr2);
1345
1346 /* Free top, but only if partial2 isn't its subtree. */
1347 if (nr) {
1348 int level = min(partial - chain, partial2 - chain2);
1349 int i;
1350 int subtree = 1;
1351
1352 for (i = 0; i <= level; i++) {
1353 if (offsets[i] != offsets2[i]) {
1354 subtree = 0;
1355 break;
1356 }
1357 }
1358
1359 if (!subtree) {
1360 if (partial == chain) {
1361 /* Shared branch grows from the inode */
1362 ext4_free_branches(handle, inode, NULL,
1363 first: &nr, last: &nr+1,
1364 depth: (chain+n-1) - partial);
1365 *partial->p = 0;
1366 } else {
1367 /* Shared branch grows from an indirect block */
1368 BUFFER_TRACE(partial->bh, "get_write_access");
1369 ext4_free_branches(handle, inode, parent_bh: partial->bh,
1370 first: partial->p,
1371 last: partial->p+1,
1372 depth: (chain+n-1) - partial);
1373 }
1374 }
1375 }
1376
1377 if (!nr2) {
1378 /*
1379 * ext4_find_shared returns Indirect structure which
1380 * points to the last element which should not be
1381 * removed by truncate. But this is end of the range
1382 * in punch_hole so we need to point to the next element
1383 */
1384 partial2->p++;
1385 }
1386
1387 while (partial > chain || partial2 > chain2) {
1388 int depth = (chain+n-1) - partial;
1389 int depth2 = (chain2+n2-1) - partial2;
1390
1391 if (partial > chain && partial2 > chain2 &&
1392 partial->bh->b_blocknr == partial2->bh->b_blocknr) {
1393 /*
1394 * We've converged on the same block. Clear the range,
1395 * then we're done.
1396 */
1397 ext4_free_branches(handle, inode, parent_bh: partial->bh,
1398 first: partial->p + 1,
1399 last: partial2->p,
1400 depth: (chain+n-1) - partial);
1401 goto cleanup;
1402 }
1403
1404 /*
1405 * The start and end partial branches may not be at the same
1406 * level even though the punch happened within one level. So, we
1407 * give them a chance to arrive at the same level, then walk
1408 * them in step with each other until we converge on the same
1409 * block.
1410 */
1411 if (partial > chain && depth <= depth2) {
1412 ext4_free_branches(handle, inode, parent_bh: partial->bh,
1413 first: partial->p + 1,
1414 last: (__le32 *)partial->bh->b_data+addr_per_block,
1415 depth: (chain+n-1) - partial);
1416 partial--;
1417 }
1418 if (partial2 > chain2 && depth2 <= depth) {
1419 ext4_free_branches(handle, inode, parent_bh: partial2->bh,
1420 first: (__le32 *)partial2->bh->b_data,
1421 last: partial2->p,
1422 depth: (chain2+n2-1) - partial2);
1423 partial2--;
1424 }
1425 }
1426
1427cleanup:
1428 while (p && p > chain) {
1429 BUFFER_TRACE(p->bh, "call brelse");
1430 brelse(bh: p->bh);
1431 p--;
1432 }
1433 while (p2 && p2 > chain2) {
1434 BUFFER_TRACE(p2->bh, "call brelse");
1435 brelse(bh: p2->bh);
1436 p2--;
1437 }
1438 return 0;
1439
1440do_indirects:
1441 /* Kill the remaining (whole) subtrees */
1442 switch (offsets[0]) {
1443 default:
1444 if (++n >= n2)
1445 break;
1446 nr = i_data[EXT4_IND_BLOCK];
1447 if (nr) {
1448 ext4_free_branches(handle, inode, NULL, first: &nr, last: &nr+1, depth: 1);
1449 i_data[EXT4_IND_BLOCK] = 0;
1450 }
1451 fallthrough;
1452 case EXT4_IND_BLOCK:
1453 if (++n >= n2)
1454 break;
1455 nr = i_data[EXT4_DIND_BLOCK];
1456 if (nr) {
1457 ext4_free_branches(handle, inode, NULL, first: &nr, last: &nr+1, depth: 2);
1458 i_data[EXT4_DIND_BLOCK] = 0;
1459 }
1460 fallthrough;
1461 case EXT4_DIND_BLOCK:
1462 if (++n >= n2)
1463 break;
1464 nr = i_data[EXT4_TIND_BLOCK];
1465 if (nr) {
1466 ext4_free_branches(handle, inode, NULL, first: &nr, last: &nr+1, depth: 3);
1467 i_data[EXT4_TIND_BLOCK] = 0;
1468 }
1469 fallthrough;
1470 case EXT4_TIND_BLOCK:
1471 ;
1472 }
1473 goto cleanup;
1474}
1475