Merge tag 'mips-fixes_5.15_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips...
[linux-2.6-microblaze.git] / fs / ext4 / indirect.c
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
31 typedef struct {
32         __le32  *p;
33         __le32  key;
34         struct buffer_head *bh;
35 } Indirect;
36
37 static 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
74 static 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  */
144 static 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         int ret = -EIO;
152
153         *err = 0;
154         /* i_data is not going away, no lock needed */
155         add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
156         if (!p->key)
157                 goto no_block;
158         while (--depth) {
159                 bh = sb_getblk(sb, le32_to_cpu(p->key));
160                 if (unlikely(!bh)) {
161                         ret = -ENOMEM;
162                         goto failure;
163                 }
164
165                 if (!bh_uptodate_or_lock(bh)) {
166                         if (ext4_read_bh(bh, 0, NULL) < 0) {
167                                 put_bh(bh);
168                                 goto failure;
169                         }
170                         /* validate block references */
171                         if (ext4_check_indirect_blockref(inode, bh)) {
172                                 put_bh(bh);
173                                 goto failure;
174                         }
175                 }
176
177                 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
178                 /* Reader: end */
179                 if (!p->key)
180                         goto no_block;
181         }
182         return NULL;
183
184 failure:
185         *err = ret;
186 no_block:
187         return p;
188 }
189
190 /**
191  *      ext4_find_near - find a place for allocation with sufficient locality
192  *      @inode: owner
193  *      @ind: descriptor of indirect block.
194  *
195  *      This function returns the preferred place for block allocation.
196  *      It is used when heuristic for sequential allocation fails.
197  *      Rules are:
198  *        + if there is a block to the left of our position - allocate near it.
199  *        + if pointer will live in indirect block - allocate near that block.
200  *        + if pointer will live in inode - allocate in the same
201  *          cylinder group.
202  *
203  * In the latter case we colour the starting block by the callers PID to
204  * prevent it from clashing with concurrent allocations for a different inode
205  * in the same block group.   The PID is used here so that functionally related
206  * files will be close-by on-disk.
207  *
208  *      Caller must make sure that @ind is valid and will stay that way.
209  */
210 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
211 {
212         struct ext4_inode_info *ei = EXT4_I(inode);
213         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
214         __le32 *p;
215
216         /* Try to find previous block */
217         for (p = ind->p - 1; p >= start; p--) {
218                 if (*p)
219                         return le32_to_cpu(*p);
220         }
221
222         /* No such thing, so let's try location of indirect block */
223         if (ind->bh)
224                 return ind->bh->b_blocknr;
225
226         /*
227          * It is going to be referred to from the inode itself? OK, just put it
228          * into the same cylinder group then.
229          */
230         return ext4_inode_to_goal_block(inode);
231 }
232
233 /**
234  *      ext4_find_goal - find a preferred place for allocation.
235  *      @inode: owner
236  *      @block:  block we want
237  *      @partial: pointer to the last triple within a chain
238  *
239  *      Normally this function find the preferred place for block allocation,
240  *      returns it.
241  *      Because this is only used for non-extent files, we limit the block nr
242  *      to 32 bits.
243  */
244 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
245                                    Indirect *partial)
246 {
247         ext4_fsblk_t goal;
248
249         /*
250          * XXX need to get goal block from mballoc's data structures
251          */
252
253         goal = ext4_find_near(inode, partial);
254         goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
255         return goal;
256 }
257
258 /**
259  *      ext4_blks_to_allocate - Look up the block map and count the number
260  *      of direct blocks need to be allocated for the given branch.
261  *
262  *      @branch: chain of indirect blocks
263  *      @k: number of blocks need for indirect blocks
264  *      @blks: number of data blocks to be mapped.
265  *      @blocks_to_boundary:  the offset in the indirect block
266  *
267  *      return the total number of blocks to be allocate, including the
268  *      direct and indirect blocks.
269  */
270 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
271                                  int blocks_to_boundary)
272 {
273         unsigned int count = 0;
274
275         /*
276          * Simple case, [t,d]Indirect block(s) has not allocated yet
277          * then it's clear blocks on that path have not allocated
278          */
279         if (k > 0) {
280                 /* right now we don't handle cross boundary allocation */
281                 if (blks < blocks_to_boundary + 1)
282                         count += blks;
283                 else
284                         count += blocks_to_boundary + 1;
285                 return count;
286         }
287
288         count++;
289         while (count < blks && count <= blocks_to_boundary &&
290                 le32_to_cpu(*(branch[0].p + count)) == 0) {
291                 count++;
292         }
293         return count;
294 }
295
296 /**
297  * ext4_alloc_branch() - allocate and set up a chain of blocks
298  * @handle: handle for this transaction
299  * @ar: structure describing the allocation request
300  * @indirect_blks: number of allocated indirect blocks
301  * @offsets: offsets (in the blocks) to store the pointers to next.
302  * @branch: place to store the chain in.
303  *
304  *      This function allocates blocks, zeroes out all but the last one,
305  *      links them into chain and (if we are synchronous) writes them to disk.
306  *      In other words, it prepares a branch that can be spliced onto the
307  *      inode. It stores the information about that chain in the branch[], in
308  *      the same format as ext4_get_branch() would do. We are calling it after
309  *      we had read the existing part of chain and partial points to the last
310  *      triple of that (one with zero ->key). Upon the exit we have the same
311  *      picture as after the successful ext4_get_block(), except that in one
312  *      place chain is disconnected - *branch->p is still zero (we did not
313  *      set the last link), but branch->key contains the number that should
314  *      be placed into *branch->p to fill that gap.
315  *
316  *      If allocation fails we free all blocks we've allocated (and forget
317  *      their buffer_heads) and return the error value the from failed
318  *      ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
319  *      as described above and return 0.
320  */
321 static int ext4_alloc_branch(handle_t *handle,
322                              struct ext4_allocation_request *ar,
323                              int indirect_blks, ext4_lblk_t *offsets,
324                              Indirect *branch)
325 {
326         struct buffer_head *            bh;
327         ext4_fsblk_t                    b, new_blocks[4];
328         __le32                          *p;
329         int                             i, j, err, len = 1;
330
331         for (i = 0; i <= indirect_blks; i++) {
332                 if (i == indirect_blks) {
333                         new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err);
334                 } else {
335                         ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle,
336                                         ar->inode, ar->goal,
337                                         ar->flags & EXT4_MB_DELALLOC_RESERVED,
338                                         NULL, &err);
339                         /* Simplify error cleanup... */
340                         branch[i+1].bh = NULL;
341                 }
342                 if (err) {
343                         i--;
344                         goto failed;
345                 }
346                 branch[i].key = cpu_to_le32(new_blocks[i]);
347                 if (i == 0)
348                         continue;
349
350                 bh = branch[i].bh = sb_getblk(ar->inode->i_sb, new_blocks[i-1]);
351                 if (unlikely(!bh)) {
352                         err = -ENOMEM;
353                         goto failed;
354                 }
355                 lock_buffer(bh);
356                 BUFFER_TRACE(bh, "call get_create_access");
357                 err = ext4_journal_get_create_access(handle, ar->inode->i_sb,
358                                                      bh, EXT4_JTR_NONE);
359                 if (err) {
360                         unlock_buffer(bh);
361                         goto failed;
362                 }
363
364                 memset(bh->b_data, 0, bh->b_size);
365                 p = branch[i].p = (__le32 *) bh->b_data + offsets[i];
366                 b = new_blocks[i];
367
368                 if (i == indirect_blks)
369                         len = ar->len;
370                 for (j = 0; j < len; j++)
371                         *p++ = cpu_to_le32(b++);
372
373                 BUFFER_TRACE(bh, "marking uptodate");
374                 set_buffer_uptodate(bh);
375                 unlock_buffer(bh);
376
377                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
378                 err = ext4_handle_dirty_metadata(handle, ar->inode, bh);
379                 if (err)
380                         goto failed;
381         }
382         return 0;
383 failed:
384         if (i == indirect_blks) {
385                 /* Free data blocks */
386                 ext4_free_blocks(handle, ar->inode, NULL, new_blocks[i],
387                                  ar->len, 0);
388                 i--;
389         }
390         for (; i >= 0; i--) {
391                 /*
392                  * We want to ext4_forget() only freshly allocated indirect
393                  * blocks. Buffer for new_blocks[i] is at branch[i+1].bh
394                  * (buffer at branch[0].bh is indirect block / inode already
395                  * existing before ext4_alloc_branch() was called). Also
396                  * because blocks are freshly allocated, we don't need to
397                  * revoke them which is why we don't set
398                  * EXT4_FREE_BLOCKS_METADATA.
399                  */
400                 ext4_free_blocks(handle, ar->inode, branch[i+1].bh,
401                                  new_blocks[i], 1,
402                                  branch[i+1].bh ? EXT4_FREE_BLOCKS_FORGET : 0);
403         }
404         return err;
405 }
406
407 /**
408  * ext4_splice_branch() - splice the allocated branch onto inode.
409  * @handle: handle for this transaction
410  * @ar: structure describing the allocation request
411  * @where: location of missing link
412  * @num:   number of indirect blocks we are adding
413  *
414  * This function fills the missing link and does all housekeeping needed in
415  * inode (->i_blocks, etc.). In case of success we end up with the full
416  * chain to new block and return 0.
417  */
418 static int ext4_splice_branch(handle_t *handle,
419                               struct ext4_allocation_request *ar,
420                               Indirect *where, int num)
421 {
422         int i;
423         int err = 0;
424         ext4_fsblk_t current_block;
425
426         /*
427          * If we're splicing into a [td]indirect block (as opposed to the
428          * inode) then we need to get write access to the [td]indirect block
429          * before the splice.
430          */
431         if (where->bh) {
432                 BUFFER_TRACE(where->bh, "get_write_access");
433                 err = ext4_journal_get_write_access(handle, ar->inode->i_sb,
434                                                     where->bh, EXT4_JTR_NONE);
435                 if (err)
436                         goto err_out;
437         }
438         /* That's it */
439
440         *where->p = where->key;
441
442         /*
443          * Update the host buffer_head or inode to point to more just allocated
444          * direct blocks blocks
445          */
446         if (num == 0 && ar->len > 1) {
447                 current_block = le32_to_cpu(where->key) + 1;
448                 for (i = 1; i < ar->len; i++)
449                         *(where->p + i) = cpu_to_le32(current_block++);
450         }
451
452         /* We are done with atomic stuff, now do the rest of housekeeping */
453         /* had we spliced it onto indirect block? */
454         if (where->bh) {
455                 /*
456                  * If we spliced it onto an indirect block, we haven't
457                  * altered the inode.  Note however that if it is being spliced
458                  * onto an indirect block at the very end of the file (the
459                  * file is growing) then we *will* alter the inode to reflect
460                  * the new i_size.  But that is not done here - it is done in
461                  * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
462                  */
463                 jbd_debug(5, "splicing indirect only\n");
464                 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
465                 err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh);
466                 if (err)
467                         goto err_out;
468         } else {
469                 /*
470                  * OK, we spliced it into the inode itself on a direct block.
471                  */
472                 err = ext4_mark_inode_dirty(handle, ar->inode);
473                 if (unlikely(err))
474                         goto err_out;
475                 jbd_debug(5, "splicing direct\n");
476         }
477         return err;
478
479 err_out:
480         for (i = 1; i <= num; i++) {
481                 /*
482                  * branch[i].bh is newly allocated, so there is no
483                  * need to revoke the block, which is why we don't
484                  * need to set EXT4_FREE_BLOCKS_METADATA.
485                  */
486                 ext4_free_blocks(handle, ar->inode, where[i].bh, 0, 1,
487                                  EXT4_FREE_BLOCKS_FORGET);
488         }
489         ext4_free_blocks(handle, ar->inode, NULL, le32_to_cpu(where[num].key),
490                          ar->len, 0);
491
492         return err;
493 }
494
495 /*
496  * The ext4_ind_map_blocks() function handles non-extents inodes
497  * (i.e., using the traditional indirect/double-indirect i_blocks
498  * scheme) for ext4_map_blocks().
499  *
500  * Allocation strategy is simple: if we have to allocate something, we will
501  * have to go the whole way to leaf. So let's do it before attaching anything
502  * to tree, set linkage between the newborn blocks, write them if sync is
503  * required, recheck the path, free and repeat if check fails, otherwise
504  * set the last missing link (that will protect us from any truncate-generated
505  * removals - all blocks on the path are immune now) and possibly force the
506  * write on the parent block.
507  * That has a nice additional property: no special recovery from the failed
508  * allocations is needed - we simply release blocks and do not touch anything
509  * reachable from inode.
510  *
511  * `handle' can be NULL if create == 0.
512  *
513  * return > 0, # of blocks mapped or allocated.
514  * return = 0, if plain lookup failed.
515  * return < 0, error case.
516  *
517  * The ext4_ind_get_blocks() function should be called with
518  * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
519  * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
520  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
521  * blocks.
522  */
523 int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
524                         struct ext4_map_blocks *map,
525                         int flags)
526 {
527         struct ext4_allocation_request ar;
528         int err = -EIO;
529         ext4_lblk_t offsets[4];
530         Indirect chain[4];
531         Indirect *partial;
532         int indirect_blks;
533         int blocks_to_boundary = 0;
534         int depth;
535         int count = 0;
536         ext4_fsblk_t first_block = 0;
537
538         trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
539         ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
540         ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
541         depth = ext4_block_to_path(inode, map->m_lblk, offsets,
542                                    &blocks_to_boundary);
543
544         if (depth == 0)
545                 goto out;
546
547         partial = ext4_get_branch(inode, depth, offsets, chain, &err);
548
549         /* Simplest case - block found, no allocation needed */
550         if (!partial) {
551                 first_block = le32_to_cpu(chain[depth - 1].key);
552                 count++;
553                 /*map more blocks*/
554                 while (count < map->m_len && count <= blocks_to_boundary) {
555                         ext4_fsblk_t blk;
556
557                         blk = le32_to_cpu(*(chain[depth-1].p + count));
558
559                         if (blk == first_block + count)
560                                 count++;
561                         else
562                                 break;
563                 }
564                 goto got_it;
565         }
566
567         /* Next simple case - plain lookup failed */
568         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
569                 unsigned epb = inode->i_sb->s_blocksize / sizeof(u32);
570                 int i;
571
572                 /*
573                  * Count number blocks in a subtree under 'partial'. At each
574                  * level we count number of complete empty subtrees beyond
575                  * current offset and then descend into the subtree only
576                  * partially beyond current offset.
577                  */
578                 count = 0;
579                 for (i = partial - chain + 1; i < depth; i++)
580                         count = count * epb + (epb - offsets[i] - 1);
581                 count++;
582                 /* Fill in size of a hole we found */
583                 map->m_pblk = 0;
584                 map->m_len = min_t(unsigned int, map->m_len, count);
585                 goto cleanup;
586         }
587
588         /* Failed read of indirect block */
589         if (err == -EIO)
590                 goto cleanup;
591
592         /*
593          * Okay, we need to do block allocation.
594         */
595         if (ext4_has_feature_bigalloc(inode->i_sb)) {
596                 EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
597                                  "non-extent mapped inodes with bigalloc");
598                 err = -EFSCORRUPTED;
599                 goto out;
600         }
601
602         /* Set up for the direct block allocation */
603         memset(&ar, 0, sizeof(ar));
604         ar.inode = inode;
605         ar.logical = map->m_lblk;
606         if (S_ISREG(inode->i_mode))
607                 ar.flags = EXT4_MB_HINT_DATA;
608         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
609                 ar.flags |= EXT4_MB_DELALLOC_RESERVED;
610         if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
611                 ar.flags |= EXT4_MB_USE_RESERVED;
612
613         ar.goal = ext4_find_goal(inode, map->m_lblk, partial);
614
615         /* the number of blocks need to allocate for [d,t]indirect blocks */
616         indirect_blks = (chain + depth) - partial - 1;
617
618         /*
619          * Next look up the indirect map to count the totoal number of
620          * direct blocks to allocate for this branch.
621          */
622         ar.len = ext4_blks_to_allocate(partial, indirect_blks,
623                                        map->m_len, blocks_to_boundary);
624
625         /*
626          * Block out ext4_truncate while we alter the tree
627          */
628         err = ext4_alloc_branch(handle, &ar, indirect_blks,
629                                 offsets + (partial - chain), partial);
630
631         /*
632          * The ext4_splice_branch call will free and forget any buffers
633          * on the new chain if there is a failure, but that risks using
634          * up transaction credits, especially for bitmaps where the
635          * credits cannot be returned.  Can we handle this somehow?  We
636          * may need to return -EAGAIN upwards in the worst case.  --sct
637          */
638         if (!err)
639                 err = ext4_splice_branch(handle, &ar, partial, indirect_blks);
640         if (err)
641                 goto cleanup;
642
643         map->m_flags |= EXT4_MAP_NEW;
644
645         ext4_update_inode_fsync_trans(handle, inode, 1);
646         count = ar.len;
647 got_it:
648         map->m_flags |= EXT4_MAP_MAPPED;
649         map->m_pblk = le32_to_cpu(chain[depth-1].key);
650         map->m_len = count;
651         if (count > blocks_to_boundary)
652                 map->m_flags |= EXT4_MAP_BOUNDARY;
653         err = count;
654         /* Clean up and exit */
655         partial = chain + depth - 1;    /* the whole chain */
656 cleanup:
657         while (partial > chain) {
658                 BUFFER_TRACE(partial->bh, "call brelse");
659                 brelse(partial->bh);
660                 partial--;
661         }
662 out:
663         trace_ext4_ind_map_blocks_exit(inode, flags, map, err);
664         return err;
665 }
666
667 /*
668  * Calculate number of indirect blocks touched by mapping @nrblocks logically
669  * contiguous blocks
670  */
671 int ext4_ind_trans_blocks(struct inode *inode, int nrblocks)
672 {
673         /*
674          * With N contiguous data blocks, we need at most
675          * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
676          * 2 dindirect blocks, and 1 tindirect block
677          */
678         return DIV_ROUND_UP(nrblocks, EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
679 }
680
681 static int ext4_ind_trunc_restart_fn(handle_t *handle, struct inode *inode,
682                                      struct buffer_head *bh, int *dropped)
683 {
684         int err;
685
686         if (bh) {
687                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
688                 err = ext4_handle_dirty_metadata(handle, inode, bh);
689                 if (unlikely(err))
690                         return err;
691         }
692         err = ext4_mark_inode_dirty(handle, inode);
693         if (unlikely(err))
694                 return err;
695         /*
696          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
697          * moment, get_block can be called only for blocks inside i_size since
698          * page cache has been already dropped and writes are blocked by
699          * i_mutex. So we can safely drop the i_data_sem here.
700          */
701         BUG_ON(EXT4_JOURNAL(inode) == NULL);
702         ext4_discard_preallocations(inode, 0);
703         up_write(&EXT4_I(inode)->i_data_sem);
704         *dropped = 1;
705         return 0;
706 }
707
708 /*
709  * Truncate transactions can be complex and absolutely huge.  So we need to
710  * be able to restart the transaction at a convenient checkpoint to make
711  * sure we don't overflow the journal.
712  *
713  * Try to extend this transaction for the purposes of truncation.  If
714  * extend fails, we restart transaction.
715  */
716 static int ext4_ind_truncate_ensure_credits(handle_t *handle,
717                                             struct inode *inode,
718                                             struct buffer_head *bh,
719                                             int revoke_creds)
720 {
721         int ret;
722         int dropped = 0;
723
724         ret = ext4_journal_ensure_credits_fn(handle, EXT4_RESERVE_TRANS_BLOCKS,
725                         ext4_blocks_for_truncate(inode), revoke_creds,
726                         ext4_ind_trunc_restart_fn(handle, inode, bh, &dropped));
727         if (dropped)
728                 down_write(&EXT4_I(inode)->i_data_sem);
729         if (ret <= 0)
730                 return ret;
731         if (bh) {
732                 BUFFER_TRACE(bh, "retaking write access");
733                 ret = ext4_journal_get_write_access(handle, inode->i_sb, bh,
734                                                     EXT4_JTR_NONE);
735                 if (unlikely(ret))
736                         return ret;
737         }
738         return 0;
739 }
740
741 /*
742  * Probably it should be a library function... search for first non-zero word
743  * or memcmp with zero_page, whatever is better for particular architecture.
744  * Linus?
745  */
746 static inline int all_zeroes(__le32 *p, __le32 *q)
747 {
748         while (p < q)
749                 if (*p++)
750                         return 0;
751         return 1;
752 }
753
754 /**
755  *      ext4_find_shared - find the indirect blocks for partial truncation.
756  *      @inode:   inode in question
757  *      @depth:   depth of the affected branch
758  *      @offsets: offsets of pointers in that branch (see ext4_block_to_path)
759  *      @chain:   place to store the pointers to partial indirect blocks
760  *      @top:     place to the (detached) top of branch
761  *
762  *      This is a helper function used by ext4_truncate().
763  *
764  *      When we do truncate() we may have to clean the ends of several
765  *      indirect blocks but leave the blocks themselves alive. Block is
766  *      partially truncated if some data below the new i_size is referred
767  *      from it (and it is on the path to the first completely truncated
768  *      data block, indeed).  We have to free the top of that path along
769  *      with everything to the right of the path. Since no allocation
770  *      past the truncation point is possible until ext4_truncate()
771  *      finishes, we may safely do the latter, but top of branch may
772  *      require special attention - pageout below the truncation point
773  *      might try to populate it.
774  *
775  *      We atomically detach the top of branch from the tree, store the
776  *      block number of its root in *@top, pointers to buffer_heads of
777  *      partially truncated blocks - in @chain[].bh and pointers to
778  *      their last elements that should not be removed - in
779  *      @chain[].p. Return value is the pointer to last filled element
780  *      of @chain.
781  *
782  *      The work left to caller to do the actual freeing of subtrees:
783  *              a) free the subtree starting from *@top
784  *              b) free the subtrees whose roots are stored in
785  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
786  *              c) free the subtrees growing from the inode past the @chain[0].
787  *                      (no partially truncated stuff there).  */
788
789 static Indirect *ext4_find_shared(struct inode *inode, int depth,
790                                   ext4_lblk_t offsets[4], Indirect chain[4],
791                                   __le32 *top)
792 {
793         Indirect *partial, *p;
794         int k, err;
795
796         *top = 0;
797         /* Make k index the deepest non-null offset + 1 */
798         for (k = depth; k > 1 && !offsets[k-1]; k--)
799                 ;
800         partial = ext4_get_branch(inode, k, offsets, chain, &err);
801         /* Writer: pointers */
802         if (!partial)
803                 partial = chain + k-1;
804         /*
805          * If the branch acquired continuation since we've looked at it -
806          * fine, it should all survive and (new) top doesn't belong to us.
807          */
808         if (!partial->key && *partial->p)
809                 /* Writer: end */
810                 goto no_top;
811         for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
812                 ;
813         /*
814          * OK, we've found the last block that must survive. The rest of our
815          * branch should be detached before unlocking. However, if that rest
816          * of branch is all ours and does not grow immediately from the inode
817          * it's easier to cheat and just decrement partial->p.
818          */
819         if (p == chain + k - 1 && p > chain) {
820                 p->p--;
821         } else {
822                 *top = *p->p;
823                 /* Nope, don't do this in ext4.  Must leave the tree intact */
824 #if 0
825                 *p->p = 0;
826 #endif
827         }
828         /* Writer: end */
829
830         while (partial > p) {
831                 brelse(partial->bh);
832                 partial--;
833         }
834 no_top:
835         return partial;
836 }
837
838 /*
839  * Zero a number of block pointers in either an inode or an indirect block.
840  * If we restart the transaction we must again get write access to the
841  * indirect block for further modification.
842  *
843  * We release `count' blocks on disk, but (last - first) may be greater
844  * than `count' because there can be holes in there.
845  *
846  * Return 0 on success, 1 on invalid block range
847  * and < 0 on fatal error.
848  */
849 static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
850                              struct buffer_head *bh,
851                              ext4_fsblk_t block_to_free,
852                              unsigned long count, __le32 *first,
853                              __le32 *last)
854 {
855         __le32 *p;
856         int     flags = EXT4_FREE_BLOCKS_VALIDATED;
857         int     err;
858
859         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
860             ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
861                 flags |= EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_METADATA;
862         else if (ext4_should_journal_data(inode))
863                 flags |= EXT4_FREE_BLOCKS_FORGET;
864
865         if (!ext4_inode_block_valid(inode, block_to_free, count)) {
866                 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
867                                  "blocks %llu len %lu",
868                                  (unsigned long long) block_to_free, count);
869                 return 1;
870         }
871
872         err = ext4_ind_truncate_ensure_credits(handle, inode, bh,
873                                 ext4_free_data_revoke_credits(inode, count));
874         if (err < 0)
875                 goto out_err;
876
877         for (p = first; p < last; p++)
878                 *p = 0;
879
880         ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
881         return 0;
882 out_err:
883         ext4_std_error(inode->i_sb, err);
884         return err;
885 }
886
887 /**
888  * ext4_free_data - free a list of data blocks
889  * @handle:     handle for this transaction
890  * @inode:      inode we are dealing with
891  * @this_bh:    indirect buffer_head which contains *@first and *@last
892  * @first:      array of block numbers
893  * @last:       points immediately past the end of array
894  *
895  * We are freeing all blocks referred from that array (numbers are stored as
896  * little-endian 32-bit) and updating @inode->i_blocks appropriately.
897  *
898  * We accumulate contiguous runs of blocks to free.  Conveniently, if these
899  * blocks are contiguous then releasing them at one time will only affect one
900  * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
901  * actually use a lot of journal space.
902  *
903  * @this_bh will be %NULL if @first and @last point into the inode's direct
904  * block pointers.
905  */
906 static void ext4_free_data(handle_t *handle, struct inode *inode,
907                            struct buffer_head *this_bh,
908                            __le32 *first, __le32 *last)
909 {
910         ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
911         unsigned long count = 0;            /* Number of blocks in the run */
912         __le32 *block_to_free_p = NULL;     /* Pointer into inode/ind
913                                                corresponding to
914                                                block_to_free */
915         ext4_fsblk_t nr;                    /* Current block # */
916         __le32 *p;                          /* Pointer into inode/ind
917                                                for current block */
918         int err = 0;
919
920         if (this_bh) {                          /* For indirect block */
921                 BUFFER_TRACE(this_bh, "get_write_access");
922                 err = ext4_journal_get_write_access(handle, inode->i_sb,
923                                                     this_bh, EXT4_JTR_NONE);
924                 /* Important: if we can't update the indirect pointers
925                  * to the blocks, we can't free them. */
926                 if (err)
927                         return;
928         }
929
930         for (p = first; p < last; p++) {
931                 nr = le32_to_cpu(*p);
932                 if (nr) {
933                         /* accumulate blocks to free if they're contiguous */
934                         if (count == 0) {
935                                 block_to_free = nr;
936                                 block_to_free_p = p;
937                                 count = 1;
938                         } else if (nr == block_to_free + count) {
939                                 count++;
940                         } else {
941                                 err = ext4_clear_blocks(handle, inode, this_bh,
942                                                         block_to_free, count,
943                                                         block_to_free_p, p);
944                                 if (err)
945                                         break;
946                                 block_to_free = nr;
947                                 block_to_free_p = p;
948                                 count = 1;
949                         }
950                 }
951         }
952
953         if (!err && count > 0)
954                 err = ext4_clear_blocks(handle, inode, this_bh, block_to_free,
955                                         count, block_to_free_p, p);
956         if (err < 0)
957                 /* fatal error */
958                 return;
959
960         if (this_bh) {
961                 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
962
963                 /*
964                  * The buffer head should have an attached journal head at this
965                  * point. However, if the data is corrupted and an indirect
966                  * block pointed to itself, it would have been detached when
967                  * the block was cleared. Check for this instead of OOPSing.
968                  */
969                 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
970                         ext4_handle_dirty_metadata(handle, inode, this_bh);
971                 else
972                         EXT4_ERROR_INODE(inode,
973                                          "circular indirect block detected at "
974                                          "block %llu",
975                                 (unsigned long long) this_bh->b_blocknr);
976         }
977 }
978
979 /**
980  *      ext4_free_branches - free an array of branches
981  *      @handle: JBD handle for this transaction
982  *      @inode: inode we are dealing with
983  *      @parent_bh: the buffer_head which contains *@first and *@last
984  *      @first: array of block numbers
985  *      @last:  pointer immediately past the end of array
986  *      @depth: depth of the branches to free
987  *
988  *      We are freeing all blocks referred from these branches (numbers are
989  *      stored as little-endian 32-bit) and updating @inode->i_blocks
990  *      appropriately.
991  */
992 static void ext4_free_branches(handle_t *handle, struct inode *inode,
993                                struct buffer_head *parent_bh,
994                                __le32 *first, __le32 *last, int depth)
995 {
996         ext4_fsblk_t nr;
997         __le32 *p;
998
999         if (ext4_handle_is_aborted(handle))
1000                 return;
1001
1002         if (depth--) {
1003                 struct buffer_head *bh;
1004                 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1005                 p = last;
1006                 while (--p >= first) {
1007                         nr = le32_to_cpu(*p);
1008                         if (!nr)
1009                                 continue;               /* A hole */
1010
1011                         if (!ext4_inode_block_valid(inode, nr, 1)) {
1012                                 EXT4_ERROR_INODE(inode,
1013                                                  "invalid indirect mapped "
1014                                                  "block %lu (level %d)",
1015                                                  (unsigned long) nr, depth);
1016                                 break;
1017                         }
1018
1019                         /* Go read the buffer for the next level down */
1020                         bh = ext4_sb_bread(inode->i_sb, nr, 0);
1021
1022                         /*
1023                          * A read failure? Report error and clear slot
1024                          * (should be rare).
1025                          */
1026                         if (IS_ERR(bh)) {
1027                                 ext4_error_inode_block(inode, nr, -PTR_ERR(bh),
1028                                                        "Read failure");
1029                                 continue;
1030                         }
1031
1032                         /* This zaps the entire block.  Bottom up. */
1033                         BUFFER_TRACE(bh, "free child branches");
1034                         ext4_free_branches(handle, inode, bh,
1035                                         (__le32 *) bh->b_data,
1036                                         (__le32 *) bh->b_data + addr_per_block,
1037                                         depth);
1038                         brelse(bh);
1039
1040                         /*
1041                          * Everything below this pointer has been
1042                          * released.  Now let this top-of-subtree go.
1043                          *
1044                          * We want the freeing of this indirect block to be
1045                          * atomic in the journal with the updating of the
1046                          * bitmap block which owns it.  So make some room in
1047                          * the journal.
1048                          *
1049                          * We zero the parent pointer *after* freeing its
1050                          * pointee in the bitmaps, so if extend_transaction()
1051                          * for some reason fails to put the bitmap changes and
1052                          * the release into the same transaction, recovery
1053                          * will merely complain about releasing a free block,
1054                          * rather than leaking blocks.
1055                          */
1056                         if (ext4_handle_is_aborted(handle))
1057                                 return;
1058                         if (ext4_ind_truncate_ensure_credits(handle, inode,
1059                                         NULL,
1060                                         ext4_free_metadata_revoke_credits(
1061                                                         inode->i_sb, 1)) < 0)
1062                                 return;
1063
1064                         /*
1065                          * The forget flag here is critical because if
1066                          * we are journaling (and not doing data
1067                          * journaling), we have to make sure a revoke
1068                          * record is written to prevent the journal
1069                          * replay from overwriting the (former)
1070                          * indirect block if it gets reallocated as a
1071                          * data block.  This must happen in the same
1072                          * transaction where the data blocks are
1073                          * actually freed.
1074                          */
1075                         ext4_free_blocks(handle, inode, NULL, nr, 1,
1076                                          EXT4_FREE_BLOCKS_METADATA|
1077                                          EXT4_FREE_BLOCKS_FORGET);
1078
1079                         if (parent_bh) {
1080                                 /*
1081                                  * The block which we have just freed is
1082                                  * pointed to by an indirect block: journal it
1083                                  */
1084                                 BUFFER_TRACE(parent_bh, "get_write_access");
1085                                 if (!ext4_journal_get_write_access(handle,
1086                                                 inode->i_sb, parent_bh,
1087                                                 EXT4_JTR_NONE)) {
1088                                         *p = 0;
1089                                         BUFFER_TRACE(parent_bh,
1090                                         "call ext4_handle_dirty_metadata");
1091                                         ext4_handle_dirty_metadata(handle,
1092                                                                    inode,
1093                                                                    parent_bh);
1094                                 }
1095                         }
1096                 }
1097         } else {
1098                 /* We have reached the bottom of the tree. */
1099                 BUFFER_TRACE(parent_bh, "free data blocks");
1100                 ext4_free_data(handle, inode, parent_bh, first, last);
1101         }
1102 }
1103
1104 void ext4_ind_truncate(handle_t *handle, struct inode *inode)
1105 {
1106         struct ext4_inode_info *ei = EXT4_I(inode);
1107         __le32 *i_data = ei->i_data;
1108         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1109         ext4_lblk_t offsets[4];
1110         Indirect chain[4];
1111         Indirect *partial;
1112         __le32 nr = 0;
1113         int n = 0;
1114         ext4_lblk_t last_block, max_block;
1115         unsigned blocksize = inode->i_sb->s_blocksize;
1116
1117         last_block = (inode->i_size + blocksize-1)
1118                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1119         max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1120                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1121
1122         if (last_block != max_block) {
1123                 n = ext4_block_to_path(inode, last_block, offsets, NULL);
1124                 if (n == 0)
1125                         return;
1126         }
1127
1128         ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block);
1129
1130         /*
1131          * The orphan list entry will now protect us from any crash which
1132          * occurs before the truncate completes, so it is now safe to propagate
1133          * the new, shorter inode size (held for now in i_size) into the
1134          * on-disk inode. We do this via i_disksize, which is the value which
1135          * ext4 *really* writes onto the disk inode.
1136          */
1137         ei->i_disksize = inode->i_size;
1138
1139         if (last_block == max_block) {
1140                 /*
1141                  * It is unnecessary to free any data blocks if last_block is
1142                  * equal to the indirect block limit.
1143                  */
1144                 return;
1145         } else if (n == 1) {            /* direct blocks */
1146                 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
1147                                i_data + EXT4_NDIR_BLOCKS);
1148                 goto do_indirects;
1149         }
1150
1151         partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1152         /* Kill the top of shared branch (not detached) */
1153         if (nr) {
1154                 if (partial == chain) {
1155                         /* Shared branch grows from the inode */
1156                         ext4_free_branches(handle, inode, NULL,
1157                                            &nr, &nr+1, (chain+n-1) - partial);
1158                         *partial->p = 0;
1159                         /*
1160                          * We mark the inode dirty prior to restart,
1161                          * and prior to stop.  No need for it here.
1162                          */
1163                 } else {
1164                         /* Shared branch grows from an indirect block */
1165                         BUFFER_TRACE(partial->bh, "get_write_access");
1166                         ext4_free_branches(handle, inode, partial->bh,
1167                                         partial->p,
1168                                         partial->p+1, (chain+n-1) - partial);
1169                 }
1170         }
1171         /* Clear the ends of indirect blocks on the shared branch */
1172         while (partial > chain) {
1173                 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
1174                                    (__le32*)partial->bh->b_data+addr_per_block,
1175                                    (chain+n-1) - partial);
1176                 BUFFER_TRACE(partial->bh, "call brelse");
1177                 brelse(partial->bh);
1178                 partial--;
1179         }
1180 do_indirects:
1181         /* Kill the remaining (whole) subtrees */
1182         switch (offsets[0]) {
1183         default:
1184                 nr = i_data[EXT4_IND_BLOCK];
1185                 if (nr) {
1186                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1187                         i_data[EXT4_IND_BLOCK] = 0;
1188                 }
1189                 fallthrough;
1190         case EXT4_IND_BLOCK:
1191                 nr = i_data[EXT4_DIND_BLOCK];
1192                 if (nr) {
1193                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1194                         i_data[EXT4_DIND_BLOCK] = 0;
1195                 }
1196                 fallthrough;
1197         case EXT4_DIND_BLOCK:
1198                 nr = i_data[EXT4_TIND_BLOCK];
1199                 if (nr) {
1200                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1201                         i_data[EXT4_TIND_BLOCK] = 0;
1202                 }
1203                 fallthrough;
1204         case EXT4_TIND_BLOCK:
1205                 ;
1206         }
1207 }
1208
1209 /**
1210  *      ext4_ind_remove_space - remove space from the range
1211  *      @handle: JBD handle for this transaction
1212  *      @inode: inode we are dealing with
1213  *      @start: First block to remove
1214  *      @end:   One block after the last block to remove (exclusive)
1215  *
1216  *      Free the blocks in the defined range (end is exclusive endpoint of
1217  *      range). This is used by ext4_punch_hole().
1218  */
1219 int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
1220                           ext4_lblk_t start, ext4_lblk_t end)
1221 {
1222         struct ext4_inode_info *ei = EXT4_I(inode);
1223         __le32 *i_data = ei->i_data;
1224         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1225         ext4_lblk_t offsets[4], offsets2[4];
1226         Indirect chain[4], chain2[4];
1227         Indirect *partial, *partial2;
1228         Indirect *p = NULL, *p2 = NULL;
1229         ext4_lblk_t max_block;
1230         __le32 nr = 0, nr2 = 0;
1231         int n = 0, n2 = 0;
1232         unsigned blocksize = inode->i_sb->s_blocksize;
1233
1234         max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1235                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1236         if (end >= max_block)
1237                 end = max_block;
1238         if ((start >= end) || (start > max_block))
1239                 return 0;
1240
1241         n = ext4_block_to_path(inode, start, offsets, NULL);
1242         n2 = ext4_block_to_path(inode, end, offsets2, NULL);
1243
1244         BUG_ON(n > n2);
1245
1246         if ((n == 1) && (n == n2)) {
1247                 /* We're punching only within direct block range */
1248                 ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1249                                i_data + offsets2[0]);
1250                 return 0;
1251         } else if (n2 > n) {
1252                 /*
1253                  * Start and end are on a different levels so we're going to
1254                  * free partial block at start, and partial block at end of
1255                  * the range. If there are some levels in between then
1256                  * do_indirects label will take care of that.
1257                  */
1258
1259                 if (n == 1) {
1260                         /*
1261                          * Start is at the direct block level, free
1262                          * everything to the end of the level.
1263                          */
1264                         ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1265                                        i_data + EXT4_NDIR_BLOCKS);
1266                         goto end_range;
1267                 }
1268
1269
1270                 partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
1271                 if (nr) {
1272                         if (partial == chain) {
1273                                 /* Shared branch grows from the inode */
1274                                 ext4_free_branches(handle, inode, NULL,
1275                                            &nr, &nr+1, (chain+n-1) - partial);
1276                                 *partial->p = 0;
1277                         } else {
1278                                 /* Shared branch grows from an indirect block */
1279                                 BUFFER_TRACE(partial->bh, "get_write_access");
1280                                 ext4_free_branches(handle, inode, partial->bh,
1281                                         partial->p,
1282                                         partial->p+1, (chain+n-1) - partial);
1283                         }
1284                 }
1285
1286                 /*
1287                  * Clear the ends of indirect blocks on the shared branch
1288                  * at the start of the range
1289                  */
1290                 while (partial > chain) {
1291                         ext4_free_branches(handle, inode, partial->bh,
1292                                 partial->p + 1,
1293                                 (__le32 *)partial->bh->b_data+addr_per_block,
1294                                 (chain+n-1) - partial);
1295                         partial--;
1296                 }
1297
1298 end_range:
1299                 partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1300                 if (nr2) {
1301                         if (partial2 == chain2) {
1302                                 /*
1303                                  * Remember, end is exclusive so here we're at
1304                                  * the start of the next level we're not going
1305                                  * to free. Everything was covered by the start
1306                                  * of the range.
1307                                  */
1308                                 goto do_indirects;
1309                         }
1310                 } else {
1311                         /*
1312                          * ext4_find_shared returns Indirect structure which
1313                          * points to the last element which should not be
1314                          * removed by truncate. But this is end of the range
1315                          * in punch_hole so we need to point to the next element
1316                          */
1317                         partial2->p++;
1318                 }
1319
1320                 /*
1321                  * Clear the ends of indirect blocks on the shared branch
1322                  * at the end of the range
1323                  */
1324                 while (partial2 > chain2) {
1325                         ext4_free_branches(handle, inode, partial2->bh,
1326                                            (__le32 *)partial2->bh->b_data,
1327                                            partial2->p,
1328                                            (chain2+n2-1) - partial2);
1329                         partial2--;
1330                 }
1331                 goto do_indirects;
1332         }
1333
1334         /* Punch happened within the same level (n == n2) */
1335         partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
1336         partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1337
1338         /* Free top, but only if partial2 isn't its subtree. */
1339         if (nr) {
1340                 int level = min(partial - chain, partial2 - chain2);
1341                 int i;
1342                 int subtree = 1;
1343
1344                 for (i = 0; i <= level; i++) {
1345                         if (offsets[i] != offsets2[i]) {
1346                                 subtree = 0;
1347                                 break;
1348                         }
1349                 }
1350
1351                 if (!subtree) {
1352                         if (partial == chain) {
1353                                 /* Shared branch grows from the inode */
1354                                 ext4_free_branches(handle, inode, NULL,
1355                                                    &nr, &nr+1,
1356                                                    (chain+n-1) - partial);
1357                                 *partial->p = 0;
1358                         } else {
1359                                 /* Shared branch grows from an indirect block */
1360                                 BUFFER_TRACE(partial->bh, "get_write_access");
1361                                 ext4_free_branches(handle, inode, partial->bh,
1362                                                    partial->p,
1363                                                    partial->p+1,
1364                                                    (chain+n-1) - partial);
1365                         }
1366                 }
1367         }
1368
1369         if (!nr2) {
1370                 /*
1371                  * ext4_find_shared returns Indirect structure which
1372                  * points to the last element which should not be
1373                  * removed by truncate. But this is end of the range
1374                  * in punch_hole so we need to point to the next element
1375                  */
1376                 partial2->p++;
1377         }
1378
1379         while (partial > chain || partial2 > chain2) {
1380                 int depth = (chain+n-1) - partial;
1381                 int depth2 = (chain2+n2-1) - partial2;
1382
1383                 if (partial > chain && partial2 > chain2 &&
1384                     partial->bh->b_blocknr == partial2->bh->b_blocknr) {
1385                         /*
1386                          * We've converged on the same block. Clear the range,
1387                          * then we're done.
1388                          */
1389                         ext4_free_branches(handle, inode, partial->bh,
1390                                            partial->p + 1,
1391                                            partial2->p,
1392                                            (chain+n-1) - partial);
1393                         goto cleanup;
1394                 }
1395
1396                 /*
1397                  * The start and end partial branches may not be at the same
1398                  * level even though the punch happened within one level. So, we
1399                  * give them a chance to arrive at the same level, then walk
1400                  * them in step with each other until we converge on the same
1401                  * block.
1402                  */
1403                 if (partial > chain && depth <= depth2) {
1404                         ext4_free_branches(handle, inode, partial->bh,
1405                                            partial->p + 1,
1406                                            (__le32 *)partial->bh->b_data+addr_per_block,
1407                                            (chain+n-1) - partial);
1408                         partial--;
1409                 }
1410                 if (partial2 > chain2 && depth2 <= depth) {
1411                         ext4_free_branches(handle, inode, partial2->bh,
1412                                            (__le32 *)partial2->bh->b_data,
1413                                            partial2->p,
1414                                            (chain2+n2-1) - partial2);
1415                         partial2--;
1416                 }
1417         }
1418
1419 cleanup:
1420         while (p && p > chain) {
1421                 BUFFER_TRACE(p->bh, "call brelse");
1422                 brelse(p->bh);
1423                 p--;
1424         }
1425         while (p2 && p2 > chain2) {
1426                 BUFFER_TRACE(p2->bh, "call brelse");
1427                 brelse(p2->bh);
1428                 p2--;
1429         }
1430         return 0;
1431
1432 do_indirects:
1433         /* Kill the remaining (whole) subtrees */
1434         switch (offsets[0]) {
1435         default:
1436                 if (++n >= n2)
1437                         break;
1438                 nr = i_data[EXT4_IND_BLOCK];
1439                 if (nr) {
1440                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1441                         i_data[EXT4_IND_BLOCK] = 0;
1442                 }
1443                 fallthrough;
1444         case EXT4_IND_BLOCK:
1445                 if (++n >= n2)
1446                         break;
1447                 nr = i_data[EXT4_DIND_BLOCK];
1448                 if (nr) {
1449                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1450                         i_data[EXT4_DIND_BLOCK] = 0;
1451                 }
1452                 fallthrough;
1453         case EXT4_DIND_BLOCK:
1454                 if (++n >= n2)
1455                         break;
1456                 nr = i_data[EXT4_TIND_BLOCK];
1457                 if (nr) {
1458                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1459                         i_data[EXT4_TIND_BLOCK] = 0;
1460                 }
1461                 fallthrough;
1462         case EXT4_TIND_BLOCK:
1463                 ;
1464         }
1465         goto cleanup;
1466 }