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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 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 (bh_submit_read(bh) < 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
184failure:
185 *err = ret;
186no_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 */
210static 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 */
244static 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 */
270static 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 * @inode: owner
300 * @indirect_blks: number of allocated indirect blocks
301 * @blks: number of allocated direct blocks
302 * @goal: preferred place for allocation
303 * @offsets: offsets (in the blocks) to store the pointers to next.
304 * @branch: place to store the chain in.
305 *
306 * This function allocates blocks, zeroes out all but the last one,
307 * links them into chain and (if we are synchronous) writes them to disk.
308 * In other words, it prepares a branch that can be spliced onto the
309 * inode. It stores the information about that chain in the branch[], in
310 * the same format as ext4_get_branch() would do. We are calling it after
311 * we had read the existing part of chain and partial points to the last
312 * triple of that (one with zero ->key). Upon the exit we have the same
313 * picture as after the successful ext4_get_block(), except that in one
314 * place chain is disconnected - *branch->p is still zero (we did not
315 * set the last link), but branch->key contains the number that should
316 * be placed into *branch->p to fill that gap.
317 *
318 * If allocation fails we free all blocks we've allocated (and forget
319 * their buffer_heads) and return the error value the from failed
320 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
321 * as described above and return 0.
322 */
323static int ext4_alloc_branch(handle_t *handle,
324 struct ext4_allocation_request *ar,
325 int indirect_blks, ext4_lblk_t *offsets,
326 Indirect *branch)
327{
328 struct buffer_head * bh;
329 ext4_fsblk_t b, new_blocks[4];
330 __le32 *p;
331 int i, j, err, len = 1;
332
333 for (i = 0; i <= indirect_blks; i++) {
334 if (i == indirect_blks) {
335 new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err);
336 } else
337 ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle,
338 ar->inode, ar->goal,
339 ar->flags & EXT4_MB_DELALLOC_RESERVED,
340 NULL, &err);
341 if (err) {
342 i--;
343 goto failed;
344 }
345 branch[i].key = cpu_to_le32(new_blocks[i]);
346 if (i == 0)
347 continue;
348
349 bh = branch[i].bh = sb_getblk(ar->inode->i_sb, new_blocks[i-1]);
350 if (unlikely(!bh)) {
351 err = -ENOMEM;
352 goto failed;
353 }
354 lock_buffer(bh);
355 BUFFER_TRACE(bh, "call get_create_access");
356 err = ext4_journal_get_create_access(handle, bh);
357 if (err) {
358 unlock_buffer(bh);
359 goto failed;
360 }
361
362 memset(bh->b_data, 0, bh->b_size);
363 p = branch[i].p = (__le32 *) bh->b_data + offsets[i];
364 b = new_blocks[i];
365
366 if (i == indirect_blks)
367 len = ar->len;
368 for (j = 0; j < len; j++)
369 *p++ = cpu_to_le32(b++);
370
371 BUFFER_TRACE(bh, "marking uptodate");
372 set_buffer_uptodate(bh);
373 unlock_buffer(bh);
374
375 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
376 err = ext4_handle_dirty_metadata(handle, ar->inode, bh);
377 if (err)
378 goto failed;
379 }
380 return 0;
381failed:
382 for (; i >= 0; i--) {
383 /*
384 * We want to ext4_forget() only freshly allocated indirect
385 * blocks. Buffer for new_blocks[i-1] is at branch[i].bh and
386 * buffer at branch[0].bh is indirect block / inode already
387 * existing before ext4_alloc_branch() was called.
388 */
389 if (i > 0 && i != indirect_blks && branch[i].bh)
390 ext4_forget(handle, 1, ar->inode, branch[i].bh,
391 branch[i].bh->b_blocknr);
392 ext4_free_blocks(handle, ar->inode, NULL, new_blocks[i],
393 (i == indirect_blks) ? ar->len : 1, 0);
394 }
395 return err;
396}
397
398/**
399 * ext4_splice_branch - splice the allocated branch onto inode.
400 * @handle: handle for this transaction
401 * @inode: owner
402 * @block: (logical) number of block we are adding
403 * @chain: chain of indirect blocks (with a missing link - see
404 * ext4_alloc_branch)
405 * @where: location of missing link
406 * @num: number of indirect blocks we are adding
407 * @blks: number of direct blocks we are adding
408 *
409 * This function fills the missing link and does all housekeeping needed in
410 * inode (->i_blocks, etc.). In case of success we end up with the full
411 * chain to new block and return 0.
412 */
413static int ext4_splice_branch(handle_t *handle,
414 struct ext4_allocation_request *ar,
415 Indirect *where, int num)
416{
417 int i;
418 int err = 0;
419 ext4_fsblk_t current_block;
420
421 /*
422 * If we're splicing into a [td]indirect block (as opposed to the
423 * inode) then we need to get write access to the [td]indirect block
424 * before the splice.
425 */
426 if (where->bh) {
427 BUFFER_TRACE(where->bh, "get_write_access");
428 err = ext4_journal_get_write_access(handle, where->bh);
429 if (err)
430 goto err_out;
431 }
432 /* That's it */
433
434 *where->p = where->key;
435
436 /*
437 * Update the host buffer_head or inode to point to more just allocated
438 * direct blocks blocks
439 */
440 if (num == 0 && ar->len > 1) {
441 current_block = le32_to_cpu(where->key) + 1;
442 for (i = 1; i < ar->len; i++)
443 *(where->p + i) = cpu_to_le32(current_block++);
444 }
445
446 /* We are done with atomic stuff, now do the rest of housekeeping */
447 /* had we spliced it onto indirect block? */
448 if (where->bh) {
449 /*
450 * If we spliced it onto an indirect block, we haven't
451 * altered the inode. Note however that if it is being spliced
452 * onto an indirect block at the very end of the file (the
453 * file is growing) then we *will* alter the inode to reflect
454 * the new i_size. But that is not done here - it is done in
455 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
456 */
457 jbd_debug(5, "splicing indirect only\n");
458 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
459 err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh);
460 if (err)
461 goto err_out;
462 } else {
463 /*
464 * OK, we spliced it into the inode itself on a direct block.
465 */
466 ext4_mark_inode_dirty(handle, ar->inode);
467 jbd_debug(5, "splicing direct\n");
468 }
469 return err;
470
471err_out:
472 for (i = 1; i <= num; i++) {
473 /*
474 * branch[i].bh is newly allocated, so there is no
475 * need to revoke the block, which is why we don't
476 * need to set EXT4_FREE_BLOCKS_METADATA.
477 */
478 ext4_free_blocks(handle, ar->inode, where[i].bh, 0, 1,
479 EXT4_FREE_BLOCKS_FORGET);
480 }
481 ext4_free_blocks(handle, ar->inode, NULL, le32_to_cpu(where[num].key),
482 ar->len, 0);
483
484 return err;
485}
486
487/*
488 * The ext4_ind_map_blocks() function handles non-extents inodes
489 * (i.e., using the traditional indirect/double-indirect i_blocks
490 * scheme) for ext4_map_blocks().
491 *
492 * Allocation strategy is simple: if we have to allocate something, we will
493 * have to go the whole way to leaf. So let's do it before attaching anything
494 * to tree, set linkage between the newborn blocks, write them if sync is
495 * required, recheck the path, free and repeat if check fails, otherwise
496 * set the last missing link (that will protect us from any truncate-generated
497 * removals - all blocks on the path are immune now) and possibly force the
498 * write on the parent block.
499 * That has a nice additional property: no special recovery from the failed
500 * allocations is needed - we simply release blocks and do not touch anything
501 * reachable from inode.
502 *
503 * `handle' can be NULL if create == 0.
504 *
505 * return > 0, # of blocks mapped or allocated.
506 * return = 0, if plain lookup failed.
507 * return < 0, error case.
508 *
509 * The ext4_ind_get_blocks() function should be called with
510 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
511 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
512 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
513 * blocks.
514 */
515int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
516 struct ext4_map_blocks *map,
517 int flags)
518{
519 struct ext4_allocation_request ar;
520 int err = -EIO;
521 ext4_lblk_t offsets[4];
522 Indirect chain[4];
523 Indirect *partial;
524 int indirect_blks;
525 int blocks_to_boundary = 0;
526 int depth;
527 int count = 0;
528 ext4_fsblk_t first_block = 0;
529
530 trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
531 J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
532 J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
533 depth = ext4_block_to_path(inode, map->m_lblk, offsets,
534 &blocks_to_boundary);
535
536 if (depth == 0)
537 goto out;
538
539 partial = ext4_get_branch(inode, depth, offsets, chain, &err);
540
541 /* Simplest case - block found, no allocation needed */
542 if (!partial) {
543 first_block = le32_to_cpu(chain[depth - 1].key);
544 count++;
545 /*map more blocks*/
546 while (count < map->m_len && count <= blocks_to_boundary) {
547 ext4_fsblk_t blk;
548
549 blk = le32_to_cpu(*(chain[depth-1].p + count));
550
551 if (blk == first_block + count)
552 count++;
553 else
554 break;
555 }
556 goto got_it;
557 }
558
559 /* Next simple case - plain lookup failed */
560 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
561 unsigned epb = inode->i_sb->s_blocksize / sizeof(u32);
562 int i;
563
564 /* Count number blocks in a subtree under 'partial' */
565 count = 1;
566 for (i = 0; partial + i != chain + depth - 1; i++)
567 count *= epb;
568 /* Fill in size of a hole we found */
569 map->m_pblk = 0;
570 map->m_len = min_t(unsigned int, map->m_len, count);
571 goto cleanup;
572 }
573
574 /* Failed read of indirect block */
575 if (err == -EIO)
576 goto cleanup;
577
578 /*
579 * Okay, we need to do block allocation.
580 */
581 if (ext4_has_feature_bigalloc(inode->i_sb)) {
582 EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
583 "non-extent mapped inodes with bigalloc");
584 return -EFSCORRUPTED;
585 }
586
587 /* Set up for the direct block allocation */
588 memset(&ar, 0, sizeof(ar));
589 ar.inode = inode;
590 ar.logical = map->m_lblk;
591 if (S_ISREG(inode->i_mode))
592 ar.flags = EXT4_MB_HINT_DATA;
593 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
594 ar.flags |= EXT4_MB_DELALLOC_RESERVED;
595 if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
596 ar.flags |= EXT4_MB_USE_RESERVED;
597
598 ar.goal = ext4_find_goal(inode, map->m_lblk, partial);
599
600 /* the number of blocks need to allocate for [d,t]indirect blocks */
601 indirect_blks = (chain + depth) - partial - 1;
602
603 /*
604 * Next look up the indirect map to count the totoal number of
605 * direct blocks to allocate for this branch.
606 */
607 ar.len = ext4_blks_to_allocate(partial, indirect_blks,
608 map->m_len, blocks_to_boundary);
609
610 /*
611 * Block out ext4_truncate while we alter the tree
612 */
613 err = ext4_alloc_branch(handle, &ar, indirect_blks,
614 offsets + (partial - chain), partial);
615
616 /*
617 * The ext4_splice_branch call will free and forget any buffers
618 * on the new chain if there is a failure, but that risks using
619 * up transaction credits, especially for bitmaps where the
620 * credits cannot be returned. Can we handle this somehow? We
621 * may need to return -EAGAIN upwards in the worst case. --sct
622 */
623 if (!err)
624 err = ext4_splice_branch(handle, &ar, partial, indirect_blks);
625 if (err)
626 goto cleanup;
627
628 map->m_flags |= EXT4_MAP_NEW;
629
630 ext4_update_inode_fsync_trans(handle, inode, 1);
631 count = ar.len;
632got_it:
633 map->m_flags |= EXT4_MAP_MAPPED;
634 map->m_pblk = le32_to_cpu(chain[depth-1].key);
635 map->m_len = count;
636 if (count > blocks_to_boundary)
637 map->m_flags |= EXT4_MAP_BOUNDARY;
638 err = count;
639 /* Clean up and exit */
640 partial = chain + depth - 1; /* the whole chain */
641cleanup:
642 while (partial > chain) {
643 BUFFER_TRACE(partial->bh, "call brelse");
644 brelse(partial->bh);
645 partial--;
646 }
647out:
648 trace_ext4_ind_map_blocks_exit(inode, flags, map, err);
649 return err;
650}
651
652/*
653 * Calculate the number of metadata blocks need to reserve
654 * to allocate a new block at @lblocks for non extent file based file
655 */
656int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock)
657{
658 struct ext4_inode_info *ei = EXT4_I(inode);
659 sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
660 int blk_bits;
661
662 if (lblock < EXT4_NDIR_BLOCKS)
663 return 0;
664
665 lblock -= EXT4_NDIR_BLOCKS;
666
667 if (ei->i_da_metadata_calc_len &&
668 (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
669 ei->i_da_metadata_calc_len++;
670 return 0;
671 }
672 ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
673 ei->i_da_metadata_calc_len = 1;
674 blk_bits = order_base_2(lblock);
675 return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
676}
677
678/*
679 * Calculate number of indirect blocks touched by mapping @nrblocks logically
680 * contiguous blocks
681 */
682int ext4_ind_trans_blocks(struct inode *inode, int nrblocks)
683{
684 /*
685 * With N contiguous data blocks, we need at most
686 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
687 * 2 dindirect blocks, and 1 tindirect block
688 */
689 return DIV_ROUND_UP(nrblocks, EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
690}
691
692/*
693 * Truncate transactions can be complex and absolutely huge. So we need to
694 * be able to restart the transaction at a conventient checkpoint to make
695 * sure we don't overflow the journal.
696 *
697 * Try to extend this transaction for the purposes of truncation. If
698 * extend fails, we need to propagate the failure up and restart the
699 * transaction in the top-level truncate loop. --sct
700 *
701 * Returns 0 if we managed to create more room. If we can't create more
702 * room, and the transaction must be restarted we return 1.
703 */
704static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
705{
706 if (!ext4_handle_valid(handle))
707 return 0;
708 if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
709 return 0;
710 if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
711 return 0;
712 return 1;
713}
714
715/*
716 * Probably it should be a library function... search for first non-zero word
717 * or memcmp with zero_page, whatever is better for particular architecture.
718 * Linus?
719 */
720static inline int all_zeroes(__le32 *p, __le32 *q)
721{
722 while (p < q)
723 if (*p++)
724 return 0;
725 return 1;
726}
727
728/**
729 * ext4_find_shared - find the indirect blocks for partial truncation.
730 * @inode: inode in question
731 * @depth: depth of the affected branch
732 * @offsets: offsets of pointers in that branch (see ext4_block_to_path)
733 * @chain: place to store the pointers to partial indirect blocks
734 * @top: place to the (detached) top of branch
735 *
736 * This is a helper function used by ext4_truncate().
737 *
738 * When we do truncate() we may have to clean the ends of several
739 * indirect blocks but leave the blocks themselves alive. Block is
740 * partially truncated if some data below the new i_size is referred
741 * from it (and it is on the path to the first completely truncated
742 * data block, indeed). We have to free the top of that path along
743 * with everything to the right of the path. Since no allocation
744 * past the truncation point is possible until ext4_truncate()
745 * finishes, we may safely do the latter, but top of branch may
746 * require special attention - pageout below the truncation point
747 * might try to populate it.
748 *
749 * We atomically detach the top of branch from the tree, store the
750 * block number of its root in *@top, pointers to buffer_heads of
751 * partially truncated blocks - in @chain[].bh and pointers to
752 * their last elements that should not be removed - in
753 * @chain[].p. Return value is the pointer to last filled element
754 * of @chain.
755 *
756 * The work left to caller to do the actual freeing of subtrees:
757 * a) free the subtree starting from *@top
758 * b) free the subtrees whose roots are stored in
759 * (@chain[i].p+1 .. end of @chain[i].bh->b_data)
760 * c) free the subtrees growing from the inode past the @chain[0].
761 * (no partially truncated stuff there). */
762
763static Indirect *ext4_find_shared(struct inode *inode, int depth,
764 ext4_lblk_t offsets[4], Indirect chain[4],
765 __le32 *top)
766{
767 Indirect *partial, *p;
768 int k, err;
769
770 *top = 0;
771 /* Make k index the deepest non-null offset + 1 */
772 for (k = depth; k > 1 && !offsets[k-1]; k--)
773 ;
774 partial = ext4_get_branch(inode, k, offsets, chain, &err);
775 /* Writer: pointers */
776 if (!partial)
777 partial = chain + k-1;
778 /*
779 * If the branch acquired continuation since we've looked at it -
780 * fine, it should all survive and (new) top doesn't belong to us.
781 */
782 if (!partial->key && *partial->p)
783 /* Writer: end */
784 goto no_top;
785 for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
786 ;
787 /*
788 * OK, we've found the last block that must survive. The rest of our
789 * branch should be detached before unlocking. However, if that rest
790 * of branch is all ours and does not grow immediately from the inode
791 * it's easier to cheat and just decrement partial->p.
792 */
793 if (p == chain + k - 1 && p > chain) {
794 p->p--;
795 } else {
796 *top = *p->p;
797 /* Nope, don't do this in ext4. Must leave the tree intact */
798#if 0
799 *p->p = 0;
800#endif
801 }
802 /* Writer: end */
803
804 while (partial > p) {
805 brelse(partial->bh);
806 partial--;
807 }
808no_top:
809 return partial;
810}
811
812/*
813 * Zero a number of block pointers in either an inode or an indirect block.
814 * If we restart the transaction we must again get write access to the
815 * indirect block for further modification.
816 *
817 * We release `count' blocks on disk, but (last - first) may be greater
818 * than `count' because there can be holes in there.
819 *
820 * Return 0 on success, 1 on invalid block range
821 * and < 0 on fatal error.
822 */
823static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
824 struct buffer_head *bh,
825 ext4_fsblk_t block_to_free,
826 unsigned long count, __le32 *first,
827 __le32 *last)
828{
829 __le32 *p;
830 int flags = EXT4_FREE_BLOCKS_VALIDATED;
831 int err;
832
833 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
834 ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
835 flags |= EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_METADATA;
836 else if (ext4_should_journal_data(inode))
837 flags |= EXT4_FREE_BLOCKS_FORGET;
838
839 if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), block_to_free,
840 count)) {
841 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
842 "blocks %llu len %lu",
843 (unsigned long long) block_to_free, count);
844 return 1;
845 }
846
847 if (try_to_extend_transaction(handle, inode)) {
848 if (bh) {
849 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
850 err = ext4_handle_dirty_metadata(handle, inode, bh);
851 if (unlikely(err))
852 goto out_err;
853 }
854 err = ext4_mark_inode_dirty(handle, inode);
855 if (unlikely(err))
856 goto out_err;
857 err = ext4_truncate_restart_trans(handle, inode,
858 ext4_blocks_for_truncate(inode));
859 if (unlikely(err))
860 goto out_err;
861 if (bh) {
862 BUFFER_TRACE(bh, "retaking write access");
863 err = ext4_journal_get_write_access(handle, bh);
864 if (unlikely(err))
865 goto out_err;
866 }
867 }
868
869 for (p = first; p < last; p++)
870 *p = 0;
871
872 ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
873 return 0;
874out_err:
875 ext4_std_error(inode->i_sb, err);
876 return err;
877}
878
879/**
880 * ext4_free_data - free a list of data blocks
881 * @handle: handle for this transaction
882 * @inode: inode we are dealing with
883 * @this_bh: indirect buffer_head which contains *@first and *@last
884 * @first: array of block numbers
885 * @last: points immediately past the end of array
886 *
887 * We are freeing all blocks referred from that array (numbers are stored as
888 * little-endian 32-bit) and updating @inode->i_blocks appropriately.
889 *
890 * We accumulate contiguous runs of blocks to free. Conveniently, if these
891 * blocks are contiguous then releasing them at one time will only affect one
892 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
893 * actually use a lot of journal space.
894 *
895 * @this_bh will be %NULL if @first and @last point into the inode's direct
896 * block pointers.
897 */
898static void ext4_free_data(handle_t *handle, struct inode *inode,
899 struct buffer_head *this_bh,
900 __le32 *first, __le32 *last)
901{
902 ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */
903 unsigned long count = 0; /* Number of blocks in the run */
904 __le32 *block_to_free_p = NULL; /* Pointer into inode/ind
905 corresponding to
906 block_to_free */
907 ext4_fsblk_t nr; /* Current block # */
908 __le32 *p; /* Pointer into inode/ind
909 for current block */
910 int err = 0;
911
912 if (this_bh) { /* For indirect block */
913 BUFFER_TRACE(this_bh, "get_write_access");
914 err = ext4_journal_get_write_access(handle, this_bh);
915 /* Important: if we can't update the indirect pointers
916 * to the blocks, we can't free them. */
917 if (err)
918 return;
919 }
920
921 for (p = first; p < last; p++) {
922 nr = le32_to_cpu(*p);
923 if (nr) {
924 /* accumulate blocks to free if they're contiguous */
925 if (count == 0) {
926 block_to_free = nr;
927 block_to_free_p = p;
928 count = 1;
929 } else if (nr == block_to_free + count) {
930 count++;
931 } else {
932 err = ext4_clear_blocks(handle, inode, this_bh,
933 block_to_free, count,
934 block_to_free_p, p);
935 if (err)
936 break;
937 block_to_free = nr;
938 block_to_free_p = p;
939 count = 1;
940 }
941 }
942 }
943
944 if (!err && count > 0)
945 err = ext4_clear_blocks(handle, inode, this_bh, block_to_free,
946 count, block_to_free_p, p);
947 if (err < 0)
948 /* fatal error */
949 return;
950
951 if (this_bh) {
952 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
953
954 /*
955 * The buffer head should have an attached journal head at this
956 * point. However, if the data is corrupted and an indirect
957 * block pointed to itself, it would have been detached when
958 * the block was cleared. Check for this instead of OOPSing.
959 */
960 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
961 ext4_handle_dirty_metadata(handle, inode, this_bh);
962 else
963 EXT4_ERROR_INODE(inode,
964 "circular indirect block detected at "
965 "block %llu",
966 (unsigned long long) this_bh->b_blocknr);
967 }
968}
969
970/**
971 * ext4_free_branches - free an array of branches
972 * @handle: JBD handle for this transaction
973 * @inode: inode we are dealing with
974 * @parent_bh: the buffer_head which contains *@first and *@last
975 * @first: array of block numbers
976 * @last: pointer immediately past the end of array
977 * @depth: depth of the branches to free
978 *
979 * We are freeing all blocks referred from these branches (numbers are
980 * stored as little-endian 32-bit) and updating @inode->i_blocks
981 * appropriately.
982 */
983static void ext4_free_branches(handle_t *handle, struct inode *inode,
984 struct buffer_head *parent_bh,
985 __le32 *first, __le32 *last, int depth)
986{
987 ext4_fsblk_t nr;
988 __le32 *p;
989
990 if (ext4_handle_is_aborted(handle))
991 return;
992
993 if (depth--) {
994 struct buffer_head *bh;
995 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
996 p = last;
997 while (--p >= first) {
998 nr = le32_to_cpu(*p);
999 if (!nr)
1000 continue; /* A hole */
1001
1002 if (!ext4_data_block_valid(EXT4_SB(inode->i_sb),
1003 nr, 1)) {
1004 EXT4_ERROR_INODE(inode,
1005 "invalid indirect mapped "
1006 "block %lu (level %d)",
1007 (unsigned long) nr, depth);
1008 break;
1009 }
1010
1011 /* Go read the buffer for the next level down */
1012 bh = sb_bread(inode->i_sb, nr);
1013
1014 /*
1015 * A read failure? Report error and clear slot
1016 * (should be rare).
1017 */
1018 if (!bh) {
1019 EXT4_ERROR_INODE_BLOCK(inode, nr,
1020 "Read failure");
1021 continue;
1022 }
1023
1024 /* This zaps the entire block. Bottom up. */
1025 BUFFER_TRACE(bh, "free child branches");
1026 ext4_free_branches(handle, inode, bh,
1027 (__le32 *) bh->b_data,
1028 (__le32 *) bh->b_data + addr_per_block,
1029 depth);
1030 brelse(bh);
1031
1032 /*
1033 * Everything below this this pointer has been
1034 * released. Now let this top-of-subtree go.
1035 *
1036 * We want the freeing of this indirect block to be
1037 * atomic in the journal with the updating of the
1038 * bitmap block which owns it. So make some room in
1039 * the journal.
1040 *
1041 * We zero the parent pointer *after* freeing its
1042 * pointee in the bitmaps, so if extend_transaction()
1043 * for some reason fails to put the bitmap changes and
1044 * the release into the same transaction, recovery
1045 * will merely complain about releasing a free block,
1046 * rather than leaking blocks.
1047 */
1048 if (ext4_handle_is_aborted(handle))
1049 return;
1050 if (try_to_extend_transaction(handle, inode)) {
1051 ext4_mark_inode_dirty(handle, inode);
1052 ext4_truncate_restart_trans(handle, inode,
1053 ext4_blocks_for_truncate(inode));
1054 }
1055
1056 /*
1057 * The forget flag here is critical because if
1058 * we are journaling (and not doing data
1059 * journaling), we have to make sure a revoke
1060 * record is written to prevent the journal
1061 * replay from overwriting the (former)
1062 * indirect block if it gets reallocated as a
1063 * data block. This must happen in the same
1064 * transaction where the data blocks are
1065 * actually freed.
1066 */
1067 ext4_free_blocks(handle, inode, NULL, nr, 1,
1068 EXT4_FREE_BLOCKS_METADATA|
1069 EXT4_FREE_BLOCKS_FORGET);
1070
1071 if (parent_bh) {
1072 /*
1073 * The block which we have just freed is
1074 * pointed to by an indirect block: journal it
1075 */
1076 BUFFER_TRACE(parent_bh, "get_write_access");
1077 if (!ext4_journal_get_write_access(handle,
1078 parent_bh)){
1079 *p = 0;
1080 BUFFER_TRACE(parent_bh,
1081 "call ext4_handle_dirty_metadata");
1082 ext4_handle_dirty_metadata(handle,
1083 inode,
1084 parent_bh);
1085 }
1086 }
1087 }
1088 } else {
1089 /* We have reached the bottom of the tree. */
1090 BUFFER_TRACE(parent_bh, "free data blocks");
1091 ext4_free_data(handle, inode, parent_bh, first, last);
1092 }
1093}
1094
1095void ext4_ind_truncate(handle_t *handle, struct inode *inode)
1096{
1097 struct ext4_inode_info *ei = EXT4_I(inode);
1098 __le32 *i_data = ei->i_data;
1099 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1100 ext4_lblk_t offsets[4];
1101 Indirect chain[4];
1102 Indirect *partial;
1103 __le32 nr = 0;
1104 int n = 0;
1105 ext4_lblk_t last_block, max_block;
1106 unsigned blocksize = inode->i_sb->s_blocksize;
1107
1108 last_block = (inode->i_size + blocksize-1)
1109 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1110 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1111 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1112
1113 if (last_block != max_block) {
1114 n = ext4_block_to_path(inode, last_block, offsets, NULL);
1115 if (n == 0)
1116 return;
1117 }
1118
1119 ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block);
1120
1121 /*
1122 * The orphan list entry will now protect us from any crash which
1123 * occurs before the truncate completes, so it is now safe to propagate
1124 * the new, shorter inode size (held for now in i_size) into the
1125 * on-disk inode. We do this via i_disksize, which is the value which
1126 * ext4 *really* writes onto the disk inode.
1127 */
1128 ei->i_disksize = inode->i_size;
1129
1130 if (last_block == max_block) {
1131 /*
1132 * It is unnecessary to free any data blocks if last_block is
1133 * equal to the indirect block limit.
1134 */
1135 return;
1136 } else if (n == 1) { /* direct blocks */
1137 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
1138 i_data + EXT4_NDIR_BLOCKS);
1139 goto do_indirects;
1140 }
1141
1142 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1143 /* Kill the top of shared branch (not detached) */
1144 if (nr) {
1145 if (partial == chain) {
1146 /* Shared branch grows from the inode */
1147 ext4_free_branches(handle, inode, NULL,
1148 &nr, &nr+1, (chain+n-1) - partial);
1149 *partial->p = 0;
1150 /*
1151 * We mark the inode dirty prior to restart,
1152 * and prior to stop. No need for it here.
1153 */
1154 } else {
1155 /* Shared branch grows from an indirect block */
1156 BUFFER_TRACE(partial->bh, "get_write_access");
1157 ext4_free_branches(handle, inode, partial->bh,
1158 partial->p,
1159 partial->p+1, (chain+n-1) - partial);
1160 }
1161 }
1162 /* Clear the ends of indirect blocks on the shared branch */
1163 while (partial > chain) {
1164 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
1165 (__le32*)partial->bh->b_data+addr_per_block,
1166 (chain+n-1) - partial);
1167 BUFFER_TRACE(partial->bh, "call brelse");
1168 brelse(partial->bh);
1169 partial--;
1170 }
1171do_indirects:
1172 /* Kill the remaining (whole) subtrees */
1173 switch (offsets[0]) {
1174 default:
1175 nr = i_data[EXT4_IND_BLOCK];
1176 if (nr) {
1177 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1178 i_data[EXT4_IND_BLOCK] = 0;
1179 }
1180 case EXT4_IND_BLOCK:
1181 nr = i_data[EXT4_DIND_BLOCK];
1182 if (nr) {
1183 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1184 i_data[EXT4_DIND_BLOCK] = 0;
1185 }
1186 case EXT4_DIND_BLOCK:
1187 nr = i_data[EXT4_TIND_BLOCK];
1188 if (nr) {
1189 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1190 i_data[EXT4_TIND_BLOCK] = 0;
1191 }
1192 case EXT4_TIND_BLOCK:
1193 ;
1194 }
1195}
1196
1197/**
1198 * ext4_ind_remove_space - remove space from the range
1199 * @handle: JBD handle for this transaction
1200 * @inode: inode we are dealing with
1201 * @start: First block to remove
1202 * @end: One block after the last block to remove (exclusive)
1203 *
1204 * Free the blocks in the defined range (end is exclusive endpoint of
1205 * range). This is used by ext4_punch_hole().
1206 */
1207int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
1208 ext4_lblk_t start, ext4_lblk_t end)
1209{
1210 struct ext4_inode_info *ei = EXT4_I(inode);
1211 __le32 *i_data = ei->i_data;
1212 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1213 ext4_lblk_t offsets[4], offsets2[4];
1214 Indirect chain[4], chain2[4];
1215 Indirect *partial, *partial2;
1216 ext4_lblk_t max_block;
1217 __le32 nr = 0, nr2 = 0;
1218 int n = 0, n2 = 0;
1219 unsigned blocksize = inode->i_sb->s_blocksize;
1220
1221 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1222 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1223 if (end >= max_block)
1224 end = max_block;
1225 if ((start >= end) || (start > max_block))
1226 return 0;
1227
1228 n = ext4_block_to_path(inode, start, offsets, NULL);
1229 n2 = ext4_block_to_path(inode, end, offsets2, NULL);
1230
1231 BUG_ON(n > n2);
1232
1233 if ((n == 1) && (n == n2)) {
1234 /* We're punching only within direct block range */
1235 ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1236 i_data + offsets2[0]);
1237 return 0;
1238 } else if (n2 > n) {
1239 /*
1240 * Start and end are on a different levels so we're going to
1241 * free partial block at start, and partial block at end of
1242 * the range. If there are some levels in between then
1243 * do_indirects label will take care of that.
1244 */
1245
1246 if (n == 1) {
1247 /*
1248 * Start is at the direct block level, free
1249 * everything to the end of the level.
1250 */
1251 ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1252 i_data + EXT4_NDIR_BLOCKS);
1253 goto end_range;
1254 }
1255
1256
1257 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1258 if (nr) {
1259 if (partial == chain) {
1260 /* Shared branch grows from the inode */
1261 ext4_free_branches(handle, inode, NULL,
1262 &nr, &nr+1, (chain+n-1) - partial);
1263 *partial->p = 0;
1264 } else {
1265 /* Shared branch grows from an indirect block */
1266 BUFFER_TRACE(partial->bh, "get_write_access");
1267 ext4_free_branches(handle, inode, partial->bh,
1268 partial->p,
1269 partial->p+1, (chain+n-1) - partial);
1270 }
1271 }
1272
1273 /*
1274 * Clear the ends of indirect blocks on the shared branch
1275 * at the start of the range
1276 */
1277 while (partial > chain) {
1278 ext4_free_branches(handle, inode, partial->bh,
1279 partial->p + 1,
1280 (__le32 *)partial->bh->b_data+addr_per_block,
1281 (chain+n-1) - partial);
1282 BUFFER_TRACE(partial->bh, "call brelse");
1283 brelse(partial->bh);
1284 partial--;
1285 }
1286
1287end_range:
1288 partial2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1289 if (nr2) {
1290 if (partial2 == chain2) {
1291 /*
1292 * Remember, end is exclusive so here we're at
1293 * the start of the next level we're not going
1294 * to free. Everything was covered by the start
1295 * of the range.
1296 */
1297 goto do_indirects;
1298 }
1299 } else {
1300 /*
1301 * ext4_find_shared returns Indirect structure which
1302 * points to the last element which should not be
1303 * removed by truncate. But this is end of the range
1304 * in punch_hole so we need to point to the next element
1305 */
1306 partial2->p++;
1307 }
1308
1309 /*
1310 * Clear the ends of indirect blocks on the shared branch
1311 * at the end of the range
1312 */
1313 while (partial2 > chain2) {
1314 ext4_free_branches(handle, inode, partial2->bh,
1315 (__le32 *)partial2->bh->b_data,
1316 partial2->p,
1317 (chain2+n2-1) - partial2);
1318 BUFFER_TRACE(partial2->bh, "call brelse");
1319 brelse(partial2->bh);
1320 partial2--;
1321 }
1322 goto do_indirects;
1323 }
1324
1325 /* Punch happened within the same level (n == n2) */
1326 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1327 partial2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1328
1329 /* Free top, but only if partial2 isn't its subtree. */
1330 if (nr) {
1331 int level = min(partial - chain, partial2 - chain2);
1332 int i;
1333 int subtree = 1;
1334
1335 for (i = 0; i <= level; i++) {
1336 if (offsets[i] != offsets2[i]) {
1337 subtree = 0;
1338 break;
1339 }
1340 }
1341
1342 if (!subtree) {
1343 if (partial == chain) {
1344 /* Shared branch grows from the inode */
1345 ext4_free_branches(handle, inode, NULL,
1346 &nr, &nr+1,
1347 (chain+n-1) - partial);
1348 *partial->p = 0;
1349 } else {
1350 /* Shared branch grows from an indirect block */
1351 BUFFER_TRACE(partial->bh, "get_write_access");
1352 ext4_free_branches(handle, inode, partial->bh,
1353 partial->p,
1354 partial->p+1,
1355 (chain+n-1) - partial);
1356 }
1357 }
1358 }
1359
1360 if (!nr2) {
1361 /*
1362 * ext4_find_shared returns Indirect structure which
1363 * points to the last element which should not be
1364 * removed by truncate. But this is end of the range
1365 * in punch_hole so we need to point to the next element
1366 */
1367 partial2->p++;
1368 }
1369
1370 while (partial > chain || partial2 > chain2) {
1371 int depth = (chain+n-1) - partial;
1372 int depth2 = (chain2+n2-1) - partial2;
1373
1374 if (partial > chain && partial2 > chain2 &&
1375 partial->bh->b_blocknr == partial2->bh->b_blocknr) {
1376 /*
1377 * We've converged on the same block. Clear the range,
1378 * then we're done.
1379 */
1380 ext4_free_branches(handle, inode, partial->bh,
1381 partial->p + 1,
1382 partial2->p,
1383 (chain+n-1) - partial);
1384 BUFFER_TRACE(partial->bh, "call brelse");
1385 brelse(partial->bh);
1386 BUFFER_TRACE(partial2->bh, "call brelse");
1387 brelse(partial2->bh);
1388 return 0;
1389 }
1390
1391 /*
1392 * The start and end partial branches may not be at the same
1393 * level even though the punch happened within one level. So, we
1394 * give them a chance to arrive at the same level, then walk
1395 * them in step with each other until we converge on the same
1396 * block.
1397 */
1398 if (partial > chain && depth <= depth2) {
1399 ext4_free_branches(handle, inode, partial->bh,
1400 partial->p + 1,
1401 (__le32 *)partial->bh->b_data+addr_per_block,
1402 (chain+n-1) - partial);
1403 BUFFER_TRACE(partial->bh, "call brelse");
1404 brelse(partial->bh);
1405 partial--;
1406 }
1407 if (partial2 > chain2 && depth2 <= depth) {
1408 ext4_free_branches(handle, inode, partial2->bh,
1409 (__le32 *)partial2->bh->b_data,
1410 partial2->p,
1411 (chain2+n2-1) - partial2);
1412 BUFFER_TRACE(partial2->bh, "call brelse");
1413 brelse(partial2->bh);
1414 partial2--;
1415 }
1416 }
1417 return 0;
1418
1419do_indirects:
1420 /* Kill the remaining (whole) subtrees */
1421 switch (offsets[0]) {
1422 default:
1423 if (++n >= n2)
1424 return 0;
1425 nr = i_data[EXT4_IND_BLOCK];
1426 if (nr) {
1427 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1428 i_data[EXT4_IND_BLOCK] = 0;
1429 }
1430 case EXT4_IND_BLOCK:
1431 if (++n >= n2)
1432 return 0;
1433 nr = i_data[EXT4_DIND_BLOCK];
1434 if (nr) {
1435 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1436 i_data[EXT4_DIND_BLOCK] = 0;
1437 }
1438 case EXT4_DIND_BLOCK:
1439 if (++n >= n2)
1440 return 0;
1441 nr = i_data[EXT4_TIND_BLOCK];
1442 if (nr) {
1443 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1444 i_data[EXT4_TIND_BLOCK] = 0;
1445 }
1446 case EXT4_TIND_BLOCK:
1447 ;
1448 }
1449 return 0;
1450}
1/*
2 * linux/fs/ext4/indirect.c
3 *
4 * from
5 *
6 * linux/fs/ext4/inode.c
7 *
8 * Copyright (C) 1992, 1993, 1994, 1995
9 * Remy Card (card@masi.ibp.fr)
10 * Laboratoire MASI - Institut Blaise Pascal
11 * Universite Pierre et Marie Curie (Paris VI)
12 *
13 * from
14 *
15 * linux/fs/minix/inode.c
16 *
17 * Copyright (C) 1991, 1992 Linus Torvalds
18 *
19 * Goal-directed block allocation by Stephen Tweedie
20 * (sct@redhat.com), 1993, 1998
21 */
22
23#include "ext4_jbd2.h"
24#include "truncate.h"
25#include <linux/dax.h>
26#include <linux/uio.h>
27
28#include <trace/events/ext4.h>
29
30typedef struct {
31 __le32 *p;
32 __le32 key;
33 struct buffer_head *bh;
34} Indirect;
35
36static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
37{
38 p->key = *(p->p = v);
39 p->bh = bh;
40}
41
42/**
43 * ext4_block_to_path - parse the block number into array of offsets
44 * @inode: inode in question (we are only interested in its superblock)
45 * @i_block: block number to be parsed
46 * @offsets: array to store the offsets in
47 * @boundary: set this non-zero if the referred-to block is likely to be
48 * followed (on disk) by an indirect block.
49 *
50 * To store the locations of file's data ext4 uses a data structure common
51 * for UNIX filesystems - tree of pointers anchored in the inode, with
52 * data blocks at leaves and indirect blocks in intermediate nodes.
53 * This function translates the block number into path in that tree -
54 * return value is the path length and @offsets[n] is the offset of
55 * pointer to (n+1)th node in the nth one. If @block is out of range
56 * (negative or too large) warning is printed and zero returned.
57 *
58 * Note: function doesn't find node addresses, so no IO is needed. All
59 * we need to know is the capacity of indirect blocks (taken from the
60 * inode->i_sb).
61 */
62
63/*
64 * Portability note: the last comparison (check that we fit into triple
65 * indirect block) is spelled differently, because otherwise on an
66 * architecture with 32-bit longs and 8Kb pages we might get into trouble
67 * if our filesystem had 8Kb blocks. We might use long long, but that would
68 * kill us on x86. Oh, well, at least the sign propagation does not matter -
69 * i_block would have to be negative in the very beginning, so we would not
70 * get there at all.
71 */
72
73static int ext4_block_to_path(struct inode *inode,
74 ext4_lblk_t i_block,
75 ext4_lblk_t offsets[4], int *boundary)
76{
77 int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
78 int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
79 const long direct_blocks = EXT4_NDIR_BLOCKS,
80 indirect_blocks = ptrs,
81 double_blocks = (1 << (ptrs_bits * 2));
82 int n = 0;
83 int final = 0;
84
85 if (i_block < direct_blocks) {
86 offsets[n++] = i_block;
87 final = direct_blocks;
88 } else if ((i_block -= direct_blocks) < indirect_blocks) {
89 offsets[n++] = EXT4_IND_BLOCK;
90 offsets[n++] = i_block;
91 final = ptrs;
92 } else if ((i_block -= indirect_blocks) < double_blocks) {
93 offsets[n++] = EXT4_DIND_BLOCK;
94 offsets[n++] = i_block >> ptrs_bits;
95 offsets[n++] = i_block & (ptrs - 1);
96 final = ptrs;
97 } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
98 offsets[n++] = EXT4_TIND_BLOCK;
99 offsets[n++] = i_block >> (ptrs_bits * 2);
100 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
101 offsets[n++] = i_block & (ptrs - 1);
102 final = ptrs;
103 } else {
104 ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
105 i_block + direct_blocks +
106 indirect_blocks + double_blocks, inode->i_ino);
107 }
108 if (boundary)
109 *boundary = final - 1 - (i_block & (ptrs - 1));
110 return n;
111}
112
113/**
114 * ext4_get_branch - read the chain of indirect blocks leading to data
115 * @inode: inode in question
116 * @depth: depth of the chain (1 - direct pointer, etc.)
117 * @offsets: offsets of pointers in inode/indirect blocks
118 * @chain: place to store the result
119 * @err: here we store the error value
120 *
121 * Function fills the array of triples <key, p, bh> and returns %NULL
122 * if everything went OK or the pointer to the last filled triple
123 * (incomplete one) otherwise. Upon the return chain[i].key contains
124 * the number of (i+1)-th block in the chain (as it is stored in memory,
125 * i.e. little-endian 32-bit), chain[i].p contains the address of that
126 * number (it points into struct inode for i==0 and into the bh->b_data
127 * for i>0) and chain[i].bh points to the buffer_head of i-th indirect
128 * block for i>0 and NULL for i==0. In other words, it holds the block
129 * numbers of the chain, addresses they were taken from (and where we can
130 * verify that chain did not change) and buffer_heads hosting these
131 * numbers.
132 *
133 * Function stops when it stumbles upon zero pointer (absent block)
134 * (pointer to last triple returned, *@err == 0)
135 * or when it gets an IO error reading an indirect block
136 * (ditto, *@err == -EIO)
137 * or when it reads all @depth-1 indirect blocks successfully and finds
138 * the whole chain, all way to the data (returns %NULL, *err == 0).
139 *
140 * Need to be called with
141 * down_read(&EXT4_I(inode)->i_data_sem)
142 */
143static Indirect *ext4_get_branch(struct inode *inode, int depth,
144 ext4_lblk_t *offsets,
145 Indirect chain[4], int *err)
146{
147 struct super_block *sb = inode->i_sb;
148 Indirect *p = chain;
149 struct buffer_head *bh;
150 int ret = -EIO;
151
152 *err = 0;
153 /* i_data is not going away, no lock needed */
154 add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
155 if (!p->key)
156 goto no_block;
157 while (--depth) {
158 bh = sb_getblk(sb, le32_to_cpu(p->key));
159 if (unlikely(!bh)) {
160 ret = -ENOMEM;
161 goto failure;
162 }
163
164 if (!bh_uptodate_or_lock(bh)) {
165 if (bh_submit_read(bh) < 0) {
166 put_bh(bh);
167 goto failure;
168 }
169 /* validate block references */
170 if (ext4_check_indirect_blockref(inode, bh)) {
171 put_bh(bh);
172 goto failure;
173 }
174 }
175
176 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
177 /* Reader: end */
178 if (!p->key)
179 goto no_block;
180 }
181 return NULL;
182
183failure:
184 *err = ret;
185no_block:
186 return p;
187}
188
189/**
190 * ext4_find_near - find a place for allocation with sufficient locality
191 * @inode: owner
192 * @ind: descriptor of indirect block.
193 *
194 * This function returns the preferred place for block allocation.
195 * It is used when heuristic for sequential allocation fails.
196 * Rules are:
197 * + if there is a block to the left of our position - allocate near it.
198 * + if pointer will live in indirect block - allocate near that block.
199 * + if pointer will live in inode - allocate in the same
200 * cylinder group.
201 *
202 * In the latter case we colour the starting block by the callers PID to
203 * prevent it from clashing with concurrent allocations for a different inode
204 * in the same block group. The PID is used here so that functionally related
205 * files will be close-by on-disk.
206 *
207 * Caller must make sure that @ind is valid and will stay that way.
208 */
209static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
210{
211 struct ext4_inode_info *ei = EXT4_I(inode);
212 __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
213 __le32 *p;
214
215 /* Try to find previous block */
216 for (p = ind->p - 1; p >= start; p--) {
217 if (*p)
218 return le32_to_cpu(*p);
219 }
220
221 /* No such thing, so let's try location of indirect block */
222 if (ind->bh)
223 return ind->bh->b_blocknr;
224
225 /*
226 * It is going to be referred to from the inode itself? OK, just put it
227 * into the same cylinder group then.
228 */
229 return ext4_inode_to_goal_block(inode);
230}
231
232/**
233 * ext4_find_goal - find a preferred place for allocation.
234 * @inode: owner
235 * @block: block we want
236 * @partial: pointer to the last triple within a chain
237 *
238 * Normally this function find the preferred place for block allocation,
239 * returns it.
240 * Because this is only used for non-extent files, we limit the block nr
241 * to 32 bits.
242 */
243static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
244 Indirect *partial)
245{
246 ext4_fsblk_t goal;
247
248 /*
249 * XXX need to get goal block from mballoc's data structures
250 */
251
252 goal = ext4_find_near(inode, partial);
253 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
254 return goal;
255}
256
257/**
258 * ext4_blks_to_allocate - Look up the block map and count the number
259 * of direct blocks need to be allocated for the given branch.
260 *
261 * @branch: chain of indirect blocks
262 * @k: number of blocks need for indirect blocks
263 * @blks: number of data blocks to be mapped.
264 * @blocks_to_boundary: the offset in the indirect block
265 *
266 * return the total number of blocks to be allocate, including the
267 * direct and indirect blocks.
268 */
269static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
270 int blocks_to_boundary)
271{
272 unsigned int count = 0;
273
274 /*
275 * Simple case, [t,d]Indirect block(s) has not allocated yet
276 * then it's clear blocks on that path have not allocated
277 */
278 if (k > 0) {
279 /* right now we don't handle cross boundary allocation */
280 if (blks < blocks_to_boundary + 1)
281 count += blks;
282 else
283 count += blocks_to_boundary + 1;
284 return count;
285 }
286
287 count++;
288 while (count < blks && count <= blocks_to_boundary &&
289 le32_to_cpu(*(branch[0].p + count)) == 0) {
290 count++;
291 }
292 return count;
293}
294
295/**
296 * ext4_alloc_branch - allocate and set up a chain of blocks.
297 * @handle: handle for this transaction
298 * @inode: owner
299 * @indirect_blks: number of allocated indirect blocks
300 * @blks: number of allocated direct blocks
301 * @goal: preferred place for allocation
302 * @offsets: offsets (in the blocks) to store the pointers to next.
303 * @branch: place to store the chain in.
304 *
305 * This function allocates blocks, zeroes out all but the last one,
306 * links them into chain and (if we are synchronous) writes them to disk.
307 * In other words, it prepares a branch that can be spliced onto the
308 * inode. It stores the information about that chain in the branch[], in
309 * the same format as ext4_get_branch() would do. We are calling it after
310 * we had read the existing part of chain and partial points to the last
311 * triple of that (one with zero ->key). Upon the exit we have the same
312 * picture as after the successful ext4_get_block(), except that in one
313 * place chain is disconnected - *branch->p is still zero (we did not
314 * set the last link), but branch->key contains the number that should
315 * be placed into *branch->p to fill that gap.
316 *
317 * If allocation fails we free all blocks we've allocated (and forget
318 * their buffer_heads) and return the error value the from failed
319 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
320 * as described above and return 0.
321 */
322static int ext4_alloc_branch(handle_t *handle,
323 struct ext4_allocation_request *ar,
324 int indirect_blks, ext4_lblk_t *offsets,
325 Indirect *branch)
326{
327 struct buffer_head * bh;
328 ext4_fsblk_t b, new_blocks[4];
329 __le32 *p;
330 int i, j, err, len = 1;
331
332 for (i = 0; i <= indirect_blks; i++) {
333 if (i == indirect_blks) {
334 new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err);
335 } else
336 ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle,
337 ar->inode, ar->goal,
338 ar->flags & EXT4_MB_DELALLOC_RESERVED,
339 NULL, &err);
340 if (err) {
341 i--;
342 goto failed;
343 }
344 branch[i].key = cpu_to_le32(new_blocks[i]);
345 if (i == 0)
346 continue;
347
348 bh = branch[i].bh = sb_getblk(ar->inode->i_sb, new_blocks[i-1]);
349 if (unlikely(!bh)) {
350 err = -ENOMEM;
351 goto failed;
352 }
353 lock_buffer(bh);
354 BUFFER_TRACE(bh, "call get_create_access");
355 err = ext4_journal_get_create_access(handle, bh);
356 if (err) {
357 unlock_buffer(bh);
358 goto failed;
359 }
360
361 memset(bh->b_data, 0, bh->b_size);
362 p = branch[i].p = (__le32 *) bh->b_data + offsets[i];
363 b = new_blocks[i];
364
365 if (i == indirect_blks)
366 len = ar->len;
367 for (j = 0; j < len; j++)
368 *p++ = cpu_to_le32(b++);
369
370 BUFFER_TRACE(bh, "marking uptodate");
371 set_buffer_uptodate(bh);
372 unlock_buffer(bh);
373
374 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
375 err = ext4_handle_dirty_metadata(handle, ar->inode, bh);
376 if (err)
377 goto failed;
378 }
379 return 0;
380failed:
381 for (; i >= 0; i--) {
382 /*
383 * We want to ext4_forget() only freshly allocated indirect
384 * blocks. Buffer for new_blocks[i-1] is at branch[i].bh and
385 * buffer at branch[0].bh is indirect block / inode already
386 * existing before ext4_alloc_branch() was called.
387 */
388 if (i > 0 && i != indirect_blks && branch[i].bh)
389 ext4_forget(handle, 1, ar->inode, branch[i].bh,
390 branch[i].bh->b_blocknr);
391 ext4_free_blocks(handle, ar->inode, NULL, new_blocks[i],
392 (i == indirect_blks) ? ar->len : 1, 0);
393 }
394 return err;
395}
396
397/**
398 * ext4_splice_branch - splice the allocated branch onto inode.
399 * @handle: handle for this transaction
400 * @inode: owner
401 * @block: (logical) number of block we are adding
402 * @chain: chain of indirect blocks (with a missing link - see
403 * ext4_alloc_branch)
404 * @where: location of missing link
405 * @num: number of indirect blocks we are adding
406 * @blks: number of direct blocks we are adding
407 *
408 * This function fills the missing link and does all housekeeping needed in
409 * inode (->i_blocks, etc.). In case of success we end up with the full
410 * chain to new block and return 0.
411 */
412static int ext4_splice_branch(handle_t *handle,
413 struct ext4_allocation_request *ar,
414 Indirect *where, int num)
415{
416 int i;
417 int err = 0;
418 ext4_fsblk_t current_block;
419
420 /*
421 * If we're splicing into a [td]indirect block (as opposed to the
422 * inode) then we need to get write access to the [td]indirect block
423 * before the splice.
424 */
425 if (where->bh) {
426 BUFFER_TRACE(where->bh, "get_write_access");
427 err = ext4_journal_get_write_access(handle, where->bh);
428 if (err)
429 goto err_out;
430 }
431 /* That's it */
432
433 *where->p = where->key;
434
435 /*
436 * Update the host buffer_head or inode to point to more just allocated
437 * direct blocks blocks
438 */
439 if (num == 0 && ar->len > 1) {
440 current_block = le32_to_cpu(where->key) + 1;
441 for (i = 1; i < ar->len; i++)
442 *(where->p + i) = cpu_to_le32(current_block++);
443 }
444
445 /* We are done with atomic stuff, now do the rest of housekeeping */
446 /* had we spliced it onto indirect block? */
447 if (where->bh) {
448 /*
449 * If we spliced it onto an indirect block, we haven't
450 * altered the inode. Note however that if it is being spliced
451 * onto an indirect block at the very end of the file (the
452 * file is growing) then we *will* alter the inode to reflect
453 * the new i_size. But that is not done here - it is done in
454 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
455 */
456 jbd_debug(5, "splicing indirect only\n");
457 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
458 err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh);
459 if (err)
460 goto err_out;
461 } else {
462 /*
463 * OK, we spliced it into the inode itself on a direct block.
464 */
465 ext4_mark_inode_dirty(handle, ar->inode);
466 jbd_debug(5, "splicing direct\n");
467 }
468 return err;
469
470err_out:
471 for (i = 1; i <= num; i++) {
472 /*
473 * branch[i].bh is newly allocated, so there is no
474 * need to revoke the block, which is why we don't
475 * need to set EXT4_FREE_BLOCKS_METADATA.
476 */
477 ext4_free_blocks(handle, ar->inode, where[i].bh, 0, 1,
478 EXT4_FREE_BLOCKS_FORGET);
479 }
480 ext4_free_blocks(handle, ar->inode, NULL, le32_to_cpu(where[num].key),
481 ar->len, 0);
482
483 return err;
484}
485
486/*
487 * The ext4_ind_map_blocks() function handles non-extents inodes
488 * (i.e., using the traditional indirect/double-indirect i_blocks
489 * scheme) for ext4_map_blocks().
490 *
491 * Allocation strategy is simple: if we have to allocate something, we will
492 * have to go the whole way to leaf. So let's do it before attaching anything
493 * to tree, set linkage between the newborn blocks, write them if sync is
494 * required, recheck the path, free and repeat if check fails, otherwise
495 * set the last missing link (that will protect us from any truncate-generated
496 * removals - all blocks on the path are immune now) and possibly force the
497 * write on the parent block.
498 * That has a nice additional property: no special recovery from the failed
499 * allocations is needed - we simply release blocks and do not touch anything
500 * reachable from inode.
501 *
502 * `handle' can be NULL if create == 0.
503 *
504 * return > 0, # of blocks mapped or allocated.
505 * return = 0, if plain lookup failed.
506 * return < 0, error case.
507 *
508 * The ext4_ind_get_blocks() function should be called with
509 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
510 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
511 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
512 * blocks.
513 */
514int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
515 struct ext4_map_blocks *map,
516 int flags)
517{
518 struct ext4_allocation_request ar;
519 int err = -EIO;
520 ext4_lblk_t offsets[4];
521 Indirect chain[4];
522 Indirect *partial;
523 int indirect_blks;
524 int blocks_to_boundary = 0;
525 int depth;
526 int count = 0;
527 ext4_fsblk_t first_block = 0;
528
529 trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
530 J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
531 J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
532 depth = ext4_block_to_path(inode, map->m_lblk, offsets,
533 &blocks_to_boundary);
534
535 if (depth == 0)
536 goto out;
537
538 partial = ext4_get_branch(inode, depth, offsets, chain, &err);
539
540 /* Simplest case - block found, no allocation needed */
541 if (!partial) {
542 first_block = le32_to_cpu(chain[depth - 1].key);
543 count++;
544 /*map more blocks*/
545 while (count < map->m_len && count <= blocks_to_boundary) {
546 ext4_fsblk_t blk;
547
548 blk = le32_to_cpu(*(chain[depth-1].p + count));
549
550 if (blk == first_block + count)
551 count++;
552 else
553 break;
554 }
555 goto got_it;
556 }
557
558 /* Next simple case - plain lookup failed */
559 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
560 unsigned epb = inode->i_sb->s_blocksize / sizeof(u32);
561 int i;
562
563 /* Count number blocks in a subtree under 'partial' */
564 count = 1;
565 for (i = 0; partial + i != chain + depth - 1; i++)
566 count *= epb;
567 /* Fill in size of a hole we found */
568 map->m_pblk = 0;
569 map->m_len = min_t(unsigned int, map->m_len, count);
570 goto cleanup;
571 }
572
573 /* Failed read of indirect block */
574 if (err == -EIO)
575 goto cleanup;
576
577 /*
578 * Okay, we need to do block allocation.
579 */
580 if (ext4_has_feature_bigalloc(inode->i_sb)) {
581 EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
582 "non-extent mapped inodes with bigalloc");
583 return -EFSCORRUPTED;
584 }
585
586 /* Set up for the direct block allocation */
587 memset(&ar, 0, sizeof(ar));
588 ar.inode = inode;
589 ar.logical = map->m_lblk;
590 if (S_ISREG(inode->i_mode))
591 ar.flags = EXT4_MB_HINT_DATA;
592 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
593 ar.flags |= EXT4_MB_DELALLOC_RESERVED;
594 if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
595 ar.flags |= EXT4_MB_USE_RESERVED;
596
597 ar.goal = ext4_find_goal(inode, map->m_lblk, partial);
598
599 /* the number of blocks need to allocate for [d,t]indirect blocks */
600 indirect_blks = (chain + depth) - partial - 1;
601
602 /*
603 * Next look up the indirect map to count the totoal number of
604 * direct blocks to allocate for this branch.
605 */
606 ar.len = ext4_blks_to_allocate(partial, indirect_blks,
607 map->m_len, blocks_to_boundary);
608
609 /*
610 * Block out ext4_truncate while we alter the tree
611 */
612 err = ext4_alloc_branch(handle, &ar, indirect_blks,
613 offsets + (partial - chain), partial);
614
615 /*
616 * The ext4_splice_branch call will free and forget any buffers
617 * on the new chain if there is a failure, but that risks using
618 * up transaction credits, especially for bitmaps where the
619 * credits cannot be returned. Can we handle this somehow? We
620 * may need to return -EAGAIN upwards in the worst case. --sct
621 */
622 if (!err)
623 err = ext4_splice_branch(handle, &ar, partial, indirect_blks);
624 if (err)
625 goto cleanup;
626
627 map->m_flags |= EXT4_MAP_NEW;
628
629 ext4_update_inode_fsync_trans(handle, inode, 1);
630 count = ar.len;
631got_it:
632 map->m_flags |= EXT4_MAP_MAPPED;
633 map->m_pblk = le32_to_cpu(chain[depth-1].key);
634 map->m_len = count;
635 if (count > blocks_to_boundary)
636 map->m_flags |= EXT4_MAP_BOUNDARY;
637 err = count;
638 /* Clean up and exit */
639 partial = chain + depth - 1; /* the whole chain */
640cleanup:
641 while (partial > chain) {
642 BUFFER_TRACE(partial->bh, "call brelse");
643 brelse(partial->bh);
644 partial--;
645 }
646out:
647 trace_ext4_ind_map_blocks_exit(inode, flags, map, err);
648 return err;
649}
650
651/*
652 * O_DIRECT for ext3 (or indirect map) based files
653 *
654 * If the O_DIRECT write will extend the file then add this inode to the
655 * orphan list. So recovery will truncate it back to the original size
656 * if the machine crashes during the write.
657 *
658 * If the O_DIRECT write is intantiating holes inside i_size and the machine
659 * crashes then stale disk data _may_ be exposed inside the file. But current
660 * VFS code falls back into buffered path in that case so we are safe.
661 */
662ssize_t ext4_ind_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
663 loff_t offset)
664{
665 struct file *file = iocb->ki_filp;
666 struct inode *inode = file->f_mapping->host;
667 struct ext4_inode_info *ei = EXT4_I(inode);
668 handle_t *handle;
669 ssize_t ret;
670 int orphan = 0;
671 size_t count = iov_iter_count(iter);
672 int retries = 0;
673
674 if (iov_iter_rw(iter) == WRITE) {
675 loff_t final_size = offset + count;
676
677 if (final_size > inode->i_size) {
678 /* Credits for sb + inode write */
679 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
680 if (IS_ERR(handle)) {
681 ret = PTR_ERR(handle);
682 goto out;
683 }
684 ret = ext4_orphan_add(handle, inode);
685 if (ret) {
686 ext4_journal_stop(handle);
687 goto out;
688 }
689 orphan = 1;
690 ei->i_disksize = inode->i_size;
691 ext4_journal_stop(handle);
692 }
693 }
694
695retry:
696 if (iov_iter_rw(iter) == READ && ext4_should_dioread_nolock(inode)) {
697 /*
698 * Nolock dioread optimization may be dynamically disabled
699 * via ext4_inode_block_unlocked_dio(). Check inode's state
700 * while holding extra i_dio_count ref.
701 */
702 inode_dio_begin(inode);
703 smp_mb();
704 if (unlikely(ext4_test_inode_state(inode,
705 EXT4_STATE_DIOREAD_LOCK))) {
706 inode_dio_end(inode);
707 goto locked;
708 }
709 if (IS_DAX(inode))
710 ret = dax_do_io(iocb, inode, iter, offset,
711 ext4_dio_get_block, NULL, 0);
712 else
713 ret = __blockdev_direct_IO(iocb, inode,
714 inode->i_sb->s_bdev, iter,
715 offset, ext4_dio_get_block,
716 NULL, NULL, 0);
717 inode_dio_end(inode);
718 } else {
719locked:
720 if (IS_DAX(inode))
721 ret = dax_do_io(iocb, inode, iter, offset,
722 ext4_dio_get_block, NULL, DIO_LOCKING);
723 else
724 ret = blockdev_direct_IO(iocb, inode, iter, offset,
725 ext4_dio_get_block);
726
727 if (unlikely(iov_iter_rw(iter) == WRITE && ret < 0)) {
728 loff_t isize = i_size_read(inode);
729 loff_t end = offset + count;
730
731 if (end > isize)
732 ext4_truncate_failed_write(inode);
733 }
734 }
735 if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
736 goto retry;
737
738 if (orphan) {
739 int err;
740
741 /* Credits for sb + inode write */
742 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
743 if (IS_ERR(handle)) {
744 /* This is really bad luck. We've written the data
745 * but cannot extend i_size. Bail out and pretend
746 * the write failed... */
747 ret = PTR_ERR(handle);
748 if (inode->i_nlink)
749 ext4_orphan_del(NULL, inode);
750
751 goto out;
752 }
753 if (inode->i_nlink)
754 ext4_orphan_del(handle, inode);
755 if (ret > 0) {
756 loff_t end = offset + ret;
757 if (end > inode->i_size) {
758 ei->i_disksize = end;
759 i_size_write(inode, end);
760 /*
761 * We're going to return a positive `ret'
762 * here due to non-zero-length I/O, so there's
763 * no way of reporting error returns from
764 * ext4_mark_inode_dirty() to userspace. So
765 * ignore it.
766 */
767 ext4_mark_inode_dirty(handle, inode);
768 }
769 }
770 err = ext4_journal_stop(handle);
771 if (ret == 0)
772 ret = err;
773 }
774out:
775 return ret;
776}
777
778/*
779 * Calculate the number of metadata blocks need to reserve
780 * to allocate a new block at @lblocks for non extent file based file
781 */
782int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock)
783{
784 struct ext4_inode_info *ei = EXT4_I(inode);
785 sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
786 int blk_bits;
787
788 if (lblock < EXT4_NDIR_BLOCKS)
789 return 0;
790
791 lblock -= EXT4_NDIR_BLOCKS;
792
793 if (ei->i_da_metadata_calc_len &&
794 (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
795 ei->i_da_metadata_calc_len++;
796 return 0;
797 }
798 ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
799 ei->i_da_metadata_calc_len = 1;
800 blk_bits = order_base_2(lblock);
801 return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
802}
803
804/*
805 * Calculate number of indirect blocks touched by mapping @nrblocks logically
806 * contiguous blocks
807 */
808int ext4_ind_trans_blocks(struct inode *inode, int nrblocks)
809{
810 /*
811 * With N contiguous data blocks, we need at most
812 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
813 * 2 dindirect blocks, and 1 tindirect block
814 */
815 return DIV_ROUND_UP(nrblocks, EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
816}
817
818/*
819 * Truncate transactions can be complex and absolutely huge. So we need to
820 * be able to restart the transaction at a conventient checkpoint to make
821 * sure we don't overflow the journal.
822 *
823 * Try to extend this transaction for the purposes of truncation. If
824 * extend fails, we need to propagate the failure up and restart the
825 * transaction in the top-level truncate loop. --sct
826 *
827 * Returns 0 if we managed to create more room. If we can't create more
828 * room, and the transaction must be restarted we return 1.
829 */
830static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
831{
832 if (!ext4_handle_valid(handle))
833 return 0;
834 if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
835 return 0;
836 if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
837 return 0;
838 return 1;
839}
840
841/*
842 * Probably it should be a library function... search for first non-zero word
843 * or memcmp with zero_page, whatever is better for particular architecture.
844 * Linus?
845 */
846static inline int all_zeroes(__le32 *p, __le32 *q)
847{
848 while (p < q)
849 if (*p++)
850 return 0;
851 return 1;
852}
853
854/**
855 * ext4_find_shared - find the indirect blocks for partial truncation.
856 * @inode: inode in question
857 * @depth: depth of the affected branch
858 * @offsets: offsets of pointers in that branch (see ext4_block_to_path)
859 * @chain: place to store the pointers to partial indirect blocks
860 * @top: place to the (detached) top of branch
861 *
862 * This is a helper function used by ext4_truncate().
863 *
864 * When we do truncate() we may have to clean the ends of several
865 * indirect blocks but leave the blocks themselves alive. Block is
866 * partially truncated if some data below the new i_size is referred
867 * from it (and it is on the path to the first completely truncated
868 * data block, indeed). We have to free the top of that path along
869 * with everything to the right of the path. Since no allocation
870 * past the truncation point is possible until ext4_truncate()
871 * finishes, we may safely do the latter, but top of branch may
872 * require special attention - pageout below the truncation point
873 * might try to populate it.
874 *
875 * We atomically detach the top of branch from the tree, store the
876 * block number of its root in *@top, pointers to buffer_heads of
877 * partially truncated blocks - in @chain[].bh and pointers to
878 * their last elements that should not be removed - in
879 * @chain[].p. Return value is the pointer to last filled element
880 * of @chain.
881 *
882 * The work left to caller to do the actual freeing of subtrees:
883 * a) free the subtree starting from *@top
884 * b) free the subtrees whose roots are stored in
885 * (@chain[i].p+1 .. end of @chain[i].bh->b_data)
886 * c) free the subtrees growing from the inode past the @chain[0].
887 * (no partially truncated stuff there). */
888
889static Indirect *ext4_find_shared(struct inode *inode, int depth,
890 ext4_lblk_t offsets[4], Indirect chain[4],
891 __le32 *top)
892{
893 Indirect *partial, *p;
894 int k, err;
895
896 *top = 0;
897 /* Make k index the deepest non-null offset + 1 */
898 for (k = depth; k > 1 && !offsets[k-1]; k--)
899 ;
900 partial = ext4_get_branch(inode, k, offsets, chain, &err);
901 /* Writer: pointers */
902 if (!partial)
903 partial = chain + k-1;
904 /*
905 * If the branch acquired continuation since we've looked at it -
906 * fine, it should all survive and (new) top doesn't belong to us.
907 */
908 if (!partial->key && *partial->p)
909 /* Writer: end */
910 goto no_top;
911 for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
912 ;
913 /*
914 * OK, we've found the last block that must survive. The rest of our
915 * branch should be detached before unlocking. However, if that rest
916 * of branch is all ours and does not grow immediately from the inode
917 * it's easier to cheat and just decrement partial->p.
918 */
919 if (p == chain + k - 1 && p > chain) {
920 p->p--;
921 } else {
922 *top = *p->p;
923 /* Nope, don't do this in ext4. Must leave the tree intact */
924#if 0
925 *p->p = 0;
926#endif
927 }
928 /* Writer: end */
929
930 while (partial > p) {
931 brelse(partial->bh);
932 partial--;
933 }
934no_top:
935 return partial;
936}
937
938/*
939 * Zero a number of block pointers in either an inode or an indirect block.
940 * If we restart the transaction we must again get write access to the
941 * indirect block for further modification.
942 *
943 * We release `count' blocks on disk, but (last - first) may be greater
944 * than `count' because there can be holes in there.
945 *
946 * Return 0 on success, 1 on invalid block range
947 * and < 0 on fatal error.
948 */
949static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
950 struct buffer_head *bh,
951 ext4_fsblk_t block_to_free,
952 unsigned long count, __le32 *first,
953 __le32 *last)
954{
955 __le32 *p;
956 int flags = EXT4_FREE_BLOCKS_VALIDATED;
957 int err;
958
959 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
960 flags |= EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_METADATA;
961 else if (ext4_should_journal_data(inode))
962 flags |= EXT4_FREE_BLOCKS_FORGET;
963
964 if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), block_to_free,
965 count)) {
966 EXT4_ERROR_INODE(inode, "attempt to clear invalid "
967 "blocks %llu len %lu",
968 (unsigned long long) block_to_free, count);
969 return 1;
970 }
971
972 if (try_to_extend_transaction(handle, inode)) {
973 if (bh) {
974 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
975 err = ext4_handle_dirty_metadata(handle, inode, bh);
976 if (unlikely(err))
977 goto out_err;
978 }
979 err = ext4_mark_inode_dirty(handle, inode);
980 if (unlikely(err))
981 goto out_err;
982 err = ext4_truncate_restart_trans(handle, inode,
983 ext4_blocks_for_truncate(inode));
984 if (unlikely(err))
985 goto out_err;
986 if (bh) {
987 BUFFER_TRACE(bh, "retaking write access");
988 err = ext4_journal_get_write_access(handle, bh);
989 if (unlikely(err))
990 goto out_err;
991 }
992 }
993
994 for (p = first; p < last; p++)
995 *p = 0;
996
997 ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
998 return 0;
999out_err:
1000 ext4_std_error(inode->i_sb, err);
1001 return err;
1002}
1003
1004/**
1005 * ext4_free_data - free a list of data blocks
1006 * @handle: handle for this transaction
1007 * @inode: inode we are dealing with
1008 * @this_bh: indirect buffer_head which contains *@first and *@last
1009 * @first: array of block numbers
1010 * @last: points immediately past the end of array
1011 *
1012 * We are freeing all blocks referred from that array (numbers are stored as
1013 * little-endian 32-bit) and updating @inode->i_blocks appropriately.
1014 *
1015 * We accumulate contiguous runs of blocks to free. Conveniently, if these
1016 * blocks are contiguous then releasing them at one time will only affect one
1017 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
1018 * actually use a lot of journal space.
1019 *
1020 * @this_bh will be %NULL if @first and @last point into the inode's direct
1021 * block pointers.
1022 */
1023static void ext4_free_data(handle_t *handle, struct inode *inode,
1024 struct buffer_head *this_bh,
1025 __le32 *first, __le32 *last)
1026{
1027 ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */
1028 unsigned long count = 0; /* Number of blocks in the run */
1029 __le32 *block_to_free_p = NULL; /* Pointer into inode/ind
1030 corresponding to
1031 block_to_free */
1032 ext4_fsblk_t nr; /* Current block # */
1033 __le32 *p; /* Pointer into inode/ind
1034 for current block */
1035 int err = 0;
1036
1037 if (this_bh) { /* For indirect block */
1038 BUFFER_TRACE(this_bh, "get_write_access");
1039 err = ext4_journal_get_write_access(handle, this_bh);
1040 /* Important: if we can't update the indirect pointers
1041 * to the blocks, we can't free them. */
1042 if (err)
1043 return;
1044 }
1045
1046 for (p = first; p < last; p++) {
1047 nr = le32_to_cpu(*p);
1048 if (nr) {
1049 /* accumulate blocks to free if they're contiguous */
1050 if (count == 0) {
1051 block_to_free = nr;
1052 block_to_free_p = p;
1053 count = 1;
1054 } else if (nr == block_to_free + count) {
1055 count++;
1056 } else {
1057 err = ext4_clear_blocks(handle, inode, this_bh,
1058 block_to_free, count,
1059 block_to_free_p, p);
1060 if (err)
1061 break;
1062 block_to_free = nr;
1063 block_to_free_p = p;
1064 count = 1;
1065 }
1066 }
1067 }
1068
1069 if (!err && count > 0)
1070 err = ext4_clear_blocks(handle, inode, this_bh, block_to_free,
1071 count, block_to_free_p, p);
1072 if (err < 0)
1073 /* fatal error */
1074 return;
1075
1076 if (this_bh) {
1077 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
1078
1079 /*
1080 * The buffer head should have an attached journal head at this
1081 * point. However, if the data is corrupted and an indirect
1082 * block pointed to itself, it would have been detached when
1083 * the block was cleared. Check for this instead of OOPSing.
1084 */
1085 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
1086 ext4_handle_dirty_metadata(handle, inode, this_bh);
1087 else
1088 EXT4_ERROR_INODE(inode,
1089 "circular indirect block detected at "
1090 "block %llu",
1091 (unsigned long long) this_bh->b_blocknr);
1092 }
1093}
1094
1095/**
1096 * ext4_free_branches - free an array of branches
1097 * @handle: JBD handle for this transaction
1098 * @inode: inode we are dealing with
1099 * @parent_bh: the buffer_head which contains *@first and *@last
1100 * @first: array of block numbers
1101 * @last: pointer immediately past the end of array
1102 * @depth: depth of the branches to free
1103 *
1104 * We are freeing all blocks referred from these branches (numbers are
1105 * stored as little-endian 32-bit) and updating @inode->i_blocks
1106 * appropriately.
1107 */
1108static void ext4_free_branches(handle_t *handle, struct inode *inode,
1109 struct buffer_head *parent_bh,
1110 __le32 *first, __le32 *last, int depth)
1111{
1112 ext4_fsblk_t nr;
1113 __le32 *p;
1114
1115 if (ext4_handle_is_aborted(handle))
1116 return;
1117
1118 if (depth--) {
1119 struct buffer_head *bh;
1120 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1121 p = last;
1122 while (--p >= first) {
1123 nr = le32_to_cpu(*p);
1124 if (!nr)
1125 continue; /* A hole */
1126
1127 if (!ext4_data_block_valid(EXT4_SB(inode->i_sb),
1128 nr, 1)) {
1129 EXT4_ERROR_INODE(inode,
1130 "invalid indirect mapped "
1131 "block %lu (level %d)",
1132 (unsigned long) nr, depth);
1133 break;
1134 }
1135
1136 /* Go read the buffer for the next level down */
1137 bh = sb_bread(inode->i_sb, nr);
1138
1139 /*
1140 * A read failure? Report error and clear slot
1141 * (should be rare).
1142 */
1143 if (!bh) {
1144 EXT4_ERROR_INODE_BLOCK(inode, nr,
1145 "Read failure");
1146 continue;
1147 }
1148
1149 /* This zaps the entire block. Bottom up. */
1150 BUFFER_TRACE(bh, "free child branches");
1151 ext4_free_branches(handle, inode, bh,
1152 (__le32 *) bh->b_data,
1153 (__le32 *) bh->b_data + addr_per_block,
1154 depth);
1155 brelse(bh);
1156
1157 /*
1158 * Everything below this this pointer has been
1159 * released. Now let this top-of-subtree go.
1160 *
1161 * We want the freeing of this indirect block to be
1162 * atomic in the journal with the updating of the
1163 * bitmap block which owns it. So make some room in
1164 * the journal.
1165 *
1166 * We zero the parent pointer *after* freeing its
1167 * pointee in the bitmaps, so if extend_transaction()
1168 * for some reason fails to put the bitmap changes and
1169 * the release into the same transaction, recovery
1170 * will merely complain about releasing a free block,
1171 * rather than leaking blocks.
1172 */
1173 if (ext4_handle_is_aborted(handle))
1174 return;
1175 if (try_to_extend_transaction(handle, inode)) {
1176 ext4_mark_inode_dirty(handle, inode);
1177 ext4_truncate_restart_trans(handle, inode,
1178 ext4_blocks_for_truncate(inode));
1179 }
1180
1181 /*
1182 * The forget flag here is critical because if
1183 * we are journaling (and not doing data
1184 * journaling), we have to make sure a revoke
1185 * record is written to prevent the journal
1186 * replay from overwriting the (former)
1187 * indirect block if it gets reallocated as a
1188 * data block. This must happen in the same
1189 * transaction where the data blocks are
1190 * actually freed.
1191 */
1192 ext4_free_blocks(handle, inode, NULL, nr, 1,
1193 EXT4_FREE_BLOCKS_METADATA|
1194 EXT4_FREE_BLOCKS_FORGET);
1195
1196 if (parent_bh) {
1197 /*
1198 * The block which we have just freed is
1199 * pointed to by an indirect block: journal it
1200 */
1201 BUFFER_TRACE(parent_bh, "get_write_access");
1202 if (!ext4_journal_get_write_access(handle,
1203 parent_bh)){
1204 *p = 0;
1205 BUFFER_TRACE(parent_bh,
1206 "call ext4_handle_dirty_metadata");
1207 ext4_handle_dirty_metadata(handle,
1208 inode,
1209 parent_bh);
1210 }
1211 }
1212 }
1213 } else {
1214 /* We have reached the bottom of the tree. */
1215 BUFFER_TRACE(parent_bh, "free data blocks");
1216 ext4_free_data(handle, inode, parent_bh, first, last);
1217 }
1218}
1219
1220void ext4_ind_truncate(handle_t *handle, struct inode *inode)
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];
1226 Indirect chain[4];
1227 Indirect *partial;
1228 __le32 nr = 0;
1229 int n = 0;
1230 ext4_lblk_t last_block, max_block;
1231 unsigned blocksize = inode->i_sb->s_blocksize;
1232
1233 last_block = (inode->i_size + blocksize-1)
1234 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1235 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1236 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1237
1238 if (last_block != max_block) {
1239 n = ext4_block_to_path(inode, last_block, offsets, NULL);
1240 if (n == 0)
1241 return;
1242 }
1243
1244 ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block);
1245
1246 /*
1247 * The orphan list entry will now protect us from any crash which
1248 * occurs before the truncate completes, so it is now safe to propagate
1249 * the new, shorter inode size (held for now in i_size) into the
1250 * on-disk inode. We do this via i_disksize, which is the value which
1251 * ext4 *really* writes onto the disk inode.
1252 */
1253 ei->i_disksize = inode->i_size;
1254
1255 if (last_block == max_block) {
1256 /*
1257 * It is unnecessary to free any data blocks if last_block is
1258 * equal to the indirect block limit.
1259 */
1260 return;
1261 } else if (n == 1) { /* direct blocks */
1262 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
1263 i_data + EXT4_NDIR_BLOCKS);
1264 goto do_indirects;
1265 }
1266
1267 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1268 /* Kill the top of shared branch (not detached) */
1269 if (nr) {
1270 if (partial == chain) {
1271 /* Shared branch grows from the inode */
1272 ext4_free_branches(handle, inode, NULL,
1273 &nr, &nr+1, (chain+n-1) - partial);
1274 *partial->p = 0;
1275 /*
1276 * We mark the inode dirty prior to restart,
1277 * and prior to stop. No need for it here.
1278 */
1279 } else {
1280 /* Shared branch grows from an indirect block */
1281 BUFFER_TRACE(partial->bh, "get_write_access");
1282 ext4_free_branches(handle, inode, partial->bh,
1283 partial->p,
1284 partial->p+1, (chain+n-1) - partial);
1285 }
1286 }
1287 /* Clear the ends of indirect blocks on the shared branch */
1288 while (partial > chain) {
1289 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
1290 (__le32*)partial->bh->b_data+addr_per_block,
1291 (chain+n-1) - partial);
1292 BUFFER_TRACE(partial->bh, "call brelse");
1293 brelse(partial->bh);
1294 partial--;
1295 }
1296do_indirects:
1297 /* Kill the remaining (whole) subtrees */
1298 switch (offsets[0]) {
1299 default:
1300 nr = i_data[EXT4_IND_BLOCK];
1301 if (nr) {
1302 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1303 i_data[EXT4_IND_BLOCK] = 0;
1304 }
1305 case EXT4_IND_BLOCK:
1306 nr = i_data[EXT4_DIND_BLOCK];
1307 if (nr) {
1308 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1309 i_data[EXT4_DIND_BLOCK] = 0;
1310 }
1311 case EXT4_DIND_BLOCK:
1312 nr = i_data[EXT4_TIND_BLOCK];
1313 if (nr) {
1314 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1315 i_data[EXT4_TIND_BLOCK] = 0;
1316 }
1317 case EXT4_TIND_BLOCK:
1318 ;
1319 }
1320}
1321
1322/**
1323 * ext4_ind_remove_space - remove space from the range
1324 * @handle: JBD handle for this transaction
1325 * @inode: inode we are dealing with
1326 * @start: First block to remove
1327 * @end: One block after the last block to remove (exclusive)
1328 *
1329 * Free the blocks in the defined range (end is exclusive endpoint of
1330 * range). This is used by ext4_punch_hole().
1331 */
1332int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
1333 ext4_lblk_t start, ext4_lblk_t end)
1334{
1335 struct ext4_inode_info *ei = EXT4_I(inode);
1336 __le32 *i_data = ei->i_data;
1337 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1338 ext4_lblk_t offsets[4], offsets2[4];
1339 Indirect chain[4], chain2[4];
1340 Indirect *partial, *partial2;
1341 ext4_lblk_t max_block;
1342 __le32 nr = 0, nr2 = 0;
1343 int n = 0, n2 = 0;
1344 unsigned blocksize = inode->i_sb->s_blocksize;
1345
1346 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1347 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1348 if (end >= max_block)
1349 end = max_block;
1350 if ((start >= end) || (start > max_block))
1351 return 0;
1352
1353 n = ext4_block_to_path(inode, start, offsets, NULL);
1354 n2 = ext4_block_to_path(inode, end, offsets2, NULL);
1355
1356 BUG_ON(n > n2);
1357
1358 if ((n == 1) && (n == n2)) {
1359 /* We're punching only within direct block range */
1360 ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1361 i_data + offsets2[0]);
1362 return 0;
1363 } else if (n2 > n) {
1364 /*
1365 * Start and end are on a different levels so we're going to
1366 * free partial block at start, and partial block at end of
1367 * the range. If there are some levels in between then
1368 * do_indirects label will take care of that.
1369 */
1370
1371 if (n == 1) {
1372 /*
1373 * Start is at the direct block level, free
1374 * everything to the end of the level.
1375 */
1376 ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1377 i_data + EXT4_NDIR_BLOCKS);
1378 goto end_range;
1379 }
1380
1381
1382 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1383 if (nr) {
1384 if (partial == chain) {
1385 /* Shared branch grows from the inode */
1386 ext4_free_branches(handle, inode, NULL,
1387 &nr, &nr+1, (chain+n-1) - partial);
1388 *partial->p = 0;
1389 } else {
1390 /* Shared branch grows from an indirect block */
1391 BUFFER_TRACE(partial->bh, "get_write_access");
1392 ext4_free_branches(handle, inode, partial->bh,
1393 partial->p,
1394 partial->p+1, (chain+n-1) - partial);
1395 }
1396 }
1397
1398 /*
1399 * Clear the ends of indirect blocks on the shared branch
1400 * at the start of the range
1401 */
1402 while (partial > chain) {
1403 ext4_free_branches(handle, inode, partial->bh,
1404 partial->p + 1,
1405 (__le32 *)partial->bh->b_data+addr_per_block,
1406 (chain+n-1) - partial);
1407 BUFFER_TRACE(partial->bh, "call brelse");
1408 brelse(partial->bh);
1409 partial--;
1410 }
1411
1412end_range:
1413 partial2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1414 if (nr2) {
1415 if (partial2 == chain2) {
1416 /*
1417 * Remember, end is exclusive so here we're at
1418 * the start of the next level we're not going
1419 * to free. Everything was covered by the start
1420 * of the range.
1421 */
1422 goto do_indirects;
1423 }
1424 } else {
1425 /*
1426 * ext4_find_shared returns Indirect structure which
1427 * points to the last element which should not be
1428 * removed by truncate. But this is end of the range
1429 * in punch_hole so we need to point to the next element
1430 */
1431 partial2->p++;
1432 }
1433
1434 /*
1435 * Clear the ends of indirect blocks on the shared branch
1436 * at the end of the range
1437 */
1438 while (partial2 > chain2) {
1439 ext4_free_branches(handle, inode, partial2->bh,
1440 (__le32 *)partial2->bh->b_data,
1441 partial2->p,
1442 (chain2+n2-1) - partial2);
1443 BUFFER_TRACE(partial2->bh, "call brelse");
1444 brelse(partial2->bh);
1445 partial2--;
1446 }
1447 goto do_indirects;
1448 }
1449
1450 /* Punch happened within the same level (n == n2) */
1451 partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1452 partial2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1453
1454 /* Free top, but only if partial2 isn't its subtree. */
1455 if (nr) {
1456 int level = min(partial - chain, partial2 - chain2);
1457 int i;
1458 int subtree = 1;
1459
1460 for (i = 0; i <= level; i++) {
1461 if (offsets[i] != offsets2[i]) {
1462 subtree = 0;
1463 break;
1464 }
1465 }
1466
1467 if (!subtree) {
1468 if (partial == chain) {
1469 /* Shared branch grows from the inode */
1470 ext4_free_branches(handle, inode, NULL,
1471 &nr, &nr+1,
1472 (chain+n-1) - partial);
1473 *partial->p = 0;
1474 } else {
1475 /* Shared branch grows from an indirect block */
1476 BUFFER_TRACE(partial->bh, "get_write_access");
1477 ext4_free_branches(handle, inode, partial->bh,
1478 partial->p,
1479 partial->p+1,
1480 (chain+n-1) - partial);
1481 }
1482 }
1483 }
1484
1485 if (!nr2) {
1486 /*
1487 * ext4_find_shared returns Indirect structure which
1488 * points to the last element which should not be
1489 * removed by truncate. But this is end of the range
1490 * in punch_hole so we need to point to the next element
1491 */
1492 partial2->p++;
1493 }
1494
1495 while (partial > chain || partial2 > chain2) {
1496 int depth = (chain+n-1) - partial;
1497 int depth2 = (chain2+n2-1) - partial2;
1498
1499 if (partial > chain && partial2 > chain2 &&
1500 partial->bh->b_blocknr == partial2->bh->b_blocknr) {
1501 /*
1502 * We've converged on the same block. Clear the range,
1503 * then we're done.
1504 */
1505 ext4_free_branches(handle, inode, partial->bh,
1506 partial->p + 1,
1507 partial2->p,
1508 (chain+n-1) - partial);
1509 BUFFER_TRACE(partial->bh, "call brelse");
1510 brelse(partial->bh);
1511 BUFFER_TRACE(partial2->bh, "call brelse");
1512 brelse(partial2->bh);
1513 return 0;
1514 }
1515
1516 /*
1517 * The start and end partial branches may not be at the same
1518 * level even though the punch happened within one level. So, we
1519 * give them a chance to arrive at the same level, then walk
1520 * them in step with each other until we converge on the same
1521 * block.
1522 */
1523 if (partial > chain && depth <= depth2) {
1524 ext4_free_branches(handle, inode, partial->bh,
1525 partial->p + 1,
1526 (__le32 *)partial->bh->b_data+addr_per_block,
1527 (chain+n-1) - partial);
1528 BUFFER_TRACE(partial->bh, "call brelse");
1529 brelse(partial->bh);
1530 partial--;
1531 }
1532 if (partial2 > chain2 && depth2 <= depth) {
1533 ext4_free_branches(handle, inode, partial2->bh,
1534 (__le32 *)partial2->bh->b_data,
1535 partial2->p,
1536 (chain2+n2-1) - partial2);
1537 BUFFER_TRACE(partial2->bh, "call brelse");
1538 brelse(partial2->bh);
1539 partial2--;
1540 }
1541 }
1542 return 0;
1543
1544do_indirects:
1545 /* Kill the remaining (whole) subtrees */
1546 switch (offsets[0]) {
1547 default:
1548 if (++n >= n2)
1549 return 0;
1550 nr = i_data[EXT4_IND_BLOCK];
1551 if (nr) {
1552 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1553 i_data[EXT4_IND_BLOCK] = 0;
1554 }
1555 case EXT4_IND_BLOCK:
1556 if (++n >= n2)
1557 return 0;
1558 nr = i_data[EXT4_DIND_BLOCK];
1559 if (nr) {
1560 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1561 i_data[EXT4_DIND_BLOCK] = 0;
1562 }
1563 case EXT4_DIND_BLOCK:
1564 if (++n >= n2)
1565 return 0;
1566 nr = i_data[EXT4_TIND_BLOCK];
1567 if (nr) {
1568 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1569 i_data[EXT4_TIND_BLOCK] = 0;
1570 }
1571 case EXT4_TIND_BLOCK:
1572 ;
1573 }
1574 return 0;
1575}