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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 : :
31 : : typedef struct {
32 : : __le32 *p;
33 : : __le32 key;
34 : : struct buffer_head *bh;
35 : : } Indirect;
36 : :
37 : : static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
38 : : {
39 : 0 : p->key = *(p->p = v);
40 : 0 : p->bh = bh;
41 : : }
42 : :
43 : : /**
44 : : * ext4_block_to_path - parse the block number into array of offsets
45 : : * @inode: inode in question (we are only interested in its superblock)
46 : : * @i_block: block number to be parsed
47 : : * @offsets: array to store the offsets in
48 : : * @boundary: set this non-zero if the referred-to block is likely to be
49 : : * followed (on disk) by an indirect block.
50 : : *
51 : : * To store the locations of file's data ext4 uses a data structure common
52 : : * for UNIX filesystems - tree of pointers anchored in the inode, with
53 : : * data blocks at leaves and indirect blocks in intermediate nodes.
54 : : * This function translates the block number into path in that tree -
55 : : * return value is the path length and @offsets[n] is the offset of
56 : : * pointer to (n+1)th node in the nth one. If @block is out of range
57 : : * (negative or too large) warning is printed and zero returned.
58 : : *
59 : : * Note: function doesn't find node addresses, so no IO is needed. All
60 : : * we need to know is the capacity of indirect blocks (taken from the
61 : : * inode->i_sb).
62 : : */
63 : :
64 : : /*
65 : : * Portability note: the last comparison (check that we fit into triple
66 : : * indirect block) is spelled differently, because otherwise on an
67 : : * architecture with 32-bit longs and 8Kb pages we might get into trouble
68 : : * if our filesystem had 8Kb blocks. We might use long long, but that would
69 : : * kill us on x86. Oh, well, at least the sign propagation does not matter -
70 : : * i_block would have to be negative in the very beginning, so we would not
71 : : * get there at all.
72 : : */
73 : :
74 : 0 : static int ext4_block_to_path(struct inode *inode,
75 : : ext4_lblk_t i_block,
76 : : ext4_lblk_t offsets[4], int *boundary)
77 : : {
78 : 0 : int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
79 : 0 : int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
80 : : const long direct_blocks = EXT4_NDIR_BLOCKS,
81 : : indirect_blocks = ptrs,
82 : 0 : double_blocks = (1 << (ptrs_bits * 2));
83 : : int n = 0;
84 : : int final = 0;
85 : :
86 : 0 : if (i_block < direct_blocks) {
87 : 0 : offsets[n++] = i_block;
88 : : final = direct_blocks;
89 : 0 : } else if ((i_block -= direct_blocks) < indirect_blocks) {
90 : 0 : offsets[n++] = EXT4_IND_BLOCK;
91 : 0 : offsets[n++] = i_block;
92 : : final = ptrs;
93 : 0 : } else if ((i_block -= indirect_blocks) < double_blocks) {
94 : 0 : offsets[n++] = EXT4_DIND_BLOCK;
95 : 0 : offsets[n++] = i_block >> ptrs_bits;
96 : 0 : offsets[n++] = i_block & (ptrs - 1);
97 : : final = ptrs;
98 : 0 : } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
99 : 0 : offsets[n++] = EXT4_TIND_BLOCK;
100 : 0 : offsets[n++] = i_block >> (ptrs_bits * 2);
101 : 0 : offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
102 : 0 : offsets[n++] = i_block & (ptrs - 1);
103 : : final = ptrs;
104 : : } else {
105 : 0 : 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 : 0 : if (boundary)
110 : 0 : *boundary = final - 1 - (i_block & (ptrs - 1));
111 : 0 : return n;
112 : : }
113 : :
114 : : /**
115 : : * ext4_get_branch - read the chain of indirect blocks leading to data
116 : : * @inode: inode in question
117 : : * @depth: depth of the chain (1 - direct pointer, etc.)
118 : : * @offsets: offsets of pointers in inode/indirect blocks
119 : : * @chain: place to store the result
120 : : * @err: here we store the error value
121 : : *
122 : : * Function fills the array of triples <key, p, bh> and returns %NULL
123 : : * if everything went OK or the pointer to the last filled triple
124 : : * (incomplete one) otherwise. Upon the return chain[i].key contains
125 : : * the number of (i+1)-th block in the chain (as it is stored in memory,
126 : : * i.e. little-endian 32-bit), chain[i].p contains the address of that
127 : : * number (it points into struct inode for i==0 and into the bh->b_data
128 : : * for i>0) and chain[i].bh points to the buffer_head of i-th indirect
129 : : * block for i>0 and NULL for i==0. In other words, it holds the block
130 : : * numbers of the chain, addresses they were taken from (and where we can
131 : : * verify that chain did not change) and buffer_heads hosting these
132 : : * numbers.
133 : : *
134 : : * Function stops when it stumbles upon zero pointer (absent block)
135 : : * (pointer to last triple returned, *@err == 0)
136 : : * or when it gets an IO error reading an indirect block
137 : : * (ditto, *@err == -EIO)
138 : : * or when it reads all @depth-1 indirect blocks successfully and finds
139 : : * the whole chain, all way to the data (returns %NULL, *err == 0).
140 : : *
141 : : * Need to be called with
142 : : * down_read(&EXT4_I(inode)->i_data_sem)
143 : : */
144 : 0 : static Indirect *ext4_get_branch(struct inode *inode, int depth,
145 : : ext4_lblk_t *offsets,
146 : : Indirect chain[4], int *err)
147 : : {
148 : 0 : struct super_block *sb = inode->i_sb;
149 : : Indirect *p = chain;
150 : : struct buffer_head *bh;
151 : : int ret = -EIO;
152 : :
153 : 0 : *err = 0;
154 : : /* i_data is not going away, no lock needed */
155 : 0 : add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
156 : 0 : if (!p->key)
157 : : goto no_block;
158 : 0 : while (--depth) {
159 : 0 : bh = sb_getblk(sb, le32_to_cpu(p->key));
160 : 0 : if (unlikely(!bh)) {
161 : : ret = -ENOMEM;
162 : : goto failure;
163 : : }
164 : :
165 : 0 : if (!bh_uptodate_or_lock(bh)) {
166 : 0 : if (bh_submit_read(bh) < 0) {
167 : 0 : put_bh(bh);
168 : 0 : goto failure;
169 : : }
170 : : /* validate block references */
171 : 0 : if (ext4_check_indirect_blockref(inode, bh)) {
172 : 0 : put_bh(bh);
173 : 0 : goto failure;
174 : : }
175 : : }
176 : :
177 : 0 : add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
178 : : /* Reader: end */
179 : 0 : if (!p->key)
180 : : goto no_block;
181 : : }
182 : : return NULL;
183 : :
184 : : failure:
185 : 0 : *err = ret;
186 : : no_block:
187 : 0 : return p;
188 : : }
189 : :
190 : : /**
191 : : * ext4_find_near - find a place for allocation with sufficient locality
192 : : * @inode: owner
193 : : * @ind: descriptor of indirect block.
194 : : *
195 : : * This function returns the preferred place for block allocation.
196 : : * It is used when heuristic for sequential allocation fails.
197 : : * Rules are:
198 : : * + if there is a block to the left of our position - allocate near it.
199 : : * + if pointer will live in indirect block - allocate near that block.
200 : : * + if pointer will live in inode - allocate in the same
201 : : * cylinder group.
202 : : *
203 : : * In the latter case we colour the starting block by the callers PID to
204 : : * prevent it from clashing with concurrent allocations for a different inode
205 : : * in the same block group. The PID is used here so that functionally related
206 : : * files will be close-by on-disk.
207 : : *
208 : : * Caller must make sure that @ind is valid and will stay that way.
209 : : */
210 : 0 : static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
211 : : {
212 : : struct ext4_inode_info *ei = EXT4_I(inode);
213 : 0 : __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
214 : : __le32 *p;
215 : :
216 : : /* Try to find previous block */
217 : 0 : for (p = ind->p - 1; p >= start; p--) {
218 : 0 : if (*p)
219 : 0 : return le32_to_cpu(*p);
220 : : }
221 : :
222 : : /* No such thing, so let's try location of indirect block */
223 : 0 : if (ind->bh)
224 : 0 : 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 : 0 : return ext4_inode_to_goal_block(inode);
231 : : }
232 : :
233 : : /**
234 : : * ext4_find_goal - find a preferred place for allocation.
235 : : * @inode: owner
236 : : * @block: block we want
237 : : * @partial: pointer to the last triple within a chain
238 : : *
239 : : * Normally this function find the preferred place for block allocation,
240 : : * returns it.
241 : : * Because this is only used for non-extent files, we limit the block nr
242 : : * to 32 bits.
243 : : */
244 : : static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
245 : : Indirect *partial)
246 : : {
247 : : ext4_fsblk_t goal;
248 : :
249 : : /*
250 : : * XXX need to get goal block from mballoc's data structures
251 : : */
252 : :
253 : 0 : goal = ext4_find_near(inode, partial);
254 : 0 : goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
255 : : return goal;
256 : : }
257 : :
258 : : /**
259 : : * ext4_blks_to_allocate - Look up the block map and count the number
260 : : * of direct blocks need to be allocated for the given branch.
261 : : *
262 : : * @branch: chain of indirect blocks
263 : : * @k: number of blocks need for indirect blocks
264 : : * @blks: number of data blocks to be mapped.
265 : : * @blocks_to_boundary: the offset in the indirect block
266 : : *
267 : : * return the total number of blocks to be allocate, including the
268 : : * direct and indirect blocks.
269 : : */
270 : 0 : static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
271 : : int blocks_to_boundary)
272 : : {
273 : : unsigned int count = 0;
274 : :
275 : : /*
276 : : * Simple case, [t,d]Indirect block(s) has not allocated yet
277 : : * then it's clear blocks on that path have not allocated
278 : : */
279 : 0 : if (k > 0) {
280 : : /* right now we don't handle cross boundary allocation */
281 : 0 : if (blks < blocks_to_boundary + 1)
282 : : count += blks;
283 : : else
284 : 0 : count += blocks_to_boundary + 1;
285 : 0 : return count;
286 : : }
287 : :
288 : : count++;
289 : 0 : while (count < blks && count <= blocks_to_boundary &&
290 : 0 : le32_to_cpu(*(branch[0].p + count)) == 0) {
291 : 0 : count++;
292 : : }
293 : 0 : return count;
294 : : }
295 : :
296 : : /**
297 : : * ext4_alloc_branch() - allocate and set up a chain of blocks
298 : : * @handle: handle for this transaction
299 : : * @ar: structure describing the allocation request
300 : : * @indirect_blks: number of allocated indirect blocks
301 : : * @offsets: offsets (in the blocks) to store the pointers to next.
302 : : * @branch: place to store the chain in.
303 : : *
304 : : * This function allocates blocks, zeroes out all but the last one,
305 : : * links them into chain and (if we are synchronous) writes them to disk.
306 : : * In other words, it prepares a branch that can be spliced onto the
307 : : * inode. It stores the information about that chain in the branch[], in
308 : : * the same format as ext4_get_branch() would do. We are calling it after
309 : : * we had read the existing part of chain and partial points to the last
310 : : * triple of that (one with zero ->key). Upon the exit we have the same
311 : : * picture as after the successful ext4_get_block(), except that in one
312 : : * place chain is disconnected - *branch->p is still zero (we did not
313 : : * set the last link), but branch->key contains the number that should
314 : : * be placed into *branch->p to fill that gap.
315 : : *
316 : : * If allocation fails we free all blocks we've allocated (and forget
317 : : * their buffer_heads) and return the error value the from failed
318 : : * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
319 : : * as described above and return 0.
320 : : */
321 : 0 : static int ext4_alloc_branch(handle_t *handle,
322 : : struct ext4_allocation_request *ar,
323 : : int indirect_blks, ext4_lblk_t *offsets,
324 : : Indirect *branch)
325 : : {
326 : : struct buffer_head * bh;
327 : : ext4_fsblk_t b, new_blocks[4];
328 : : __le32 *p;
329 : : int i, j, err, len = 1;
330 : :
331 : 0 : for (i = 0; i <= indirect_blks; i++) {
332 : 0 : if (i == indirect_blks) {
333 : 0 : new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err);
334 : : } else
335 : 0 : ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle,
336 : : ar->inode, ar->goal,
337 : 0 : ar->flags & EXT4_MB_DELALLOC_RESERVED,
338 : : NULL, &err);
339 : 0 : if (err) {
340 : 0 : i--;
341 : 0 : goto failed;
342 : : }
343 : 0 : branch[i].key = cpu_to_le32(new_blocks[i]);
344 : 0 : if (i == 0)
345 : 0 : continue;
346 : :
347 : 0 : bh = branch[i].bh = sb_getblk(ar->inode->i_sb, new_blocks[i-1]);
348 : 0 : if (unlikely(!bh)) {
349 : 0 : err = -ENOMEM;
350 : 0 : goto failed;
351 : : }
352 : 0 : lock_buffer(bh);
353 : : BUFFER_TRACE(bh, "call get_create_access");
354 : 0 : err = ext4_journal_get_create_access(handle, bh);
355 : 0 : if (err) {
356 : 0 : unlock_buffer(bh);
357 : 0 : goto failed;
358 : : }
359 : :
360 : 0 : memset(bh->b_data, 0, bh->b_size);
361 : 0 : p = branch[i].p = (__le32 *) bh->b_data + offsets[i];
362 : : b = new_blocks[i];
363 : :
364 : 0 : if (i == indirect_blks)
365 : 0 : len = ar->len;
366 : 0 : for (j = 0; j < len; j++)
367 : 0 : *p++ = cpu_to_le32(b++);
368 : :
369 : : BUFFER_TRACE(bh, "marking uptodate");
370 : : set_buffer_uptodate(bh);
371 : 0 : unlock_buffer(bh);
372 : :
373 : : BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
374 : 0 : err = ext4_handle_dirty_metadata(handle, ar->inode, bh);
375 : 0 : if (err)
376 : : goto failed;
377 : : }
378 : : return 0;
379 : : failed:
380 : 0 : for (; i >= 0; i--) {
381 : : /*
382 : : * We want to ext4_forget() only freshly allocated indirect
383 : : * blocks. Buffer for new_blocks[i-1] is at branch[i].bh and
384 : : * buffer at branch[0].bh is indirect block / inode already
385 : : * existing before ext4_alloc_branch() was called.
386 : : */
387 : 0 : if (i > 0 && i != indirect_blks && branch[i].bh)
388 : 0 : ext4_forget(handle, 1, ar->inode, branch[i].bh,
389 : : branch[i].bh->b_blocknr);
390 : 0 : ext4_free_blocks(handle, ar->inode, NULL, new_blocks[i],
391 : : (i == indirect_blks) ? ar->len : 1, 0);
392 : : }
393 : 0 : return err;
394 : : }
395 : :
396 : : /**
397 : : * ext4_splice_branch() - splice the allocated branch onto inode.
398 : : * @handle: handle for this transaction
399 : : * @ar: structure describing the allocation request
400 : : * @where: location of missing link
401 : : * @num: number of indirect blocks we are adding
402 : : *
403 : : * This function fills the missing link and does all housekeeping needed in
404 : : * inode (->i_blocks, etc.). In case of success we end up with the full
405 : : * chain to new block and return 0.
406 : : */
407 : 0 : static int ext4_splice_branch(handle_t *handle,
408 : : struct ext4_allocation_request *ar,
409 : : Indirect *where, int num)
410 : : {
411 : : int i;
412 : : int err = 0;
413 : : ext4_fsblk_t current_block;
414 : :
415 : : /*
416 : : * If we're splicing into a [td]indirect block (as opposed to the
417 : : * inode) then we need to get write access to the [td]indirect block
418 : : * before the splice.
419 : : */
420 : 0 : if (where->bh) {
421 : : BUFFER_TRACE(where->bh, "get_write_access");
422 : 0 : err = ext4_journal_get_write_access(handle, where->bh);
423 : 0 : if (err)
424 : : goto err_out;
425 : : }
426 : : /* That's it */
427 : :
428 : 0 : *where->p = where->key;
429 : :
430 : : /*
431 : : * Update the host buffer_head or inode to point to more just allocated
432 : : * direct blocks blocks
433 : : */
434 : 0 : if (num == 0 && ar->len > 1) {
435 : 0 : current_block = le32_to_cpu(where->key) + 1;
436 : 0 : for (i = 1; i < ar->len; i++)
437 : 0 : *(where->p + i) = cpu_to_le32(current_block++);
438 : : }
439 : :
440 : : /* We are done with atomic stuff, now do the rest of housekeeping */
441 : : /* had we spliced it onto indirect block? */
442 : 0 : if (where->bh) {
443 : : /*
444 : : * If we spliced it onto an indirect block, we haven't
445 : : * altered the inode. Note however that if it is being spliced
446 : : * onto an indirect block at the very end of the file (the
447 : : * file is growing) then we *will* alter the inode to reflect
448 : : * the new i_size. But that is not done here - it is done in
449 : : * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
450 : : */
451 : : jbd_debug(5, "splicing indirect only\n");
452 : : BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
453 : 0 : err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh);
454 : 0 : if (err)
455 : : goto err_out;
456 : : } else {
457 : : /*
458 : : * OK, we spliced it into the inode itself on a direct block.
459 : : */
460 : 0 : ext4_mark_inode_dirty(handle, ar->inode);
461 : : jbd_debug(5, "splicing direct\n");
462 : : }
463 : 0 : return err;
464 : :
465 : : err_out:
466 : 0 : for (i = 1; i <= num; i++) {
467 : : /*
468 : : * branch[i].bh is newly allocated, so there is no
469 : : * need to revoke the block, which is why we don't
470 : : * need to set EXT4_FREE_BLOCKS_METADATA.
471 : : */
472 : 0 : ext4_free_blocks(handle, ar->inode, where[i].bh, 0, 1,
473 : : EXT4_FREE_BLOCKS_FORGET);
474 : : }
475 : 0 : ext4_free_blocks(handle, ar->inode, NULL, le32_to_cpu(where[num].key),
476 : 0 : ar->len, 0);
477 : :
478 : 0 : return err;
479 : : }
480 : :
481 : : /*
482 : : * The ext4_ind_map_blocks() function handles non-extents inodes
483 : : * (i.e., using the traditional indirect/double-indirect i_blocks
484 : : * scheme) for ext4_map_blocks().
485 : : *
486 : : * Allocation strategy is simple: if we have to allocate something, we will
487 : : * have to go the whole way to leaf. So let's do it before attaching anything
488 : : * to tree, set linkage between the newborn blocks, write them if sync is
489 : : * required, recheck the path, free and repeat if check fails, otherwise
490 : : * set the last missing link (that will protect us from any truncate-generated
491 : : * removals - all blocks on the path are immune now) and possibly force the
492 : : * write on the parent block.
493 : : * That has a nice additional property: no special recovery from the failed
494 : : * allocations is needed - we simply release blocks and do not touch anything
495 : : * reachable from inode.
496 : : *
497 : : * `handle' can be NULL if create == 0.
498 : : *
499 : : * return > 0, # of blocks mapped or allocated.
500 : : * return = 0, if plain lookup failed.
501 : : * return < 0, error case.
502 : : *
503 : : * The ext4_ind_get_blocks() function should be called with
504 : : * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
505 : : * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
506 : : * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
507 : : * blocks.
508 : : */
509 : 0 : int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
510 : : struct ext4_map_blocks *map,
511 : : int flags)
512 : : {
513 : : struct ext4_allocation_request ar;
514 : 0 : int err = -EIO;
515 : : ext4_lblk_t offsets[4];
516 : : Indirect chain[4];
517 : : Indirect *partial;
518 : : int indirect_blks;
519 : 0 : int blocks_to_boundary = 0;
520 : : int depth;
521 : : int count = 0;
522 : : ext4_fsblk_t first_block = 0;
523 : :
524 : 0 : trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
525 : 0 : J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
526 : 0 : J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
527 : 0 : depth = ext4_block_to_path(inode, map->m_lblk, offsets,
528 : : &blocks_to_boundary);
529 : :
530 : 0 : if (depth == 0)
531 : : goto out;
532 : :
533 : 0 : partial = ext4_get_branch(inode, depth, offsets, chain, &err);
534 : :
535 : : /* Simplest case - block found, no allocation needed */
536 : 0 : if (!partial) {
537 : 0 : first_block = le32_to_cpu(chain[depth - 1].key);
538 : : count++;
539 : : /*map more blocks*/
540 : 0 : while (count < map->m_len && count <= blocks_to_boundary) {
541 : : ext4_fsblk_t blk;
542 : :
543 : 0 : blk = le32_to_cpu(*(chain[depth-1].p + count));
544 : :
545 : 0 : if (blk == first_block + count)
546 : 0 : count++;
547 : : else
548 : : break;
549 : : }
550 : : goto got_it;
551 : : }
552 : :
553 : : /* Next simple case - plain lookup failed */
554 : 0 : if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
555 : 0 : unsigned epb = inode->i_sb->s_blocksize / sizeof(u32);
556 : : int i;
557 : :
558 : : /*
559 : : * Count number blocks in a subtree under 'partial'. At each
560 : : * level we count number of complete empty subtrees beyond
561 : : * current offset and then descend into the subtree only
562 : : * partially beyond current offset.
563 : : */
564 : : count = 0;
565 : 0 : for (i = partial - chain + 1; i < depth; i++)
566 : 0 : count = count * epb + (epb - offsets[i] - 1);
567 : 0 : count++;
568 : : /* Fill in size of a hole we found */
569 : 0 : map->m_pblk = 0;
570 : 0 : map->m_len = min_t(unsigned int, map->m_len, count);
571 : 0 : goto cleanup;
572 : : }
573 : :
574 : : /* Failed read of indirect block */
575 : 0 : if (err == -EIO)
576 : : goto cleanup;
577 : :
578 : : /*
579 : : * Okay, we need to do block allocation.
580 : : */
581 : 0 : if (ext4_has_feature_bigalloc(inode->i_sb)) {
582 : 0 : EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
583 : : "non-extent mapped inodes with bigalloc");
584 : 0 : return -EFSCORRUPTED;
585 : : }
586 : :
587 : : /* Set up for the direct block allocation */
588 : 0 : memset(&ar, 0, sizeof(ar));
589 : 0 : ar.inode = inode;
590 : 0 : ar.logical = map->m_lblk;
591 : 0 : if (S_ISREG(inode->i_mode))
592 : 0 : ar.flags = EXT4_MB_HINT_DATA;
593 : 0 : if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
594 : 0 : ar.flags |= EXT4_MB_DELALLOC_RESERVED;
595 : 0 : if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
596 : 0 : ar.flags |= EXT4_MB_USE_RESERVED;
597 : :
598 : 0 : 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 : 0 : 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 : 0 : 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 : 0 : err = ext4_alloc_branch(handle, &ar, indirect_blks,
614 : 0 : 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 : 0 : if (!err)
624 : 0 : err = ext4_splice_branch(handle, &ar, partial, indirect_blks);
625 : 0 : if (err)
626 : : goto cleanup;
627 : :
628 : 0 : map->m_flags |= EXT4_MAP_NEW;
629 : :
630 : 0 : ext4_update_inode_fsync_trans(handle, inode, 1);
631 : 0 : count = ar.len;
632 : : got_it:
633 : 0 : map->m_flags |= EXT4_MAP_MAPPED;
634 : 0 : map->m_pblk = le32_to_cpu(chain[depth-1].key);
635 : 0 : map->m_len = count;
636 : 0 : if (count > blocks_to_boundary)
637 : 0 : map->m_flags |= EXT4_MAP_BOUNDARY;
638 : 0 : err = count;
639 : : /* Clean up and exit */
640 : 0 : partial = chain + depth - 1; /* the whole chain */
641 : : cleanup:
642 : 0 : while (partial > chain) {
643 : : BUFFER_TRACE(partial->bh, "call brelse");
644 : 0 : brelse(partial->bh);
645 : 0 : partial--;
646 : : }
647 : : out:
648 : 0 : trace_ext4_ind_map_blocks_exit(inode, flags, map, err);
649 : 0 : 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 : : */
656 : 0 : int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock)
657 : : {
658 : : struct ext4_inode_info *ei = EXT4_I(inode);
659 : 0 : sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
660 : : int blk_bits;
661 : :
662 : 0 : if (lblock < EXT4_NDIR_BLOCKS)
663 : : return 0;
664 : :
665 : 0 : lblock -= EXT4_NDIR_BLOCKS;
666 : :
667 : 0 : if (ei->i_da_metadata_calc_len &&
668 : 0 : (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
669 : 0 : ei->i_da_metadata_calc_len++;
670 : 0 : return 0;
671 : : }
672 : 0 : ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
673 : 0 : ei->i_da_metadata_calc_len = 1;
674 : 0 : blk_bits = order_base_2(lblock);
675 : 0 : 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 : : */
682 : 0 : int 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 : 0 : 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 : : */
704 : 0 : static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
705 : : {
706 : 0 : if (!ext4_handle_valid(handle))
707 : : return 0;
708 : 0 : if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
709 : : return 0;
710 : 0 : if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
711 : : return 0;
712 : 0 : 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 : : */
720 : : static inline int all_zeroes(__le32 *p, __le32 *q)
721 : : {
722 : 0 : while (p < q)
723 : 0 : 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 : :
763 : 0 : static 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 : 0 : *top = 0;
771 : : /* Make k index the deepest non-null offset + 1 */
772 : 0 : for (k = depth; k > 1 && !offsets[k-1]; k--)
773 : : ;
774 : 0 : partial = ext4_get_branch(inode, k, offsets, chain, &err);
775 : : /* Writer: pointers */
776 : 0 : if (!partial)
777 : 0 : 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 : 0 : if (!partial->key && *partial->p)
783 : : /* Writer: end */
784 : : goto no_top;
785 : 0 : 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 : 0 : if (p == chain + k - 1 && p > chain) {
794 : 0 : p->p--;
795 : : } else {
796 : 0 : *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 : 0 : while (partial > p) {
805 : 0 : brelse(partial->bh);
806 : 0 : partial--;
807 : : }
808 : : no_top:
809 : 0 : 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 : : */
823 : 0 : static 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 : 0 : 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 : 0 : else if (ext4_should_journal_data(inode))
837 : : flags |= EXT4_FREE_BLOCKS_FORGET;
838 : :
839 : 0 : if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), block_to_free,
840 : : count)) {
841 : 0 : EXT4_ERROR_INODE(inode, "attempt to clear invalid "
842 : : "blocks %llu len %lu",
843 : : (unsigned long long) block_to_free, count);
844 : 0 : return 1;
845 : : }
846 : :
847 : 0 : if (try_to_extend_transaction(handle, inode)) {
848 : 0 : if (bh) {
849 : : BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
850 : 0 : err = ext4_handle_dirty_metadata(handle, inode, bh);
851 : 0 : if (unlikely(err))
852 : : goto out_err;
853 : : }
854 : 0 : err = ext4_mark_inode_dirty(handle, inode);
855 : 0 : if (unlikely(err))
856 : : goto out_err;
857 : 0 : err = ext4_truncate_restart_trans(handle, inode,
858 : 0 : ext4_blocks_for_truncate(inode));
859 : 0 : if (unlikely(err))
860 : : goto out_err;
861 : 0 : if (bh) {
862 : : BUFFER_TRACE(bh, "retaking write access");
863 : 0 : err = ext4_journal_get_write_access(handle, bh);
864 : 0 : if (unlikely(err))
865 : : goto out_err;
866 : : }
867 : : }
868 : :
869 : 0 : for (p = first; p < last; p++)
870 : 0 : *p = 0;
871 : :
872 : 0 : ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
873 : 0 : return 0;
874 : : out_err:
875 : 0 : ext4_std_error(inode->i_sb, err);
876 : 0 : 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 : : */
898 : 0 : static 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 : 0 : if (this_bh) { /* For indirect block */
913 : : BUFFER_TRACE(this_bh, "get_write_access");
914 : 0 : 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 : 0 : if (err)
918 : : return;
919 : : }
920 : :
921 : 0 : for (p = first; p < last; p++) {
922 : 0 : nr = le32_to_cpu(*p);
923 : 0 : if (nr) {
924 : : /* accumulate blocks to free if they're contiguous */
925 : 0 : if (count == 0) {
926 : : block_to_free = nr;
927 : : block_to_free_p = p;
928 : : count = 1;
929 : 0 : } else if (nr == block_to_free + count) {
930 : 0 : count++;
931 : : } else {
932 : 0 : err = ext4_clear_blocks(handle, inode, this_bh,
933 : : block_to_free, count,
934 : : block_to_free_p, p);
935 : 0 : if (err)
936 : : break;
937 : : block_to_free = nr;
938 : : block_to_free_p = p;
939 : : count = 1;
940 : : }
941 : : }
942 : : }
943 : :
944 : 0 : if (!err && count > 0)
945 : 0 : err = ext4_clear_blocks(handle, inode, this_bh, block_to_free,
946 : : count, block_to_free_p, p);
947 : 0 : if (err < 0)
948 : : /* fatal error */
949 : : return;
950 : :
951 : 0 : 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 : 0 : if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
961 : 0 : ext4_handle_dirty_metadata(handle, inode, this_bh);
962 : : else
963 : 0 : 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 : : */
983 : 0 : static 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 : 0 : if (ext4_handle_is_aborted(handle))
991 : : return;
992 : :
993 : 0 : if (depth--) {
994 : : struct buffer_head *bh;
995 : 0 : int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
996 : : p = last;
997 : 0 : while (--p >= first) {
998 : 0 : nr = le32_to_cpu(*p);
999 : 0 : if (!nr)
1000 : 0 : continue; /* A hole */
1001 : :
1002 : 0 : if (!ext4_data_block_valid(EXT4_SB(inode->i_sb),
1003 : : nr, 1)) {
1004 : 0 : EXT4_ERROR_INODE(inode,
1005 : : "invalid indirect mapped "
1006 : : "block %lu (level %d)",
1007 : : (unsigned long) nr, depth);
1008 : 0 : break;
1009 : : }
1010 : :
1011 : : /* Go read the buffer for the next level down */
1012 : 0 : bh = sb_bread(inode->i_sb, nr);
1013 : :
1014 : : /*
1015 : : * A read failure? Report error and clear slot
1016 : : * (should be rare).
1017 : : */
1018 : 0 : if (!bh) {
1019 : 0 : EXT4_ERROR_INODE_BLOCK(inode, nr,
1020 : : "Read failure");
1021 : 0 : continue;
1022 : : }
1023 : :
1024 : : /* This zaps the entire block. Bottom up. */
1025 : : BUFFER_TRACE(bh, "free child branches");
1026 : 0 : ext4_free_branches(handle, inode, bh,
1027 : : (__le32 *) bh->b_data,
1028 : 0 : (__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 : 0 : if (ext4_handle_is_aborted(handle))
1049 : : return;
1050 : 0 : if (try_to_extend_transaction(handle, inode)) {
1051 : 0 : ext4_mark_inode_dirty(handle, inode);
1052 : 0 : ext4_truncate_restart_trans(handle, inode,
1053 : 0 : 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 : 0 : ext4_free_blocks(handle, inode, NULL, nr, 1,
1068 : : EXT4_FREE_BLOCKS_METADATA|
1069 : : EXT4_FREE_BLOCKS_FORGET);
1070 : :
1071 : 0 : 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 : 0 : if (!ext4_journal_get_write_access(handle,
1078 : : parent_bh)){
1079 : 0 : *p = 0;
1080 : : BUFFER_TRACE(parent_bh,
1081 : : "call ext4_handle_dirty_metadata");
1082 : 0 : 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 : 0 : ext4_free_data(handle, inode, parent_bh, first, last);
1092 : : }
1093 : : }
1094 : :
1095 : 0 : void ext4_ind_truncate(handle_t *handle, struct inode *inode)
1096 : : {
1097 : : struct ext4_inode_info *ei = EXT4_I(inode);
1098 : 0 : __le32 *i_data = ei->i_data;
1099 : 0 : 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 : 0 : __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 : 0 : last_block = (inode->i_size + blocksize-1)
1109 : 0 : >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1110 : 0 : max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1111 : 0 : >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1112 : :
1113 : 0 : if (last_block != max_block) {
1114 : 0 : n = ext4_block_to_path(inode, last_block, offsets, NULL);
1115 : 0 : if (n == 0)
1116 : 0 : return;
1117 : : }
1118 : :
1119 : 0 : 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 : 0 : ei->i_disksize = inode->i_size;
1129 : :
1130 : 0 : 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 : 0 : } else if (n == 1) { /* direct blocks */
1137 : 0 : ext4_free_data(handle, inode, NULL, i_data+offsets[0],
1138 : : i_data + EXT4_NDIR_BLOCKS);
1139 : 0 : goto do_indirects;
1140 : : }
1141 : :
1142 : 0 : partial = ext4_find_shared(inode, n, offsets, chain, &nr);
1143 : : /* Kill the top of shared branch (not detached) */
1144 : 0 : if (nr) {
1145 : 0 : if (partial == chain) {
1146 : : /* Shared branch grows from the inode */
1147 : 0 : ext4_free_branches(handle, inode, NULL,
1148 : 0 : &nr, &nr+1, (chain+n-1) - partial);
1149 : 0 : *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 : 0 : ext4_free_branches(handle, inode, partial->bh,
1158 : : partial->p,
1159 : 0 : partial->p+1, (chain+n-1) - partial);
1160 : : }
1161 : : }
1162 : : /* Clear the ends of indirect blocks on the shared branch */
1163 : 0 : while (partial > chain) {
1164 : 0 : ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
1165 : 0 : (__le32*)partial->bh->b_data+addr_per_block,
1166 : 0 : (chain+n-1) - partial);
1167 : : BUFFER_TRACE(partial->bh, "call brelse");
1168 : 0 : brelse(partial->bh);
1169 : 0 : partial--;
1170 : : }
1171 : : do_indirects:
1172 : : /* Kill the remaining (whole) subtrees */
1173 : 0 : switch (offsets[0]) {
1174 : : default:
1175 : 0 : nr = i_data[EXT4_IND_BLOCK];
1176 : 0 : if (nr) {
1177 : 0 : ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1178 : 0 : i_data[EXT4_IND_BLOCK] = 0;
1179 : : }
1180 : : /* fall through */
1181 : : case EXT4_IND_BLOCK:
1182 : 0 : nr = i_data[EXT4_DIND_BLOCK];
1183 : 0 : if (nr) {
1184 : 0 : ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1185 : 0 : i_data[EXT4_DIND_BLOCK] = 0;
1186 : : }
1187 : : /* fall through */
1188 : : case EXT4_DIND_BLOCK:
1189 : 0 : nr = i_data[EXT4_TIND_BLOCK];
1190 : 0 : if (nr) {
1191 : 0 : ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1192 : 0 : i_data[EXT4_TIND_BLOCK] = 0;
1193 : : }
1194 : : /* fall through */
1195 : : case EXT4_TIND_BLOCK:
1196 : : ;
1197 : : }
1198 : : }
1199 : :
1200 : : /**
1201 : : * ext4_ind_remove_space - remove space from the range
1202 : : * @handle: JBD handle for this transaction
1203 : : * @inode: inode we are dealing with
1204 : : * @start: First block to remove
1205 : : * @end: One block after the last block to remove (exclusive)
1206 : : *
1207 : : * Free the blocks in the defined range (end is exclusive endpoint of
1208 : : * range). This is used by ext4_punch_hole().
1209 : : */
1210 : 0 : int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
1211 : : ext4_lblk_t start, ext4_lblk_t end)
1212 : : {
1213 : : struct ext4_inode_info *ei = EXT4_I(inode);
1214 : 0 : __le32 *i_data = ei->i_data;
1215 : 0 : int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1216 : : ext4_lblk_t offsets[4], offsets2[4];
1217 : : Indirect chain[4], chain2[4];
1218 : : Indirect *partial, *partial2;
1219 : : Indirect *p = NULL, *p2 = NULL;
1220 : : ext4_lblk_t max_block;
1221 : 0 : __le32 nr = 0, nr2 = 0;
1222 : : int n = 0, n2 = 0;
1223 : : unsigned blocksize = inode->i_sb->s_blocksize;
1224 : :
1225 : 0 : max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
1226 : 0 : >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
1227 : 0 : if (end >= max_block)
1228 : : end = max_block;
1229 : 0 : if ((start >= end) || (start > max_block))
1230 : : return 0;
1231 : :
1232 : 0 : n = ext4_block_to_path(inode, start, offsets, NULL);
1233 : 0 : n2 = ext4_block_to_path(inode, end, offsets2, NULL);
1234 : :
1235 : 0 : BUG_ON(n > n2);
1236 : :
1237 : 0 : if ((n == 1) && (n == n2)) {
1238 : : /* We're punching only within direct block range */
1239 : 0 : ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1240 : 0 : i_data + offsets2[0]);
1241 : 0 : return 0;
1242 : 0 : } else if (n2 > n) {
1243 : : /*
1244 : : * Start and end are on a different levels so we're going to
1245 : : * free partial block at start, and partial block at end of
1246 : : * the range. If there are some levels in between then
1247 : : * do_indirects label will take care of that.
1248 : : */
1249 : :
1250 : 0 : if (n == 1) {
1251 : : /*
1252 : : * Start is at the direct block level, free
1253 : : * everything to the end of the level.
1254 : : */
1255 : 0 : ext4_free_data(handle, inode, NULL, i_data + offsets[0],
1256 : : i_data + EXT4_NDIR_BLOCKS);
1257 : 0 : goto end_range;
1258 : : }
1259 : :
1260 : :
1261 : 0 : partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
1262 : 0 : if (nr) {
1263 : 0 : if (partial == chain) {
1264 : : /* Shared branch grows from the inode */
1265 : 0 : ext4_free_branches(handle, inode, NULL,
1266 : 0 : &nr, &nr+1, (chain+n-1) - partial);
1267 : 0 : *partial->p = 0;
1268 : : } else {
1269 : : /* Shared branch grows from an indirect block */
1270 : : BUFFER_TRACE(partial->bh, "get_write_access");
1271 : 0 : ext4_free_branches(handle, inode, partial->bh,
1272 : : partial->p,
1273 : 0 : partial->p+1, (chain+n-1) - partial);
1274 : : }
1275 : : }
1276 : :
1277 : : /*
1278 : : * Clear the ends of indirect blocks on the shared branch
1279 : : * at the start of the range
1280 : : */
1281 : 0 : while (partial > chain) {
1282 : 0 : ext4_free_branches(handle, inode, partial->bh,
1283 : 0 : partial->p + 1,
1284 : 0 : (__le32 *)partial->bh->b_data+addr_per_block,
1285 : 0 : (chain+n-1) - partial);
1286 : 0 : partial--;
1287 : : }
1288 : :
1289 : : end_range:
1290 : 0 : partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1291 : 0 : if (nr2) {
1292 : 0 : if (partial2 == chain2) {
1293 : : /*
1294 : : * Remember, end is exclusive so here we're at
1295 : : * the start of the next level we're not going
1296 : : * to free. Everything was covered by the start
1297 : : * of the range.
1298 : : */
1299 : : goto do_indirects;
1300 : : }
1301 : : } else {
1302 : : /*
1303 : : * ext4_find_shared returns Indirect structure which
1304 : : * points to the last element which should not be
1305 : : * removed by truncate. But this is end of the range
1306 : : * in punch_hole so we need to point to the next element
1307 : : */
1308 : 0 : partial2->p++;
1309 : : }
1310 : :
1311 : : /*
1312 : : * Clear the ends of indirect blocks on the shared branch
1313 : : * at the end of the range
1314 : : */
1315 : 0 : while (partial2 > chain2) {
1316 : 0 : ext4_free_branches(handle, inode, partial2->bh,
1317 : 0 : (__le32 *)partial2->bh->b_data,
1318 : : partial2->p,
1319 : 0 : (chain2+n2-1) - partial2);
1320 : 0 : partial2--;
1321 : : }
1322 : : goto do_indirects;
1323 : : }
1324 : :
1325 : : /* Punch happened within the same level (n == n2) */
1326 : 0 : partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
1327 : 0 : partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
1328 : :
1329 : : /* Free top, but only if partial2 isn't its subtree. */
1330 : 0 : if (nr) {
1331 : 0 : int level = min(partial - chain, partial2 - chain2);
1332 : : int i;
1333 : : int subtree = 1;
1334 : :
1335 : 0 : for (i = 0; i <= level; i++) {
1336 : 0 : if (offsets[i] != offsets2[i]) {
1337 : : subtree = 0;
1338 : : break;
1339 : : }
1340 : : }
1341 : :
1342 : 0 : if (!subtree) {
1343 : 0 : if (partial == chain) {
1344 : : /* Shared branch grows from the inode */
1345 : 0 : ext4_free_branches(handle, inode, NULL,
1346 : : &nr, &nr+1,
1347 : 0 : (chain+n-1) - partial);
1348 : 0 : *partial->p = 0;
1349 : : } else {
1350 : : /* Shared branch grows from an indirect block */
1351 : : BUFFER_TRACE(partial->bh, "get_write_access");
1352 : 0 : ext4_free_branches(handle, inode, partial->bh,
1353 : : partial->p,
1354 : 0 : partial->p+1,
1355 : 0 : (chain+n-1) - partial);
1356 : : }
1357 : : }
1358 : : }
1359 : :
1360 : 0 : 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 : 0 : partial2->p++;
1368 : : }
1369 : :
1370 : 0 : while (partial > chain || partial2 > chain2) {
1371 : 0 : int depth = (chain+n-1) - partial;
1372 : 0 : int depth2 = (chain2+n2-1) - partial2;
1373 : :
1374 : 0 : if (partial > chain && partial2 > chain2 &&
1375 : 0 : 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 : 0 : ext4_free_branches(handle, inode, partial->bh,
1381 : 0 : partial->p + 1,
1382 : : partial2->p,
1383 : : (chain+n-1) - partial);
1384 : 0 : goto cleanup;
1385 : : }
1386 : :
1387 : : /*
1388 : : * The start and end partial branches may not be at the same
1389 : : * level even though the punch happened within one level. So, we
1390 : : * give them a chance to arrive at the same level, then walk
1391 : : * them in step with each other until we converge on the same
1392 : : * block.
1393 : : */
1394 : 0 : if (partial > chain && depth <= depth2) {
1395 : 0 : ext4_free_branches(handle, inode, partial->bh,
1396 : 0 : partial->p + 1,
1397 : 0 : (__le32 *)partial->bh->b_data+addr_per_block,
1398 : : (chain+n-1) - partial);
1399 : 0 : partial--;
1400 : : }
1401 : 0 : if (partial2 > chain2 && depth2 <= depth) {
1402 : 0 : ext4_free_branches(handle, inode, partial2->bh,
1403 : 0 : (__le32 *)partial2->bh->b_data,
1404 : : partial2->p,
1405 : : (chain2+n2-1) - partial2);
1406 : 0 : partial2--;
1407 : : }
1408 : : }
1409 : :
1410 : : cleanup:
1411 : 0 : while (p && p > chain) {
1412 : : BUFFER_TRACE(p->bh, "call brelse");
1413 : 0 : brelse(p->bh);
1414 : 0 : p--;
1415 : : }
1416 : 0 : while (p2 && p2 > chain2) {
1417 : : BUFFER_TRACE(p2->bh, "call brelse");
1418 : 0 : brelse(p2->bh);
1419 : 0 : p2--;
1420 : : }
1421 : : return 0;
1422 : :
1423 : : do_indirects:
1424 : : /* Kill the remaining (whole) subtrees */
1425 : 0 : switch (offsets[0]) {
1426 : : default:
1427 : 0 : if (++n >= n2)
1428 : : break;
1429 : 0 : nr = i_data[EXT4_IND_BLOCK];
1430 : 0 : if (nr) {
1431 : 0 : ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
1432 : 0 : i_data[EXT4_IND_BLOCK] = 0;
1433 : : }
1434 : : /* fall through */
1435 : : case EXT4_IND_BLOCK:
1436 : 0 : if (++n >= n2)
1437 : : break;
1438 : 0 : nr = i_data[EXT4_DIND_BLOCK];
1439 : 0 : if (nr) {
1440 : 0 : ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
1441 : 0 : i_data[EXT4_DIND_BLOCK] = 0;
1442 : : }
1443 : : /* fall through */
1444 : : case EXT4_DIND_BLOCK:
1445 : 0 : if (++n >= n2)
1446 : : break;
1447 : 0 : nr = i_data[EXT4_TIND_BLOCK];
1448 : 0 : if (nr) {
1449 : 0 : ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
1450 : 0 : i_data[EXT4_TIND_BLOCK] = 0;
1451 : : }
1452 : : /* fall through */
1453 : : case EXT4_TIND_BLOCK:
1454 : : ;
1455 : : }
1456 : : goto cleanup;
1457 : : }
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