1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Oracle. All rights reserved.
4 */
5
6#include "ctree.h"
7#include "fs.h"
8#include "messages.h"
9#include "inode-item.h"
10#include "disk-io.h"
11#include "transaction.h"
12#include "print-tree.h"
13#include "space-info.h"
14#include "accessors.h"
15#include "extent-tree.h"
16#include "file-item.h"
17
18struct btrfs_inode_ref *btrfs_find_name_in_backref(struct extent_buffer *leaf,
19 int slot,
20 const struct fscrypt_str *name)
21{
22 struct btrfs_inode_ref *ref;
23 unsigned long ptr;
24 unsigned long name_ptr;
25 u32 item_size;
26 u32 cur_offset = 0;
27 int len;
28
29 item_size = btrfs_item_size(eb: leaf, slot);
30 ptr = btrfs_item_ptr_offset(leaf, slot);
31 while (cur_offset < item_size) {
32 ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
33 len = btrfs_inode_ref_name_len(eb: leaf, s: ref);
34 name_ptr = (unsigned long)(ref + 1);
35 cur_offset += len + sizeof(*ref);
36 if (len != name->len)
37 continue;
38 if (memcmp_extent_buffer(eb: leaf, ptrv: name->name, start: name_ptr,
39 len: name->len) == 0)
40 return ref;
41 }
42 return NULL;
43}
44
45struct btrfs_inode_extref *btrfs_find_name_in_ext_backref(
46 struct extent_buffer *leaf, int slot, u64 ref_objectid,
47 const struct fscrypt_str *name)
48{
49 struct btrfs_inode_extref *extref;
50 unsigned long ptr;
51 unsigned long name_ptr;
52 u32 item_size;
53 u32 cur_offset = 0;
54 int ref_name_len;
55
56 item_size = btrfs_item_size(eb: leaf, slot);
57 ptr = btrfs_item_ptr_offset(leaf, slot);
58
59 /*
60 * Search all extended backrefs in this item. We're only
61 * looking through any collisions so most of the time this is
62 * just going to compare against one buffer. If all is well,
63 * we'll return success and the inode ref object.
64 */
65 while (cur_offset < item_size) {
66 extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
67 name_ptr = (unsigned long)(&extref->name);
68 ref_name_len = btrfs_inode_extref_name_len(eb: leaf, s: extref);
69
70 if (ref_name_len == name->len &&
71 btrfs_inode_extref_parent(eb: leaf, s: extref) == ref_objectid &&
72 (memcmp_extent_buffer(eb: leaf, ptrv: name->name, start: name_ptr,
73 len: name->len) == 0))
74 return extref;
75
76 cur_offset += ref_name_len + sizeof(*extref);
77 }
78 return NULL;
79}
80
81/* Returns NULL if no extref found */
82struct btrfs_inode_extref *
83btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
84 struct btrfs_root *root,
85 struct btrfs_path *path,
86 const struct fscrypt_str *name,
87 u64 inode_objectid, u64 ref_objectid, int ins_len,
88 int cow)
89{
90 int ret;
91 struct btrfs_key key;
92
93 key.objectid = inode_objectid;
94 key.type = BTRFS_INODE_EXTREF_KEY;
95 key.offset = btrfs_extref_hash(parent_objectid: ref_objectid, name: name->name, len: name->len);
96
97 ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len, cow);
98 if (ret < 0)
99 return ERR_PTR(error: ret);
100 if (ret > 0)
101 return NULL;
102 return btrfs_find_name_in_ext_backref(leaf: path->nodes[0], slot: path->slots[0],
103 ref_objectid, name);
104
105}
106
107static int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
108 struct btrfs_root *root,
109 const struct fscrypt_str *name,
110 u64 inode_objectid, u64 ref_objectid,
111 u64 *index)
112{
113 struct btrfs_path *path;
114 struct btrfs_key key;
115 struct btrfs_inode_extref *extref;
116 struct extent_buffer *leaf;
117 int ret;
118 int del_len = name->len + sizeof(*extref);
119 unsigned long ptr;
120 unsigned long item_start;
121 u32 item_size;
122
123 key.objectid = inode_objectid;
124 key.type = BTRFS_INODE_EXTREF_KEY;
125 key.offset = btrfs_extref_hash(parent_objectid: ref_objectid, name: name->name, len: name->len);
126
127 path = btrfs_alloc_path();
128 if (!path)
129 return -ENOMEM;
130
131 ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len: -1, cow: 1);
132 if (ret > 0)
133 ret = -ENOENT;
134 if (ret < 0)
135 goto out;
136
137 /*
138 * Sanity check - did we find the right item for this name?
139 * This should always succeed so error here will make the FS
140 * readonly.
141 */
142 extref = btrfs_find_name_in_ext_backref(leaf: path->nodes[0], slot: path->slots[0],
143 ref_objectid, name);
144 if (!extref) {
145 btrfs_handle_fs_error(root->fs_info, -ENOENT, NULL);
146 ret = -EROFS;
147 goto out;
148 }
149
150 leaf = path->nodes[0];
151 item_size = btrfs_item_size(eb: leaf, slot: path->slots[0]);
152 if (index)
153 *index = btrfs_inode_extref_index(eb: leaf, s: extref);
154
155 if (del_len == item_size) {
156 /*
157 * Common case only one ref in the item, remove the
158 * whole item.
159 */
160 ret = btrfs_del_item(trans, root, path);
161 goto out;
162 }
163
164 ptr = (unsigned long)extref;
165 item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
166
167 memmove_extent_buffer(dst: leaf, dst_offset: ptr, src_offset: ptr + del_len,
168 len: item_size - (ptr + del_len - item_start));
169
170 btrfs_truncate_item(trans, path, new_size: item_size - del_len, from_end: 1);
171
172out:
173 btrfs_free_path(p: path);
174
175 return ret;
176}
177
178int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
179 struct btrfs_root *root, const struct fscrypt_str *name,
180 u64 inode_objectid, u64 ref_objectid, u64 *index)
181{
182 struct btrfs_path *path;
183 struct btrfs_key key;
184 struct btrfs_inode_ref *ref;
185 struct extent_buffer *leaf;
186 unsigned long ptr;
187 unsigned long item_start;
188 u32 item_size;
189 u32 sub_item_len;
190 int ret;
191 int search_ext_refs = 0;
192 int del_len = name->len + sizeof(*ref);
193
194 key.objectid = inode_objectid;
195 key.offset = ref_objectid;
196 key.type = BTRFS_INODE_REF_KEY;
197
198 path = btrfs_alloc_path();
199 if (!path)
200 return -ENOMEM;
201
202 ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len: -1, cow: 1);
203 if (ret > 0) {
204 ret = -ENOENT;
205 search_ext_refs = 1;
206 goto out;
207 } else if (ret < 0) {
208 goto out;
209 }
210
211 ref = btrfs_find_name_in_backref(leaf: path->nodes[0], slot: path->slots[0], name);
212 if (!ref) {
213 ret = -ENOENT;
214 search_ext_refs = 1;
215 goto out;
216 }
217 leaf = path->nodes[0];
218 item_size = btrfs_item_size(eb: leaf, slot: path->slots[0]);
219
220 if (index)
221 *index = btrfs_inode_ref_index(eb: leaf, s: ref);
222
223 if (del_len == item_size) {
224 ret = btrfs_del_item(trans, root, path);
225 goto out;
226 }
227 ptr = (unsigned long)ref;
228 sub_item_len = name->len + sizeof(*ref);
229 item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
230 memmove_extent_buffer(dst: leaf, dst_offset: ptr, src_offset: ptr + sub_item_len,
231 len: item_size - (ptr + sub_item_len - item_start));
232 btrfs_truncate_item(trans, path, new_size: item_size - sub_item_len, from_end: 1);
233out:
234 btrfs_free_path(p: path);
235
236 if (search_ext_refs) {
237 /*
238 * No refs were found, or we could not find the
239 * name in our ref array. Find and remove the extended
240 * inode ref then.
241 */
242 return btrfs_del_inode_extref(trans, root, name,
243 inode_objectid, ref_objectid, index);
244 }
245
246 return ret;
247}
248
249/*
250 * Insert an extended inode ref into a tree.
251 *
252 * The caller must have checked against BTRFS_LINK_MAX already.
253 */
254static int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
255 struct btrfs_root *root,
256 const struct fscrypt_str *name,
257 u64 inode_objectid, u64 ref_objectid,
258 u64 index)
259{
260 struct btrfs_inode_extref *extref;
261 int ret;
262 int ins_len = name->len + sizeof(*extref);
263 unsigned long ptr;
264 struct btrfs_path *path;
265 struct btrfs_key key;
266 struct extent_buffer *leaf;
267
268 key.objectid = inode_objectid;
269 key.type = BTRFS_INODE_EXTREF_KEY;
270 key.offset = btrfs_extref_hash(parent_objectid: ref_objectid, name: name->name, len: name->len);
271
272 path = btrfs_alloc_path();
273 if (!path)
274 return -ENOMEM;
275
276 ret = btrfs_insert_empty_item(trans, root, path, key: &key,
277 data_size: ins_len);
278 if (ret == -EEXIST) {
279 if (btrfs_find_name_in_ext_backref(leaf: path->nodes[0],
280 slot: path->slots[0],
281 ref_objectid,
282 name))
283 goto out;
284
285 btrfs_extend_item(trans, path, data_size: ins_len);
286 ret = 0;
287 }
288 if (ret < 0)
289 goto out;
290
291 leaf = path->nodes[0];
292 ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
293 ptr += btrfs_item_size(eb: leaf, slot: path->slots[0]) - ins_len;
294 extref = (struct btrfs_inode_extref *)ptr;
295
296 btrfs_set_inode_extref_name_len(eb: path->nodes[0], s: extref, val: name->len);
297 btrfs_set_inode_extref_index(eb: path->nodes[0], s: extref, val: index);
298 btrfs_set_inode_extref_parent(eb: path->nodes[0], s: extref, val: ref_objectid);
299
300 ptr = (unsigned long)&extref->name;
301 write_extent_buffer(eb: path->nodes[0], src: name->name, start: ptr, len: name->len);
302 btrfs_mark_buffer_dirty(trans, buf: path->nodes[0]);
303
304out:
305 btrfs_free_path(p: path);
306 return ret;
307}
308
309/* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
310int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
311 struct btrfs_root *root, const struct fscrypt_str *name,
312 u64 inode_objectid, u64 ref_objectid, u64 index)
313{
314 struct btrfs_fs_info *fs_info = root->fs_info;
315 struct btrfs_path *path;
316 struct btrfs_key key;
317 struct btrfs_inode_ref *ref;
318 unsigned long ptr;
319 int ret;
320 int ins_len = name->len + sizeof(*ref);
321
322 key.objectid = inode_objectid;
323 key.offset = ref_objectid;
324 key.type = BTRFS_INODE_REF_KEY;
325
326 path = btrfs_alloc_path();
327 if (!path)
328 return -ENOMEM;
329
330 path->skip_release_on_error = 1;
331 ret = btrfs_insert_empty_item(trans, root, path, key: &key,
332 data_size: ins_len);
333 if (ret == -EEXIST) {
334 u32 old_size;
335 ref = btrfs_find_name_in_backref(leaf: path->nodes[0], slot: path->slots[0],
336 name);
337 if (ref)
338 goto out;
339
340 old_size = btrfs_item_size(eb: path->nodes[0], slot: path->slots[0]);
341 btrfs_extend_item(trans, path, data_size: ins_len);
342 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
343 struct btrfs_inode_ref);
344 ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
345 btrfs_set_inode_ref_name_len(eb: path->nodes[0], s: ref, val: name->len);
346 btrfs_set_inode_ref_index(eb: path->nodes[0], s: ref, val: index);
347 ptr = (unsigned long)(ref + 1);
348 ret = 0;
349 } else if (ret < 0) {
350 if (ret == -EOVERFLOW) {
351 if (btrfs_find_name_in_backref(leaf: path->nodes[0],
352 slot: path->slots[0],
353 name))
354 ret = -EEXIST;
355 else
356 ret = -EMLINK;
357 }
358 goto out;
359 } else {
360 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
361 struct btrfs_inode_ref);
362 btrfs_set_inode_ref_name_len(eb: path->nodes[0], s: ref, val: name->len);
363 btrfs_set_inode_ref_index(eb: path->nodes[0], s: ref, val: index);
364 ptr = (unsigned long)(ref + 1);
365 }
366 write_extent_buffer(eb: path->nodes[0], src: name->name, start: ptr, len: name->len);
367 btrfs_mark_buffer_dirty(trans, buf: path->nodes[0]);
368
369out:
370 btrfs_free_path(p: path);
371
372 if (ret == -EMLINK) {
373 struct btrfs_super_block *disk_super = fs_info->super_copy;
374 /* We ran out of space in the ref array. Need to
375 * add an extended ref. */
376 if (btrfs_super_incompat_flags(s: disk_super)
377 & BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
378 ret = btrfs_insert_inode_extref(trans, root, name,
379 inode_objectid,
380 ref_objectid, index);
381 }
382
383 return ret;
384}
385
386int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
387 struct btrfs_root *root,
388 struct btrfs_path *path, u64 objectid)
389{
390 struct btrfs_key key;
391 int ret;
392 key.objectid = objectid;
393 key.type = BTRFS_INODE_ITEM_KEY;
394 key.offset = 0;
395
396 ret = btrfs_insert_empty_item(trans, root, path, key: &key,
397 data_size: sizeof(struct btrfs_inode_item));
398 return ret;
399}
400
401int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
402 *root, struct btrfs_path *path,
403 struct btrfs_key *location, int mod)
404{
405 int ins_len = mod < 0 ? -1 : 0;
406 int cow = mod != 0;
407 int ret;
408 int slot;
409 struct extent_buffer *leaf;
410 struct btrfs_key found_key;
411
412 ret = btrfs_search_slot(trans, root, key: location, p: path, ins_len, cow);
413 if (ret > 0 && location->type == BTRFS_ROOT_ITEM_KEY &&
414 location->offset == (u64)-1 && path->slots[0] != 0) {
415 slot = path->slots[0] - 1;
416 leaf = path->nodes[0];
417 btrfs_item_key_to_cpu(eb: leaf, cpu_key: &found_key, nr: slot);
418 if (found_key.objectid == location->objectid &&
419 found_key.type == location->type) {
420 path->slots[0]--;
421 return 0;
422 }
423 }
424 return ret;
425}
426
427static inline void btrfs_trace_truncate(struct btrfs_inode *inode,
428 struct extent_buffer *leaf,
429 struct btrfs_file_extent_item *fi,
430 u64 offset, int extent_type, int slot)
431{
432 if (!inode)
433 return;
434 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
435 trace_btrfs_truncate_show_fi_inline(bi: inode, l: leaf, fi, slot,
436 start: offset);
437 else
438 trace_btrfs_truncate_show_fi_regular(bi: inode, l: leaf, fi, start: offset);
439}
440
441/*
442 * Remove inode items from a given root.
443 *
444 * @trans: A transaction handle.
445 * @root: The root from which to remove items.
446 * @inode: The inode whose items we want to remove.
447 * @control: The btrfs_truncate_control to control how and what we
448 * are truncating.
449 *
450 * Remove all keys associated with the inode from the given root that have a key
451 * with a type greater than or equals to @min_type. When @min_type has a value of
452 * BTRFS_EXTENT_DATA_KEY, only remove file extent items that have an offset value
453 * greater than or equals to @new_size. If a file extent item that starts before
454 * @new_size and ends after it is found, its length is adjusted.
455 *
456 * Returns: 0 on success, < 0 on error and NEED_TRUNCATE_BLOCK when @min_type is
457 * BTRFS_EXTENT_DATA_KEY and the caller must truncate the last block.
458 */
459int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
460 struct btrfs_root *root,
461 struct btrfs_truncate_control *control)
462{
463 struct btrfs_fs_info *fs_info = root->fs_info;
464 struct btrfs_path *path;
465 struct extent_buffer *leaf;
466 struct btrfs_file_extent_item *fi;
467 struct btrfs_key key;
468 struct btrfs_key found_key;
469 u64 new_size = control->new_size;
470 u64 extent_num_bytes = 0;
471 u64 extent_offset = 0;
472 u64 item_end = 0;
473 u32 found_type = (u8)-1;
474 int del_item;
475 int pending_del_nr = 0;
476 int pending_del_slot = 0;
477 int extent_type = -1;
478 int ret;
479 u64 bytes_deleted = 0;
480 bool be_nice = false;
481
482 ASSERT(control->inode || !control->clear_extent_range);
483 ASSERT(new_size == 0 || control->min_type == BTRFS_EXTENT_DATA_KEY);
484
485 control->last_size = new_size;
486 control->sub_bytes = 0;
487
488 /*
489 * For shareable roots we want to back off from time to time, this turns
490 * out to be subvolume roots, reloc roots, and data reloc roots.
491 */
492 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
493 be_nice = true;
494
495 path = btrfs_alloc_path();
496 if (!path)
497 return -ENOMEM;
498 path->reada = READA_BACK;
499
500 key.objectid = control->ino;
501 key.offset = (u64)-1;
502 key.type = (u8)-1;
503
504search_again:
505 /*
506 * With a 16K leaf size and 128MiB extents, you can actually queue up a
507 * huge file in a single leaf. Most of the time that bytes_deleted is
508 * > 0, it will be huge by the time we get here
509 */
510 if (be_nice && bytes_deleted > SZ_32M &&
511 btrfs_should_end_transaction(trans)) {
512 ret = -EAGAIN;
513 goto out;
514 }
515
516 ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len: -1, cow: 1);
517 if (ret < 0)
518 goto out;
519
520 if (ret > 0) {
521 ret = 0;
522 /* There are no items in the tree for us to truncate, we're done */
523 if (path->slots[0] == 0)
524 goto out;
525 path->slots[0]--;
526 }
527
528 while (1) {
529 u64 clear_start = 0, clear_len = 0, extent_start = 0;
530 bool refill_delayed_refs_rsv = false;
531
532 fi = NULL;
533 leaf = path->nodes[0];
534 btrfs_item_key_to_cpu(eb: leaf, cpu_key: &found_key, nr: path->slots[0]);
535 found_type = found_key.type;
536
537 if (found_key.objectid != control->ino)
538 break;
539
540 if (found_type < control->min_type)
541 break;
542
543 item_end = found_key.offset;
544 if (found_type == BTRFS_EXTENT_DATA_KEY) {
545 fi = btrfs_item_ptr(leaf, path->slots[0],
546 struct btrfs_file_extent_item);
547 extent_type = btrfs_file_extent_type(eb: leaf, s: fi);
548 if (extent_type != BTRFS_FILE_EXTENT_INLINE)
549 item_end +=
550 btrfs_file_extent_num_bytes(eb: leaf, s: fi);
551 else if (extent_type == BTRFS_FILE_EXTENT_INLINE)
552 item_end += btrfs_file_extent_ram_bytes(eb: leaf, s: fi);
553
554 btrfs_trace_truncate(inode: control->inode, leaf, fi,
555 offset: found_key.offset, extent_type,
556 slot: path->slots[0]);
557 item_end--;
558 }
559 if (found_type > control->min_type) {
560 del_item = 1;
561 } else {
562 if (item_end < new_size)
563 break;
564 if (found_key.offset >= new_size)
565 del_item = 1;
566 else
567 del_item = 0;
568 }
569
570 /* FIXME, shrink the extent if the ref count is only 1 */
571 if (found_type != BTRFS_EXTENT_DATA_KEY)
572 goto delete;
573
574 control->extents_found++;
575
576 if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
577 u64 num_dec;
578
579 clear_start = found_key.offset;
580 extent_start = btrfs_file_extent_disk_bytenr(eb: leaf, s: fi);
581 if (!del_item) {
582 u64 orig_num_bytes =
583 btrfs_file_extent_num_bytes(eb: leaf, s: fi);
584 extent_num_bytes = ALIGN(new_size -
585 found_key.offset,
586 fs_info->sectorsize);
587 clear_start = ALIGN(new_size, fs_info->sectorsize);
588
589 btrfs_set_file_extent_num_bytes(eb: leaf, s: fi,
590 val: extent_num_bytes);
591 num_dec = (orig_num_bytes - extent_num_bytes);
592 if (extent_start != 0)
593 control->sub_bytes += num_dec;
594 btrfs_mark_buffer_dirty(trans, buf: leaf);
595 } else {
596 extent_num_bytes =
597 btrfs_file_extent_disk_num_bytes(eb: leaf, s: fi);
598 extent_offset = found_key.offset -
599 btrfs_file_extent_offset(eb: leaf, s: fi);
600
601 /* FIXME blocksize != 4096 */
602 num_dec = btrfs_file_extent_num_bytes(eb: leaf, s: fi);
603 if (extent_start != 0)
604 control->sub_bytes += num_dec;
605 }
606 clear_len = num_dec;
607 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
608 /*
609 * We can't truncate inline items that have had
610 * special encodings
611 */
612 if (!del_item &&
613 btrfs_file_extent_encryption(eb: leaf, s: fi) == 0 &&
614 btrfs_file_extent_other_encoding(eb: leaf, s: fi) == 0 &&
615 btrfs_file_extent_compression(eb: leaf, s: fi) == 0) {
616 u32 size = (u32)(new_size - found_key.offset);
617
618 btrfs_set_file_extent_ram_bytes(eb: leaf, s: fi, val: size);
619 size = btrfs_file_extent_calc_inline_size(datasize: size);
620 btrfs_truncate_item(trans, path, new_size: size, from_end: 1);
621 } else if (!del_item) {
622 /*
623 * We have to bail so the last_size is set to
624 * just before this extent.
625 */
626 ret = BTRFS_NEED_TRUNCATE_BLOCK;
627 break;
628 } else {
629 /*
630 * Inline extents are special, we just treat
631 * them as a full sector worth in the file
632 * extent tree just for simplicity sake.
633 */
634 clear_len = fs_info->sectorsize;
635 }
636
637 control->sub_bytes += item_end + 1 - new_size;
638 }
639delete:
640 /*
641 * We only want to clear the file extent range if we're
642 * modifying the actual inode's mapping, which is just the
643 * normal truncate path.
644 */
645 if (control->clear_extent_range) {
646 ret = btrfs_inode_clear_file_extent_range(inode: control->inode,
647 start: clear_start, len: clear_len);
648 if (ret) {
649 btrfs_abort_transaction(trans, ret);
650 break;
651 }
652 }
653
654 if (del_item) {
655 ASSERT(!pending_del_nr ||
656 ((path->slots[0] + 1) == pending_del_slot));
657
658 control->last_size = found_key.offset;
659 if (!pending_del_nr) {
660 /* No pending yet, add ourselves */
661 pending_del_slot = path->slots[0];
662 pending_del_nr = 1;
663 } else if (path->slots[0] + 1 == pending_del_slot) {
664 /* Hop on the pending chunk */
665 pending_del_nr++;
666 pending_del_slot = path->slots[0];
667 }
668 } else {
669 control->last_size = new_size;
670 break;
671 }
672
673 if (del_item && extent_start != 0 && !control->skip_ref_updates) {
674 struct btrfs_ref ref = { 0 };
675
676 bytes_deleted += extent_num_bytes;
677
678 btrfs_init_generic_ref(generic_ref: &ref, action: BTRFS_DROP_DELAYED_REF,
679 bytenr: extent_start, len: extent_num_bytes, parent: 0,
680 owning_root: root->root_key.objectid);
681 btrfs_init_data_ref(generic_ref: &ref, ref_root: btrfs_header_owner(eb: leaf),
682 ino: control->ino, offset: extent_offset,
683 mod_root: root->root_key.objectid, skip_qgroup: false);
684 ret = btrfs_free_extent(trans, ref: &ref);
685 if (ret) {
686 btrfs_abort_transaction(trans, ret);
687 break;
688 }
689 if (be_nice && btrfs_check_space_for_delayed_refs(fs_info))
690 refill_delayed_refs_rsv = true;
691 }
692
693 if (found_type == BTRFS_INODE_ITEM_KEY)
694 break;
695
696 if (path->slots[0] == 0 ||
697 path->slots[0] != pending_del_slot ||
698 refill_delayed_refs_rsv) {
699 if (pending_del_nr) {
700 ret = btrfs_del_items(trans, root, path,
701 slot: pending_del_slot,
702 nr: pending_del_nr);
703 if (ret) {
704 btrfs_abort_transaction(trans, ret);
705 break;
706 }
707 pending_del_nr = 0;
708 }
709 btrfs_release_path(p: path);
710
711 /*
712 * We can generate a lot of delayed refs, so we need to
713 * throttle every once and a while and make sure we're
714 * adding enough space to keep up with the work we are
715 * generating. Since we hold a transaction here we
716 * can't flush, and we don't want to FLUSH_LIMIT because
717 * we could have generated too many delayed refs to
718 * actually allocate, so just bail if we're short and
719 * let the normal reservation dance happen higher up.
720 */
721 if (refill_delayed_refs_rsv) {
722 ret = btrfs_delayed_refs_rsv_refill(fs_info,
723 flush: BTRFS_RESERVE_NO_FLUSH);
724 if (ret) {
725 ret = -EAGAIN;
726 break;
727 }
728 }
729 goto search_again;
730 } else {
731 path->slots[0]--;
732 }
733 }
734out:
735 if (ret >= 0 && pending_del_nr) {
736 int err;
737
738 err = btrfs_del_items(trans, root, path, slot: pending_del_slot,
739 nr: pending_del_nr);
740 if (err) {
741 btrfs_abort_transaction(trans, err);
742 ret = err;
743 }
744 }
745
746 ASSERT(control->last_size >= new_size);
747 if (!ret && control->last_size > new_size)
748 control->last_size = new_size;
749
750 btrfs_free_path(p: path);
751 return ret;
752}
753

source code of linux/fs/btrfs/inode-item.c