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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2015 Facebook. All rights reserved.
4 */
5
6#include <linux/kernel.h>
7#include <linux/sched/mm.h>
8#include "messages.h"
9#include "ctree.h"
10#include "disk-io.h"
11#include "locking.h"
12#include "free-space-tree.h"
13#include "transaction.h"
14#include "block-group.h"
15#include "fs.h"
16#include "accessors.h"
17#include "extent-tree.h"
18#include "root-tree.h"
19
20static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
21 struct btrfs_block_group *block_group,
22 struct btrfs_path *path);
23
24static struct btrfs_root *btrfs_free_space_root(
25 struct btrfs_block_group *block_group)
26{
27 struct btrfs_key key = {
28 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
29 .type = BTRFS_ROOT_ITEM_KEY,
30 .offset = 0,
31 };
32
33 if (btrfs_fs_incompat(block_group->fs_info, EXTENT_TREE_V2))
34 key.offset = block_group->global_root_id;
35 return btrfs_global_root(block_group->fs_info, &key);
36}
37
38void set_free_space_tree_thresholds(struct btrfs_block_group *cache)
39{
40 u32 bitmap_range;
41 size_t bitmap_size;
42 u64 num_bitmaps, total_bitmap_size;
43
44 if (WARN_ON(cache->length == 0))
45 btrfs_warn(cache->fs_info, "block group %llu length is zero",
46 cache->start);
47
48 /*
49 * We convert to bitmaps when the disk space required for using extents
50 * exceeds that required for using bitmaps.
51 */
52 bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
53 num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range);
54 bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
55 total_bitmap_size = num_bitmaps * bitmap_size;
56 cache->bitmap_high_thresh = div_u64(total_bitmap_size,
57 sizeof(struct btrfs_item));
58
59 /*
60 * We allow for a small buffer between the high threshold and low
61 * threshold to avoid thrashing back and forth between the two formats.
62 */
63 if (cache->bitmap_high_thresh > 100)
64 cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
65 else
66 cache->bitmap_low_thresh = 0;
67}
68
69static int add_new_free_space_info(struct btrfs_trans_handle *trans,
70 struct btrfs_block_group *block_group,
71 struct btrfs_path *path)
72{
73 struct btrfs_root *root = btrfs_free_space_root(block_group);
74 struct btrfs_free_space_info *info;
75 struct btrfs_key key;
76 struct extent_buffer *leaf;
77 int ret;
78
79 key.objectid = block_group->start;
80 key.type = BTRFS_FREE_SPACE_INFO_KEY;
81 key.offset = block_group->length;
82
83 ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
84 if (ret)
85 goto out;
86
87 leaf = path->nodes[0];
88 info = btrfs_item_ptr(leaf, path->slots[0],
89 struct btrfs_free_space_info);
90 btrfs_set_free_space_extent_count(leaf, info, 0);
91 btrfs_set_free_space_flags(leaf, info, 0);
92 btrfs_mark_buffer_dirty(leaf);
93
94 ret = 0;
95out:
96 btrfs_release_path(path);
97 return ret;
98}
99
100EXPORT_FOR_TESTS
101struct btrfs_free_space_info *search_free_space_info(
102 struct btrfs_trans_handle *trans,
103 struct btrfs_block_group *block_group,
104 struct btrfs_path *path, int cow)
105{
106 struct btrfs_fs_info *fs_info = block_group->fs_info;
107 struct btrfs_root *root = btrfs_free_space_root(block_group);
108 struct btrfs_key key;
109 int ret;
110
111 key.objectid = block_group->start;
112 key.type = BTRFS_FREE_SPACE_INFO_KEY;
113 key.offset = block_group->length;
114
115 ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
116 if (ret < 0)
117 return ERR_PTR(ret);
118 if (ret != 0) {
119 btrfs_warn(fs_info, "missing free space info for %llu",
120 block_group->start);
121 ASSERT(0);
122 return ERR_PTR(-ENOENT);
123 }
124
125 return btrfs_item_ptr(path->nodes[0], path->slots[0],
126 struct btrfs_free_space_info);
127}
128
129/*
130 * btrfs_search_slot() but we're looking for the greatest key less than the
131 * passed key.
132 */
133static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
134 struct btrfs_root *root,
135 struct btrfs_key *key, struct btrfs_path *p,
136 int ins_len, int cow)
137{
138 int ret;
139
140 ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
141 if (ret < 0)
142 return ret;
143
144 if (ret == 0) {
145 ASSERT(0);
146 return -EIO;
147 }
148
149 if (p->slots[0] == 0) {
150 ASSERT(0);
151 return -EIO;
152 }
153 p->slots[0]--;
154
155 return 0;
156}
157
158static inline u32 free_space_bitmap_size(const struct btrfs_fs_info *fs_info,
159 u64 size)
160{
161 return DIV_ROUND_UP(size >> fs_info->sectorsize_bits, BITS_PER_BYTE);
162}
163
164static unsigned long *alloc_bitmap(u32 bitmap_size)
165{
166 unsigned long *ret;
167 unsigned int nofs_flag;
168 u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long));
169
170 /*
171 * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
172 * into the filesystem as the free space bitmap can be modified in the
173 * critical section of a transaction commit.
174 *
175 * TODO: push the memalloc_nofs_{save,restore}() to the caller where we
176 * know that recursion is unsafe.
177 */
178 nofs_flag = memalloc_nofs_save();
179 ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);
180 memalloc_nofs_restore(nofs_flag);
181 return ret;
182}
183
184static void le_bitmap_set(unsigned long *map, unsigned int start, int len)
185{
186 u8 *p = ((u8 *)map) + BIT_BYTE(start);
187 const unsigned int size = start + len;
188 int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
189 u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
190
191 while (len - bits_to_set >= 0) {
192 *p |= mask_to_set;
193 len -= bits_to_set;
194 bits_to_set = BITS_PER_BYTE;
195 mask_to_set = ~0;
196 p++;
197 }
198 if (len) {
199 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
200 *p |= mask_to_set;
201 }
202}
203
204EXPORT_FOR_TESTS
205int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
206 struct btrfs_block_group *block_group,
207 struct btrfs_path *path)
208{
209 struct btrfs_fs_info *fs_info = trans->fs_info;
210 struct btrfs_root *root = btrfs_free_space_root(block_group);
211 struct btrfs_free_space_info *info;
212 struct btrfs_key key, found_key;
213 struct extent_buffer *leaf;
214 unsigned long *bitmap;
215 char *bitmap_cursor;
216 u64 start, end;
217 u64 bitmap_range, i;
218 u32 bitmap_size, flags, expected_extent_count;
219 u32 extent_count = 0;
220 int done = 0, nr;
221 int ret;
222
223 bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
224 bitmap = alloc_bitmap(bitmap_size);
225 if (!bitmap) {
226 ret = -ENOMEM;
227 goto out;
228 }
229
230 start = block_group->start;
231 end = block_group->start + block_group->length;
232
233 key.objectid = end - 1;
234 key.type = (u8)-1;
235 key.offset = (u64)-1;
236
237 while (!done) {
238 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
239 if (ret)
240 goto out;
241
242 leaf = path->nodes[0];
243 nr = 0;
244 path->slots[0]++;
245 while (path->slots[0] > 0) {
246 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
247
248 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
249 ASSERT(found_key.objectid == block_group->start);
250 ASSERT(found_key.offset == block_group->length);
251 done = 1;
252 break;
253 } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
254 u64 first, last;
255
256 ASSERT(found_key.objectid >= start);
257 ASSERT(found_key.objectid < end);
258 ASSERT(found_key.objectid + found_key.offset <= end);
259
260 first = div_u64(found_key.objectid - start,
261 fs_info->sectorsize);
262 last = div_u64(found_key.objectid + found_key.offset - start,
263 fs_info->sectorsize);
264 le_bitmap_set(bitmap, first, last - first);
265
266 extent_count++;
267 nr++;
268 path->slots[0]--;
269 } else {
270 ASSERT(0);
271 }
272 }
273
274 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
275 if (ret)
276 goto out;
277 btrfs_release_path(path);
278 }
279
280 info = search_free_space_info(trans, block_group, path, 1);
281 if (IS_ERR(info)) {
282 ret = PTR_ERR(info);
283 goto out;
284 }
285 leaf = path->nodes[0];
286 flags = btrfs_free_space_flags(leaf, info);
287 flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
288 btrfs_set_free_space_flags(leaf, info, flags);
289 expected_extent_count = btrfs_free_space_extent_count(leaf, info);
290 btrfs_mark_buffer_dirty(leaf);
291 btrfs_release_path(path);
292
293 if (extent_count != expected_extent_count) {
294 btrfs_err(fs_info,
295 "incorrect extent count for %llu; counted %u, expected %u",
296 block_group->start, extent_count,
297 expected_extent_count);
298 ASSERT(0);
299 ret = -EIO;
300 goto out;
301 }
302
303 bitmap_cursor = (char *)bitmap;
304 bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
305 i = start;
306 while (i < end) {
307 unsigned long ptr;
308 u64 extent_size;
309 u32 data_size;
310
311 extent_size = min(end - i, bitmap_range);
312 data_size = free_space_bitmap_size(fs_info, extent_size);
313
314 key.objectid = i;
315 key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
316 key.offset = extent_size;
317
318 ret = btrfs_insert_empty_item(trans, root, path, &key,
319 data_size);
320 if (ret)
321 goto out;
322
323 leaf = path->nodes[0];
324 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
325 write_extent_buffer(leaf, bitmap_cursor, ptr,
326 data_size);
327 btrfs_mark_buffer_dirty(leaf);
328 btrfs_release_path(path);
329
330 i += extent_size;
331 bitmap_cursor += data_size;
332 }
333
334 ret = 0;
335out:
336 kvfree(bitmap);
337 if (ret)
338 btrfs_abort_transaction(trans, ret);
339 return ret;
340}
341
342EXPORT_FOR_TESTS
343int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
344 struct btrfs_block_group *block_group,
345 struct btrfs_path *path)
346{
347 struct btrfs_fs_info *fs_info = trans->fs_info;
348 struct btrfs_root *root = btrfs_free_space_root(block_group);
349 struct btrfs_free_space_info *info;
350 struct btrfs_key key, found_key;
351 struct extent_buffer *leaf;
352 unsigned long *bitmap;
353 u64 start, end;
354 u32 bitmap_size, flags, expected_extent_count;
355 unsigned long nrbits, start_bit, end_bit;
356 u32 extent_count = 0;
357 int done = 0, nr;
358 int ret;
359
360 bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
361 bitmap = alloc_bitmap(bitmap_size);
362 if (!bitmap) {
363 ret = -ENOMEM;
364 goto out;
365 }
366
367 start = block_group->start;
368 end = block_group->start + block_group->length;
369
370 key.objectid = end - 1;
371 key.type = (u8)-1;
372 key.offset = (u64)-1;
373
374 while (!done) {
375 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
376 if (ret)
377 goto out;
378
379 leaf = path->nodes[0];
380 nr = 0;
381 path->slots[0]++;
382 while (path->slots[0] > 0) {
383 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
384
385 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
386 ASSERT(found_key.objectid == block_group->start);
387 ASSERT(found_key.offset == block_group->length);
388 done = 1;
389 break;
390 } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
391 unsigned long ptr;
392 char *bitmap_cursor;
393 u32 bitmap_pos, data_size;
394
395 ASSERT(found_key.objectid >= start);
396 ASSERT(found_key.objectid < end);
397 ASSERT(found_key.objectid + found_key.offset <= end);
398
399 bitmap_pos = div_u64(found_key.objectid - start,
400 fs_info->sectorsize *
401 BITS_PER_BYTE);
402 bitmap_cursor = ((char *)bitmap) + bitmap_pos;
403 data_size = free_space_bitmap_size(fs_info,
404 found_key.offset);
405
406 ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
407 read_extent_buffer(leaf, bitmap_cursor, ptr,
408 data_size);
409
410 nr++;
411 path->slots[0]--;
412 } else {
413 ASSERT(0);
414 }
415 }
416
417 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
418 if (ret)
419 goto out;
420 btrfs_release_path(path);
421 }
422
423 info = search_free_space_info(trans, block_group, path, 1);
424 if (IS_ERR(info)) {
425 ret = PTR_ERR(info);
426 goto out;
427 }
428 leaf = path->nodes[0];
429 flags = btrfs_free_space_flags(leaf, info);
430 flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
431 btrfs_set_free_space_flags(leaf, info, flags);
432 expected_extent_count = btrfs_free_space_extent_count(leaf, info);
433 btrfs_mark_buffer_dirty(leaf);
434 btrfs_release_path(path);
435
436 nrbits = block_group->length >> block_group->fs_info->sectorsize_bits;
437 start_bit = find_next_bit_le(bitmap, nrbits, 0);
438
439 while (start_bit < nrbits) {
440 end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit);
441 ASSERT(start_bit < end_bit);
442
443 key.objectid = start + start_bit * block_group->fs_info->sectorsize;
444 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
445 key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize;
446
447 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
448 if (ret)
449 goto out;
450 btrfs_release_path(path);
451
452 extent_count++;
453
454 start_bit = find_next_bit_le(bitmap, nrbits, end_bit);
455 }
456
457 if (extent_count != expected_extent_count) {
458 btrfs_err(fs_info,
459 "incorrect extent count for %llu; counted %u, expected %u",
460 block_group->start, extent_count,
461 expected_extent_count);
462 ASSERT(0);
463 ret = -EIO;
464 goto out;
465 }
466
467 ret = 0;
468out:
469 kvfree(bitmap);
470 if (ret)
471 btrfs_abort_transaction(trans, ret);
472 return ret;
473}
474
475static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
476 struct btrfs_block_group *block_group,
477 struct btrfs_path *path,
478 int new_extents)
479{
480 struct btrfs_free_space_info *info;
481 u32 flags;
482 u32 extent_count;
483 int ret = 0;
484
485 if (new_extents == 0)
486 return 0;
487
488 info = search_free_space_info(trans, block_group, path, 1);
489 if (IS_ERR(info)) {
490 ret = PTR_ERR(info);
491 goto out;
492 }
493 flags = btrfs_free_space_flags(path->nodes[0], info);
494 extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
495
496 extent_count += new_extents;
497 btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
498 btrfs_mark_buffer_dirty(path->nodes[0]);
499 btrfs_release_path(path);
500
501 if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
502 extent_count > block_group->bitmap_high_thresh) {
503 ret = convert_free_space_to_bitmaps(trans, block_group, path);
504 } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
505 extent_count < block_group->bitmap_low_thresh) {
506 ret = convert_free_space_to_extents(trans, block_group, path);
507 }
508
509out:
510 return ret;
511}
512
513EXPORT_FOR_TESTS
514int free_space_test_bit(struct btrfs_block_group *block_group,
515 struct btrfs_path *path, u64 offset)
516{
517 struct extent_buffer *leaf;
518 struct btrfs_key key;
519 u64 found_start, found_end;
520 unsigned long ptr, i;
521
522 leaf = path->nodes[0];
523 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
524 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
525
526 found_start = key.objectid;
527 found_end = key.objectid + key.offset;
528 ASSERT(offset >= found_start && offset < found_end);
529
530 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
531 i = div_u64(offset - found_start,
532 block_group->fs_info->sectorsize);
533 return !!extent_buffer_test_bit(leaf, ptr, i);
534}
535
536static void free_space_set_bits(struct btrfs_block_group *block_group,
537 struct btrfs_path *path, u64 *start, u64 *size,
538 int bit)
539{
540 struct btrfs_fs_info *fs_info = block_group->fs_info;
541 struct extent_buffer *leaf;
542 struct btrfs_key key;
543 u64 end = *start + *size;
544 u64 found_start, found_end;
545 unsigned long ptr, first, last;
546
547 leaf = path->nodes[0];
548 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
549 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
550
551 found_start = key.objectid;
552 found_end = key.objectid + key.offset;
553 ASSERT(*start >= found_start && *start < found_end);
554 ASSERT(end > found_start);
555
556 if (end > found_end)
557 end = found_end;
558
559 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
560 first = (*start - found_start) >> fs_info->sectorsize_bits;
561 last = (end - found_start) >> fs_info->sectorsize_bits;
562 if (bit)
563 extent_buffer_bitmap_set(leaf, ptr, first, last - first);
564 else
565 extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
566 btrfs_mark_buffer_dirty(leaf);
567
568 *size -= end - *start;
569 *start = end;
570}
571
572/*
573 * We can't use btrfs_next_item() in modify_free_space_bitmap() because
574 * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
575 * tree walking in btrfs_next_leaf() anyways because we know exactly what we're
576 * looking for.
577 */
578static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
579 struct btrfs_root *root, struct btrfs_path *p)
580{
581 struct btrfs_key key;
582
583 if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
584 p->slots[0]++;
585 return 0;
586 }
587
588 btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
589 btrfs_release_path(p);
590
591 key.objectid += key.offset;
592 key.type = (u8)-1;
593 key.offset = (u64)-1;
594
595 return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
596}
597
598/*
599 * If remove is 1, then we are removing free space, thus clearing bits in the
600 * bitmap. If remove is 0, then we are adding free space, thus setting bits in
601 * the bitmap.
602 */
603static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
604 struct btrfs_block_group *block_group,
605 struct btrfs_path *path,
606 u64 start, u64 size, int remove)
607{
608 struct btrfs_root *root = btrfs_free_space_root(block_group);
609 struct btrfs_key key;
610 u64 end = start + size;
611 u64 cur_start, cur_size;
612 int prev_bit, next_bit;
613 int new_extents;
614 int ret;
615
616 /*
617 * Read the bit for the block immediately before the extent of space if
618 * that block is within the block group.
619 */
620 if (start > block_group->start) {
621 u64 prev_block = start - block_group->fs_info->sectorsize;
622
623 key.objectid = prev_block;
624 key.type = (u8)-1;
625 key.offset = (u64)-1;
626
627 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
628 if (ret)
629 goto out;
630
631 prev_bit = free_space_test_bit(block_group, path, prev_block);
632
633 /* The previous block may have been in the previous bitmap. */
634 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
635 if (start >= key.objectid + key.offset) {
636 ret = free_space_next_bitmap(trans, root, path);
637 if (ret)
638 goto out;
639 }
640 } else {
641 key.objectid = start;
642 key.type = (u8)-1;
643 key.offset = (u64)-1;
644
645 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
646 if (ret)
647 goto out;
648
649 prev_bit = -1;
650 }
651
652 /*
653 * Iterate over all of the bitmaps overlapped by the extent of space,
654 * clearing/setting bits as required.
655 */
656 cur_start = start;
657 cur_size = size;
658 while (1) {
659 free_space_set_bits(block_group, path, &cur_start, &cur_size,
660 !remove);
661 if (cur_size == 0)
662 break;
663 ret = free_space_next_bitmap(trans, root, path);
664 if (ret)
665 goto out;
666 }
667
668 /*
669 * Read the bit for the block immediately after the extent of space if
670 * that block is within the block group.
671 */
672 if (end < block_group->start + block_group->length) {
673 /* The next block may be in the next bitmap. */
674 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
675 if (end >= key.objectid + key.offset) {
676 ret = free_space_next_bitmap(trans, root, path);
677 if (ret)
678 goto out;
679 }
680
681 next_bit = free_space_test_bit(block_group, path, end);
682 } else {
683 next_bit = -1;
684 }
685
686 if (remove) {
687 new_extents = -1;
688 if (prev_bit == 1) {
689 /* Leftover on the left. */
690 new_extents++;
691 }
692 if (next_bit == 1) {
693 /* Leftover on the right. */
694 new_extents++;
695 }
696 } else {
697 new_extents = 1;
698 if (prev_bit == 1) {
699 /* Merging with neighbor on the left. */
700 new_extents--;
701 }
702 if (next_bit == 1) {
703 /* Merging with neighbor on the right. */
704 new_extents--;
705 }
706 }
707
708 btrfs_release_path(path);
709 ret = update_free_space_extent_count(trans, block_group, path,
710 new_extents);
711
712out:
713 return ret;
714}
715
716static int remove_free_space_extent(struct btrfs_trans_handle *trans,
717 struct btrfs_block_group *block_group,
718 struct btrfs_path *path,
719 u64 start, u64 size)
720{
721 struct btrfs_root *root = btrfs_free_space_root(block_group);
722 struct btrfs_key key;
723 u64 found_start, found_end;
724 u64 end = start + size;
725 int new_extents = -1;
726 int ret;
727
728 key.objectid = start;
729 key.type = (u8)-1;
730 key.offset = (u64)-1;
731
732 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
733 if (ret)
734 goto out;
735
736 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
737
738 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
739
740 found_start = key.objectid;
741 found_end = key.objectid + key.offset;
742 ASSERT(start >= found_start && end <= found_end);
743
744 /*
745 * Okay, now that we've found the free space extent which contains the
746 * free space that we are removing, there are four cases:
747 *
748 * 1. We're using the whole extent: delete the key we found and
749 * decrement the free space extent count.
750 * 2. We are using part of the extent starting at the beginning: delete
751 * the key we found and insert a new key representing the leftover at
752 * the end. There is no net change in the number of extents.
753 * 3. We are using part of the extent ending at the end: delete the key
754 * we found and insert a new key representing the leftover at the
755 * beginning. There is no net change in the number of extents.
756 * 4. We are using part of the extent in the middle: delete the key we
757 * found and insert two new keys representing the leftovers on each
758 * side. Where we used to have one extent, we now have two, so increment
759 * the extent count. We may need to convert the block group to bitmaps
760 * as a result.
761 */
762
763 /* Delete the existing key (cases 1-4). */
764 ret = btrfs_del_item(trans, root, path);
765 if (ret)
766 goto out;
767
768 /* Add a key for leftovers at the beginning (cases 3 and 4). */
769 if (start > found_start) {
770 key.objectid = found_start;
771 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
772 key.offset = start - found_start;
773
774 btrfs_release_path(path);
775 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
776 if (ret)
777 goto out;
778 new_extents++;
779 }
780
781 /* Add a key for leftovers at the end (cases 2 and 4). */
782 if (end < found_end) {
783 key.objectid = end;
784 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
785 key.offset = found_end - end;
786
787 btrfs_release_path(path);
788 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
789 if (ret)
790 goto out;
791 new_extents++;
792 }
793
794 btrfs_release_path(path);
795 ret = update_free_space_extent_count(trans, block_group, path,
796 new_extents);
797
798out:
799 return ret;
800}
801
802EXPORT_FOR_TESTS
803int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
804 struct btrfs_block_group *block_group,
805 struct btrfs_path *path, u64 start, u64 size)
806{
807 struct btrfs_free_space_info *info;
808 u32 flags;
809 int ret;
810
811 if (test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags)) {
812 ret = __add_block_group_free_space(trans, block_group, path);
813 if (ret)
814 return ret;
815 }
816
817 info = search_free_space_info(NULL, block_group, path, 0);
818 if (IS_ERR(info))
819 return PTR_ERR(info);
820 flags = btrfs_free_space_flags(path->nodes[0], info);
821 btrfs_release_path(path);
822
823 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
824 return modify_free_space_bitmap(trans, block_group, path,
825 start, size, 1);
826 } else {
827 return remove_free_space_extent(trans, block_group, path,
828 start, size);
829 }
830}
831
832int remove_from_free_space_tree(struct btrfs_trans_handle *trans,
833 u64 start, u64 size)
834{
835 struct btrfs_block_group *block_group;
836 struct btrfs_path *path;
837 int ret;
838
839 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
840 return 0;
841
842 path = btrfs_alloc_path();
843 if (!path) {
844 ret = -ENOMEM;
845 goto out;
846 }
847
848 block_group = btrfs_lookup_block_group(trans->fs_info, start);
849 if (!block_group) {
850 ASSERT(0);
851 ret = -ENOENT;
852 goto out;
853 }
854
855 mutex_lock(&block_group->free_space_lock);
856 ret = __remove_from_free_space_tree(trans, block_group, path, start,
857 size);
858 mutex_unlock(&block_group->free_space_lock);
859
860 btrfs_put_block_group(block_group);
861out:
862 btrfs_free_path(path);
863 if (ret)
864 btrfs_abort_transaction(trans, ret);
865 return ret;
866}
867
868static int add_free_space_extent(struct btrfs_trans_handle *trans,
869 struct btrfs_block_group *block_group,
870 struct btrfs_path *path,
871 u64 start, u64 size)
872{
873 struct btrfs_root *root = btrfs_free_space_root(block_group);
874 struct btrfs_key key, new_key;
875 u64 found_start, found_end;
876 u64 end = start + size;
877 int new_extents = 1;
878 int ret;
879
880 /*
881 * We are adding a new extent of free space, but we need to merge
882 * extents. There are four cases here:
883 *
884 * 1. The new extent does not have any immediate neighbors to merge
885 * with: add the new key and increment the free space extent count. We
886 * may need to convert the block group to bitmaps as a result.
887 * 2. The new extent has an immediate neighbor before it: remove the
888 * previous key and insert a new key combining both of them. There is no
889 * net change in the number of extents.
890 * 3. The new extent has an immediate neighbor after it: remove the next
891 * key and insert a new key combining both of them. There is no net
892 * change in the number of extents.
893 * 4. The new extent has immediate neighbors on both sides: remove both
894 * of the keys and insert a new key combining all of them. Where we used
895 * to have two extents, we now have one, so decrement the extent count.
896 */
897
898 new_key.objectid = start;
899 new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
900 new_key.offset = size;
901
902 /* Search for a neighbor on the left. */
903 if (start == block_group->start)
904 goto right;
905 key.objectid = start - 1;
906 key.type = (u8)-1;
907 key.offset = (u64)-1;
908
909 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
910 if (ret)
911 goto out;
912
913 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
914
915 if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
916 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
917 btrfs_release_path(path);
918 goto right;
919 }
920
921 found_start = key.objectid;
922 found_end = key.objectid + key.offset;
923 ASSERT(found_start >= block_group->start &&
924 found_end > block_group->start);
925 ASSERT(found_start < start && found_end <= start);
926
927 /*
928 * Delete the neighbor on the left and absorb it into the new key (cases
929 * 2 and 4).
930 */
931 if (found_end == start) {
932 ret = btrfs_del_item(trans, root, path);
933 if (ret)
934 goto out;
935 new_key.objectid = found_start;
936 new_key.offset += key.offset;
937 new_extents--;
938 }
939 btrfs_release_path(path);
940
941right:
942 /* Search for a neighbor on the right. */
943 if (end == block_group->start + block_group->length)
944 goto insert;
945 key.objectid = end;
946 key.type = (u8)-1;
947 key.offset = (u64)-1;
948
949 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
950 if (ret)
951 goto out;
952
953 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
954
955 if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
956 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
957 btrfs_release_path(path);
958 goto insert;
959 }
960
961 found_start = key.objectid;
962 found_end = key.objectid + key.offset;
963 ASSERT(found_start >= block_group->start &&
964 found_end > block_group->start);
965 ASSERT((found_start < start && found_end <= start) ||
966 (found_start >= end && found_end > end));
967
968 /*
969 * Delete the neighbor on the right and absorb it into the new key
970 * (cases 3 and 4).
971 */
972 if (found_start == end) {
973 ret = btrfs_del_item(trans, root, path);
974 if (ret)
975 goto out;
976 new_key.offset += key.offset;
977 new_extents--;
978 }
979 btrfs_release_path(path);
980
981insert:
982 /* Insert the new key (cases 1-4). */
983 ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0);
984 if (ret)
985 goto out;
986
987 btrfs_release_path(path);
988 ret = update_free_space_extent_count(trans, block_group, path,
989 new_extents);
990
991out:
992 return ret;
993}
994
995EXPORT_FOR_TESTS
996int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
997 struct btrfs_block_group *block_group,
998 struct btrfs_path *path, u64 start, u64 size)
999{
1000 struct btrfs_free_space_info *info;
1001 u32 flags;
1002 int ret;
1003
1004 if (test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags)) {
1005 ret = __add_block_group_free_space(trans, block_group, path);
1006 if (ret)
1007 return ret;
1008 }
1009
1010 info = search_free_space_info(NULL, block_group, path, 0);
1011 if (IS_ERR(info))
1012 return PTR_ERR(info);
1013 flags = btrfs_free_space_flags(path->nodes[0], info);
1014 btrfs_release_path(path);
1015
1016 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
1017 return modify_free_space_bitmap(trans, block_group, path,
1018 start, size, 0);
1019 } else {
1020 return add_free_space_extent(trans, block_group, path, start,
1021 size);
1022 }
1023}
1024
1025int add_to_free_space_tree(struct btrfs_trans_handle *trans,
1026 u64 start, u64 size)
1027{
1028 struct btrfs_block_group *block_group;
1029 struct btrfs_path *path;
1030 int ret;
1031
1032 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1033 return 0;
1034
1035 path = btrfs_alloc_path();
1036 if (!path) {
1037 ret = -ENOMEM;
1038 goto out;
1039 }
1040
1041 block_group = btrfs_lookup_block_group(trans->fs_info, start);
1042 if (!block_group) {
1043 ASSERT(0);
1044 ret = -ENOENT;
1045 goto out;
1046 }
1047
1048 mutex_lock(&block_group->free_space_lock);
1049 ret = __add_to_free_space_tree(trans, block_group, path, start, size);
1050 mutex_unlock(&block_group->free_space_lock);
1051
1052 btrfs_put_block_group(block_group);
1053out:
1054 btrfs_free_path(path);
1055 if (ret)
1056 btrfs_abort_transaction(trans, ret);
1057 return ret;
1058}
1059
1060/*
1061 * Populate the free space tree by walking the extent tree. Operations on the
1062 * extent tree that happen as a result of writes to the free space tree will go
1063 * through the normal add/remove hooks.
1064 */
1065static int populate_free_space_tree(struct btrfs_trans_handle *trans,
1066 struct btrfs_block_group *block_group)
1067{
1068 struct btrfs_root *extent_root;
1069 struct btrfs_path *path, *path2;
1070 struct btrfs_key key;
1071 u64 start, end;
1072 int ret;
1073
1074 path = btrfs_alloc_path();
1075 if (!path)
1076 return -ENOMEM;
1077 path->reada = READA_FORWARD;
1078
1079 path2 = btrfs_alloc_path();
1080 if (!path2) {
1081 btrfs_free_path(path);
1082 return -ENOMEM;
1083 }
1084
1085 ret = add_new_free_space_info(trans, block_group, path2);
1086 if (ret)
1087 goto out;
1088
1089 mutex_lock(&block_group->free_space_lock);
1090
1091 /*
1092 * Iterate through all of the extent and metadata items in this block
1093 * group, adding the free space between them and the free space at the
1094 * end. Note that EXTENT_ITEM and METADATA_ITEM are less than
1095 * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
1096 * contained in.
1097 */
1098 key.objectid = block_group->start;
1099 key.type = BTRFS_EXTENT_ITEM_KEY;
1100 key.offset = 0;
1101
1102 extent_root = btrfs_extent_root(trans->fs_info, key.objectid);
1103 ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
1104 if (ret < 0)
1105 goto out_locked;
1106 ASSERT(ret == 0);
1107
1108 start = block_group->start;
1109 end = block_group->start + block_group->length;
1110 while (1) {
1111 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1112
1113 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
1114 key.type == BTRFS_METADATA_ITEM_KEY) {
1115 if (key.objectid >= end)
1116 break;
1117
1118 if (start < key.objectid) {
1119 ret = __add_to_free_space_tree(trans,
1120 block_group,
1121 path2, start,
1122 key.objectid -
1123 start);
1124 if (ret)
1125 goto out_locked;
1126 }
1127 start = key.objectid;
1128 if (key.type == BTRFS_METADATA_ITEM_KEY)
1129 start += trans->fs_info->nodesize;
1130 else
1131 start += key.offset;
1132 } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
1133 if (key.objectid != block_group->start)
1134 break;
1135 }
1136
1137 ret = btrfs_next_item(extent_root, path);
1138 if (ret < 0)
1139 goto out_locked;
1140 if (ret)
1141 break;
1142 }
1143 if (start < end) {
1144 ret = __add_to_free_space_tree(trans, block_group, path2,
1145 start, end - start);
1146 if (ret)
1147 goto out_locked;
1148 }
1149
1150 ret = 0;
1151out_locked:
1152 mutex_unlock(&block_group->free_space_lock);
1153out:
1154 btrfs_free_path(path2);
1155 btrfs_free_path(path);
1156 return ret;
1157}
1158
1159int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
1160{
1161 struct btrfs_trans_handle *trans;
1162 struct btrfs_root *tree_root = fs_info->tree_root;
1163 struct btrfs_root *free_space_root;
1164 struct btrfs_block_group *block_group;
1165 struct rb_node *node;
1166 int ret;
1167
1168 trans = btrfs_start_transaction(tree_root, 0);
1169 if (IS_ERR(trans))
1170 return PTR_ERR(trans);
1171
1172 set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1173 set_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1174 free_space_root = btrfs_create_tree(trans,
1175 BTRFS_FREE_SPACE_TREE_OBJECTID);
1176 if (IS_ERR(free_space_root)) {
1177 ret = PTR_ERR(free_space_root);
1178 goto abort;
1179 }
1180 ret = btrfs_global_root_insert(free_space_root);
1181 if (ret) {
1182 btrfs_put_root(free_space_root);
1183 goto abort;
1184 }
1185
1186 node = rb_first_cached(&fs_info->block_group_cache_tree);
1187 while (node) {
1188 block_group = rb_entry(node, struct btrfs_block_group,
1189 cache_node);
1190 ret = populate_free_space_tree(trans, block_group);
1191 if (ret)
1192 goto abort;
1193 node = rb_next(node);
1194 }
1195
1196 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1197 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1198 clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1199 ret = btrfs_commit_transaction(trans);
1200
1201 /*
1202 * Now that we've committed the transaction any reading of our commit
1203 * root will be safe, so we can cache from the free space tree now.
1204 */
1205 clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1206 return ret;
1207
1208abort:
1209 clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1210 clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1211 btrfs_abort_transaction(trans, ret);
1212 btrfs_end_transaction(trans);
1213 return ret;
1214}
1215
1216static int clear_free_space_tree(struct btrfs_trans_handle *trans,
1217 struct btrfs_root *root)
1218{
1219 struct btrfs_path *path;
1220 struct btrfs_key key;
1221 int nr;
1222 int ret;
1223
1224 path = btrfs_alloc_path();
1225 if (!path)
1226 return -ENOMEM;
1227
1228 key.objectid = 0;
1229 key.type = 0;
1230 key.offset = 0;
1231
1232 while (1) {
1233 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1234 if (ret < 0)
1235 goto out;
1236
1237 nr = btrfs_header_nritems(path->nodes[0]);
1238 if (!nr)
1239 break;
1240
1241 path->slots[0] = 0;
1242 ret = btrfs_del_items(trans, root, path, 0, nr);
1243 if (ret)
1244 goto out;
1245
1246 btrfs_release_path(path);
1247 }
1248
1249 ret = 0;
1250out:
1251 btrfs_free_path(path);
1252 return ret;
1253}
1254
1255int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
1256{
1257 struct btrfs_trans_handle *trans;
1258 struct btrfs_root *tree_root = fs_info->tree_root;
1259 struct btrfs_key key = {
1260 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
1261 .type = BTRFS_ROOT_ITEM_KEY,
1262 .offset = 0,
1263 };
1264 struct btrfs_root *free_space_root = btrfs_global_root(fs_info, &key);
1265 int ret;
1266
1267 trans = btrfs_start_transaction(tree_root, 0);
1268 if (IS_ERR(trans))
1269 return PTR_ERR(trans);
1270
1271 btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1272 btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1273
1274 ret = clear_free_space_tree(trans, free_space_root);
1275 if (ret)
1276 goto abort;
1277
1278 ret = btrfs_del_root(trans, &free_space_root->root_key);
1279 if (ret)
1280 goto abort;
1281
1282 btrfs_global_root_delete(free_space_root);
1283 list_del(&free_space_root->dirty_list);
1284
1285 btrfs_tree_lock(free_space_root->node);
1286 btrfs_clean_tree_block(free_space_root->node);
1287 btrfs_tree_unlock(free_space_root->node);
1288 btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
1289 free_space_root->node, 0, 1);
1290
1291 btrfs_put_root(free_space_root);
1292
1293 return btrfs_commit_transaction(trans);
1294
1295abort:
1296 btrfs_abort_transaction(trans, ret);
1297 btrfs_end_transaction(trans);
1298 return ret;
1299}
1300
1301static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
1302 struct btrfs_block_group *block_group,
1303 struct btrfs_path *path)
1304{
1305 int ret;
1306
1307 clear_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags);
1308
1309 ret = add_new_free_space_info(trans, block_group, path);
1310 if (ret)
1311 return ret;
1312
1313 return __add_to_free_space_tree(trans, block_group, path,
1314 block_group->start,
1315 block_group->length);
1316}
1317
1318int add_block_group_free_space(struct btrfs_trans_handle *trans,
1319 struct btrfs_block_group *block_group)
1320{
1321 struct btrfs_fs_info *fs_info = trans->fs_info;
1322 struct btrfs_path *path = NULL;
1323 int ret = 0;
1324
1325 if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
1326 return 0;
1327
1328 mutex_lock(&block_group->free_space_lock);
1329 if (!test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags))
1330 goto out;
1331
1332 path = btrfs_alloc_path();
1333 if (!path) {
1334 ret = -ENOMEM;
1335 goto out;
1336 }
1337
1338 ret = __add_block_group_free_space(trans, block_group, path);
1339
1340out:
1341 btrfs_free_path(path);
1342 mutex_unlock(&block_group->free_space_lock);
1343 if (ret)
1344 btrfs_abort_transaction(trans, ret);
1345 return ret;
1346}
1347
1348int remove_block_group_free_space(struct btrfs_trans_handle *trans,
1349 struct btrfs_block_group *block_group)
1350{
1351 struct btrfs_root *root = btrfs_free_space_root(block_group);
1352 struct btrfs_path *path;
1353 struct btrfs_key key, found_key;
1354 struct extent_buffer *leaf;
1355 u64 start, end;
1356 int done = 0, nr;
1357 int ret;
1358
1359 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1360 return 0;
1361
1362 if (test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags)) {
1363 /* We never added this block group to the free space tree. */
1364 return 0;
1365 }
1366
1367 path = btrfs_alloc_path();
1368 if (!path) {
1369 ret = -ENOMEM;
1370 goto out;
1371 }
1372
1373 start = block_group->start;
1374 end = block_group->start + block_group->length;
1375
1376 key.objectid = end - 1;
1377 key.type = (u8)-1;
1378 key.offset = (u64)-1;
1379
1380 while (!done) {
1381 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
1382 if (ret)
1383 goto out;
1384
1385 leaf = path->nodes[0];
1386 nr = 0;
1387 path->slots[0]++;
1388 while (path->slots[0] > 0) {
1389 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
1390
1391 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
1392 ASSERT(found_key.objectid == block_group->start);
1393 ASSERT(found_key.offset == block_group->length);
1394 done = 1;
1395 nr++;
1396 path->slots[0]--;
1397 break;
1398 } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
1399 found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
1400 ASSERT(found_key.objectid >= start);
1401 ASSERT(found_key.objectid < end);
1402 ASSERT(found_key.objectid + found_key.offset <= end);
1403 nr++;
1404 path->slots[0]--;
1405 } else {
1406 ASSERT(0);
1407 }
1408 }
1409
1410 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
1411 if (ret)
1412 goto out;
1413 btrfs_release_path(path);
1414 }
1415
1416 ret = 0;
1417out:
1418 btrfs_free_path(path);
1419 if (ret)
1420 btrfs_abort_transaction(trans, ret);
1421 return ret;
1422}
1423
1424static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
1425 struct btrfs_path *path,
1426 u32 expected_extent_count)
1427{
1428 struct btrfs_block_group *block_group;
1429 struct btrfs_fs_info *fs_info;
1430 struct btrfs_root *root;
1431 struct btrfs_key key;
1432 int prev_bit = 0, bit;
1433 /* Initialize to silence GCC. */
1434 u64 extent_start = 0;
1435 u64 end, offset;
1436 u64 total_found = 0;
1437 u32 extent_count = 0;
1438 int ret;
1439
1440 block_group = caching_ctl->block_group;
1441 fs_info = block_group->fs_info;
1442 root = btrfs_free_space_root(block_group);
1443
1444 end = block_group->start + block_group->length;
1445
1446 while (1) {
1447 ret = btrfs_next_item(root, path);
1448 if (ret < 0)
1449 goto out;
1450 if (ret)
1451 break;
1452
1453 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1454
1455 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1456 break;
1457
1458 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
1459 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1460
1461 offset = key.objectid;
1462 while (offset < key.objectid + key.offset) {
1463 bit = free_space_test_bit(block_group, path, offset);
1464 if (prev_bit == 0 && bit == 1) {
1465 extent_start = offset;
1466 } else if (prev_bit == 1 && bit == 0) {
1467 total_found += add_new_free_space(block_group,
1468 extent_start,
1469 offset);
1470 if (total_found > CACHING_CTL_WAKE_UP) {
1471 total_found = 0;
1472 wake_up(&caching_ctl->wait);
1473 }
1474 extent_count++;
1475 }
1476 prev_bit = bit;
1477 offset += fs_info->sectorsize;
1478 }
1479 }
1480 if (prev_bit == 1) {
1481 total_found += add_new_free_space(block_group, extent_start,
1482 end);
1483 extent_count++;
1484 }
1485
1486 if (extent_count != expected_extent_count) {
1487 btrfs_err(fs_info,
1488 "incorrect extent count for %llu; counted %u, expected %u",
1489 block_group->start, extent_count,
1490 expected_extent_count);
1491 ASSERT(0);
1492 ret = -EIO;
1493 goto out;
1494 }
1495
1496 ret = 0;
1497out:
1498 return ret;
1499}
1500
1501static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
1502 struct btrfs_path *path,
1503 u32 expected_extent_count)
1504{
1505 struct btrfs_block_group *block_group;
1506 struct btrfs_fs_info *fs_info;
1507 struct btrfs_root *root;
1508 struct btrfs_key key;
1509 u64 end;
1510 u64 total_found = 0;
1511 u32 extent_count = 0;
1512 int ret;
1513
1514 block_group = caching_ctl->block_group;
1515 fs_info = block_group->fs_info;
1516 root = btrfs_free_space_root(block_group);
1517
1518 end = block_group->start + block_group->length;
1519
1520 while (1) {
1521 ret = btrfs_next_item(root, path);
1522 if (ret < 0)
1523 goto out;
1524 if (ret)
1525 break;
1526
1527 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1528
1529 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1530 break;
1531
1532 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
1533 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1534
1535 total_found += add_new_free_space(block_group, key.objectid,
1536 key.objectid + key.offset);
1537 if (total_found > CACHING_CTL_WAKE_UP) {
1538 total_found = 0;
1539 wake_up(&caching_ctl->wait);
1540 }
1541 extent_count++;
1542 }
1543
1544 if (extent_count != expected_extent_count) {
1545 btrfs_err(fs_info,
1546 "incorrect extent count for %llu; counted %u, expected %u",
1547 block_group->start, extent_count,
1548 expected_extent_count);
1549 ASSERT(0);
1550 ret = -EIO;
1551 goto out;
1552 }
1553
1554 ret = 0;
1555out:
1556 return ret;
1557}
1558
1559int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
1560{
1561 struct btrfs_block_group *block_group;
1562 struct btrfs_free_space_info *info;
1563 struct btrfs_path *path;
1564 u32 extent_count, flags;
1565 int ret;
1566
1567 block_group = caching_ctl->block_group;
1568
1569 path = btrfs_alloc_path();
1570 if (!path)
1571 return -ENOMEM;
1572
1573 /*
1574 * Just like caching_thread() doesn't want to deadlock on the extent
1575 * tree, we don't want to deadlock on the free space tree.
1576 */
1577 path->skip_locking = 1;
1578 path->search_commit_root = 1;
1579 path->reada = READA_FORWARD;
1580
1581 info = search_free_space_info(NULL, block_group, path, 0);
1582 if (IS_ERR(info)) {
1583 ret = PTR_ERR(info);
1584 goto out;
1585 }
1586 extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
1587 flags = btrfs_free_space_flags(path->nodes[0], info);
1588
1589 /*
1590 * We left path pointing to the free space info item, so now
1591 * load_free_space_foo can just iterate through the free space tree from
1592 * there.
1593 */
1594 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
1595 ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
1596 else
1597 ret = load_free_space_extents(caching_ctl, path, extent_count);
1598
1599out:
1600 btrfs_free_path(path);
1601 return ret;
1602}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2015 Facebook. All rights reserved.
4 */
5
6#include <linux/kernel.h>
7#include <linux/sched/mm.h>
8#include "ctree.h"
9#include "disk-io.h"
10#include "locking.h"
11#include "free-space-tree.h"
12#include "transaction.h"
13#include "block-group.h"
14
15static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
16 struct btrfs_block_group *block_group,
17 struct btrfs_path *path);
18
19void set_free_space_tree_thresholds(struct btrfs_block_group *cache)
20{
21 u32 bitmap_range;
22 size_t bitmap_size;
23 u64 num_bitmaps, total_bitmap_size;
24
25 if (WARN_ON(cache->length == 0))
26 btrfs_warn(cache->fs_info, "block group %llu length is zero",
27 cache->start);
28
29 /*
30 * We convert to bitmaps when the disk space required for using extents
31 * exceeds that required for using bitmaps.
32 */
33 bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
34 num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range);
35 bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
36 total_bitmap_size = num_bitmaps * bitmap_size;
37 cache->bitmap_high_thresh = div_u64(total_bitmap_size,
38 sizeof(struct btrfs_item));
39
40 /*
41 * We allow for a small buffer between the high threshold and low
42 * threshold to avoid thrashing back and forth between the two formats.
43 */
44 if (cache->bitmap_high_thresh > 100)
45 cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
46 else
47 cache->bitmap_low_thresh = 0;
48}
49
50static int add_new_free_space_info(struct btrfs_trans_handle *trans,
51 struct btrfs_block_group *block_group,
52 struct btrfs_path *path)
53{
54 struct btrfs_root *root = trans->fs_info->free_space_root;
55 struct btrfs_free_space_info *info;
56 struct btrfs_key key;
57 struct extent_buffer *leaf;
58 int ret;
59
60 key.objectid = block_group->start;
61 key.type = BTRFS_FREE_SPACE_INFO_KEY;
62 key.offset = block_group->length;
63
64 ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
65 if (ret)
66 goto out;
67
68 leaf = path->nodes[0];
69 info = btrfs_item_ptr(leaf, path->slots[0],
70 struct btrfs_free_space_info);
71 btrfs_set_free_space_extent_count(leaf, info, 0);
72 btrfs_set_free_space_flags(leaf, info, 0);
73 btrfs_mark_buffer_dirty(leaf);
74
75 ret = 0;
76out:
77 btrfs_release_path(path);
78 return ret;
79}
80
81EXPORT_FOR_TESTS
82struct btrfs_free_space_info *search_free_space_info(
83 struct btrfs_trans_handle *trans,
84 struct btrfs_block_group *block_group,
85 struct btrfs_path *path, int cow)
86{
87 struct btrfs_fs_info *fs_info = block_group->fs_info;
88 struct btrfs_root *root = fs_info->free_space_root;
89 struct btrfs_key key;
90 int ret;
91
92 key.objectid = block_group->start;
93 key.type = BTRFS_FREE_SPACE_INFO_KEY;
94 key.offset = block_group->length;
95
96 ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
97 if (ret < 0)
98 return ERR_PTR(ret);
99 if (ret != 0) {
100 btrfs_warn(fs_info, "missing free space info for %llu",
101 block_group->start);
102 ASSERT(0);
103 return ERR_PTR(-ENOENT);
104 }
105
106 return btrfs_item_ptr(path->nodes[0], path->slots[0],
107 struct btrfs_free_space_info);
108}
109
110/*
111 * btrfs_search_slot() but we're looking for the greatest key less than the
112 * passed key.
113 */
114static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
115 struct btrfs_root *root,
116 struct btrfs_key *key, struct btrfs_path *p,
117 int ins_len, int cow)
118{
119 int ret;
120
121 ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
122 if (ret < 0)
123 return ret;
124
125 if (ret == 0) {
126 ASSERT(0);
127 return -EIO;
128 }
129
130 if (p->slots[0] == 0) {
131 ASSERT(0);
132 return -EIO;
133 }
134 p->slots[0]--;
135
136 return 0;
137}
138
139static inline u32 free_space_bitmap_size(u64 size, u32 sectorsize)
140{
141 return DIV_ROUND_UP((u32)div_u64(size, sectorsize), BITS_PER_BYTE);
142}
143
144static unsigned long *alloc_bitmap(u32 bitmap_size)
145{
146 unsigned long *ret;
147 unsigned int nofs_flag;
148 u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long));
149
150 /*
151 * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
152 * into the filesystem as the free space bitmap can be modified in the
153 * critical section of a transaction commit.
154 *
155 * TODO: push the memalloc_nofs_{save,restore}() to the caller where we
156 * know that recursion is unsafe.
157 */
158 nofs_flag = memalloc_nofs_save();
159 ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);
160 memalloc_nofs_restore(nofs_flag);
161 return ret;
162}
163
164static void le_bitmap_set(unsigned long *map, unsigned int start, int len)
165{
166 u8 *p = ((u8 *)map) + BIT_BYTE(start);
167 const unsigned int size = start + len;
168 int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
169 u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
170
171 while (len - bits_to_set >= 0) {
172 *p |= mask_to_set;
173 len -= bits_to_set;
174 bits_to_set = BITS_PER_BYTE;
175 mask_to_set = ~0;
176 p++;
177 }
178 if (len) {
179 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
180 *p |= mask_to_set;
181 }
182}
183
184EXPORT_FOR_TESTS
185int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
186 struct btrfs_block_group *block_group,
187 struct btrfs_path *path)
188{
189 struct btrfs_fs_info *fs_info = trans->fs_info;
190 struct btrfs_root *root = fs_info->free_space_root;
191 struct btrfs_free_space_info *info;
192 struct btrfs_key key, found_key;
193 struct extent_buffer *leaf;
194 unsigned long *bitmap;
195 char *bitmap_cursor;
196 u64 start, end;
197 u64 bitmap_range, i;
198 u32 bitmap_size, flags, expected_extent_count;
199 u32 extent_count = 0;
200 int done = 0, nr;
201 int ret;
202
203 bitmap_size = free_space_bitmap_size(block_group->length,
204 fs_info->sectorsize);
205 bitmap = alloc_bitmap(bitmap_size);
206 if (!bitmap) {
207 ret = -ENOMEM;
208 goto out;
209 }
210
211 start = block_group->start;
212 end = block_group->start + block_group->length;
213
214 key.objectid = end - 1;
215 key.type = (u8)-1;
216 key.offset = (u64)-1;
217
218 while (!done) {
219 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
220 if (ret)
221 goto out;
222
223 leaf = path->nodes[0];
224 nr = 0;
225 path->slots[0]++;
226 while (path->slots[0] > 0) {
227 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
228
229 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
230 ASSERT(found_key.objectid == block_group->start);
231 ASSERT(found_key.offset == block_group->length);
232 done = 1;
233 break;
234 } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
235 u64 first, last;
236
237 ASSERT(found_key.objectid >= start);
238 ASSERT(found_key.objectid < end);
239 ASSERT(found_key.objectid + found_key.offset <= end);
240
241 first = div_u64(found_key.objectid - start,
242 fs_info->sectorsize);
243 last = div_u64(found_key.objectid + found_key.offset - start,
244 fs_info->sectorsize);
245 le_bitmap_set(bitmap, first, last - first);
246
247 extent_count++;
248 nr++;
249 path->slots[0]--;
250 } else {
251 ASSERT(0);
252 }
253 }
254
255 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
256 if (ret)
257 goto out;
258 btrfs_release_path(path);
259 }
260
261 info = search_free_space_info(trans, block_group, path, 1);
262 if (IS_ERR(info)) {
263 ret = PTR_ERR(info);
264 goto out;
265 }
266 leaf = path->nodes[0];
267 flags = btrfs_free_space_flags(leaf, info);
268 flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
269 btrfs_set_free_space_flags(leaf, info, flags);
270 expected_extent_count = btrfs_free_space_extent_count(leaf, info);
271 btrfs_mark_buffer_dirty(leaf);
272 btrfs_release_path(path);
273
274 if (extent_count != expected_extent_count) {
275 btrfs_err(fs_info,
276 "incorrect extent count for %llu; counted %u, expected %u",
277 block_group->start, extent_count,
278 expected_extent_count);
279 ASSERT(0);
280 ret = -EIO;
281 goto out;
282 }
283
284 bitmap_cursor = (char *)bitmap;
285 bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
286 i = start;
287 while (i < end) {
288 unsigned long ptr;
289 u64 extent_size;
290 u32 data_size;
291
292 extent_size = min(end - i, bitmap_range);
293 data_size = free_space_bitmap_size(extent_size,
294 fs_info->sectorsize);
295
296 key.objectid = i;
297 key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
298 key.offset = extent_size;
299
300 ret = btrfs_insert_empty_item(trans, root, path, &key,
301 data_size);
302 if (ret)
303 goto out;
304
305 leaf = path->nodes[0];
306 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
307 write_extent_buffer(leaf, bitmap_cursor, ptr,
308 data_size);
309 btrfs_mark_buffer_dirty(leaf);
310 btrfs_release_path(path);
311
312 i += extent_size;
313 bitmap_cursor += data_size;
314 }
315
316 ret = 0;
317out:
318 kvfree(bitmap);
319 if (ret)
320 btrfs_abort_transaction(trans, ret);
321 return ret;
322}
323
324EXPORT_FOR_TESTS
325int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
326 struct btrfs_block_group *block_group,
327 struct btrfs_path *path)
328{
329 struct btrfs_fs_info *fs_info = trans->fs_info;
330 struct btrfs_root *root = fs_info->free_space_root;
331 struct btrfs_free_space_info *info;
332 struct btrfs_key key, found_key;
333 struct extent_buffer *leaf;
334 unsigned long *bitmap;
335 u64 start, end;
336 u32 bitmap_size, flags, expected_extent_count;
337 unsigned long nrbits, start_bit, end_bit;
338 u32 extent_count = 0;
339 int done = 0, nr;
340 int ret;
341
342 bitmap_size = free_space_bitmap_size(block_group->length,
343 fs_info->sectorsize);
344 bitmap = alloc_bitmap(bitmap_size);
345 if (!bitmap) {
346 ret = -ENOMEM;
347 goto out;
348 }
349
350 start = block_group->start;
351 end = block_group->start + block_group->length;
352
353 key.objectid = end - 1;
354 key.type = (u8)-1;
355 key.offset = (u64)-1;
356
357 while (!done) {
358 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
359 if (ret)
360 goto out;
361
362 leaf = path->nodes[0];
363 nr = 0;
364 path->slots[0]++;
365 while (path->slots[0] > 0) {
366 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
367
368 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
369 ASSERT(found_key.objectid == block_group->start);
370 ASSERT(found_key.offset == block_group->length);
371 done = 1;
372 break;
373 } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
374 unsigned long ptr;
375 char *bitmap_cursor;
376 u32 bitmap_pos, data_size;
377
378 ASSERT(found_key.objectid >= start);
379 ASSERT(found_key.objectid < end);
380 ASSERT(found_key.objectid + found_key.offset <= end);
381
382 bitmap_pos = div_u64(found_key.objectid - start,
383 fs_info->sectorsize *
384 BITS_PER_BYTE);
385 bitmap_cursor = ((char *)bitmap) + bitmap_pos;
386 data_size = free_space_bitmap_size(found_key.offset,
387 fs_info->sectorsize);
388
389 ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
390 read_extent_buffer(leaf, bitmap_cursor, ptr,
391 data_size);
392
393 nr++;
394 path->slots[0]--;
395 } else {
396 ASSERT(0);
397 }
398 }
399
400 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
401 if (ret)
402 goto out;
403 btrfs_release_path(path);
404 }
405
406 info = search_free_space_info(trans, block_group, path, 1);
407 if (IS_ERR(info)) {
408 ret = PTR_ERR(info);
409 goto out;
410 }
411 leaf = path->nodes[0];
412 flags = btrfs_free_space_flags(leaf, info);
413 flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
414 btrfs_set_free_space_flags(leaf, info, flags);
415 expected_extent_count = btrfs_free_space_extent_count(leaf, info);
416 btrfs_mark_buffer_dirty(leaf);
417 btrfs_release_path(path);
418
419 nrbits = div_u64(block_group->length, block_group->fs_info->sectorsize);
420 start_bit = find_next_bit_le(bitmap, nrbits, 0);
421
422 while (start_bit < nrbits) {
423 end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit);
424 ASSERT(start_bit < end_bit);
425
426 key.objectid = start + start_bit * block_group->fs_info->sectorsize;
427 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
428 key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize;
429
430 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
431 if (ret)
432 goto out;
433 btrfs_release_path(path);
434
435 extent_count++;
436
437 start_bit = find_next_bit_le(bitmap, nrbits, end_bit);
438 }
439
440 if (extent_count != expected_extent_count) {
441 btrfs_err(fs_info,
442 "incorrect extent count for %llu; counted %u, expected %u",
443 block_group->start, extent_count,
444 expected_extent_count);
445 ASSERT(0);
446 ret = -EIO;
447 goto out;
448 }
449
450 ret = 0;
451out:
452 kvfree(bitmap);
453 if (ret)
454 btrfs_abort_transaction(trans, ret);
455 return ret;
456}
457
458static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
459 struct btrfs_block_group *block_group,
460 struct btrfs_path *path,
461 int new_extents)
462{
463 struct btrfs_free_space_info *info;
464 u32 flags;
465 u32 extent_count;
466 int ret = 0;
467
468 if (new_extents == 0)
469 return 0;
470
471 info = search_free_space_info(trans, block_group, path, 1);
472 if (IS_ERR(info)) {
473 ret = PTR_ERR(info);
474 goto out;
475 }
476 flags = btrfs_free_space_flags(path->nodes[0], info);
477 extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
478
479 extent_count += new_extents;
480 btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
481 btrfs_mark_buffer_dirty(path->nodes[0]);
482 btrfs_release_path(path);
483
484 if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
485 extent_count > block_group->bitmap_high_thresh) {
486 ret = convert_free_space_to_bitmaps(trans, block_group, path);
487 } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
488 extent_count < block_group->bitmap_low_thresh) {
489 ret = convert_free_space_to_extents(trans, block_group, path);
490 }
491
492out:
493 return ret;
494}
495
496EXPORT_FOR_TESTS
497int free_space_test_bit(struct btrfs_block_group *block_group,
498 struct btrfs_path *path, u64 offset)
499{
500 struct extent_buffer *leaf;
501 struct btrfs_key key;
502 u64 found_start, found_end;
503 unsigned long ptr, i;
504
505 leaf = path->nodes[0];
506 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
507 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
508
509 found_start = key.objectid;
510 found_end = key.objectid + key.offset;
511 ASSERT(offset >= found_start && offset < found_end);
512
513 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
514 i = div_u64(offset - found_start,
515 block_group->fs_info->sectorsize);
516 return !!extent_buffer_test_bit(leaf, ptr, i);
517}
518
519static void free_space_set_bits(struct btrfs_block_group *block_group,
520 struct btrfs_path *path, u64 *start, u64 *size,
521 int bit)
522{
523 struct btrfs_fs_info *fs_info = block_group->fs_info;
524 struct extent_buffer *leaf;
525 struct btrfs_key key;
526 u64 end = *start + *size;
527 u64 found_start, found_end;
528 unsigned long ptr, first, last;
529
530 leaf = path->nodes[0];
531 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
532 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
533
534 found_start = key.objectid;
535 found_end = key.objectid + key.offset;
536 ASSERT(*start >= found_start && *start < found_end);
537 ASSERT(end > found_start);
538
539 if (end > found_end)
540 end = found_end;
541
542 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
543 first = div_u64(*start - found_start, fs_info->sectorsize);
544 last = div_u64(end - found_start, fs_info->sectorsize);
545 if (bit)
546 extent_buffer_bitmap_set(leaf, ptr, first, last - first);
547 else
548 extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
549 btrfs_mark_buffer_dirty(leaf);
550
551 *size -= end - *start;
552 *start = end;
553}
554
555/*
556 * We can't use btrfs_next_item() in modify_free_space_bitmap() because
557 * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
558 * tree walking in btrfs_next_leaf() anyways because we know exactly what we're
559 * looking for.
560 */
561static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
562 struct btrfs_root *root, struct btrfs_path *p)
563{
564 struct btrfs_key key;
565
566 if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
567 p->slots[0]++;
568 return 0;
569 }
570
571 btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
572 btrfs_release_path(p);
573
574 key.objectid += key.offset;
575 key.type = (u8)-1;
576 key.offset = (u64)-1;
577
578 return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
579}
580
581/*
582 * If remove is 1, then we are removing free space, thus clearing bits in the
583 * bitmap. If remove is 0, then we are adding free space, thus setting bits in
584 * the bitmap.
585 */
586static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
587 struct btrfs_block_group *block_group,
588 struct btrfs_path *path,
589 u64 start, u64 size, int remove)
590{
591 struct btrfs_root *root = block_group->fs_info->free_space_root;
592 struct btrfs_key key;
593 u64 end = start + size;
594 u64 cur_start, cur_size;
595 int prev_bit, next_bit;
596 int new_extents;
597 int ret;
598
599 /*
600 * Read the bit for the block immediately before the extent of space if
601 * that block is within the block group.
602 */
603 if (start > block_group->start) {
604 u64 prev_block = start - block_group->fs_info->sectorsize;
605
606 key.objectid = prev_block;
607 key.type = (u8)-1;
608 key.offset = (u64)-1;
609
610 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
611 if (ret)
612 goto out;
613
614 prev_bit = free_space_test_bit(block_group, path, prev_block);
615
616 /* The previous block may have been in the previous bitmap. */
617 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
618 if (start >= key.objectid + key.offset) {
619 ret = free_space_next_bitmap(trans, root, path);
620 if (ret)
621 goto out;
622 }
623 } else {
624 key.objectid = start;
625 key.type = (u8)-1;
626 key.offset = (u64)-1;
627
628 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
629 if (ret)
630 goto out;
631
632 prev_bit = -1;
633 }
634
635 /*
636 * Iterate over all of the bitmaps overlapped by the extent of space,
637 * clearing/setting bits as required.
638 */
639 cur_start = start;
640 cur_size = size;
641 while (1) {
642 free_space_set_bits(block_group, path, &cur_start, &cur_size,
643 !remove);
644 if (cur_size == 0)
645 break;
646 ret = free_space_next_bitmap(trans, root, path);
647 if (ret)
648 goto out;
649 }
650
651 /*
652 * Read the bit for the block immediately after the extent of space if
653 * that block is within the block group.
654 */
655 if (end < block_group->start + block_group->length) {
656 /* The next block may be in the next bitmap. */
657 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
658 if (end >= key.objectid + key.offset) {
659 ret = free_space_next_bitmap(trans, root, path);
660 if (ret)
661 goto out;
662 }
663
664 next_bit = free_space_test_bit(block_group, path, end);
665 } else {
666 next_bit = -1;
667 }
668
669 if (remove) {
670 new_extents = -1;
671 if (prev_bit == 1) {
672 /* Leftover on the left. */
673 new_extents++;
674 }
675 if (next_bit == 1) {
676 /* Leftover on the right. */
677 new_extents++;
678 }
679 } else {
680 new_extents = 1;
681 if (prev_bit == 1) {
682 /* Merging with neighbor on the left. */
683 new_extents--;
684 }
685 if (next_bit == 1) {
686 /* Merging with neighbor on the right. */
687 new_extents--;
688 }
689 }
690
691 btrfs_release_path(path);
692 ret = update_free_space_extent_count(trans, block_group, path,
693 new_extents);
694
695out:
696 return ret;
697}
698
699static int remove_free_space_extent(struct btrfs_trans_handle *trans,
700 struct btrfs_block_group *block_group,
701 struct btrfs_path *path,
702 u64 start, u64 size)
703{
704 struct btrfs_root *root = trans->fs_info->free_space_root;
705 struct btrfs_key key;
706 u64 found_start, found_end;
707 u64 end = start + size;
708 int new_extents = -1;
709 int ret;
710
711 key.objectid = start;
712 key.type = (u8)-1;
713 key.offset = (u64)-1;
714
715 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
716 if (ret)
717 goto out;
718
719 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
720
721 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
722
723 found_start = key.objectid;
724 found_end = key.objectid + key.offset;
725 ASSERT(start >= found_start && end <= found_end);
726
727 /*
728 * Okay, now that we've found the free space extent which contains the
729 * free space that we are removing, there are four cases:
730 *
731 * 1. We're using the whole extent: delete the key we found and
732 * decrement the free space extent count.
733 * 2. We are using part of the extent starting at the beginning: delete
734 * the key we found and insert a new key representing the leftover at
735 * the end. There is no net change in the number of extents.
736 * 3. We are using part of the extent ending at the end: delete the key
737 * we found and insert a new key representing the leftover at the
738 * beginning. There is no net change in the number of extents.
739 * 4. We are using part of the extent in the middle: delete the key we
740 * found and insert two new keys representing the leftovers on each
741 * side. Where we used to have one extent, we now have two, so increment
742 * the extent count. We may need to convert the block group to bitmaps
743 * as a result.
744 */
745
746 /* Delete the existing key (cases 1-4). */
747 ret = btrfs_del_item(trans, root, path);
748 if (ret)
749 goto out;
750
751 /* Add a key for leftovers at the beginning (cases 3 and 4). */
752 if (start > found_start) {
753 key.objectid = found_start;
754 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
755 key.offset = start - found_start;
756
757 btrfs_release_path(path);
758 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
759 if (ret)
760 goto out;
761 new_extents++;
762 }
763
764 /* Add a key for leftovers at the end (cases 2 and 4). */
765 if (end < found_end) {
766 key.objectid = end;
767 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
768 key.offset = found_end - end;
769
770 btrfs_release_path(path);
771 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
772 if (ret)
773 goto out;
774 new_extents++;
775 }
776
777 btrfs_release_path(path);
778 ret = update_free_space_extent_count(trans, block_group, path,
779 new_extents);
780
781out:
782 return ret;
783}
784
785EXPORT_FOR_TESTS
786int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
787 struct btrfs_block_group *block_group,
788 struct btrfs_path *path, u64 start, u64 size)
789{
790 struct btrfs_free_space_info *info;
791 u32 flags;
792 int ret;
793
794 if (block_group->needs_free_space) {
795 ret = __add_block_group_free_space(trans, block_group, path);
796 if (ret)
797 return ret;
798 }
799
800 info = search_free_space_info(NULL, block_group, path, 0);
801 if (IS_ERR(info))
802 return PTR_ERR(info);
803 flags = btrfs_free_space_flags(path->nodes[0], info);
804 btrfs_release_path(path);
805
806 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
807 return modify_free_space_bitmap(trans, block_group, path,
808 start, size, 1);
809 } else {
810 return remove_free_space_extent(trans, block_group, path,
811 start, size);
812 }
813}
814
815int remove_from_free_space_tree(struct btrfs_trans_handle *trans,
816 u64 start, u64 size)
817{
818 struct btrfs_block_group *block_group;
819 struct btrfs_path *path;
820 int ret;
821
822 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
823 return 0;
824
825 path = btrfs_alloc_path();
826 if (!path) {
827 ret = -ENOMEM;
828 goto out;
829 }
830
831 block_group = btrfs_lookup_block_group(trans->fs_info, start);
832 if (!block_group) {
833 ASSERT(0);
834 ret = -ENOENT;
835 goto out;
836 }
837
838 mutex_lock(&block_group->free_space_lock);
839 ret = __remove_from_free_space_tree(trans, block_group, path, start,
840 size);
841 mutex_unlock(&block_group->free_space_lock);
842
843 btrfs_put_block_group(block_group);
844out:
845 btrfs_free_path(path);
846 if (ret)
847 btrfs_abort_transaction(trans, ret);
848 return ret;
849}
850
851static int add_free_space_extent(struct btrfs_trans_handle *trans,
852 struct btrfs_block_group *block_group,
853 struct btrfs_path *path,
854 u64 start, u64 size)
855{
856 struct btrfs_root *root = trans->fs_info->free_space_root;
857 struct btrfs_key key, new_key;
858 u64 found_start, found_end;
859 u64 end = start + size;
860 int new_extents = 1;
861 int ret;
862
863 /*
864 * We are adding a new extent of free space, but we need to merge
865 * extents. There are four cases here:
866 *
867 * 1. The new extent does not have any immediate neighbors to merge
868 * with: add the new key and increment the free space extent count. We
869 * may need to convert the block group to bitmaps as a result.
870 * 2. The new extent has an immediate neighbor before it: remove the
871 * previous key and insert a new key combining both of them. There is no
872 * net change in the number of extents.
873 * 3. The new extent has an immediate neighbor after it: remove the next
874 * key and insert a new key combining both of them. There is no net
875 * change in the number of extents.
876 * 4. The new extent has immediate neighbors on both sides: remove both
877 * of the keys and insert a new key combining all of them. Where we used
878 * to have two extents, we now have one, so decrement the extent count.
879 */
880
881 new_key.objectid = start;
882 new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
883 new_key.offset = size;
884
885 /* Search for a neighbor on the left. */
886 if (start == block_group->start)
887 goto right;
888 key.objectid = start - 1;
889 key.type = (u8)-1;
890 key.offset = (u64)-1;
891
892 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
893 if (ret)
894 goto out;
895
896 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
897
898 if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
899 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
900 btrfs_release_path(path);
901 goto right;
902 }
903
904 found_start = key.objectid;
905 found_end = key.objectid + key.offset;
906 ASSERT(found_start >= block_group->start &&
907 found_end > block_group->start);
908 ASSERT(found_start < start && found_end <= start);
909
910 /*
911 * Delete the neighbor on the left and absorb it into the new key (cases
912 * 2 and 4).
913 */
914 if (found_end == start) {
915 ret = btrfs_del_item(trans, root, path);
916 if (ret)
917 goto out;
918 new_key.objectid = found_start;
919 new_key.offset += key.offset;
920 new_extents--;
921 }
922 btrfs_release_path(path);
923
924right:
925 /* Search for a neighbor on the right. */
926 if (end == block_group->start + block_group->length)
927 goto insert;
928 key.objectid = end;
929 key.type = (u8)-1;
930 key.offset = (u64)-1;
931
932 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
933 if (ret)
934 goto out;
935
936 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
937
938 if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
939 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
940 btrfs_release_path(path);
941 goto insert;
942 }
943
944 found_start = key.objectid;
945 found_end = key.objectid + key.offset;
946 ASSERT(found_start >= block_group->start &&
947 found_end > block_group->start);
948 ASSERT((found_start < start && found_end <= start) ||
949 (found_start >= end && found_end > end));
950
951 /*
952 * Delete the neighbor on the right and absorb it into the new key
953 * (cases 3 and 4).
954 */
955 if (found_start == end) {
956 ret = btrfs_del_item(trans, root, path);
957 if (ret)
958 goto out;
959 new_key.offset += key.offset;
960 new_extents--;
961 }
962 btrfs_release_path(path);
963
964insert:
965 /* Insert the new key (cases 1-4). */
966 ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0);
967 if (ret)
968 goto out;
969
970 btrfs_release_path(path);
971 ret = update_free_space_extent_count(trans, block_group, path,
972 new_extents);
973
974out:
975 return ret;
976}
977
978EXPORT_FOR_TESTS
979int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
980 struct btrfs_block_group *block_group,
981 struct btrfs_path *path, u64 start, u64 size)
982{
983 struct btrfs_free_space_info *info;
984 u32 flags;
985 int ret;
986
987 if (block_group->needs_free_space) {
988 ret = __add_block_group_free_space(trans, block_group, path);
989 if (ret)
990 return ret;
991 }
992
993 info = search_free_space_info(NULL, block_group, path, 0);
994 if (IS_ERR(info))
995 return PTR_ERR(info);
996 flags = btrfs_free_space_flags(path->nodes[0], info);
997 btrfs_release_path(path);
998
999 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
1000 return modify_free_space_bitmap(trans, block_group, path,
1001 start, size, 0);
1002 } else {
1003 return add_free_space_extent(trans, block_group, path, start,
1004 size);
1005 }
1006}
1007
1008int add_to_free_space_tree(struct btrfs_trans_handle *trans,
1009 u64 start, u64 size)
1010{
1011 struct btrfs_block_group *block_group;
1012 struct btrfs_path *path;
1013 int ret;
1014
1015 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1016 return 0;
1017
1018 path = btrfs_alloc_path();
1019 if (!path) {
1020 ret = -ENOMEM;
1021 goto out;
1022 }
1023
1024 block_group = btrfs_lookup_block_group(trans->fs_info, start);
1025 if (!block_group) {
1026 ASSERT(0);
1027 ret = -ENOENT;
1028 goto out;
1029 }
1030
1031 mutex_lock(&block_group->free_space_lock);
1032 ret = __add_to_free_space_tree(trans, block_group, path, start, size);
1033 mutex_unlock(&block_group->free_space_lock);
1034
1035 btrfs_put_block_group(block_group);
1036out:
1037 btrfs_free_path(path);
1038 if (ret)
1039 btrfs_abort_transaction(trans, ret);
1040 return ret;
1041}
1042
1043/*
1044 * Populate the free space tree by walking the extent tree. Operations on the
1045 * extent tree that happen as a result of writes to the free space tree will go
1046 * through the normal add/remove hooks.
1047 */
1048static int populate_free_space_tree(struct btrfs_trans_handle *trans,
1049 struct btrfs_block_group *block_group)
1050{
1051 struct btrfs_root *extent_root = trans->fs_info->extent_root;
1052 struct btrfs_path *path, *path2;
1053 struct btrfs_key key;
1054 u64 start, end;
1055 int ret;
1056
1057 path = btrfs_alloc_path();
1058 if (!path)
1059 return -ENOMEM;
1060 path->reada = READA_FORWARD;
1061
1062 path2 = btrfs_alloc_path();
1063 if (!path2) {
1064 btrfs_free_path(path);
1065 return -ENOMEM;
1066 }
1067
1068 ret = add_new_free_space_info(trans, block_group, path2);
1069 if (ret)
1070 goto out;
1071
1072 mutex_lock(&block_group->free_space_lock);
1073
1074 /*
1075 * Iterate through all of the extent and metadata items in this block
1076 * group, adding the free space between them and the free space at the
1077 * end. Note that EXTENT_ITEM and METADATA_ITEM are less than
1078 * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
1079 * contained in.
1080 */
1081 key.objectid = block_group->start;
1082 key.type = BTRFS_EXTENT_ITEM_KEY;
1083 key.offset = 0;
1084
1085 ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
1086 if (ret < 0)
1087 goto out_locked;
1088 ASSERT(ret == 0);
1089
1090 start = block_group->start;
1091 end = block_group->start + block_group->length;
1092 while (1) {
1093 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1094
1095 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
1096 key.type == BTRFS_METADATA_ITEM_KEY) {
1097 if (key.objectid >= end)
1098 break;
1099
1100 if (start < key.objectid) {
1101 ret = __add_to_free_space_tree(trans,
1102 block_group,
1103 path2, start,
1104 key.objectid -
1105 start);
1106 if (ret)
1107 goto out_locked;
1108 }
1109 start = key.objectid;
1110 if (key.type == BTRFS_METADATA_ITEM_KEY)
1111 start += trans->fs_info->nodesize;
1112 else
1113 start += key.offset;
1114 } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
1115 if (key.objectid != block_group->start)
1116 break;
1117 }
1118
1119 ret = btrfs_next_item(extent_root, path);
1120 if (ret < 0)
1121 goto out_locked;
1122 if (ret)
1123 break;
1124 }
1125 if (start < end) {
1126 ret = __add_to_free_space_tree(trans, block_group, path2,
1127 start, end - start);
1128 if (ret)
1129 goto out_locked;
1130 }
1131
1132 ret = 0;
1133out_locked:
1134 mutex_unlock(&block_group->free_space_lock);
1135out:
1136 btrfs_free_path(path2);
1137 btrfs_free_path(path);
1138 return ret;
1139}
1140
1141int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
1142{
1143 struct btrfs_trans_handle *trans;
1144 struct btrfs_root *tree_root = fs_info->tree_root;
1145 struct btrfs_root *free_space_root;
1146 struct btrfs_block_group *block_group;
1147 struct rb_node *node;
1148 int ret;
1149
1150 trans = btrfs_start_transaction(tree_root, 0);
1151 if (IS_ERR(trans))
1152 return PTR_ERR(trans);
1153
1154 set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1155 free_space_root = btrfs_create_tree(trans,
1156 BTRFS_FREE_SPACE_TREE_OBJECTID);
1157 if (IS_ERR(free_space_root)) {
1158 ret = PTR_ERR(free_space_root);
1159 goto abort;
1160 }
1161 fs_info->free_space_root = free_space_root;
1162
1163 node = rb_first(&fs_info->block_group_cache_tree);
1164 while (node) {
1165 block_group = rb_entry(node, struct btrfs_block_group,
1166 cache_node);
1167 ret = populate_free_space_tree(trans, block_group);
1168 if (ret)
1169 goto abort;
1170 node = rb_next(node);
1171 }
1172
1173 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1174 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1175 clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1176
1177 return btrfs_commit_transaction(trans);
1178
1179abort:
1180 clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1181 btrfs_abort_transaction(trans, ret);
1182 btrfs_end_transaction(trans);
1183 return ret;
1184}
1185
1186static int clear_free_space_tree(struct btrfs_trans_handle *trans,
1187 struct btrfs_root *root)
1188{
1189 struct btrfs_path *path;
1190 struct btrfs_key key;
1191 int nr;
1192 int ret;
1193
1194 path = btrfs_alloc_path();
1195 if (!path)
1196 return -ENOMEM;
1197
1198 path->leave_spinning = 1;
1199
1200 key.objectid = 0;
1201 key.type = 0;
1202 key.offset = 0;
1203
1204 while (1) {
1205 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1206 if (ret < 0)
1207 goto out;
1208
1209 nr = btrfs_header_nritems(path->nodes[0]);
1210 if (!nr)
1211 break;
1212
1213 path->slots[0] = 0;
1214 ret = btrfs_del_items(trans, root, path, 0, nr);
1215 if (ret)
1216 goto out;
1217
1218 btrfs_release_path(path);
1219 }
1220
1221 ret = 0;
1222out:
1223 btrfs_free_path(path);
1224 return ret;
1225}
1226
1227int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
1228{
1229 struct btrfs_trans_handle *trans;
1230 struct btrfs_root *tree_root = fs_info->tree_root;
1231 struct btrfs_root *free_space_root = fs_info->free_space_root;
1232 int ret;
1233
1234 trans = btrfs_start_transaction(tree_root, 0);
1235 if (IS_ERR(trans))
1236 return PTR_ERR(trans);
1237
1238 btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1239 btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1240 fs_info->free_space_root = NULL;
1241
1242 ret = clear_free_space_tree(trans, free_space_root);
1243 if (ret)
1244 goto abort;
1245
1246 ret = btrfs_del_root(trans, &free_space_root->root_key);
1247 if (ret)
1248 goto abort;
1249
1250 list_del(&free_space_root->dirty_list);
1251
1252 btrfs_tree_lock(free_space_root->node);
1253 btrfs_clean_tree_block(free_space_root->node);
1254 btrfs_tree_unlock(free_space_root->node);
1255 btrfs_free_tree_block(trans, free_space_root, free_space_root->node,
1256 0, 1);
1257
1258 btrfs_put_root(free_space_root);
1259
1260 return btrfs_commit_transaction(trans);
1261
1262abort:
1263 btrfs_abort_transaction(trans, ret);
1264 btrfs_end_transaction(trans);
1265 return ret;
1266}
1267
1268static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
1269 struct btrfs_block_group *block_group,
1270 struct btrfs_path *path)
1271{
1272 int ret;
1273
1274 block_group->needs_free_space = 0;
1275
1276 ret = add_new_free_space_info(trans, block_group, path);
1277 if (ret)
1278 return ret;
1279
1280 return __add_to_free_space_tree(trans, block_group, path,
1281 block_group->start,
1282 block_group->length);
1283}
1284
1285int add_block_group_free_space(struct btrfs_trans_handle *trans,
1286 struct btrfs_block_group *block_group)
1287{
1288 struct btrfs_fs_info *fs_info = trans->fs_info;
1289 struct btrfs_path *path = NULL;
1290 int ret = 0;
1291
1292 if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
1293 return 0;
1294
1295 mutex_lock(&block_group->free_space_lock);
1296 if (!block_group->needs_free_space)
1297 goto out;
1298
1299 path = btrfs_alloc_path();
1300 if (!path) {
1301 ret = -ENOMEM;
1302 goto out;
1303 }
1304
1305 ret = __add_block_group_free_space(trans, block_group, path);
1306
1307out:
1308 btrfs_free_path(path);
1309 mutex_unlock(&block_group->free_space_lock);
1310 if (ret)
1311 btrfs_abort_transaction(trans, ret);
1312 return ret;
1313}
1314
1315int remove_block_group_free_space(struct btrfs_trans_handle *trans,
1316 struct btrfs_block_group *block_group)
1317{
1318 struct btrfs_root *root = trans->fs_info->free_space_root;
1319 struct btrfs_path *path;
1320 struct btrfs_key key, found_key;
1321 struct extent_buffer *leaf;
1322 u64 start, end;
1323 int done = 0, nr;
1324 int ret;
1325
1326 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1327 return 0;
1328
1329 if (block_group->needs_free_space) {
1330 /* We never added this block group to the free space tree. */
1331 return 0;
1332 }
1333
1334 path = btrfs_alloc_path();
1335 if (!path) {
1336 ret = -ENOMEM;
1337 goto out;
1338 }
1339
1340 start = block_group->start;
1341 end = block_group->start + block_group->length;
1342
1343 key.objectid = end - 1;
1344 key.type = (u8)-1;
1345 key.offset = (u64)-1;
1346
1347 while (!done) {
1348 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
1349 if (ret)
1350 goto out;
1351
1352 leaf = path->nodes[0];
1353 nr = 0;
1354 path->slots[0]++;
1355 while (path->slots[0] > 0) {
1356 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
1357
1358 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
1359 ASSERT(found_key.objectid == block_group->start);
1360 ASSERT(found_key.offset == block_group->length);
1361 done = 1;
1362 nr++;
1363 path->slots[0]--;
1364 break;
1365 } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
1366 found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
1367 ASSERT(found_key.objectid >= start);
1368 ASSERT(found_key.objectid < end);
1369 ASSERT(found_key.objectid + found_key.offset <= end);
1370 nr++;
1371 path->slots[0]--;
1372 } else {
1373 ASSERT(0);
1374 }
1375 }
1376
1377 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
1378 if (ret)
1379 goto out;
1380 btrfs_release_path(path);
1381 }
1382
1383 ret = 0;
1384out:
1385 btrfs_free_path(path);
1386 if (ret)
1387 btrfs_abort_transaction(trans, ret);
1388 return ret;
1389}
1390
1391static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
1392 struct btrfs_path *path,
1393 u32 expected_extent_count)
1394{
1395 struct btrfs_block_group *block_group;
1396 struct btrfs_fs_info *fs_info;
1397 struct btrfs_root *root;
1398 struct btrfs_key key;
1399 int prev_bit = 0, bit;
1400 /* Initialize to silence GCC. */
1401 u64 extent_start = 0;
1402 u64 end, offset;
1403 u64 total_found = 0;
1404 u32 extent_count = 0;
1405 int ret;
1406
1407 block_group = caching_ctl->block_group;
1408 fs_info = block_group->fs_info;
1409 root = fs_info->free_space_root;
1410
1411 end = block_group->start + block_group->length;
1412
1413 while (1) {
1414 ret = btrfs_next_item(root, path);
1415 if (ret < 0)
1416 goto out;
1417 if (ret)
1418 break;
1419
1420 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1421
1422 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1423 break;
1424
1425 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
1426 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1427
1428 caching_ctl->progress = key.objectid;
1429
1430 offset = key.objectid;
1431 while (offset < key.objectid + key.offset) {
1432 bit = free_space_test_bit(block_group, path, offset);
1433 if (prev_bit == 0 && bit == 1) {
1434 extent_start = offset;
1435 } else if (prev_bit == 1 && bit == 0) {
1436 total_found += add_new_free_space(block_group,
1437 extent_start,
1438 offset);
1439 if (total_found > CACHING_CTL_WAKE_UP) {
1440 total_found = 0;
1441 wake_up(&caching_ctl->wait);
1442 }
1443 extent_count++;
1444 }
1445 prev_bit = bit;
1446 offset += fs_info->sectorsize;
1447 }
1448 }
1449 if (prev_bit == 1) {
1450 total_found += add_new_free_space(block_group, extent_start,
1451 end);
1452 extent_count++;
1453 }
1454
1455 if (extent_count != expected_extent_count) {
1456 btrfs_err(fs_info,
1457 "incorrect extent count for %llu; counted %u, expected %u",
1458 block_group->start, extent_count,
1459 expected_extent_count);
1460 ASSERT(0);
1461 ret = -EIO;
1462 goto out;
1463 }
1464
1465 caching_ctl->progress = (u64)-1;
1466
1467 ret = 0;
1468out:
1469 return ret;
1470}
1471
1472static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
1473 struct btrfs_path *path,
1474 u32 expected_extent_count)
1475{
1476 struct btrfs_block_group *block_group;
1477 struct btrfs_fs_info *fs_info;
1478 struct btrfs_root *root;
1479 struct btrfs_key key;
1480 u64 end;
1481 u64 total_found = 0;
1482 u32 extent_count = 0;
1483 int ret;
1484
1485 block_group = caching_ctl->block_group;
1486 fs_info = block_group->fs_info;
1487 root = fs_info->free_space_root;
1488
1489 end = block_group->start + block_group->length;
1490
1491 while (1) {
1492 ret = btrfs_next_item(root, path);
1493 if (ret < 0)
1494 goto out;
1495 if (ret)
1496 break;
1497
1498 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1499
1500 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1501 break;
1502
1503 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
1504 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1505
1506 caching_ctl->progress = key.objectid;
1507
1508 total_found += add_new_free_space(block_group, key.objectid,
1509 key.objectid + key.offset);
1510 if (total_found > CACHING_CTL_WAKE_UP) {
1511 total_found = 0;
1512 wake_up(&caching_ctl->wait);
1513 }
1514 extent_count++;
1515 }
1516
1517 if (extent_count != expected_extent_count) {
1518 btrfs_err(fs_info,
1519 "incorrect extent count for %llu; counted %u, expected %u",
1520 block_group->start, extent_count,
1521 expected_extent_count);
1522 ASSERT(0);
1523 ret = -EIO;
1524 goto out;
1525 }
1526
1527 caching_ctl->progress = (u64)-1;
1528
1529 ret = 0;
1530out:
1531 return ret;
1532}
1533
1534int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
1535{
1536 struct btrfs_block_group *block_group;
1537 struct btrfs_free_space_info *info;
1538 struct btrfs_path *path;
1539 u32 extent_count, flags;
1540 int ret;
1541
1542 block_group = caching_ctl->block_group;
1543
1544 path = btrfs_alloc_path();
1545 if (!path)
1546 return -ENOMEM;
1547
1548 /*
1549 * Just like caching_thread() doesn't want to deadlock on the extent
1550 * tree, we don't want to deadlock on the free space tree.
1551 */
1552 path->skip_locking = 1;
1553 path->search_commit_root = 1;
1554 path->reada = READA_FORWARD;
1555
1556 info = search_free_space_info(NULL, block_group, path, 0);
1557 if (IS_ERR(info)) {
1558 ret = PTR_ERR(info);
1559 goto out;
1560 }
1561 extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
1562 flags = btrfs_free_space_flags(path->nodes[0], info);
1563
1564 /*
1565 * We left path pointing to the free space info item, so now
1566 * load_free_space_foo can just iterate through the free space tree from
1567 * there.
1568 */
1569 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
1570 ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
1571 else
1572 ret = load_free_space_extents(caching_ctl, path, extent_count);
1573
1574out:
1575 btrfs_free_path(path);
1576 return ret;
1577}