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