GNU Linux-libre 5.19-rc6-gnu
[releases.git] / fs / btrfs / free-space-tree.c
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
15 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
16                                         struct btrfs_block_group *block_group,
17                                         struct btrfs_path *path);
18
19 static struct btrfs_root *btrfs_free_space_root(
20                                 struct btrfs_block_group *block_group)
21 {
22         struct btrfs_key key = {
23                 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
24                 .type = BTRFS_ROOT_ITEM_KEY,
25                 .offset = 0,
26         };
27
28         if (btrfs_fs_incompat(block_group->fs_info, EXTENT_TREE_V2))
29                 key.offset = block_group->global_root_id;
30         return btrfs_global_root(block_group->fs_info, &key);
31 }
32
33 void set_free_space_tree_thresholds(struct btrfs_block_group *cache)
34 {
35         u32 bitmap_range;
36         size_t bitmap_size;
37         u64 num_bitmaps, total_bitmap_size;
38
39         if (WARN_ON(cache->length == 0))
40                 btrfs_warn(cache->fs_info, "block group %llu length is zero",
41                            cache->start);
42
43         /*
44          * We convert to bitmaps when the disk space required for using extents
45          * exceeds that required for using bitmaps.
46          */
47         bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
48         num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range);
49         bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
50         total_bitmap_size = num_bitmaps * bitmap_size;
51         cache->bitmap_high_thresh = div_u64(total_bitmap_size,
52                                             sizeof(struct btrfs_item));
53
54         /*
55          * We allow for a small buffer between the high threshold and low
56          * threshold to avoid thrashing back and forth between the two formats.
57          */
58         if (cache->bitmap_high_thresh > 100)
59                 cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
60         else
61                 cache->bitmap_low_thresh = 0;
62 }
63
64 static int add_new_free_space_info(struct btrfs_trans_handle *trans,
65                                    struct btrfs_block_group *block_group,
66                                    struct btrfs_path *path)
67 {
68         struct btrfs_root *root = btrfs_free_space_root(block_group);
69         struct btrfs_free_space_info *info;
70         struct btrfs_key key;
71         struct extent_buffer *leaf;
72         int ret;
73
74         key.objectid = block_group->start;
75         key.type = BTRFS_FREE_SPACE_INFO_KEY;
76         key.offset = block_group->length;
77
78         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
79         if (ret)
80                 goto out;
81
82         leaf = path->nodes[0];
83         info = btrfs_item_ptr(leaf, path->slots[0],
84                               struct btrfs_free_space_info);
85         btrfs_set_free_space_extent_count(leaf, info, 0);
86         btrfs_set_free_space_flags(leaf, info, 0);
87         btrfs_mark_buffer_dirty(leaf);
88
89         ret = 0;
90 out:
91         btrfs_release_path(path);
92         return ret;
93 }
94
95 EXPORT_FOR_TESTS
96 struct btrfs_free_space_info *search_free_space_info(
97                 struct btrfs_trans_handle *trans,
98                 struct btrfs_block_group *block_group,
99                 struct btrfs_path *path, int cow)
100 {
101         struct btrfs_fs_info *fs_info = block_group->fs_info;
102         struct btrfs_root *root = btrfs_free_space_root(block_group);
103         struct btrfs_key key;
104         int ret;
105
106         key.objectid = block_group->start;
107         key.type = BTRFS_FREE_SPACE_INFO_KEY;
108         key.offset = block_group->length;
109
110         ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
111         if (ret < 0)
112                 return ERR_PTR(ret);
113         if (ret != 0) {
114                 btrfs_warn(fs_info, "missing free space info for %llu",
115                            block_group->start);
116                 ASSERT(0);
117                 return ERR_PTR(-ENOENT);
118         }
119
120         return btrfs_item_ptr(path->nodes[0], path->slots[0],
121                               struct btrfs_free_space_info);
122 }
123
124 /*
125  * btrfs_search_slot() but we're looking for the greatest key less than the
126  * passed key.
127  */
128 static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
129                                   struct btrfs_root *root,
130                                   struct btrfs_key *key, struct btrfs_path *p,
131                                   int ins_len, int cow)
132 {
133         int ret;
134
135         ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
136         if (ret < 0)
137                 return ret;
138
139         if (ret == 0) {
140                 ASSERT(0);
141                 return -EIO;
142         }
143
144         if (p->slots[0] == 0) {
145                 ASSERT(0);
146                 return -EIO;
147         }
148         p->slots[0]--;
149
150         return 0;
151 }
152
153 static inline u32 free_space_bitmap_size(const struct btrfs_fs_info *fs_info,
154                                          u64 size)
155 {
156         return DIV_ROUND_UP(size >> fs_info->sectorsize_bits, BITS_PER_BYTE);
157 }
158
159 static unsigned long *alloc_bitmap(u32 bitmap_size)
160 {
161         unsigned long *ret;
162         unsigned int nofs_flag;
163         u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long));
164
165         /*
166          * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
167          * into the filesystem as the free space bitmap can be modified in the
168          * critical section of a transaction commit.
169          *
170          * TODO: push the memalloc_nofs_{save,restore}() to the caller where we
171          * know that recursion is unsafe.
172          */
173         nofs_flag = memalloc_nofs_save();
174         ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);
175         memalloc_nofs_restore(nofs_flag);
176         return ret;
177 }
178
179 static void le_bitmap_set(unsigned long *map, unsigned int start, int len)
180 {
181         u8 *p = ((u8 *)map) + BIT_BYTE(start);
182         const unsigned int size = start + len;
183         int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
184         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
185
186         while (len - bits_to_set >= 0) {
187                 *p |= mask_to_set;
188                 len -= bits_to_set;
189                 bits_to_set = BITS_PER_BYTE;
190                 mask_to_set = ~0;
191                 p++;
192         }
193         if (len) {
194                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
195                 *p |= mask_to_set;
196         }
197 }
198
199 EXPORT_FOR_TESTS
200 int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
201                                   struct btrfs_block_group *block_group,
202                                   struct btrfs_path *path)
203 {
204         struct btrfs_fs_info *fs_info = trans->fs_info;
205         struct btrfs_root *root = btrfs_free_space_root(block_group);
206         struct btrfs_free_space_info *info;
207         struct btrfs_key key, found_key;
208         struct extent_buffer *leaf;
209         unsigned long *bitmap;
210         char *bitmap_cursor;
211         u64 start, end;
212         u64 bitmap_range, i;
213         u32 bitmap_size, flags, expected_extent_count;
214         u32 extent_count = 0;
215         int done = 0, nr;
216         int ret;
217
218         bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
219         bitmap = alloc_bitmap(bitmap_size);
220         if (!bitmap) {
221                 ret = -ENOMEM;
222                 goto out;
223         }
224
225         start = block_group->start;
226         end = block_group->start + block_group->length;
227
228         key.objectid = end - 1;
229         key.type = (u8)-1;
230         key.offset = (u64)-1;
231
232         while (!done) {
233                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
234                 if (ret)
235                         goto out;
236
237                 leaf = path->nodes[0];
238                 nr = 0;
239                 path->slots[0]++;
240                 while (path->slots[0] > 0) {
241                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
242
243                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
244                                 ASSERT(found_key.objectid == block_group->start);
245                                 ASSERT(found_key.offset == block_group->length);
246                                 done = 1;
247                                 break;
248                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
249                                 u64 first, last;
250
251                                 ASSERT(found_key.objectid >= start);
252                                 ASSERT(found_key.objectid < end);
253                                 ASSERT(found_key.objectid + found_key.offset <= end);
254
255                                 first = div_u64(found_key.objectid - start,
256                                                 fs_info->sectorsize);
257                                 last = div_u64(found_key.objectid + found_key.offset - start,
258                                                fs_info->sectorsize);
259                                 le_bitmap_set(bitmap, first, last - first);
260
261                                 extent_count++;
262                                 nr++;
263                                 path->slots[0]--;
264                         } else {
265                                 ASSERT(0);
266                         }
267                 }
268
269                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
270                 if (ret)
271                         goto out;
272                 btrfs_release_path(path);
273         }
274
275         info = search_free_space_info(trans, block_group, path, 1);
276         if (IS_ERR(info)) {
277                 ret = PTR_ERR(info);
278                 goto out;
279         }
280         leaf = path->nodes[0];
281         flags = btrfs_free_space_flags(leaf, info);
282         flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
283         btrfs_set_free_space_flags(leaf, info, flags);
284         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
285         btrfs_mark_buffer_dirty(leaf);
286         btrfs_release_path(path);
287
288         if (extent_count != expected_extent_count) {
289                 btrfs_err(fs_info,
290                           "incorrect extent count for %llu; counted %u, expected %u",
291                           block_group->start, extent_count,
292                           expected_extent_count);
293                 ASSERT(0);
294                 ret = -EIO;
295                 goto out;
296         }
297
298         bitmap_cursor = (char *)bitmap;
299         bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
300         i = start;
301         while (i < end) {
302                 unsigned long ptr;
303                 u64 extent_size;
304                 u32 data_size;
305
306                 extent_size = min(end - i, bitmap_range);
307                 data_size = free_space_bitmap_size(fs_info, extent_size);
308
309                 key.objectid = i;
310                 key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
311                 key.offset = extent_size;
312
313                 ret = btrfs_insert_empty_item(trans, root, path, &key,
314                                               data_size);
315                 if (ret)
316                         goto out;
317
318                 leaf = path->nodes[0];
319                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
320                 write_extent_buffer(leaf, bitmap_cursor, ptr,
321                                     data_size);
322                 btrfs_mark_buffer_dirty(leaf);
323                 btrfs_release_path(path);
324
325                 i += extent_size;
326                 bitmap_cursor += data_size;
327         }
328
329         ret = 0;
330 out:
331         kvfree(bitmap);
332         if (ret)
333                 btrfs_abort_transaction(trans, ret);
334         return ret;
335 }
336
337 EXPORT_FOR_TESTS
338 int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
339                                   struct btrfs_block_group *block_group,
340                                   struct btrfs_path *path)
341 {
342         struct btrfs_fs_info *fs_info = trans->fs_info;
343         struct btrfs_root *root = btrfs_free_space_root(block_group);
344         struct btrfs_free_space_info *info;
345         struct btrfs_key key, found_key;
346         struct extent_buffer *leaf;
347         unsigned long *bitmap;
348         u64 start, end;
349         u32 bitmap_size, flags, expected_extent_count;
350         unsigned long nrbits, start_bit, end_bit;
351         u32 extent_count = 0;
352         int done = 0, nr;
353         int ret;
354
355         bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
356         bitmap = alloc_bitmap(bitmap_size);
357         if (!bitmap) {
358                 ret = -ENOMEM;
359                 goto out;
360         }
361
362         start = block_group->start;
363         end = block_group->start + block_group->length;
364
365         key.objectid = end - 1;
366         key.type = (u8)-1;
367         key.offset = (u64)-1;
368
369         while (!done) {
370                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
371                 if (ret)
372                         goto out;
373
374                 leaf = path->nodes[0];
375                 nr = 0;
376                 path->slots[0]++;
377                 while (path->slots[0] > 0) {
378                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
379
380                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
381                                 ASSERT(found_key.objectid == block_group->start);
382                                 ASSERT(found_key.offset == block_group->length);
383                                 done = 1;
384                                 break;
385                         } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
386                                 unsigned long ptr;
387                                 char *bitmap_cursor;
388                                 u32 bitmap_pos, data_size;
389
390                                 ASSERT(found_key.objectid >= start);
391                                 ASSERT(found_key.objectid < end);
392                                 ASSERT(found_key.objectid + found_key.offset <= end);
393
394                                 bitmap_pos = div_u64(found_key.objectid - start,
395                                                      fs_info->sectorsize *
396                                                      BITS_PER_BYTE);
397                                 bitmap_cursor = ((char *)bitmap) + bitmap_pos;
398                                 data_size = free_space_bitmap_size(fs_info,
399                                                                 found_key.offset);
400
401                                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
402                                 read_extent_buffer(leaf, bitmap_cursor, ptr,
403                                                    data_size);
404
405                                 nr++;
406                                 path->slots[0]--;
407                         } else {
408                                 ASSERT(0);
409                         }
410                 }
411
412                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
413                 if (ret)
414                         goto out;
415                 btrfs_release_path(path);
416         }
417
418         info = search_free_space_info(trans, block_group, path, 1);
419         if (IS_ERR(info)) {
420                 ret = PTR_ERR(info);
421                 goto out;
422         }
423         leaf = path->nodes[0];
424         flags = btrfs_free_space_flags(leaf, info);
425         flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
426         btrfs_set_free_space_flags(leaf, info, flags);
427         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
428         btrfs_mark_buffer_dirty(leaf);
429         btrfs_release_path(path);
430
431         nrbits = block_group->length >> block_group->fs_info->sectorsize_bits;
432         start_bit = find_next_bit_le(bitmap, nrbits, 0);
433
434         while (start_bit < nrbits) {
435                 end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit);
436                 ASSERT(start_bit < end_bit);
437
438                 key.objectid = start + start_bit * block_group->fs_info->sectorsize;
439                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
440                 key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize;
441
442                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
443                 if (ret)
444                         goto out;
445                 btrfs_release_path(path);
446
447                 extent_count++;
448
449                 start_bit = find_next_bit_le(bitmap, nrbits, end_bit);
450         }
451
452         if (extent_count != expected_extent_count) {
453                 btrfs_err(fs_info,
454                           "incorrect extent count for %llu; counted %u, expected %u",
455                           block_group->start, extent_count,
456                           expected_extent_count);
457                 ASSERT(0);
458                 ret = -EIO;
459                 goto out;
460         }
461
462         ret = 0;
463 out:
464         kvfree(bitmap);
465         if (ret)
466                 btrfs_abort_transaction(trans, ret);
467         return ret;
468 }
469
470 static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
471                                           struct btrfs_block_group *block_group,
472                                           struct btrfs_path *path,
473                                           int new_extents)
474 {
475         struct btrfs_free_space_info *info;
476         u32 flags;
477         u32 extent_count;
478         int ret = 0;
479
480         if (new_extents == 0)
481                 return 0;
482
483         info = search_free_space_info(trans, block_group, path, 1);
484         if (IS_ERR(info)) {
485                 ret = PTR_ERR(info);
486                 goto out;
487         }
488         flags = btrfs_free_space_flags(path->nodes[0], info);
489         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
490
491         extent_count += new_extents;
492         btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
493         btrfs_mark_buffer_dirty(path->nodes[0]);
494         btrfs_release_path(path);
495
496         if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
497             extent_count > block_group->bitmap_high_thresh) {
498                 ret = convert_free_space_to_bitmaps(trans, block_group, path);
499         } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
500                    extent_count < block_group->bitmap_low_thresh) {
501                 ret = convert_free_space_to_extents(trans, block_group, path);
502         }
503
504 out:
505         return ret;
506 }
507
508 EXPORT_FOR_TESTS
509 int free_space_test_bit(struct btrfs_block_group *block_group,
510                         struct btrfs_path *path, u64 offset)
511 {
512         struct extent_buffer *leaf;
513         struct btrfs_key key;
514         u64 found_start, found_end;
515         unsigned long ptr, i;
516
517         leaf = path->nodes[0];
518         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
519         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
520
521         found_start = key.objectid;
522         found_end = key.objectid + key.offset;
523         ASSERT(offset >= found_start && offset < found_end);
524
525         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
526         i = div_u64(offset - found_start,
527                     block_group->fs_info->sectorsize);
528         return !!extent_buffer_test_bit(leaf, ptr, i);
529 }
530
531 static void free_space_set_bits(struct btrfs_block_group *block_group,
532                                 struct btrfs_path *path, u64 *start, u64 *size,
533                                 int bit)
534 {
535         struct btrfs_fs_info *fs_info = block_group->fs_info;
536         struct extent_buffer *leaf;
537         struct btrfs_key key;
538         u64 end = *start + *size;
539         u64 found_start, found_end;
540         unsigned long ptr, first, last;
541
542         leaf = path->nodes[0];
543         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
544         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
545
546         found_start = key.objectid;
547         found_end = key.objectid + key.offset;
548         ASSERT(*start >= found_start && *start < found_end);
549         ASSERT(end > found_start);
550
551         if (end > found_end)
552                 end = found_end;
553
554         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
555         first = (*start - found_start) >> fs_info->sectorsize_bits;
556         last = (end - found_start) >> fs_info->sectorsize_bits;
557         if (bit)
558                 extent_buffer_bitmap_set(leaf, ptr, first, last - first);
559         else
560                 extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
561         btrfs_mark_buffer_dirty(leaf);
562
563         *size -= end - *start;
564         *start = end;
565 }
566
567 /*
568  * We can't use btrfs_next_item() in modify_free_space_bitmap() because
569  * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
570  * tree walking in btrfs_next_leaf() anyways because we know exactly what we're
571  * looking for.
572  */
573 static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
574                                   struct btrfs_root *root, struct btrfs_path *p)
575 {
576         struct btrfs_key key;
577
578         if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
579                 p->slots[0]++;
580                 return 0;
581         }
582
583         btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
584         btrfs_release_path(p);
585
586         key.objectid += key.offset;
587         key.type = (u8)-1;
588         key.offset = (u64)-1;
589
590         return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
591 }
592
593 /*
594  * If remove is 1, then we are removing free space, thus clearing bits in the
595  * bitmap. If remove is 0, then we are adding free space, thus setting bits in
596  * the bitmap.
597  */
598 static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
599                                     struct btrfs_block_group *block_group,
600                                     struct btrfs_path *path,
601                                     u64 start, u64 size, int remove)
602 {
603         struct btrfs_root *root = btrfs_free_space_root(block_group);
604         struct btrfs_key key;
605         u64 end = start + size;
606         u64 cur_start, cur_size;
607         int prev_bit, next_bit;
608         int new_extents;
609         int ret;
610
611         /*
612          * Read the bit for the block immediately before the extent of space if
613          * that block is within the block group.
614          */
615         if (start > block_group->start) {
616                 u64 prev_block = start - block_group->fs_info->sectorsize;
617
618                 key.objectid = prev_block;
619                 key.type = (u8)-1;
620                 key.offset = (u64)-1;
621
622                 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
623                 if (ret)
624                         goto out;
625
626                 prev_bit = free_space_test_bit(block_group, path, prev_block);
627
628                 /* The previous block may have been in the previous bitmap. */
629                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
630                 if (start >= key.objectid + key.offset) {
631                         ret = free_space_next_bitmap(trans, root, path);
632                         if (ret)
633                                 goto out;
634                 }
635         } else {
636                 key.objectid = start;
637                 key.type = (u8)-1;
638                 key.offset = (u64)-1;
639
640                 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
641                 if (ret)
642                         goto out;
643
644                 prev_bit = -1;
645         }
646
647         /*
648          * Iterate over all of the bitmaps overlapped by the extent of space,
649          * clearing/setting bits as required.
650          */
651         cur_start = start;
652         cur_size = size;
653         while (1) {
654                 free_space_set_bits(block_group, path, &cur_start, &cur_size,
655                                     !remove);
656                 if (cur_size == 0)
657                         break;
658                 ret = free_space_next_bitmap(trans, root, path);
659                 if (ret)
660                         goto out;
661         }
662
663         /*
664          * Read the bit for the block immediately after the extent of space if
665          * that block is within the block group.
666          */
667         if (end < block_group->start + block_group->length) {
668                 /* The next block may be in the next bitmap. */
669                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
670                 if (end >= key.objectid + key.offset) {
671                         ret = free_space_next_bitmap(trans, root, path);
672                         if (ret)
673                                 goto out;
674                 }
675
676                 next_bit = free_space_test_bit(block_group, path, end);
677         } else {
678                 next_bit = -1;
679         }
680
681         if (remove) {
682                 new_extents = -1;
683                 if (prev_bit == 1) {
684                         /* Leftover on the left. */
685                         new_extents++;
686                 }
687                 if (next_bit == 1) {
688                         /* Leftover on the right. */
689                         new_extents++;
690                 }
691         } else {
692                 new_extents = 1;
693                 if (prev_bit == 1) {
694                         /* Merging with neighbor on the left. */
695                         new_extents--;
696                 }
697                 if (next_bit == 1) {
698                         /* Merging with neighbor on the right. */
699                         new_extents--;
700                 }
701         }
702
703         btrfs_release_path(path);
704         ret = update_free_space_extent_count(trans, block_group, path,
705                                              new_extents);
706
707 out:
708         return ret;
709 }
710
711 static int remove_free_space_extent(struct btrfs_trans_handle *trans,
712                                     struct btrfs_block_group *block_group,
713                                     struct btrfs_path *path,
714                                     u64 start, u64 size)
715 {
716         struct btrfs_root *root = btrfs_free_space_root(block_group);
717         struct btrfs_key key;
718         u64 found_start, found_end;
719         u64 end = start + size;
720         int new_extents = -1;
721         int ret;
722
723         key.objectid = start;
724         key.type = (u8)-1;
725         key.offset = (u64)-1;
726
727         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
728         if (ret)
729                 goto out;
730
731         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
732
733         ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
734
735         found_start = key.objectid;
736         found_end = key.objectid + key.offset;
737         ASSERT(start >= found_start && end <= found_end);
738
739         /*
740          * Okay, now that we've found the free space extent which contains the
741          * free space that we are removing, there are four cases:
742          *
743          * 1. We're using the whole extent: delete the key we found and
744          * decrement the free space extent count.
745          * 2. We are using part of the extent starting at the beginning: delete
746          * the key we found and insert a new key representing the leftover at
747          * the end. There is no net change in the number of extents.
748          * 3. We are using part of the extent ending at the end: delete the key
749          * we found and insert a new key representing the leftover at the
750          * beginning. There is no net change in the number of extents.
751          * 4. We are using part of the extent in the middle: delete the key we
752          * found and insert two new keys representing the leftovers on each
753          * side. Where we used to have one extent, we now have two, so increment
754          * the extent count. We may need to convert the block group to bitmaps
755          * as a result.
756          */
757
758         /* Delete the existing key (cases 1-4). */
759         ret = btrfs_del_item(trans, root, path);
760         if (ret)
761                 goto out;
762
763         /* Add a key for leftovers at the beginning (cases 3 and 4). */
764         if (start > found_start) {
765                 key.objectid = found_start;
766                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
767                 key.offset = start - found_start;
768
769                 btrfs_release_path(path);
770                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
771                 if (ret)
772                         goto out;
773                 new_extents++;
774         }
775
776         /* Add a key for leftovers at the end (cases 2 and 4). */
777         if (end < found_end) {
778                 key.objectid = end;
779                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
780                 key.offset = found_end - end;
781
782                 btrfs_release_path(path);
783                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
784                 if (ret)
785                         goto out;
786                 new_extents++;
787         }
788
789         btrfs_release_path(path);
790         ret = update_free_space_extent_count(trans, block_group, path,
791                                              new_extents);
792
793 out:
794         return ret;
795 }
796
797 EXPORT_FOR_TESTS
798 int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
799                                   struct btrfs_block_group *block_group,
800                                   struct btrfs_path *path, u64 start, u64 size)
801 {
802         struct btrfs_free_space_info *info;
803         u32 flags;
804         int ret;
805
806         if (block_group->needs_free_space) {
807                 ret = __add_block_group_free_space(trans, block_group, path);
808                 if (ret)
809                         return ret;
810         }
811
812         info = search_free_space_info(NULL, block_group, path, 0);
813         if (IS_ERR(info))
814                 return PTR_ERR(info);
815         flags = btrfs_free_space_flags(path->nodes[0], info);
816         btrfs_release_path(path);
817
818         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
819                 return modify_free_space_bitmap(trans, block_group, path,
820                                                 start, size, 1);
821         } else {
822                 return remove_free_space_extent(trans, block_group, path,
823                                                 start, size);
824         }
825 }
826
827 int remove_from_free_space_tree(struct btrfs_trans_handle *trans,
828                                 u64 start, u64 size)
829 {
830         struct btrfs_block_group *block_group;
831         struct btrfs_path *path;
832         int ret;
833
834         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
835                 return 0;
836
837         path = btrfs_alloc_path();
838         if (!path) {
839                 ret = -ENOMEM;
840                 goto out;
841         }
842
843         block_group = btrfs_lookup_block_group(trans->fs_info, start);
844         if (!block_group) {
845                 ASSERT(0);
846                 ret = -ENOENT;
847                 goto out;
848         }
849
850         mutex_lock(&block_group->free_space_lock);
851         ret = __remove_from_free_space_tree(trans, block_group, path, start,
852                                             size);
853         mutex_unlock(&block_group->free_space_lock);
854
855         btrfs_put_block_group(block_group);
856 out:
857         btrfs_free_path(path);
858         if (ret)
859                 btrfs_abort_transaction(trans, ret);
860         return ret;
861 }
862
863 static int add_free_space_extent(struct btrfs_trans_handle *trans,
864                                  struct btrfs_block_group *block_group,
865                                  struct btrfs_path *path,
866                                  u64 start, u64 size)
867 {
868         struct btrfs_root *root = btrfs_free_space_root(block_group);
869         struct btrfs_key key, new_key;
870         u64 found_start, found_end;
871         u64 end = start + size;
872         int new_extents = 1;
873         int ret;
874
875         /*
876          * We are adding a new extent of free space, but we need to merge
877          * extents. There are four cases here:
878          *
879          * 1. The new extent does not have any immediate neighbors to merge
880          * with: add the new key and increment the free space extent count. We
881          * may need to convert the block group to bitmaps as a result.
882          * 2. The new extent has an immediate neighbor before it: remove the
883          * previous key and insert a new key combining both of them. There is no
884          * net change in the number of extents.
885          * 3. The new extent has an immediate neighbor after it: remove the next
886          * key and insert a new key combining both of them. There is no net
887          * change in the number of extents.
888          * 4. The new extent has immediate neighbors on both sides: remove both
889          * of the keys and insert a new key combining all of them. Where we used
890          * to have two extents, we now have one, so decrement the extent count.
891          */
892
893         new_key.objectid = start;
894         new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
895         new_key.offset = size;
896
897         /* Search for a neighbor on the left. */
898         if (start == block_group->start)
899                 goto right;
900         key.objectid = start - 1;
901         key.type = (u8)-1;
902         key.offset = (u64)-1;
903
904         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
905         if (ret)
906                 goto out;
907
908         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
909
910         if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
911                 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
912                 btrfs_release_path(path);
913                 goto right;
914         }
915
916         found_start = key.objectid;
917         found_end = key.objectid + key.offset;
918         ASSERT(found_start >= block_group->start &&
919                found_end > block_group->start);
920         ASSERT(found_start < start && found_end <= start);
921
922         /*
923          * Delete the neighbor on the left and absorb it into the new key (cases
924          * 2 and 4).
925          */
926         if (found_end == start) {
927                 ret = btrfs_del_item(trans, root, path);
928                 if (ret)
929                         goto out;
930                 new_key.objectid = found_start;
931                 new_key.offset += key.offset;
932                 new_extents--;
933         }
934         btrfs_release_path(path);
935
936 right:
937         /* Search for a neighbor on the right. */
938         if (end == block_group->start + block_group->length)
939                 goto insert;
940         key.objectid = end;
941         key.type = (u8)-1;
942         key.offset = (u64)-1;
943
944         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
945         if (ret)
946                 goto out;
947
948         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
949
950         if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
951                 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
952                 btrfs_release_path(path);
953                 goto insert;
954         }
955
956         found_start = key.objectid;
957         found_end = key.objectid + key.offset;
958         ASSERT(found_start >= block_group->start &&
959                found_end > block_group->start);
960         ASSERT((found_start < start && found_end <= start) ||
961                (found_start >= end && found_end > end));
962
963         /*
964          * Delete the neighbor on the right and absorb it into the new key
965          * (cases 3 and 4).
966          */
967         if (found_start == end) {
968                 ret = btrfs_del_item(trans, root, path);
969                 if (ret)
970                         goto out;
971                 new_key.offset += key.offset;
972                 new_extents--;
973         }
974         btrfs_release_path(path);
975
976 insert:
977         /* Insert the new key (cases 1-4). */
978         ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0);
979         if (ret)
980                 goto out;
981
982         btrfs_release_path(path);
983         ret = update_free_space_extent_count(trans, block_group, path,
984                                              new_extents);
985
986 out:
987         return ret;
988 }
989
990 EXPORT_FOR_TESTS
991 int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
992                              struct btrfs_block_group *block_group,
993                              struct btrfs_path *path, u64 start, u64 size)
994 {
995         struct btrfs_free_space_info *info;
996         u32 flags;
997         int ret;
998
999         if (block_group->needs_free_space) {
1000                 ret = __add_block_group_free_space(trans, block_group, path);
1001                 if (ret)
1002                         return ret;
1003         }
1004
1005         info = search_free_space_info(NULL, block_group, path, 0);
1006         if (IS_ERR(info))
1007                 return PTR_ERR(info);
1008         flags = btrfs_free_space_flags(path->nodes[0], info);
1009         btrfs_release_path(path);
1010
1011         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
1012                 return modify_free_space_bitmap(trans, block_group, path,
1013                                                 start, size, 0);
1014         } else {
1015                 return add_free_space_extent(trans, block_group, path, start,
1016                                              size);
1017         }
1018 }
1019
1020 int add_to_free_space_tree(struct btrfs_trans_handle *trans,
1021                            u64 start, u64 size)
1022 {
1023         struct btrfs_block_group *block_group;
1024         struct btrfs_path *path;
1025         int ret;
1026
1027         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1028                 return 0;
1029
1030         path = btrfs_alloc_path();
1031         if (!path) {
1032                 ret = -ENOMEM;
1033                 goto out;
1034         }
1035
1036         block_group = btrfs_lookup_block_group(trans->fs_info, start);
1037         if (!block_group) {
1038                 ASSERT(0);
1039                 ret = -ENOENT;
1040                 goto out;
1041         }
1042
1043         mutex_lock(&block_group->free_space_lock);
1044         ret = __add_to_free_space_tree(trans, block_group, path, start, size);
1045         mutex_unlock(&block_group->free_space_lock);
1046
1047         btrfs_put_block_group(block_group);
1048 out:
1049         btrfs_free_path(path);
1050         if (ret)
1051                 btrfs_abort_transaction(trans, ret);
1052         return ret;
1053 }
1054
1055 /*
1056  * Populate the free space tree by walking the extent tree. Operations on the
1057  * extent tree that happen as a result of writes to the free space tree will go
1058  * through the normal add/remove hooks.
1059  */
1060 static int populate_free_space_tree(struct btrfs_trans_handle *trans,
1061                                     struct btrfs_block_group *block_group)
1062 {
1063         struct btrfs_root *extent_root;
1064         struct btrfs_path *path, *path2;
1065         struct btrfs_key key;
1066         u64 start, end;
1067         int ret;
1068
1069         path = btrfs_alloc_path();
1070         if (!path)
1071                 return -ENOMEM;
1072         path->reada = READA_FORWARD;
1073
1074         path2 = btrfs_alloc_path();
1075         if (!path2) {
1076                 btrfs_free_path(path);
1077                 return -ENOMEM;
1078         }
1079
1080         ret = add_new_free_space_info(trans, block_group, path2);
1081         if (ret)
1082                 goto out;
1083
1084         mutex_lock(&block_group->free_space_lock);
1085
1086         /*
1087          * Iterate through all of the extent and metadata items in this block
1088          * group, adding the free space between them and the free space at the
1089          * end. Note that EXTENT_ITEM and METADATA_ITEM are less than
1090          * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
1091          * contained in.
1092          */
1093         key.objectid = block_group->start;
1094         key.type = BTRFS_EXTENT_ITEM_KEY;
1095         key.offset = 0;
1096
1097         extent_root = btrfs_extent_root(trans->fs_info, key.objectid);
1098         ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
1099         if (ret < 0)
1100                 goto out_locked;
1101         ASSERT(ret == 0);
1102
1103         start = block_group->start;
1104         end = block_group->start + block_group->length;
1105         while (1) {
1106                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1107
1108                 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
1109                     key.type == BTRFS_METADATA_ITEM_KEY) {
1110                         if (key.objectid >= end)
1111                                 break;
1112
1113                         if (start < key.objectid) {
1114                                 ret = __add_to_free_space_tree(trans,
1115                                                                block_group,
1116                                                                path2, start,
1117                                                                key.objectid -
1118                                                                start);
1119                                 if (ret)
1120                                         goto out_locked;
1121                         }
1122                         start = key.objectid;
1123                         if (key.type == BTRFS_METADATA_ITEM_KEY)
1124                                 start += trans->fs_info->nodesize;
1125                         else
1126                                 start += key.offset;
1127                 } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
1128                         if (key.objectid != block_group->start)
1129                                 break;
1130                 }
1131
1132                 ret = btrfs_next_item(extent_root, path);
1133                 if (ret < 0)
1134                         goto out_locked;
1135                 if (ret)
1136                         break;
1137         }
1138         if (start < end) {
1139                 ret = __add_to_free_space_tree(trans, block_group, path2,
1140                                                start, end - start);
1141                 if (ret)
1142                         goto out_locked;
1143         }
1144
1145         ret = 0;
1146 out_locked:
1147         mutex_unlock(&block_group->free_space_lock);
1148 out:
1149         btrfs_free_path(path2);
1150         btrfs_free_path(path);
1151         return ret;
1152 }
1153
1154 int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
1155 {
1156         struct btrfs_trans_handle *trans;
1157         struct btrfs_root *tree_root = fs_info->tree_root;
1158         struct btrfs_root *free_space_root;
1159         struct btrfs_block_group *block_group;
1160         struct rb_node *node;
1161         int ret;
1162
1163         trans = btrfs_start_transaction(tree_root, 0);
1164         if (IS_ERR(trans))
1165                 return PTR_ERR(trans);
1166
1167         set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1168         set_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1169         free_space_root = btrfs_create_tree(trans,
1170                                             BTRFS_FREE_SPACE_TREE_OBJECTID);
1171         if (IS_ERR(free_space_root)) {
1172                 ret = PTR_ERR(free_space_root);
1173                 goto abort;
1174         }
1175         ret = btrfs_global_root_insert(free_space_root);
1176         if (ret) {
1177                 btrfs_put_root(free_space_root);
1178                 goto abort;
1179         }
1180
1181         node = rb_first_cached(&fs_info->block_group_cache_tree);
1182         while (node) {
1183                 block_group = rb_entry(node, struct btrfs_block_group,
1184                                        cache_node);
1185                 ret = populate_free_space_tree(trans, block_group);
1186                 if (ret)
1187                         goto abort;
1188                 node = rb_next(node);
1189         }
1190
1191         btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1192         btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1193         clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1194         ret = btrfs_commit_transaction(trans);
1195
1196         /*
1197          * Now that we've committed the transaction any reading of our commit
1198          * root will be safe, so we can cache from the free space tree now.
1199          */
1200         clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1201         return ret;
1202
1203 abort:
1204         clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1205         clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1206         btrfs_abort_transaction(trans, ret);
1207         btrfs_end_transaction(trans);
1208         return ret;
1209 }
1210
1211 static int clear_free_space_tree(struct btrfs_trans_handle *trans,
1212                                  struct btrfs_root *root)
1213 {
1214         struct btrfs_path *path;
1215         struct btrfs_key key;
1216         int nr;
1217         int ret;
1218
1219         path = btrfs_alloc_path();
1220         if (!path)
1221                 return -ENOMEM;
1222
1223         key.objectid = 0;
1224         key.type = 0;
1225         key.offset = 0;
1226
1227         while (1) {
1228                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1229                 if (ret < 0)
1230                         goto out;
1231
1232                 nr = btrfs_header_nritems(path->nodes[0]);
1233                 if (!nr)
1234                         break;
1235
1236                 path->slots[0] = 0;
1237                 ret = btrfs_del_items(trans, root, path, 0, nr);
1238                 if (ret)
1239                         goto out;
1240
1241                 btrfs_release_path(path);
1242         }
1243
1244         ret = 0;
1245 out:
1246         btrfs_free_path(path);
1247         return ret;
1248 }
1249
1250 int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
1251 {
1252         struct btrfs_trans_handle *trans;
1253         struct btrfs_root *tree_root = fs_info->tree_root;
1254         struct btrfs_key key = {
1255                 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
1256                 .type = BTRFS_ROOT_ITEM_KEY,
1257                 .offset = 0,
1258         };
1259         struct btrfs_root *free_space_root = btrfs_global_root(fs_info, &key);
1260         int ret;
1261
1262         trans = btrfs_start_transaction(tree_root, 0);
1263         if (IS_ERR(trans))
1264                 return PTR_ERR(trans);
1265
1266         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1267         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1268
1269         ret = clear_free_space_tree(trans, free_space_root);
1270         if (ret)
1271                 goto abort;
1272
1273         ret = btrfs_del_root(trans, &free_space_root->root_key);
1274         if (ret)
1275                 goto abort;
1276
1277         btrfs_global_root_delete(free_space_root);
1278         list_del(&free_space_root->dirty_list);
1279
1280         btrfs_tree_lock(free_space_root->node);
1281         btrfs_clean_tree_block(free_space_root->node);
1282         btrfs_tree_unlock(free_space_root->node);
1283         btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
1284                               free_space_root->node, 0, 1);
1285
1286         btrfs_put_root(free_space_root);
1287
1288         return btrfs_commit_transaction(trans);
1289
1290 abort:
1291         btrfs_abort_transaction(trans, ret);
1292         btrfs_end_transaction(trans);
1293         return ret;
1294 }
1295
1296 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
1297                                         struct btrfs_block_group *block_group,
1298                                         struct btrfs_path *path)
1299 {
1300         int ret;
1301
1302         block_group->needs_free_space = 0;
1303
1304         ret = add_new_free_space_info(trans, block_group, path);
1305         if (ret)
1306                 return ret;
1307
1308         return __add_to_free_space_tree(trans, block_group, path,
1309                                         block_group->start,
1310                                         block_group->length);
1311 }
1312
1313 int add_block_group_free_space(struct btrfs_trans_handle *trans,
1314                                struct btrfs_block_group *block_group)
1315 {
1316         struct btrfs_fs_info *fs_info = trans->fs_info;
1317         struct btrfs_path *path = NULL;
1318         int ret = 0;
1319
1320         if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
1321                 return 0;
1322
1323         mutex_lock(&block_group->free_space_lock);
1324         if (!block_group->needs_free_space)
1325                 goto out;
1326
1327         path = btrfs_alloc_path();
1328         if (!path) {
1329                 ret = -ENOMEM;
1330                 goto out;
1331         }
1332
1333         ret = __add_block_group_free_space(trans, block_group, path);
1334
1335 out:
1336         btrfs_free_path(path);
1337         mutex_unlock(&block_group->free_space_lock);
1338         if (ret)
1339                 btrfs_abort_transaction(trans, ret);
1340         return ret;
1341 }
1342
1343 int remove_block_group_free_space(struct btrfs_trans_handle *trans,
1344                                   struct btrfs_block_group *block_group)
1345 {
1346         struct btrfs_root *root = btrfs_free_space_root(block_group);
1347         struct btrfs_path *path;
1348         struct btrfs_key key, found_key;
1349         struct extent_buffer *leaf;
1350         u64 start, end;
1351         int done = 0, nr;
1352         int ret;
1353
1354         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1355                 return 0;
1356
1357         if (block_group->needs_free_space) {
1358                 /* We never added this block group to the free space tree. */
1359                 return 0;
1360         }
1361
1362         path = btrfs_alloc_path();
1363         if (!path) {
1364                 ret = -ENOMEM;
1365                 goto out;
1366         }
1367
1368         start = block_group->start;
1369         end = block_group->start + block_group->length;
1370
1371         key.objectid = end - 1;
1372         key.type = (u8)-1;
1373         key.offset = (u64)-1;
1374
1375         while (!done) {
1376                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
1377                 if (ret)
1378                         goto out;
1379
1380                 leaf = path->nodes[0];
1381                 nr = 0;
1382                 path->slots[0]++;
1383                 while (path->slots[0] > 0) {
1384                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
1385
1386                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
1387                                 ASSERT(found_key.objectid == block_group->start);
1388                                 ASSERT(found_key.offset == block_group->length);
1389                                 done = 1;
1390                                 nr++;
1391                                 path->slots[0]--;
1392                                 break;
1393                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
1394                                    found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
1395                                 ASSERT(found_key.objectid >= start);
1396                                 ASSERT(found_key.objectid < end);
1397                                 ASSERT(found_key.objectid + found_key.offset <= end);
1398                                 nr++;
1399                                 path->slots[0]--;
1400                         } else {
1401                                 ASSERT(0);
1402                         }
1403                 }
1404
1405                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
1406                 if (ret)
1407                         goto out;
1408                 btrfs_release_path(path);
1409         }
1410
1411         ret = 0;
1412 out:
1413         btrfs_free_path(path);
1414         if (ret)
1415                 btrfs_abort_transaction(trans, ret);
1416         return ret;
1417 }
1418
1419 static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
1420                                    struct btrfs_path *path,
1421                                    u32 expected_extent_count)
1422 {
1423         struct btrfs_block_group *block_group;
1424         struct btrfs_fs_info *fs_info;
1425         struct btrfs_root *root;
1426         struct btrfs_key key;
1427         int prev_bit = 0, bit;
1428         /* Initialize to silence GCC. */
1429         u64 extent_start = 0;
1430         u64 end, offset;
1431         u64 total_found = 0;
1432         u32 extent_count = 0;
1433         int ret;
1434
1435         block_group = caching_ctl->block_group;
1436         fs_info = block_group->fs_info;
1437         root = btrfs_free_space_root(block_group);
1438
1439         end = block_group->start + block_group->length;
1440
1441         while (1) {
1442                 ret = btrfs_next_item(root, path);
1443                 if (ret < 0)
1444                         goto out;
1445                 if (ret)
1446                         break;
1447
1448                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1449
1450                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1451                         break;
1452
1453                 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
1454                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1455
1456                 caching_ctl->progress = key.objectid;
1457
1458                 offset = key.objectid;
1459                 while (offset < key.objectid + key.offset) {
1460                         bit = free_space_test_bit(block_group, path, offset);
1461                         if (prev_bit == 0 && bit == 1) {
1462                                 extent_start = offset;
1463                         } else if (prev_bit == 1 && bit == 0) {
1464                                 total_found += add_new_free_space(block_group,
1465                                                                   extent_start,
1466                                                                   offset);
1467                                 if (total_found > CACHING_CTL_WAKE_UP) {
1468                                         total_found = 0;
1469                                         wake_up(&caching_ctl->wait);
1470                                 }
1471                                 extent_count++;
1472                         }
1473                         prev_bit = bit;
1474                         offset += fs_info->sectorsize;
1475                 }
1476         }
1477         if (prev_bit == 1) {
1478                 total_found += add_new_free_space(block_group, extent_start,
1479                                                   end);
1480                 extent_count++;
1481         }
1482
1483         if (extent_count != expected_extent_count) {
1484                 btrfs_err(fs_info,
1485                           "incorrect extent count for %llu; counted %u, expected %u",
1486                           block_group->start, extent_count,
1487                           expected_extent_count);
1488                 ASSERT(0);
1489                 ret = -EIO;
1490                 goto out;
1491         }
1492
1493         caching_ctl->progress = (u64)-1;
1494
1495         ret = 0;
1496 out:
1497         return ret;
1498 }
1499
1500 static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
1501                                    struct btrfs_path *path,
1502                                    u32 expected_extent_count)
1503 {
1504         struct btrfs_block_group *block_group;
1505         struct btrfs_fs_info *fs_info;
1506         struct btrfs_root *root;
1507         struct btrfs_key key;
1508         u64 end;
1509         u64 total_found = 0;
1510         u32 extent_count = 0;
1511         int ret;
1512
1513         block_group = caching_ctl->block_group;
1514         fs_info = block_group->fs_info;
1515         root = btrfs_free_space_root(block_group);
1516
1517         end = block_group->start + block_group->length;
1518
1519         while (1) {
1520                 ret = btrfs_next_item(root, path);
1521                 if (ret < 0)
1522                         goto out;
1523                 if (ret)
1524                         break;
1525
1526                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1527
1528                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1529                         break;
1530
1531                 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
1532                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1533
1534                 caching_ctl->progress = key.objectid;
1535
1536                 total_found += add_new_free_space(block_group, key.objectid,
1537                                                   key.objectid + key.offset);
1538                 if (total_found > CACHING_CTL_WAKE_UP) {
1539                         total_found = 0;
1540                         wake_up(&caching_ctl->wait);
1541                 }
1542                 extent_count++;
1543         }
1544
1545         if (extent_count != expected_extent_count) {
1546                 btrfs_err(fs_info,
1547                           "incorrect extent count for %llu; counted %u, expected %u",
1548                           block_group->start, extent_count,
1549                           expected_extent_count);
1550                 ASSERT(0);
1551                 ret = -EIO;
1552                 goto out;
1553         }
1554
1555         caching_ctl->progress = (u64)-1;
1556
1557         ret = 0;
1558 out:
1559         return ret;
1560 }
1561
1562 int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
1563 {
1564         struct btrfs_block_group *block_group;
1565         struct btrfs_free_space_info *info;
1566         struct btrfs_path *path;
1567         u32 extent_count, flags;
1568         int ret;
1569
1570         block_group = caching_ctl->block_group;
1571
1572         path = btrfs_alloc_path();
1573         if (!path)
1574                 return -ENOMEM;
1575
1576         /*
1577          * Just like caching_thread() doesn't want to deadlock on the extent
1578          * tree, we don't want to deadlock on the free space tree.
1579          */
1580         path->skip_locking = 1;
1581         path->search_commit_root = 1;
1582         path->reada = READA_FORWARD;
1583
1584         info = search_free_space_info(NULL, block_group, path, 0);
1585         if (IS_ERR(info)) {
1586                 ret = PTR_ERR(info);
1587                 goto out;
1588         }
1589         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
1590         flags = btrfs_free_space_flags(path->nodes[0], info);
1591
1592         /*
1593          * We left path pointing to the free space info item, so now
1594          * load_free_space_foo can just iterate through the free space tree from
1595          * there.
1596          */
1597         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
1598                 ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
1599         else
1600                 ret = load_free_space_extents(caching_ctl, path, extent_count);
1601
1602 out:
1603         btrfs_free_path(path);
1604         return ret;
1605 }