btrfs: Remove fs_info argument from update_free_space_extent_count
[sfrench/cifs-2.6.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
14 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
15                                         struct btrfs_block_group_cache *block_group,
16                                         struct btrfs_path *path);
17
18 void set_free_space_tree_thresholds(struct btrfs_block_group_cache *cache)
19 {
20         u32 bitmap_range;
21         size_t bitmap_size;
22         u64 num_bitmaps, total_bitmap_size;
23
24         /*
25          * We convert to bitmaps when the disk space required for using extents
26          * exceeds that required for using bitmaps.
27          */
28         bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
29         num_bitmaps = div_u64(cache->key.offset + bitmap_range - 1,
30                               bitmap_range);
31         bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
32         total_bitmap_size = num_bitmaps * bitmap_size;
33         cache->bitmap_high_thresh = div_u64(total_bitmap_size,
34                                             sizeof(struct btrfs_item));
35
36         /*
37          * We allow for a small buffer between the high threshold and low
38          * threshold to avoid thrashing back and forth between the two formats.
39          */
40         if (cache->bitmap_high_thresh > 100)
41                 cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
42         else
43                 cache->bitmap_low_thresh = 0;
44 }
45
46 static int add_new_free_space_info(struct btrfs_trans_handle *trans,
47                                    struct btrfs_block_group_cache *block_group,
48                                    struct btrfs_path *path)
49 {
50         struct btrfs_root *root = trans->fs_info->free_space_root;
51         struct btrfs_free_space_info *info;
52         struct btrfs_key key;
53         struct extent_buffer *leaf;
54         int ret;
55
56         key.objectid = block_group->key.objectid;
57         key.type = BTRFS_FREE_SPACE_INFO_KEY;
58         key.offset = block_group->key.offset;
59
60         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
61         if (ret)
62                 goto out;
63
64         leaf = path->nodes[0];
65         info = btrfs_item_ptr(leaf, path->slots[0],
66                               struct btrfs_free_space_info);
67         btrfs_set_free_space_extent_count(leaf, info, 0);
68         btrfs_set_free_space_flags(leaf, info, 0);
69         btrfs_mark_buffer_dirty(leaf);
70
71         ret = 0;
72 out:
73         btrfs_release_path(path);
74         return ret;
75 }
76
77 struct btrfs_free_space_info *
78 search_free_space_info(struct btrfs_trans_handle *trans,
79                        struct btrfs_fs_info *fs_info,
80                        struct btrfs_block_group_cache *block_group,
81                        struct btrfs_path *path, int cow)
82 {
83         struct btrfs_root *root = fs_info->free_space_root;
84         struct btrfs_key key;
85         int ret;
86
87         key.objectid = block_group->key.objectid;
88         key.type = BTRFS_FREE_SPACE_INFO_KEY;
89         key.offset = block_group->key.offset;
90
91         ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
92         if (ret < 0)
93                 return ERR_PTR(ret);
94         if (ret != 0) {
95                 btrfs_warn(fs_info, "missing free space info for %llu",
96                            block_group->key.objectid);
97                 ASSERT(0);
98                 return ERR_PTR(-ENOENT);
99         }
100
101         return btrfs_item_ptr(path->nodes[0], path->slots[0],
102                               struct btrfs_free_space_info);
103 }
104
105 /*
106  * btrfs_search_slot() but we're looking for the greatest key less than the
107  * passed key.
108  */
109 static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
110                                   struct btrfs_root *root,
111                                   struct btrfs_key *key, struct btrfs_path *p,
112                                   int ins_len, int cow)
113 {
114         int ret;
115
116         ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
117         if (ret < 0)
118                 return ret;
119
120         if (ret == 0) {
121                 ASSERT(0);
122                 return -EIO;
123         }
124
125         if (p->slots[0] == 0) {
126                 ASSERT(0);
127                 return -EIO;
128         }
129         p->slots[0]--;
130
131         return 0;
132 }
133
134 static inline u32 free_space_bitmap_size(u64 size, u32 sectorsize)
135 {
136         return DIV_ROUND_UP((u32)div_u64(size, sectorsize), BITS_PER_BYTE);
137 }
138
139 static unsigned long *alloc_bitmap(u32 bitmap_size)
140 {
141         unsigned long *ret;
142         unsigned int nofs_flag;
143         u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long));
144
145         /*
146          * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
147          * into the filesystem as the free space bitmap can be modified in the
148          * critical section of a transaction commit.
149          *
150          * TODO: push the memalloc_nofs_{save,restore}() to the caller where we
151          * know that recursion is unsafe.
152          */
153         nofs_flag = memalloc_nofs_save();
154         ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);
155         memalloc_nofs_restore(nofs_flag);
156         return ret;
157 }
158
159 static void le_bitmap_set(unsigned long *map, unsigned int start, int len)
160 {
161         u8 *p = ((u8 *)map) + BIT_BYTE(start);
162         const unsigned int size = start + len;
163         int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
164         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
165
166         while (len - bits_to_set >= 0) {
167                 *p |= mask_to_set;
168                 len -= bits_to_set;
169                 bits_to_set = BITS_PER_BYTE;
170                 mask_to_set = ~0;
171                 p++;
172         }
173         if (len) {
174                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
175                 *p |= mask_to_set;
176         }
177 }
178
179 int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
180                                   struct btrfs_block_group_cache *block_group,
181                                   struct btrfs_path *path)
182 {
183         struct btrfs_fs_info *fs_info = trans->fs_info;
184         struct btrfs_root *root = fs_info->free_space_root;
185         struct btrfs_free_space_info *info;
186         struct btrfs_key key, found_key;
187         struct extent_buffer *leaf;
188         unsigned long *bitmap;
189         char *bitmap_cursor;
190         u64 start, end;
191         u64 bitmap_range, i;
192         u32 bitmap_size, flags, expected_extent_count;
193         u32 extent_count = 0;
194         int done = 0, nr;
195         int ret;
196
197         bitmap_size = free_space_bitmap_size(block_group->key.offset,
198                                              fs_info->sectorsize);
199         bitmap = alloc_bitmap(bitmap_size);
200         if (!bitmap) {
201                 ret = -ENOMEM;
202                 goto out;
203         }
204
205         start = block_group->key.objectid;
206         end = block_group->key.objectid + block_group->key.offset;
207
208         key.objectid = end - 1;
209         key.type = (u8)-1;
210         key.offset = (u64)-1;
211
212         while (!done) {
213                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
214                 if (ret)
215                         goto out;
216
217                 leaf = path->nodes[0];
218                 nr = 0;
219                 path->slots[0]++;
220                 while (path->slots[0] > 0) {
221                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
222
223                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
224                                 ASSERT(found_key.objectid == block_group->key.objectid);
225                                 ASSERT(found_key.offset == block_group->key.offset);
226                                 done = 1;
227                                 break;
228                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
229                                 u64 first, last;
230
231                                 ASSERT(found_key.objectid >= start);
232                                 ASSERT(found_key.objectid < end);
233                                 ASSERT(found_key.objectid + found_key.offset <= end);
234
235                                 first = div_u64(found_key.objectid - start,
236                                                 fs_info->sectorsize);
237                                 last = div_u64(found_key.objectid + found_key.offset - start,
238                                                fs_info->sectorsize);
239                                 le_bitmap_set(bitmap, first, last - first);
240
241                                 extent_count++;
242                                 nr++;
243                                 path->slots[0]--;
244                         } else {
245                                 ASSERT(0);
246                         }
247                 }
248
249                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
250                 if (ret)
251                         goto out;
252                 btrfs_release_path(path);
253         }
254
255         info = search_free_space_info(trans, fs_info, block_group, path, 1);
256         if (IS_ERR(info)) {
257                 ret = PTR_ERR(info);
258                 goto out;
259         }
260         leaf = path->nodes[0];
261         flags = btrfs_free_space_flags(leaf, info);
262         flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
263         btrfs_set_free_space_flags(leaf, info, flags);
264         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
265         btrfs_mark_buffer_dirty(leaf);
266         btrfs_release_path(path);
267
268         if (extent_count != expected_extent_count) {
269                 btrfs_err(fs_info,
270                           "incorrect extent count for %llu; counted %u, expected %u",
271                           block_group->key.objectid, extent_count,
272                           expected_extent_count);
273                 ASSERT(0);
274                 ret = -EIO;
275                 goto out;
276         }
277
278         bitmap_cursor = (char *)bitmap;
279         bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
280         i = start;
281         while (i < end) {
282                 unsigned long ptr;
283                 u64 extent_size;
284                 u32 data_size;
285
286                 extent_size = min(end - i, bitmap_range);
287                 data_size = free_space_bitmap_size(extent_size,
288                                                    fs_info->sectorsize);
289
290                 key.objectid = i;
291                 key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
292                 key.offset = extent_size;
293
294                 ret = btrfs_insert_empty_item(trans, root, path, &key,
295                                               data_size);
296                 if (ret)
297                         goto out;
298
299                 leaf = path->nodes[0];
300                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
301                 write_extent_buffer(leaf, bitmap_cursor, ptr,
302                                     data_size);
303                 btrfs_mark_buffer_dirty(leaf);
304                 btrfs_release_path(path);
305
306                 i += extent_size;
307                 bitmap_cursor += data_size;
308         }
309
310         ret = 0;
311 out:
312         kvfree(bitmap);
313         if (ret)
314                 btrfs_abort_transaction(trans, ret);
315         return ret;
316 }
317
318 int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
319                                   struct btrfs_block_group_cache *block_group,
320                                   struct btrfs_path *path)
321 {
322         struct btrfs_fs_info *fs_info = trans->fs_info;
323         struct btrfs_root *root = fs_info->free_space_root;
324         struct btrfs_free_space_info *info;
325         struct btrfs_key key, found_key;
326         struct extent_buffer *leaf;
327         unsigned long *bitmap;
328         u64 start, end;
329         u32 bitmap_size, flags, expected_extent_count;
330         unsigned long nrbits, start_bit, end_bit;
331         u32 extent_count = 0;
332         int done = 0, nr;
333         int ret;
334
335         bitmap_size = free_space_bitmap_size(block_group->key.offset,
336                                              fs_info->sectorsize);
337         bitmap = alloc_bitmap(bitmap_size);
338         if (!bitmap) {
339                 ret = -ENOMEM;
340                 goto out;
341         }
342
343         start = block_group->key.objectid;
344         end = block_group->key.objectid + block_group->key.offset;
345
346         key.objectid = end - 1;
347         key.type = (u8)-1;
348         key.offset = (u64)-1;
349
350         while (!done) {
351                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
352                 if (ret)
353                         goto out;
354
355                 leaf = path->nodes[0];
356                 nr = 0;
357                 path->slots[0]++;
358                 while (path->slots[0] > 0) {
359                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
360
361                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
362                                 ASSERT(found_key.objectid == block_group->key.objectid);
363                                 ASSERT(found_key.offset == block_group->key.offset);
364                                 done = 1;
365                                 break;
366                         } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
367                                 unsigned long ptr;
368                                 char *bitmap_cursor;
369                                 u32 bitmap_pos, data_size;
370
371                                 ASSERT(found_key.objectid >= start);
372                                 ASSERT(found_key.objectid < end);
373                                 ASSERT(found_key.objectid + found_key.offset <= end);
374
375                                 bitmap_pos = div_u64(found_key.objectid - start,
376                                                      fs_info->sectorsize *
377                                                      BITS_PER_BYTE);
378                                 bitmap_cursor = ((char *)bitmap) + bitmap_pos;
379                                 data_size = free_space_bitmap_size(found_key.offset,
380                                                                    fs_info->sectorsize);
381
382                                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
383                                 read_extent_buffer(leaf, bitmap_cursor, ptr,
384                                                    data_size);
385
386                                 nr++;
387                                 path->slots[0]--;
388                         } else {
389                                 ASSERT(0);
390                         }
391                 }
392
393                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
394                 if (ret)
395                         goto out;
396                 btrfs_release_path(path);
397         }
398
399         info = search_free_space_info(trans, fs_info, block_group, path, 1);
400         if (IS_ERR(info)) {
401                 ret = PTR_ERR(info);
402                 goto out;
403         }
404         leaf = path->nodes[0];
405         flags = btrfs_free_space_flags(leaf, info);
406         flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
407         btrfs_set_free_space_flags(leaf, info, flags);
408         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
409         btrfs_mark_buffer_dirty(leaf);
410         btrfs_release_path(path);
411
412         nrbits = div_u64(block_group->key.offset, block_group->fs_info->sectorsize);
413         start_bit = find_next_bit_le(bitmap, nrbits, 0);
414
415         while (start_bit < nrbits) {
416                 end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit);
417                 ASSERT(start_bit < end_bit);
418
419                 key.objectid = start + start_bit * block_group->fs_info->sectorsize;
420                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
421                 key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize;
422
423                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
424                 if (ret)
425                         goto out;
426                 btrfs_release_path(path);
427
428                 extent_count++;
429
430                 start_bit = find_next_bit_le(bitmap, nrbits, end_bit);
431         }
432
433         if (extent_count != expected_extent_count) {
434                 btrfs_err(fs_info,
435                           "incorrect extent count for %llu; counted %u, expected %u",
436                           block_group->key.objectid, extent_count,
437                           expected_extent_count);
438                 ASSERT(0);
439                 ret = -EIO;
440                 goto out;
441         }
442
443         ret = 0;
444 out:
445         kvfree(bitmap);
446         if (ret)
447                 btrfs_abort_transaction(trans, ret);
448         return ret;
449 }
450
451 static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
452                                           struct btrfs_block_group_cache *block_group,
453                                           struct btrfs_path *path,
454                                           int new_extents)
455 {
456         struct btrfs_free_space_info *info;
457         u32 flags;
458         u32 extent_count;
459         int ret = 0;
460
461         if (new_extents == 0)
462                 return 0;
463
464         info = search_free_space_info(trans, trans->fs_info, block_group, path,
465                                       1);
466         if (IS_ERR(info)) {
467                 ret = PTR_ERR(info);
468                 goto out;
469         }
470         flags = btrfs_free_space_flags(path->nodes[0], info);
471         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
472
473         extent_count += new_extents;
474         btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
475         btrfs_mark_buffer_dirty(path->nodes[0]);
476         btrfs_release_path(path);
477
478         if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
479             extent_count > block_group->bitmap_high_thresh) {
480                 ret = convert_free_space_to_bitmaps(trans, block_group, path);
481         } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
482                    extent_count < block_group->bitmap_low_thresh) {
483                 ret = convert_free_space_to_extents(trans, block_group, path);
484         }
485
486 out:
487         return ret;
488 }
489
490 int free_space_test_bit(struct btrfs_block_group_cache *block_group,
491                         struct btrfs_path *path, u64 offset)
492 {
493         struct extent_buffer *leaf;
494         struct btrfs_key key;
495         u64 found_start, found_end;
496         unsigned long ptr, i;
497
498         leaf = path->nodes[0];
499         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
500         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
501
502         found_start = key.objectid;
503         found_end = key.objectid + key.offset;
504         ASSERT(offset >= found_start && offset < found_end);
505
506         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
507         i = div_u64(offset - found_start,
508                     block_group->fs_info->sectorsize);
509         return !!extent_buffer_test_bit(leaf, ptr, i);
510 }
511
512 static void free_space_set_bits(struct btrfs_block_group_cache *block_group,
513                                 struct btrfs_path *path, u64 *start, u64 *size,
514                                 int bit)
515 {
516         struct btrfs_fs_info *fs_info = block_group->fs_info;
517         struct extent_buffer *leaf;
518         struct btrfs_key key;
519         u64 end = *start + *size;
520         u64 found_start, found_end;
521         unsigned long ptr, first, last;
522
523         leaf = path->nodes[0];
524         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
525         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
526
527         found_start = key.objectid;
528         found_end = key.objectid + key.offset;
529         ASSERT(*start >= found_start && *start < found_end);
530         ASSERT(end > found_start);
531
532         if (end > found_end)
533                 end = found_end;
534
535         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
536         first = div_u64(*start - found_start, fs_info->sectorsize);
537         last = div_u64(end - found_start, fs_info->sectorsize);
538         if (bit)
539                 extent_buffer_bitmap_set(leaf, ptr, first, last - first);
540         else
541                 extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
542         btrfs_mark_buffer_dirty(leaf);
543
544         *size -= end - *start;
545         *start = end;
546 }
547
548 /*
549  * We can't use btrfs_next_item() in modify_free_space_bitmap() because
550  * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
551  * tree walking in btrfs_next_leaf() anyways because we know exactly what we're
552  * looking for.
553  */
554 static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
555                                   struct btrfs_root *root, struct btrfs_path *p)
556 {
557         struct btrfs_key key;
558
559         if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
560                 p->slots[0]++;
561                 return 0;
562         }
563
564         btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
565         btrfs_release_path(p);
566
567         key.objectid += key.offset;
568         key.type = (u8)-1;
569         key.offset = (u64)-1;
570
571         return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
572 }
573
574 /*
575  * If remove is 1, then we are removing free space, thus clearing bits in the
576  * bitmap. If remove is 0, then we are adding free space, thus setting bits in
577  * the bitmap.
578  */
579 static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
580                                     struct btrfs_fs_info *fs_info,
581                                     struct btrfs_block_group_cache *block_group,
582                                     struct btrfs_path *path,
583                                     u64 start, u64 size, int remove)
584 {
585         struct btrfs_root *root = fs_info->free_space_root;
586         struct btrfs_key key;
587         u64 end = start + size;
588         u64 cur_start, cur_size;
589         int prev_bit, next_bit;
590         int new_extents;
591         int ret;
592
593         /*
594          * Read the bit for the block immediately before the extent of space if
595          * that block is within the block group.
596          */
597         if (start > block_group->key.objectid) {
598                 u64 prev_block = start - block_group->fs_info->sectorsize;
599
600                 key.objectid = prev_block;
601                 key.type = (u8)-1;
602                 key.offset = (u64)-1;
603
604                 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
605                 if (ret)
606                         goto out;
607
608                 prev_bit = free_space_test_bit(block_group, path, prev_block);
609
610                 /* The previous block may have been in the previous bitmap. */
611                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
612                 if (start >= key.objectid + key.offset) {
613                         ret = free_space_next_bitmap(trans, root, path);
614                         if (ret)
615                                 goto out;
616                 }
617         } else {
618                 key.objectid = start;
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 = -1;
627         }
628
629         /*
630          * Iterate over all of the bitmaps overlapped by the extent of space,
631          * clearing/setting bits as required.
632          */
633         cur_start = start;
634         cur_size = size;
635         while (1) {
636                 free_space_set_bits(block_group, path, &cur_start, &cur_size,
637                                     !remove);
638                 if (cur_size == 0)
639                         break;
640                 ret = free_space_next_bitmap(trans, root, path);
641                 if (ret)
642                         goto out;
643         }
644
645         /*
646          * Read the bit for the block immediately after the extent of space if
647          * that block is within the block group.
648          */
649         if (end < block_group->key.objectid + block_group->key.offset) {
650                 /* The next block may be in the next bitmap. */
651                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
652                 if (end >= key.objectid + key.offset) {
653                         ret = free_space_next_bitmap(trans, root, path);
654                         if (ret)
655                                 goto out;
656                 }
657
658                 next_bit = free_space_test_bit(block_group, path, end);
659         } else {
660                 next_bit = -1;
661         }
662
663         if (remove) {
664                 new_extents = -1;
665                 if (prev_bit == 1) {
666                         /* Leftover on the left. */
667                         new_extents++;
668                 }
669                 if (next_bit == 1) {
670                         /* Leftover on the right. */
671                         new_extents++;
672                 }
673         } else {
674                 new_extents = 1;
675                 if (prev_bit == 1) {
676                         /* Merging with neighbor on the left. */
677                         new_extents--;
678                 }
679                 if (next_bit == 1) {
680                         /* Merging with neighbor on the right. */
681                         new_extents--;
682                 }
683         }
684
685         btrfs_release_path(path);
686         ret = update_free_space_extent_count(trans, block_group, path,
687                                              new_extents);
688
689 out:
690         return ret;
691 }
692
693 static int remove_free_space_extent(struct btrfs_trans_handle *trans,
694                                     struct btrfs_fs_info *fs_info,
695                                     struct btrfs_block_group_cache *block_group,
696                                     struct btrfs_path *path,
697                                     u64 start, u64 size)
698 {
699         struct btrfs_root *root = fs_info->free_space_root;
700         struct btrfs_key key;
701         u64 found_start, found_end;
702         u64 end = start + size;
703         int new_extents = -1;
704         int ret;
705
706         key.objectid = start;
707         key.type = (u8)-1;
708         key.offset = (u64)-1;
709
710         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
711         if (ret)
712                 goto out;
713
714         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
715
716         ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
717
718         found_start = key.objectid;
719         found_end = key.objectid + key.offset;
720         ASSERT(start >= found_start && end <= found_end);
721
722         /*
723          * Okay, now that we've found the free space extent which contains the
724          * free space that we are removing, there are four cases:
725          *
726          * 1. We're using the whole extent: delete the key we found and
727          * decrement the free space extent count.
728          * 2. We are using part of the extent starting at the beginning: delete
729          * the key we found and insert a new key representing the leftover at
730          * the end. There is no net change in the number of extents.
731          * 3. We are using part of the extent ending at the end: delete the key
732          * we found and insert a new key representing the leftover at the
733          * beginning. There is no net change in the number of extents.
734          * 4. We are using part of the extent in the middle: delete the key we
735          * found and insert two new keys representing the leftovers on each
736          * side. Where we used to have one extent, we now have two, so increment
737          * the extent count. We may need to convert the block group to bitmaps
738          * as a result.
739          */
740
741         /* Delete the existing key (cases 1-4). */
742         ret = btrfs_del_item(trans, root, path);
743         if (ret)
744                 goto out;
745
746         /* Add a key for leftovers at the beginning (cases 3 and 4). */
747         if (start > found_start) {
748                 key.objectid = found_start;
749                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
750                 key.offset = start - found_start;
751
752                 btrfs_release_path(path);
753                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
754                 if (ret)
755                         goto out;
756                 new_extents++;
757         }
758
759         /* Add a key for leftovers at the end (cases 2 and 4). */
760         if (end < found_end) {
761                 key.objectid = end;
762                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
763                 key.offset = found_end - end;
764
765                 btrfs_release_path(path);
766                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
767                 if (ret)
768                         goto out;
769                 new_extents++;
770         }
771
772         btrfs_release_path(path);
773         ret = update_free_space_extent_count(trans, block_group, path,
774                                              new_extents);
775
776 out:
777         return ret;
778 }
779
780 int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
781                                   struct btrfs_fs_info *fs_info,
782                                   struct btrfs_block_group_cache *block_group,
783                                   struct btrfs_path *path, u64 start, u64 size)
784 {
785         struct btrfs_free_space_info *info;
786         u32 flags;
787         int ret;
788
789         if (block_group->needs_free_space) {
790                 ret = __add_block_group_free_space(trans, block_group, 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
810 int 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);
840 out:
841         btrfs_free_path(path);
842         if (ret)
843                 btrfs_abort_transaction(trans, ret);
844         return ret;
845 }
846
847 static 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
921 right:
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
961 insert:
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, block_group, path,
969                                              new_extents);
970
971 out:
972         return ret;
973 }
974
975 int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
976                              struct btrfs_block_group_cache *block_group,
977                              struct btrfs_path *path, u64 start, u64 size)
978 {
979         struct btrfs_fs_info *fs_info = trans->fs_info;
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, block_group, path);
986                 if (ret)
987                         return ret;
988         }
989
990         info = search_free_space_info(NULL, fs_info, block_group, path, 0);
991         if (IS_ERR(info))
992                 return PTR_ERR(info);
993         flags = btrfs_free_space_flags(path->nodes[0], info);
994         btrfs_release_path(path);
995
996         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
997                 return modify_free_space_bitmap(trans, fs_info, block_group,
998                                                 path, start, size, 0);
999         } else {
1000                 return add_free_space_extent(trans, fs_info, block_group, path,
1001                                              start, size);
1002         }
1003 }
1004
1005 int add_to_free_space_tree(struct btrfs_trans_handle *trans,
1006                            struct btrfs_fs_info *fs_info,
1007                            u64 start, u64 size)
1008 {
1009         struct btrfs_block_group_cache *block_group;
1010         struct btrfs_path *path;
1011         int ret;
1012
1013         if (!btrfs_fs_compat_ro(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(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);
1034 out:
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  */
1046 static int populate_free_space_tree(struct btrfs_trans_handle *trans,
1047                                     struct btrfs_fs_info *fs_info,
1048                                     struct btrfs_block_group_cache *block_group)
1049 {
1050         struct btrfs_root *extent_root = fs_info->extent_root;
1051         struct btrfs_path *path, *path2;
1052         struct btrfs_key key;
1053         u64 start, end;
1054         int ret;
1055
1056         path = btrfs_alloc_path();
1057         if (!path)
1058                 return -ENOMEM;
1059         path->reada = READA_FORWARD;
1060
1061         path2 = btrfs_alloc_path();
1062         if (!path2) {
1063                 btrfs_free_path(path);
1064                 return -ENOMEM;
1065         }
1066
1067         ret = add_new_free_space_info(trans, block_group, path2);
1068         if (ret)
1069                 goto out;
1070
1071         mutex_lock(&block_group->free_space_lock);
1072
1073         /*
1074          * Iterate through all of the extent and metadata items in this block
1075          * group, adding the free space between them and the free space at the
1076          * end. Note that EXTENT_ITEM and METADATA_ITEM are less than
1077          * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
1078          * contained in.
1079          */
1080         key.objectid = block_group->key.objectid;
1081         key.type = BTRFS_EXTENT_ITEM_KEY;
1082         key.offset = 0;
1083
1084         ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
1085         if (ret < 0)
1086                 goto out_locked;
1087         ASSERT(ret == 0);
1088
1089         start = block_group->key.objectid;
1090         end = block_group->key.objectid + block_group->key.offset;
1091         while (1) {
1092                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1093
1094                 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
1095                     key.type == BTRFS_METADATA_ITEM_KEY) {
1096                         if (key.objectid >= end)
1097                                 break;
1098
1099                         if (start < key.objectid) {
1100                                 ret = __add_to_free_space_tree(trans,
1101                                                                block_group,
1102                                                                path2, start,
1103                                                                key.objectid -
1104                                                                start);
1105                                 if (ret)
1106                                         goto out_locked;
1107                         }
1108                         start = key.objectid;
1109                         if (key.type == BTRFS_METADATA_ITEM_KEY)
1110                                 start += fs_info->nodesize;
1111                         else
1112                                 start += key.offset;
1113                 } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
1114                         if (key.objectid != block_group->key.objectid)
1115                                 break;
1116                 }
1117
1118                 ret = btrfs_next_item(extent_root, path);
1119                 if (ret < 0)
1120                         goto out_locked;
1121                 if (ret)
1122                         break;
1123         }
1124         if (start < end) {
1125                 ret = __add_to_free_space_tree(trans, block_group, path2,
1126                                                start, end - start);
1127                 if (ret)
1128                         goto out_locked;
1129         }
1130
1131         ret = 0;
1132 out_locked:
1133         mutex_unlock(&block_group->free_space_lock);
1134 out:
1135         btrfs_free_path(path2);
1136         btrfs_free_path(path);
1137         return ret;
1138 }
1139
1140 int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
1141 {
1142         struct btrfs_trans_handle *trans;
1143         struct btrfs_root *tree_root = fs_info->tree_root;
1144         struct btrfs_root *free_space_root;
1145         struct btrfs_block_group_cache *block_group;
1146         struct rb_node *node;
1147         int ret;
1148
1149         trans = btrfs_start_transaction(tree_root, 0);
1150         if (IS_ERR(trans))
1151                 return PTR_ERR(trans);
1152
1153         set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1154         free_space_root = btrfs_create_tree(trans, fs_info,
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_cache,
1165                                        cache_node);
1166                 ret = populate_free_space_tree(trans, fs_info, 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
1176         return btrfs_commit_transaction(trans);
1177
1178 abort:
1179         clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1180         btrfs_abort_transaction(trans, ret);
1181         btrfs_end_transaction(trans);
1182         return ret;
1183 }
1184
1185 static int clear_free_space_tree(struct btrfs_trans_handle *trans,
1186                                  struct btrfs_root *root)
1187 {
1188         struct btrfs_path *path;
1189         struct btrfs_key key;
1190         int nr;
1191         int ret;
1192
1193         path = btrfs_alloc_path();
1194         if (!path)
1195                 return -ENOMEM;
1196
1197         path->leave_spinning = 1;
1198
1199         key.objectid = 0;
1200         key.type = 0;
1201         key.offset = 0;
1202
1203         while (1) {
1204                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1205                 if (ret < 0)
1206                         goto out;
1207
1208                 nr = btrfs_header_nritems(path->nodes[0]);
1209                 if (!nr)
1210                         break;
1211
1212                 path->slots[0] = 0;
1213                 ret = btrfs_del_items(trans, root, path, 0, nr);
1214                 if (ret)
1215                         goto out;
1216
1217                 btrfs_release_path(path);
1218         }
1219
1220         ret = 0;
1221 out:
1222         btrfs_free_path(path);
1223         return ret;
1224 }
1225
1226 int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
1227 {
1228         struct btrfs_trans_handle *trans;
1229         struct btrfs_root *tree_root = fs_info->tree_root;
1230         struct btrfs_root *free_space_root = fs_info->free_space_root;
1231         int ret;
1232
1233         trans = btrfs_start_transaction(tree_root, 0);
1234         if (IS_ERR(trans))
1235                 return PTR_ERR(trans);
1236
1237         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1238         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1239         fs_info->free_space_root = NULL;
1240
1241         ret = clear_free_space_tree(trans, free_space_root);
1242         if (ret)
1243                 goto abort;
1244
1245         ret = btrfs_del_root(trans, fs_info, &free_space_root->root_key);
1246         if (ret)
1247                 goto abort;
1248
1249         list_del(&free_space_root->dirty_list);
1250
1251         btrfs_tree_lock(free_space_root->node);
1252         clean_tree_block(fs_info, free_space_root->node);
1253         btrfs_tree_unlock(free_space_root->node);
1254         btrfs_free_tree_block(trans, free_space_root, free_space_root->node,
1255                               0, 1);
1256
1257         free_extent_buffer(free_space_root->node);
1258         free_extent_buffer(free_space_root->commit_root);
1259         kfree(free_space_root);
1260
1261         return btrfs_commit_transaction(trans);
1262
1263 abort:
1264         btrfs_abort_transaction(trans, ret);
1265         btrfs_end_transaction(trans);
1266         return ret;
1267 }
1268
1269 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
1270                                         struct btrfs_block_group_cache *block_group,
1271                                         struct btrfs_path *path)
1272 {
1273         int ret;
1274
1275         block_group->needs_free_space = 0;
1276
1277         ret = add_new_free_space_info(trans, block_group, path);
1278         if (ret)
1279                 return ret;
1280
1281         return __add_to_free_space_tree(trans, block_group, path,
1282                                         block_group->key.objectid,
1283                                         block_group->key.offset);
1284 }
1285
1286 int add_block_group_free_space(struct btrfs_trans_handle *trans,
1287                                struct btrfs_block_group_cache *block_group)
1288 {
1289         struct btrfs_fs_info *fs_info = trans->fs_info;
1290         struct btrfs_path *path = NULL;
1291         int ret = 0;
1292
1293         if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
1294                 return 0;
1295
1296         mutex_lock(&block_group->free_space_lock);
1297         if (!block_group->needs_free_space)
1298                 goto out;
1299
1300         path = btrfs_alloc_path();
1301         if (!path) {
1302                 ret = -ENOMEM;
1303                 goto out;
1304         }
1305
1306         ret = __add_block_group_free_space(trans, block_group, path);
1307
1308 out:
1309         btrfs_free_path(path);
1310         mutex_unlock(&block_group->free_space_lock);
1311         if (ret)
1312                 btrfs_abort_transaction(trans, ret);
1313         return ret;
1314 }
1315
1316 int remove_block_group_free_space(struct btrfs_trans_handle *trans,
1317                                   struct btrfs_block_group_cache *block_group)
1318 {
1319         struct btrfs_root *root = trans->fs_info->free_space_root;
1320         struct btrfs_path *path;
1321         struct btrfs_key key, found_key;
1322         struct extent_buffer *leaf;
1323         u64 start, end;
1324         int done = 0, nr;
1325         int ret;
1326
1327         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1328                 return 0;
1329
1330         if (block_group->needs_free_space) {
1331                 /* We never added this block group to the free space tree. */
1332                 return 0;
1333         }
1334
1335         path = btrfs_alloc_path();
1336         if (!path) {
1337                 ret = -ENOMEM;
1338                 goto out;
1339         }
1340
1341         start = block_group->key.objectid;
1342         end = block_group->key.objectid + block_group->key.offset;
1343
1344         key.objectid = end - 1;
1345         key.type = (u8)-1;
1346         key.offset = (u64)-1;
1347
1348         while (!done) {
1349                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
1350                 if (ret)
1351                         goto out;
1352
1353                 leaf = path->nodes[0];
1354                 nr = 0;
1355                 path->slots[0]++;
1356                 while (path->slots[0] > 0) {
1357                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
1358
1359                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
1360                                 ASSERT(found_key.objectid == block_group->key.objectid);
1361                                 ASSERT(found_key.offset == block_group->key.offset);
1362                                 done = 1;
1363                                 nr++;
1364                                 path->slots[0]--;
1365                                 break;
1366                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
1367                                    found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
1368                                 ASSERT(found_key.objectid >= start);
1369                                 ASSERT(found_key.objectid < end);
1370                                 ASSERT(found_key.objectid + found_key.offset <= end);
1371                                 nr++;
1372                                 path->slots[0]--;
1373                         } else {
1374                                 ASSERT(0);
1375                         }
1376                 }
1377
1378                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
1379                 if (ret)
1380                         goto out;
1381                 btrfs_release_path(path);
1382         }
1383
1384         ret = 0;
1385 out:
1386         btrfs_free_path(path);
1387         if (ret)
1388                 btrfs_abort_transaction(trans, ret);
1389         return ret;
1390 }
1391
1392 static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
1393                                    struct btrfs_path *path,
1394                                    u32 expected_extent_count)
1395 {
1396         struct btrfs_block_group_cache *block_group;
1397         struct btrfs_fs_info *fs_info;
1398         struct btrfs_root *root;
1399         struct btrfs_key key;
1400         int prev_bit = 0, bit;
1401         /* Initialize to silence GCC. */
1402         u64 extent_start = 0;
1403         u64 end, offset;
1404         u64 total_found = 0;
1405         u32 extent_count = 0;
1406         int ret;
1407
1408         block_group = caching_ctl->block_group;
1409         fs_info = block_group->fs_info;
1410         root = fs_info->free_space_root;
1411
1412         end = block_group->key.objectid + block_group->key.offset;
1413
1414         while (1) {
1415                 ret = btrfs_next_item(root, path);
1416                 if (ret < 0)
1417                         goto out;
1418                 if (ret)
1419                         break;
1420
1421                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1422
1423                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1424                         break;
1425
1426                 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
1427                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1428
1429                 caching_ctl->progress = key.objectid;
1430
1431                 offset = key.objectid;
1432                 while (offset < key.objectid + key.offset) {
1433                         bit = free_space_test_bit(block_group, path, offset);
1434                         if (prev_bit == 0 && bit == 1) {
1435                                 extent_start = offset;
1436                         } else if (prev_bit == 1 && bit == 0) {
1437                                 total_found += add_new_free_space(block_group,
1438                                                                   extent_start,
1439                                                                   offset);
1440                                 if (total_found > CACHING_CTL_WAKE_UP) {
1441                                         total_found = 0;
1442                                         wake_up(&caching_ctl->wait);
1443                                 }
1444                                 extent_count++;
1445                         }
1446                         prev_bit = bit;
1447                         offset += fs_info->sectorsize;
1448                 }
1449         }
1450         if (prev_bit == 1) {
1451                 total_found += add_new_free_space(block_group, extent_start,
1452                                                   end);
1453                 extent_count++;
1454         }
1455
1456         if (extent_count != expected_extent_count) {
1457                 btrfs_err(fs_info,
1458                           "incorrect extent count for %llu; counted %u, expected %u",
1459                           block_group->key.objectid, extent_count,
1460                           expected_extent_count);
1461                 ASSERT(0);
1462                 ret = -EIO;
1463                 goto out;
1464         }
1465
1466         caching_ctl->progress = (u64)-1;
1467
1468         ret = 0;
1469 out:
1470         return ret;
1471 }
1472
1473 static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
1474                                    struct btrfs_path *path,
1475                                    u32 expected_extent_count)
1476 {
1477         struct btrfs_block_group_cache *block_group;
1478         struct btrfs_fs_info *fs_info;
1479         struct btrfs_root *root;
1480         struct btrfs_key key;
1481         u64 end;
1482         u64 total_found = 0;
1483         u32 extent_count = 0;
1484         int ret;
1485
1486         block_group = caching_ctl->block_group;
1487         fs_info = block_group->fs_info;
1488         root = fs_info->free_space_root;
1489
1490         end = block_group->key.objectid + block_group->key.offset;
1491
1492         while (1) {
1493                 ret = btrfs_next_item(root, path);
1494                 if (ret < 0)
1495                         goto out;
1496                 if (ret)
1497                         break;
1498
1499                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1500
1501                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1502                         break;
1503
1504                 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
1505                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1506
1507                 caching_ctl->progress = key.objectid;
1508
1509                 total_found += add_new_free_space(block_group, key.objectid,
1510                                                   key.objectid + key.offset);
1511                 if (total_found > CACHING_CTL_WAKE_UP) {
1512                         total_found = 0;
1513                         wake_up(&caching_ctl->wait);
1514                 }
1515                 extent_count++;
1516         }
1517
1518         if (extent_count != expected_extent_count) {
1519                 btrfs_err(fs_info,
1520                           "incorrect extent count for %llu; counted %u, expected %u",
1521                           block_group->key.objectid, extent_count,
1522                           expected_extent_count);
1523                 ASSERT(0);
1524                 ret = -EIO;
1525                 goto out;
1526         }
1527
1528         caching_ctl->progress = (u64)-1;
1529
1530         ret = 0;
1531 out:
1532         return ret;
1533 }
1534
1535 int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
1536 {
1537         struct btrfs_block_group_cache *block_group;
1538         struct btrfs_fs_info *fs_info;
1539         struct btrfs_free_space_info *info;
1540         struct btrfs_path *path;
1541         u32 extent_count, flags;
1542         int ret;
1543
1544         block_group = caching_ctl->block_group;
1545         fs_info = block_group->fs_info;
1546
1547         path = btrfs_alloc_path();
1548         if (!path)
1549                 return -ENOMEM;
1550
1551         /*
1552          * Just like caching_thread() doesn't want to deadlock on the extent
1553          * tree, we don't want to deadlock on the free space tree.
1554          */
1555         path->skip_locking = 1;
1556         path->search_commit_root = 1;
1557         path->reada = READA_FORWARD;
1558
1559         info = search_free_space_info(NULL, fs_info, block_group, path, 0);
1560         if (IS_ERR(info)) {
1561                 ret = PTR_ERR(info);
1562                 goto out;
1563         }
1564         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
1565         flags = btrfs_free_space_flags(path->nodes[0], info);
1566
1567         /*
1568          * We left path pointing to the free space info item, so now
1569          * load_free_space_foo can just iterate through the free space tree from
1570          * there.
1571          */
1572         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
1573                 ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
1574         else
1575                 ret = load_free_space_extents(caching_ctl, path, extent_count);
1576
1577 out:
1578         btrfs_free_path(path);
1579         return ret;
1580 }