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Linux/fs/btrfs/free-space-tree.c

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

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