Btrfs: create special free space cache inode
[linux-3.10.git] / fs / btrfs / free-space-cache.c
1 /*
2  * Copyright (C) 2008 Red Hat.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/pagemap.h>
20 #include <linux/sched.h>
21 #include <linux/slab.h>
22 #include <linux/math64.h>
23 #include "ctree.h"
24 #include "free-space-cache.h"
25 #include "transaction.h"
26 #include "disk-io.h"
27
28 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
29 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
30
31 struct inode *lookup_free_space_inode(struct btrfs_root *root,
32                                       struct btrfs_block_group_cache
33                                       *block_group, struct btrfs_path *path)
34 {
35         struct btrfs_key key;
36         struct btrfs_key location;
37         struct btrfs_disk_key disk_key;
38         struct btrfs_free_space_header *header;
39         struct extent_buffer *leaf;
40         struct inode *inode = NULL;
41         int ret;
42
43         spin_lock(&block_group->lock);
44         if (block_group->inode)
45                 inode = igrab(block_group->inode);
46         spin_unlock(&block_group->lock);
47         if (inode)
48                 return inode;
49
50         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
51         key.offset = block_group->key.objectid;
52         key.type = 0;
53
54         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
55         if (ret < 0)
56                 return ERR_PTR(ret);
57         if (ret > 0) {
58                 btrfs_release_path(root, path);
59                 return ERR_PTR(-ENOENT);
60         }
61
62         leaf = path->nodes[0];
63         header = btrfs_item_ptr(leaf, path->slots[0],
64                                 struct btrfs_free_space_header);
65         btrfs_free_space_key(leaf, header, &disk_key);
66         btrfs_disk_key_to_cpu(&location, &disk_key);
67         btrfs_release_path(root, path);
68
69         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
70         if (!inode)
71                 return ERR_PTR(-ENOENT);
72         if (IS_ERR(inode))
73                 return inode;
74         if (is_bad_inode(inode)) {
75                 iput(inode);
76                 return ERR_PTR(-ENOENT);
77         }
78
79         spin_lock(&block_group->lock);
80         if (!root->fs_info->closing) {
81                 block_group->inode = igrab(inode);
82                 block_group->iref = 1;
83         }
84         spin_unlock(&block_group->lock);
85
86         return inode;
87 }
88
89 int create_free_space_inode(struct btrfs_root *root,
90                             struct btrfs_trans_handle *trans,
91                             struct btrfs_block_group_cache *block_group,
92                             struct btrfs_path *path)
93 {
94         struct btrfs_key key;
95         struct btrfs_disk_key disk_key;
96         struct btrfs_free_space_header *header;
97         struct btrfs_inode_item *inode_item;
98         struct extent_buffer *leaf;
99         u64 objectid;
100         int ret;
101
102         ret = btrfs_find_free_objectid(trans, root, 0, &objectid);
103         if (ret < 0)
104                 return ret;
105
106         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
107         if (ret)
108                 return ret;
109
110         leaf = path->nodes[0];
111         inode_item = btrfs_item_ptr(leaf, path->slots[0],
112                                     struct btrfs_inode_item);
113         btrfs_item_key(leaf, &disk_key, path->slots[0]);
114         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
115                              sizeof(*inode_item));
116         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
117         btrfs_set_inode_size(leaf, inode_item, 0);
118         btrfs_set_inode_nbytes(leaf, inode_item, 0);
119         btrfs_set_inode_uid(leaf, inode_item, 0);
120         btrfs_set_inode_gid(leaf, inode_item, 0);
121         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
122         btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
123                               BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
124         btrfs_set_inode_nlink(leaf, inode_item, 1);
125         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
126         btrfs_set_inode_block_group(leaf, inode_item,
127                                     block_group->key.objectid);
128         btrfs_mark_buffer_dirty(leaf);
129         btrfs_release_path(root, path);
130
131         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
132         key.offset = block_group->key.objectid;
133         key.type = 0;
134
135         ret = btrfs_insert_empty_item(trans, root, path, &key,
136                                       sizeof(struct btrfs_free_space_header));
137         if (ret < 0) {
138                 btrfs_release_path(root, path);
139                 return ret;
140         }
141         leaf = path->nodes[0];
142         header = btrfs_item_ptr(leaf, path->slots[0],
143                                 struct btrfs_free_space_header);
144         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
145         btrfs_set_free_space_key(leaf, header, &disk_key);
146         btrfs_mark_buffer_dirty(leaf);
147         btrfs_release_path(root, path);
148
149         return 0;
150 }
151
152 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
153                                     struct btrfs_trans_handle *trans,
154                                     struct btrfs_path *path,
155                                     struct inode *inode)
156 {
157         loff_t oldsize;
158         int ret = 0;
159
160         trans->block_rsv = root->orphan_block_rsv;
161         ret = btrfs_block_rsv_check(trans, root,
162                                     root->orphan_block_rsv,
163                                     0, 5);
164         if (ret)
165                 return ret;
166
167         oldsize = i_size_read(inode);
168         btrfs_i_size_write(inode, 0);
169         truncate_pagecache(inode, oldsize, 0);
170
171         /*
172          * We don't need an orphan item because truncating the free space cache
173          * will never be split across transactions.
174          */
175         ret = btrfs_truncate_inode_items(trans, root, inode,
176                                          0, BTRFS_EXTENT_DATA_KEY);
177         if (ret) {
178                 WARN_ON(1);
179                 return ret;
180         }
181
182         return btrfs_update_inode(trans, root, inode);
183 }
184
185 static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize,
186                                           u64 offset)
187 {
188         BUG_ON(offset < bitmap_start);
189         offset -= bitmap_start;
190         return (unsigned long)(div64_u64(offset, sectorsize));
191 }
192
193 static inline unsigned long bytes_to_bits(u64 bytes, u64 sectorsize)
194 {
195         return (unsigned long)(div64_u64(bytes, sectorsize));
196 }
197
198 static inline u64 offset_to_bitmap(struct btrfs_block_group_cache *block_group,
199                                    u64 offset)
200 {
201         u64 bitmap_start;
202         u64 bytes_per_bitmap;
203
204         bytes_per_bitmap = BITS_PER_BITMAP * block_group->sectorsize;
205         bitmap_start = offset - block_group->key.objectid;
206         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
207         bitmap_start *= bytes_per_bitmap;
208         bitmap_start += block_group->key.objectid;
209
210         return bitmap_start;
211 }
212
213 static int tree_insert_offset(struct rb_root *root, u64 offset,
214                               struct rb_node *node, int bitmap)
215 {
216         struct rb_node **p = &root->rb_node;
217         struct rb_node *parent = NULL;
218         struct btrfs_free_space *info;
219
220         while (*p) {
221                 parent = *p;
222                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
223
224                 if (offset < info->offset) {
225                         p = &(*p)->rb_left;
226                 } else if (offset > info->offset) {
227                         p = &(*p)->rb_right;
228                 } else {
229                         /*
230                          * we could have a bitmap entry and an extent entry
231                          * share the same offset.  If this is the case, we want
232                          * the extent entry to always be found first if we do a
233                          * linear search through the tree, since we want to have
234                          * the quickest allocation time, and allocating from an
235                          * extent is faster than allocating from a bitmap.  So
236                          * if we're inserting a bitmap and we find an entry at
237                          * this offset, we want to go right, or after this entry
238                          * logically.  If we are inserting an extent and we've
239                          * found a bitmap, we want to go left, or before
240                          * logically.
241                          */
242                         if (bitmap) {
243                                 WARN_ON(info->bitmap);
244                                 p = &(*p)->rb_right;
245                         } else {
246                                 WARN_ON(!info->bitmap);
247                                 p = &(*p)->rb_left;
248                         }
249                 }
250         }
251
252         rb_link_node(node, parent, p);
253         rb_insert_color(node, root);
254
255         return 0;
256 }
257
258 /*
259  * searches the tree for the given offset.
260  *
261  * fuzzy - If this is set, then we are trying to make an allocation, and we just
262  * want a section that has at least bytes size and comes at or after the given
263  * offset.
264  */
265 static struct btrfs_free_space *
266 tree_search_offset(struct btrfs_block_group_cache *block_group,
267                    u64 offset, int bitmap_only, int fuzzy)
268 {
269         struct rb_node *n = block_group->free_space_offset.rb_node;
270         struct btrfs_free_space *entry, *prev = NULL;
271
272         /* find entry that is closest to the 'offset' */
273         while (1) {
274                 if (!n) {
275                         entry = NULL;
276                         break;
277                 }
278
279                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
280                 prev = entry;
281
282                 if (offset < entry->offset)
283                         n = n->rb_left;
284                 else if (offset > entry->offset)
285                         n = n->rb_right;
286                 else
287                         break;
288         }
289
290         if (bitmap_only) {
291                 if (!entry)
292                         return NULL;
293                 if (entry->bitmap)
294                         return entry;
295
296                 /*
297                  * bitmap entry and extent entry may share same offset,
298                  * in that case, bitmap entry comes after extent entry.
299                  */
300                 n = rb_next(n);
301                 if (!n)
302                         return NULL;
303                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
304                 if (entry->offset != offset)
305                         return NULL;
306
307                 WARN_ON(!entry->bitmap);
308                 return entry;
309         } else if (entry) {
310                 if (entry->bitmap) {
311                         /*
312                          * if previous extent entry covers the offset,
313                          * we should return it instead of the bitmap entry
314                          */
315                         n = &entry->offset_index;
316                         while (1) {
317                                 n = rb_prev(n);
318                                 if (!n)
319                                         break;
320                                 prev = rb_entry(n, struct btrfs_free_space,
321                                                 offset_index);
322                                 if (!prev->bitmap) {
323                                         if (prev->offset + prev->bytes > offset)
324                                                 entry = prev;
325                                         break;
326                                 }
327                         }
328                 }
329                 return entry;
330         }
331
332         if (!prev)
333                 return NULL;
334
335         /* find last entry before the 'offset' */
336         entry = prev;
337         if (entry->offset > offset) {
338                 n = rb_prev(&entry->offset_index);
339                 if (n) {
340                         entry = rb_entry(n, struct btrfs_free_space,
341                                         offset_index);
342                         BUG_ON(entry->offset > offset);
343                 } else {
344                         if (fuzzy)
345                                 return entry;
346                         else
347                                 return NULL;
348                 }
349         }
350
351         if (entry->bitmap) {
352                 n = &entry->offset_index;
353                 while (1) {
354                         n = rb_prev(n);
355                         if (!n)
356                                 break;
357                         prev = rb_entry(n, struct btrfs_free_space,
358                                         offset_index);
359                         if (!prev->bitmap) {
360                                 if (prev->offset + prev->bytes > offset)
361                                         return prev;
362                                 break;
363                         }
364                 }
365                 if (entry->offset + BITS_PER_BITMAP *
366                     block_group->sectorsize > offset)
367                         return entry;
368         } else if (entry->offset + entry->bytes > offset)
369                 return entry;
370
371         if (!fuzzy)
372                 return NULL;
373
374         while (1) {
375                 if (entry->bitmap) {
376                         if (entry->offset + BITS_PER_BITMAP *
377                             block_group->sectorsize > offset)
378                                 break;
379                 } else {
380                         if (entry->offset + entry->bytes > offset)
381                                 break;
382                 }
383
384                 n = rb_next(&entry->offset_index);
385                 if (!n)
386                         return NULL;
387                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
388         }
389         return entry;
390 }
391
392 static void unlink_free_space(struct btrfs_block_group_cache *block_group,
393                               struct btrfs_free_space *info)
394 {
395         rb_erase(&info->offset_index, &block_group->free_space_offset);
396         block_group->free_extents--;
397         block_group->free_space -= info->bytes;
398 }
399
400 static int link_free_space(struct btrfs_block_group_cache *block_group,
401                            struct btrfs_free_space *info)
402 {
403         int ret = 0;
404
405         BUG_ON(!info->bitmap && !info->bytes);
406         ret = tree_insert_offset(&block_group->free_space_offset, info->offset,
407                                  &info->offset_index, (info->bitmap != NULL));
408         if (ret)
409                 return ret;
410
411         block_group->free_space += info->bytes;
412         block_group->free_extents++;
413         return ret;
414 }
415
416 static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
417 {
418         u64 max_bytes;
419         u64 bitmap_bytes;
420         u64 extent_bytes;
421
422         /*
423          * The goal is to keep the total amount of memory used per 1gb of space
424          * at or below 32k, so we need to adjust how much memory we allow to be
425          * used by extent based free space tracking
426          */
427         max_bytes = MAX_CACHE_BYTES_PER_GIG *
428                 (div64_u64(block_group->key.offset, 1024 * 1024 * 1024));
429
430         /*
431          * we want to account for 1 more bitmap than what we have so we can make
432          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
433          * we add more bitmaps.
434          */
435         bitmap_bytes = (block_group->total_bitmaps + 1) * PAGE_CACHE_SIZE;
436
437         if (bitmap_bytes >= max_bytes) {
438                 block_group->extents_thresh = 0;
439                 return;
440         }
441
442         /*
443          * we want the extent entry threshold to always be at most 1/2 the maxw
444          * bytes we can have, or whatever is less than that.
445          */
446         extent_bytes = max_bytes - bitmap_bytes;
447         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
448
449         block_group->extents_thresh =
450                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
451 }
452
453 static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
454                               struct btrfs_free_space *info, u64 offset,
455                               u64 bytes)
456 {
457         unsigned long start, end;
458         unsigned long i;
459
460         start = offset_to_bit(info->offset, block_group->sectorsize, offset);
461         end = start + bytes_to_bits(bytes, block_group->sectorsize);
462         BUG_ON(end > BITS_PER_BITMAP);
463
464         for (i = start; i < end; i++)
465                 clear_bit(i, info->bitmap);
466
467         info->bytes -= bytes;
468         block_group->free_space -= bytes;
469 }
470
471 static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
472                             struct btrfs_free_space *info, u64 offset,
473                             u64 bytes)
474 {
475         unsigned long start, end;
476         unsigned long i;
477
478         start = offset_to_bit(info->offset, block_group->sectorsize, offset);
479         end = start + bytes_to_bits(bytes, block_group->sectorsize);
480         BUG_ON(end > BITS_PER_BITMAP);
481
482         for (i = start; i < end; i++)
483                 set_bit(i, info->bitmap);
484
485         info->bytes += bytes;
486         block_group->free_space += bytes;
487 }
488
489 static int search_bitmap(struct btrfs_block_group_cache *block_group,
490                          struct btrfs_free_space *bitmap_info, u64 *offset,
491                          u64 *bytes)
492 {
493         unsigned long found_bits = 0;
494         unsigned long bits, i;
495         unsigned long next_zero;
496
497         i = offset_to_bit(bitmap_info->offset, block_group->sectorsize,
498                           max_t(u64, *offset, bitmap_info->offset));
499         bits = bytes_to_bits(*bytes, block_group->sectorsize);
500
501         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
502              i < BITS_PER_BITMAP;
503              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
504                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
505                                                BITS_PER_BITMAP, i);
506                 if ((next_zero - i) >= bits) {
507                         found_bits = next_zero - i;
508                         break;
509                 }
510                 i = next_zero;
511         }
512
513         if (found_bits) {
514                 *offset = (u64)(i * block_group->sectorsize) +
515                         bitmap_info->offset;
516                 *bytes = (u64)(found_bits) * block_group->sectorsize;
517                 return 0;
518         }
519
520         return -1;
521 }
522
523 static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
524                                                 *block_group, u64 *offset,
525                                                 u64 *bytes, int debug)
526 {
527         struct btrfs_free_space *entry;
528         struct rb_node *node;
529         int ret;
530
531         if (!block_group->free_space_offset.rb_node)
532                 return NULL;
533
534         entry = tree_search_offset(block_group,
535                                    offset_to_bitmap(block_group, *offset),
536                                    0, 1);
537         if (!entry)
538                 return NULL;
539
540         for (node = &entry->offset_index; node; node = rb_next(node)) {
541                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
542                 if (entry->bytes < *bytes)
543                         continue;
544
545                 if (entry->bitmap) {
546                         ret = search_bitmap(block_group, entry, offset, bytes);
547                         if (!ret)
548                                 return entry;
549                         continue;
550                 }
551
552                 *offset = entry->offset;
553                 *bytes = entry->bytes;
554                 return entry;
555         }
556
557         return NULL;
558 }
559
560 static void add_new_bitmap(struct btrfs_block_group_cache *block_group,
561                            struct btrfs_free_space *info, u64 offset)
562 {
563         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
564         int max_bitmaps = (int)div64_u64(block_group->key.offset +
565                                          bytes_per_bg - 1, bytes_per_bg);
566         BUG_ON(block_group->total_bitmaps >= max_bitmaps);
567
568         info->offset = offset_to_bitmap(block_group, offset);
569         info->bytes = 0;
570         link_free_space(block_group, info);
571         block_group->total_bitmaps++;
572
573         recalculate_thresholds(block_group);
574 }
575
576 static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group,
577                               struct btrfs_free_space *bitmap_info,
578                               u64 *offset, u64 *bytes)
579 {
580         u64 end;
581         u64 search_start, search_bytes;
582         int ret;
583
584 again:
585         end = bitmap_info->offset +
586                 (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
587
588         /*
589          * XXX - this can go away after a few releases.
590          *
591          * since the only user of btrfs_remove_free_space is the tree logging
592          * stuff, and the only way to test that is under crash conditions, we
593          * want to have this debug stuff here just in case somethings not
594          * working.  Search the bitmap for the space we are trying to use to
595          * make sure its actually there.  If its not there then we need to stop
596          * because something has gone wrong.
597          */
598         search_start = *offset;
599         search_bytes = *bytes;
600         ret = search_bitmap(block_group, bitmap_info, &search_start,
601                             &search_bytes);
602         BUG_ON(ret < 0 || search_start != *offset);
603
604         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
605                 bitmap_clear_bits(block_group, bitmap_info, *offset,
606                                   end - *offset + 1);
607                 *bytes -= end - *offset + 1;
608                 *offset = end + 1;
609         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
610                 bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
611                 *bytes = 0;
612         }
613
614         if (*bytes) {
615                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
616                 if (!bitmap_info->bytes) {
617                         unlink_free_space(block_group, bitmap_info);
618                         kfree(bitmap_info->bitmap);
619                         kfree(bitmap_info);
620                         block_group->total_bitmaps--;
621                         recalculate_thresholds(block_group);
622                 }
623
624                 /*
625                  * no entry after this bitmap, but we still have bytes to
626                  * remove, so something has gone wrong.
627                  */
628                 if (!next)
629                         return -EINVAL;
630
631                 bitmap_info = rb_entry(next, struct btrfs_free_space,
632                                        offset_index);
633
634                 /*
635                  * if the next entry isn't a bitmap we need to return to let the
636                  * extent stuff do its work.
637                  */
638                 if (!bitmap_info->bitmap)
639                         return -EAGAIN;
640
641                 /*
642                  * Ok the next item is a bitmap, but it may not actually hold
643                  * the information for the rest of this free space stuff, so
644                  * look for it, and if we don't find it return so we can try
645                  * everything over again.
646                  */
647                 search_start = *offset;
648                 search_bytes = *bytes;
649                 ret = search_bitmap(block_group, bitmap_info, &search_start,
650                                     &search_bytes);
651                 if (ret < 0 || search_start != *offset)
652                         return -EAGAIN;
653
654                 goto again;
655         } else if (!bitmap_info->bytes) {
656                 unlink_free_space(block_group, bitmap_info);
657                 kfree(bitmap_info->bitmap);
658                 kfree(bitmap_info);
659                 block_group->total_bitmaps--;
660                 recalculate_thresholds(block_group);
661         }
662
663         return 0;
664 }
665
666 static int insert_into_bitmap(struct btrfs_block_group_cache *block_group,
667                               struct btrfs_free_space *info)
668 {
669         struct btrfs_free_space *bitmap_info;
670         int added = 0;
671         u64 bytes, offset, end;
672         int ret;
673
674         /*
675          * If we are below the extents threshold then we can add this as an
676          * extent, and don't have to deal with the bitmap
677          */
678         if (block_group->free_extents < block_group->extents_thresh &&
679             info->bytes > block_group->sectorsize * 4)
680                 return 0;
681
682         /*
683          * some block groups are so tiny they can't be enveloped by a bitmap, so
684          * don't even bother to create a bitmap for this
685          */
686         if (BITS_PER_BITMAP * block_group->sectorsize >
687             block_group->key.offset)
688                 return 0;
689
690         bytes = info->bytes;
691         offset = info->offset;
692
693 again:
694         bitmap_info = tree_search_offset(block_group,
695                                          offset_to_bitmap(block_group, offset),
696                                          1, 0);
697         if (!bitmap_info) {
698                 BUG_ON(added);
699                 goto new_bitmap;
700         }
701
702         end = bitmap_info->offset +
703                 (u64)(BITS_PER_BITMAP * block_group->sectorsize);
704
705         if (offset >= bitmap_info->offset && offset + bytes > end) {
706                 bitmap_set_bits(block_group, bitmap_info, offset,
707                                 end - offset);
708                 bytes -= end - offset;
709                 offset = end;
710                 added = 0;
711         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
712                 bitmap_set_bits(block_group, bitmap_info, offset, bytes);
713                 bytes = 0;
714         } else {
715                 BUG();
716         }
717
718         if (!bytes) {
719                 ret = 1;
720                 goto out;
721         } else
722                 goto again;
723
724 new_bitmap:
725         if (info && info->bitmap) {
726                 add_new_bitmap(block_group, info, offset);
727                 added = 1;
728                 info = NULL;
729                 goto again;
730         } else {
731                 spin_unlock(&block_group->tree_lock);
732
733                 /* no pre-allocated info, allocate a new one */
734                 if (!info) {
735                         info = kzalloc(sizeof(struct btrfs_free_space),
736                                        GFP_NOFS);
737                         if (!info) {
738                                 spin_lock(&block_group->tree_lock);
739                                 ret = -ENOMEM;
740                                 goto out;
741                         }
742                 }
743
744                 /* allocate the bitmap */
745                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
746                 spin_lock(&block_group->tree_lock);
747                 if (!info->bitmap) {
748                         ret = -ENOMEM;
749                         goto out;
750                 }
751                 goto again;
752         }
753
754 out:
755         if (info) {
756                 if (info->bitmap)
757                         kfree(info->bitmap);
758                 kfree(info);
759         }
760
761         return ret;
762 }
763
764 int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
765                          u64 offset, u64 bytes)
766 {
767         struct btrfs_free_space *right_info = NULL;
768         struct btrfs_free_space *left_info = NULL;
769         struct btrfs_free_space *info = NULL;
770         int ret = 0;
771
772         info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
773         if (!info)
774                 return -ENOMEM;
775
776         info->offset = offset;
777         info->bytes = bytes;
778
779         spin_lock(&block_group->tree_lock);
780
781         /*
782          * first we want to see if there is free space adjacent to the range we
783          * are adding, if there is remove that struct and add a new one to
784          * cover the entire range
785          */
786         right_info = tree_search_offset(block_group, offset + bytes, 0, 0);
787         if (right_info && rb_prev(&right_info->offset_index))
788                 left_info = rb_entry(rb_prev(&right_info->offset_index),
789                                      struct btrfs_free_space, offset_index);
790         else
791                 left_info = tree_search_offset(block_group, offset - 1, 0, 0);
792
793         /*
794          * If there was no extent directly to the left or right of this new
795          * extent then we know we're going to have to allocate a new extent, so
796          * before we do that see if we need to drop this into a bitmap
797          */
798         if ((!left_info || left_info->bitmap) &&
799             (!right_info || right_info->bitmap)) {
800                 ret = insert_into_bitmap(block_group, info);
801
802                 if (ret < 0) {
803                         goto out;
804                 } else if (ret) {
805                         ret = 0;
806                         goto out;
807                 }
808         }
809
810         if (right_info && !right_info->bitmap) {
811                 unlink_free_space(block_group, right_info);
812                 info->bytes += right_info->bytes;
813                 kfree(right_info);
814         }
815
816         if (left_info && !left_info->bitmap &&
817             left_info->offset + left_info->bytes == offset) {
818                 unlink_free_space(block_group, left_info);
819                 info->offset = left_info->offset;
820                 info->bytes += left_info->bytes;
821                 kfree(left_info);
822         }
823
824         ret = link_free_space(block_group, info);
825         if (ret)
826                 kfree(info);
827 out:
828         spin_unlock(&block_group->tree_lock);
829
830         if (ret) {
831                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
832                 BUG_ON(ret == -EEXIST);
833         }
834
835         return ret;
836 }
837
838 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
839                             u64 offset, u64 bytes)
840 {
841         struct btrfs_free_space *info;
842         struct btrfs_free_space *next_info = NULL;
843         int ret = 0;
844
845         spin_lock(&block_group->tree_lock);
846
847 again:
848         info = tree_search_offset(block_group, offset, 0, 0);
849         if (!info) {
850                 /*
851                  * oops didn't find an extent that matched the space we wanted
852                  * to remove, look for a bitmap instead
853                  */
854                 info = tree_search_offset(block_group,
855                                           offset_to_bitmap(block_group, offset),
856                                           1, 0);
857                 if (!info) {
858                         WARN_ON(1);
859                         goto out_lock;
860                 }
861         }
862
863         if (info->bytes < bytes && rb_next(&info->offset_index)) {
864                 u64 end;
865                 next_info = rb_entry(rb_next(&info->offset_index),
866                                              struct btrfs_free_space,
867                                              offset_index);
868
869                 if (next_info->bitmap)
870                         end = next_info->offset + BITS_PER_BITMAP *
871                                 block_group->sectorsize - 1;
872                 else
873                         end = next_info->offset + next_info->bytes;
874
875                 if (next_info->bytes < bytes ||
876                     next_info->offset > offset || offset > end) {
877                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
878                               " trying to use %llu\n",
879                               (unsigned long long)info->offset,
880                               (unsigned long long)info->bytes,
881                               (unsigned long long)bytes);
882                         WARN_ON(1);
883                         ret = -EINVAL;
884                         goto out_lock;
885                 }
886
887                 info = next_info;
888         }
889
890         if (info->bytes == bytes) {
891                 unlink_free_space(block_group, info);
892                 if (info->bitmap) {
893                         kfree(info->bitmap);
894                         block_group->total_bitmaps--;
895                 }
896                 kfree(info);
897                 goto out_lock;
898         }
899
900         if (!info->bitmap && info->offset == offset) {
901                 unlink_free_space(block_group, info);
902                 info->offset += bytes;
903                 info->bytes -= bytes;
904                 link_free_space(block_group, info);
905                 goto out_lock;
906         }
907
908         if (!info->bitmap && info->offset <= offset &&
909             info->offset + info->bytes >= offset + bytes) {
910                 u64 old_start = info->offset;
911                 /*
912                  * we're freeing space in the middle of the info,
913                  * this can happen during tree log replay
914                  *
915                  * first unlink the old info and then
916                  * insert it again after the hole we're creating
917                  */
918                 unlink_free_space(block_group, info);
919                 if (offset + bytes < info->offset + info->bytes) {
920                         u64 old_end = info->offset + info->bytes;
921
922                         info->offset = offset + bytes;
923                         info->bytes = old_end - info->offset;
924                         ret = link_free_space(block_group, info);
925                         WARN_ON(ret);
926                         if (ret)
927                                 goto out_lock;
928                 } else {
929                         /* the hole we're creating ends at the end
930                          * of the info struct, just free the info
931                          */
932                         kfree(info);
933                 }
934                 spin_unlock(&block_group->tree_lock);
935
936                 /* step two, insert a new info struct to cover
937                  * anything before the hole
938                  */
939                 ret = btrfs_add_free_space(block_group, old_start,
940                                            offset - old_start);
941                 WARN_ON(ret);
942                 goto out;
943         }
944
945         ret = remove_from_bitmap(block_group, info, &offset, &bytes);
946         if (ret == -EAGAIN)
947                 goto again;
948         BUG_ON(ret);
949 out_lock:
950         spin_unlock(&block_group->tree_lock);
951 out:
952         return ret;
953 }
954
955 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
956                            u64 bytes)
957 {
958         struct btrfs_free_space *info;
959         struct rb_node *n;
960         int count = 0;
961
962         for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
963                 info = rb_entry(n, struct btrfs_free_space, offset_index);
964                 if (info->bytes >= bytes)
965                         count++;
966                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
967                        (unsigned long long)info->offset,
968                        (unsigned long long)info->bytes,
969                        (info->bitmap) ? "yes" : "no");
970         }
971         printk(KERN_INFO "block group has cluster?: %s\n",
972                list_empty(&block_group->cluster_list) ? "no" : "yes");
973         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
974                "\n", count);
975 }
976
977 u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
978 {
979         struct btrfs_free_space *info;
980         struct rb_node *n;
981         u64 ret = 0;
982
983         for (n = rb_first(&block_group->free_space_offset); n;
984              n = rb_next(n)) {
985                 info = rb_entry(n, struct btrfs_free_space, offset_index);
986                 ret += info->bytes;
987         }
988
989         return ret;
990 }
991
992 /*
993  * for a given cluster, put all of its extents back into the free
994  * space cache.  If the block group passed doesn't match the block group
995  * pointed to by the cluster, someone else raced in and freed the
996  * cluster already.  In that case, we just return without changing anything
997  */
998 static int
999 __btrfs_return_cluster_to_free_space(
1000                              struct btrfs_block_group_cache *block_group,
1001                              struct btrfs_free_cluster *cluster)
1002 {
1003         struct btrfs_free_space *entry;
1004         struct rb_node *node;
1005         bool bitmap;
1006
1007         spin_lock(&cluster->lock);
1008         if (cluster->block_group != block_group)
1009                 goto out;
1010
1011         bitmap = cluster->points_to_bitmap;
1012         cluster->block_group = NULL;
1013         cluster->window_start = 0;
1014         list_del_init(&cluster->block_group_list);
1015         cluster->points_to_bitmap = false;
1016
1017         if (bitmap)
1018                 goto out;
1019
1020         node = rb_first(&cluster->root);
1021         while (node) {
1022                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1023                 node = rb_next(&entry->offset_index);
1024                 rb_erase(&entry->offset_index, &cluster->root);
1025                 BUG_ON(entry->bitmap);
1026                 tree_insert_offset(&block_group->free_space_offset,
1027                                    entry->offset, &entry->offset_index, 0);
1028         }
1029         cluster->root = RB_ROOT;
1030
1031 out:
1032         spin_unlock(&cluster->lock);
1033         btrfs_put_block_group(block_group);
1034         return 0;
1035 }
1036
1037 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1038 {
1039         struct btrfs_free_space *info;
1040         struct rb_node *node;
1041         struct btrfs_free_cluster *cluster;
1042         struct list_head *head;
1043
1044         spin_lock(&block_group->tree_lock);
1045         while ((head = block_group->cluster_list.next) !=
1046                &block_group->cluster_list) {
1047                 cluster = list_entry(head, struct btrfs_free_cluster,
1048                                      block_group_list);
1049
1050                 WARN_ON(cluster->block_group != block_group);
1051                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1052                 if (need_resched()) {
1053                         spin_unlock(&block_group->tree_lock);
1054                         cond_resched();
1055                         spin_lock(&block_group->tree_lock);
1056                 }
1057         }
1058
1059         while ((node = rb_last(&block_group->free_space_offset)) != NULL) {
1060                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1061                 unlink_free_space(block_group, info);
1062                 if (info->bitmap)
1063                         kfree(info->bitmap);
1064                 kfree(info);
1065                 if (need_resched()) {
1066                         spin_unlock(&block_group->tree_lock);
1067                         cond_resched();
1068                         spin_lock(&block_group->tree_lock);
1069                 }
1070         }
1071
1072         spin_unlock(&block_group->tree_lock);
1073 }
1074
1075 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1076                                u64 offset, u64 bytes, u64 empty_size)
1077 {
1078         struct btrfs_free_space *entry = NULL;
1079         u64 bytes_search = bytes + empty_size;
1080         u64 ret = 0;
1081
1082         spin_lock(&block_group->tree_lock);
1083         entry = find_free_space(block_group, &offset, &bytes_search, 0);
1084         if (!entry)
1085                 goto out;
1086
1087         ret = offset;
1088         if (entry->bitmap) {
1089                 bitmap_clear_bits(block_group, entry, offset, bytes);
1090                 if (!entry->bytes) {
1091                         unlink_free_space(block_group, entry);
1092                         kfree(entry->bitmap);
1093                         kfree(entry);
1094                         block_group->total_bitmaps--;
1095                         recalculate_thresholds(block_group);
1096                 }
1097         } else {
1098                 unlink_free_space(block_group, entry);
1099                 entry->offset += bytes;
1100                 entry->bytes -= bytes;
1101                 if (!entry->bytes)
1102                         kfree(entry);
1103                 else
1104                         link_free_space(block_group, entry);
1105         }
1106
1107 out:
1108         spin_unlock(&block_group->tree_lock);
1109
1110         return ret;
1111 }
1112
1113 /*
1114  * given a cluster, put all of its extents back into the free space
1115  * cache.  If a block group is passed, this function will only free
1116  * a cluster that belongs to the passed block group.
1117  *
1118  * Otherwise, it'll get a reference on the block group pointed to by the
1119  * cluster and remove the cluster from it.
1120  */
1121 int btrfs_return_cluster_to_free_space(
1122                                struct btrfs_block_group_cache *block_group,
1123                                struct btrfs_free_cluster *cluster)
1124 {
1125         int ret;
1126
1127         /* first, get a safe pointer to the block group */
1128         spin_lock(&cluster->lock);
1129         if (!block_group) {
1130                 block_group = cluster->block_group;
1131                 if (!block_group) {
1132                         spin_unlock(&cluster->lock);
1133                         return 0;
1134                 }
1135         } else if (cluster->block_group != block_group) {
1136                 /* someone else has already freed it don't redo their work */
1137                 spin_unlock(&cluster->lock);
1138                 return 0;
1139         }
1140         atomic_inc(&block_group->count);
1141         spin_unlock(&cluster->lock);
1142
1143         /* now return any extents the cluster had on it */
1144         spin_lock(&block_group->tree_lock);
1145         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1146         spin_unlock(&block_group->tree_lock);
1147
1148         /* finally drop our ref */
1149         btrfs_put_block_group(block_group);
1150         return ret;
1151 }
1152
1153 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1154                                    struct btrfs_free_cluster *cluster,
1155                                    u64 bytes, u64 min_start)
1156 {
1157         struct btrfs_free_space *entry;
1158         int err;
1159         u64 search_start = cluster->window_start;
1160         u64 search_bytes = bytes;
1161         u64 ret = 0;
1162
1163         spin_lock(&block_group->tree_lock);
1164         spin_lock(&cluster->lock);
1165
1166         if (!cluster->points_to_bitmap)
1167                 goto out;
1168
1169         if (cluster->block_group != block_group)
1170                 goto out;
1171
1172         /*
1173          * search_start is the beginning of the bitmap, but at some point it may
1174          * be a good idea to point to the actual start of the free area in the
1175          * bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only
1176          * to 1 to make sure we get the bitmap entry
1177          */
1178         entry = tree_search_offset(block_group,
1179                                    offset_to_bitmap(block_group, search_start),
1180                                    1, 0);
1181         if (!entry || !entry->bitmap)
1182                 goto out;
1183
1184         search_start = min_start;
1185         search_bytes = bytes;
1186
1187         err = search_bitmap(block_group, entry, &search_start,
1188                             &search_bytes);
1189         if (err)
1190                 goto out;
1191
1192         ret = search_start;
1193         bitmap_clear_bits(block_group, entry, ret, bytes);
1194 out:
1195         spin_unlock(&cluster->lock);
1196         spin_unlock(&block_group->tree_lock);
1197
1198         return ret;
1199 }
1200
1201 /*
1202  * given a cluster, try to allocate 'bytes' from it, returns 0
1203  * if it couldn't find anything suitably large, or a logical disk offset
1204  * if things worked out
1205  */
1206 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1207                              struct btrfs_free_cluster *cluster, u64 bytes,
1208                              u64 min_start)
1209 {
1210         struct btrfs_free_space *entry = NULL;
1211         struct rb_node *node;
1212         u64 ret = 0;
1213
1214         if (cluster->points_to_bitmap)
1215                 return btrfs_alloc_from_bitmap(block_group, cluster, bytes,
1216                                                min_start);
1217
1218         spin_lock(&cluster->lock);
1219         if (bytes > cluster->max_size)
1220                 goto out;
1221
1222         if (cluster->block_group != block_group)
1223                 goto out;
1224
1225         node = rb_first(&cluster->root);
1226         if (!node)
1227                 goto out;
1228
1229         entry = rb_entry(node, struct btrfs_free_space, offset_index);
1230
1231         while(1) {
1232                 if (entry->bytes < bytes || entry->offset < min_start) {
1233                         struct rb_node *node;
1234
1235                         node = rb_next(&entry->offset_index);
1236                         if (!node)
1237                                 break;
1238                         entry = rb_entry(node, struct btrfs_free_space,
1239                                          offset_index);
1240                         continue;
1241                 }
1242                 ret = entry->offset;
1243
1244                 entry->offset += bytes;
1245                 entry->bytes -= bytes;
1246
1247                 if (entry->bytes == 0) {
1248                         rb_erase(&entry->offset_index, &cluster->root);
1249                         kfree(entry);
1250                 }
1251                 break;
1252         }
1253 out:
1254         spin_unlock(&cluster->lock);
1255
1256         return ret;
1257 }
1258
1259 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
1260                                 struct btrfs_free_space *entry,
1261                                 struct btrfs_free_cluster *cluster,
1262                                 u64 offset, u64 bytes, u64 min_bytes)
1263 {
1264         unsigned long next_zero;
1265         unsigned long i;
1266         unsigned long search_bits;
1267         unsigned long total_bits;
1268         unsigned long found_bits;
1269         unsigned long start = 0;
1270         unsigned long total_found = 0;
1271         bool found = false;
1272
1273         i = offset_to_bit(entry->offset, block_group->sectorsize,
1274                           max_t(u64, offset, entry->offset));
1275         search_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
1276         total_bits = bytes_to_bits(bytes, block_group->sectorsize);
1277
1278 again:
1279         found_bits = 0;
1280         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
1281              i < BITS_PER_BITMAP;
1282              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
1283                 next_zero = find_next_zero_bit(entry->bitmap,
1284                                                BITS_PER_BITMAP, i);
1285                 if (next_zero - i >= search_bits) {
1286                         found_bits = next_zero - i;
1287                         break;
1288                 }
1289                 i = next_zero;
1290         }
1291
1292         if (!found_bits)
1293                 return -1;
1294
1295         if (!found) {
1296                 start = i;
1297                 found = true;
1298         }
1299
1300         total_found += found_bits;
1301
1302         if (cluster->max_size < found_bits * block_group->sectorsize)
1303                 cluster->max_size = found_bits * block_group->sectorsize;
1304
1305         if (total_found < total_bits) {
1306                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
1307                 if (i - start > total_bits * 2) {
1308                         total_found = 0;
1309                         cluster->max_size = 0;
1310                         found = false;
1311                 }
1312                 goto again;
1313         }
1314
1315         cluster->window_start = start * block_group->sectorsize +
1316                 entry->offset;
1317         cluster->points_to_bitmap = true;
1318
1319         return 0;
1320 }
1321
1322 /*
1323  * here we try to find a cluster of blocks in a block group.  The goal
1324  * is to find at least bytes free and up to empty_size + bytes free.
1325  * We might not find them all in one contiguous area.
1326  *
1327  * returns zero and sets up cluster if things worked out, otherwise
1328  * it returns -enospc
1329  */
1330 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
1331                              struct btrfs_root *root,
1332                              struct btrfs_block_group_cache *block_group,
1333                              struct btrfs_free_cluster *cluster,
1334                              u64 offset, u64 bytes, u64 empty_size)
1335 {
1336         struct btrfs_free_space *entry = NULL;
1337         struct rb_node *node;
1338         struct btrfs_free_space *next;
1339         struct btrfs_free_space *last = NULL;
1340         u64 min_bytes;
1341         u64 window_start;
1342         u64 window_free;
1343         u64 max_extent = 0;
1344         bool found_bitmap = false;
1345         int ret;
1346
1347         /* for metadata, allow allocates with more holes */
1348         if (btrfs_test_opt(root, SSD_SPREAD)) {
1349                 min_bytes = bytes + empty_size;
1350         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
1351                 /*
1352                  * we want to do larger allocations when we are
1353                  * flushing out the delayed refs, it helps prevent
1354                  * making more work as we go along.
1355                  */
1356                 if (trans->transaction->delayed_refs.flushing)
1357                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
1358                 else
1359                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
1360         } else
1361                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
1362
1363         spin_lock(&block_group->tree_lock);
1364         spin_lock(&cluster->lock);
1365
1366         /* someone already found a cluster, hooray */
1367         if (cluster->block_group) {
1368                 ret = 0;
1369                 goto out;
1370         }
1371 again:
1372         entry = tree_search_offset(block_group, offset, found_bitmap, 1);
1373         if (!entry) {
1374                 ret = -ENOSPC;
1375                 goto out;
1376         }
1377
1378         /*
1379          * If found_bitmap is true, we exhausted our search for extent entries,
1380          * and we just want to search all of the bitmaps that we can find, and
1381          * ignore any extent entries we find.
1382          */
1383         while (entry->bitmap || found_bitmap ||
1384                (!entry->bitmap && entry->bytes < min_bytes)) {
1385                 struct rb_node *node = rb_next(&entry->offset_index);
1386
1387                 if (entry->bitmap && entry->bytes > bytes + empty_size) {
1388                         ret = btrfs_bitmap_cluster(block_group, entry, cluster,
1389                                                    offset, bytes + empty_size,
1390                                                    min_bytes);
1391                         if (!ret)
1392                                 goto got_it;
1393                 }
1394
1395                 if (!node) {
1396                         ret = -ENOSPC;
1397                         goto out;
1398                 }
1399                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1400         }
1401
1402         /*
1403          * We already searched all the extent entries from the passed in offset
1404          * to the end and didn't find enough space for the cluster, and we also
1405          * didn't find any bitmaps that met our criteria, just go ahead and exit
1406          */
1407         if (found_bitmap) {
1408                 ret = -ENOSPC;
1409                 goto out;
1410         }
1411
1412         cluster->points_to_bitmap = false;
1413         window_start = entry->offset;
1414         window_free = entry->bytes;
1415         last = entry;
1416         max_extent = entry->bytes;
1417
1418         while (1) {
1419                 /* out window is just right, lets fill it */
1420                 if (window_free >= bytes + empty_size)
1421                         break;
1422
1423                 node = rb_next(&last->offset_index);
1424                 if (!node) {
1425                         if (found_bitmap)
1426                                 goto again;
1427                         ret = -ENOSPC;
1428                         goto out;
1429                 }
1430                 next = rb_entry(node, struct btrfs_free_space, offset_index);
1431
1432                 /*
1433                  * we found a bitmap, so if this search doesn't result in a
1434                  * cluster, we know to go and search again for the bitmaps and
1435                  * start looking for space there
1436                  */
1437                 if (next->bitmap) {
1438                         if (!found_bitmap)
1439                                 offset = next->offset;
1440                         found_bitmap = true;
1441                         last = next;
1442                         continue;
1443                 }
1444
1445                 /*
1446                  * we haven't filled the empty size and the window is
1447                  * very large.  reset and try again
1448                  */
1449                 if (next->offset - (last->offset + last->bytes) > 128 * 1024 ||
1450                     next->offset - window_start > (bytes + empty_size) * 2) {
1451                         entry = next;
1452                         window_start = entry->offset;
1453                         window_free = entry->bytes;
1454                         last = entry;
1455                         max_extent = entry->bytes;
1456                 } else {
1457                         last = next;
1458                         window_free += next->bytes;
1459                         if (entry->bytes > max_extent)
1460                                 max_extent = entry->bytes;
1461                 }
1462         }
1463
1464         cluster->window_start = entry->offset;
1465
1466         /*
1467          * now we've found our entries, pull them out of the free space
1468          * cache and put them into the cluster rbtree
1469          *
1470          * The cluster includes an rbtree, but only uses the offset index
1471          * of each free space cache entry.
1472          */
1473         while (1) {
1474                 node = rb_next(&entry->offset_index);
1475                 if (entry->bitmap && node) {
1476                         entry = rb_entry(node, struct btrfs_free_space,
1477                                          offset_index);
1478                         continue;
1479                 } else if (entry->bitmap && !node) {
1480                         break;
1481                 }
1482
1483                 rb_erase(&entry->offset_index, &block_group->free_space_offset);
1484                 ret = tree_insert_offset(&cluster->root, entry->offset,
1485                                          &entry->offset_index, 0);
1486                 BUG_ON(ret);
1487
1488                 if (!node || entry == last)
1489                         break;
1490
1491                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1492         }
1493
1494         cluster->max_size = max_extent;
1495 got_it:
1496         ret = 0;
1497         atomic_inc(&block_group->count);
1498         list_add_tail(&cluster->block_group_list, &block_group->cluster_list);
1499         cluster->block_group = block_group;
1500 out:
1501         spin_unlock(&cluster->lock);
1502         spin_unlock(&block_group->tree_lock);
1503
1504         return ret;
1505 }
1506
1507 /*
1508  * simple code to zero out a cluster
1509  */
1510 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
1511 {
1512         spin_lock_init(&cluster->lock);
1513         spin_lock_init(&cluster->refill_lock);
1514         cluster->root = RB_ROOT;
1515         cluster->max_size = 0;
1516         cluster->points_to_bitmap = false;
1517         INIT_LIST_HEAD(&cluster->block_group_list);
1518         cluster->block_group = NULL;
1519 }
1520