8a9ce33dfdbc4046d8717d7934ce69a1db7b12fc
[sfrench/cifs-2.6.git] / fs / btrfs / extent-tree.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2007 Oracle.  All rights reserved.
4  */
5
6 #include <linux/sched.h>
7 #include <linux/sched/signal.h>
8 #include <linux/pagemap.h>
9 #include <linux/writeback.h>
10 #include <linux/blkdev.h>
11 #include <linux/sort.h>
12 #include <linux/rcupdate.h>
13 #include <linux/kthread.h>
14 #include <linux/slab.h>
15 #include <linux/ratelimit.h>
16 #include <linux/percpu_counter.h>
17 #include <linux/lockdep.h>
18 #include <linux/crc32c.h>
19 #include "tree-log.h"
20 #include "disk-io.h"
21 #include "print-tree.h"
22 #include "volumes.h"
23 #include "raid56.h"
24 #include "locking.h"
25 #include "free-space-cache.h"
26 #include "free-space-tree.h"
27 #include "math.h"
28 #include "sysfs.h"
29 #include "qgroup.h"
30 #include "ref-verify.h"
31
32 #undef SCRAMBLE_DELAYED_REFS
33
34 /*
35  * control flags for do_chunk_alloc's force field
36  * CHUNK_ALLOC_NO_FORCE means to only allocate a chunk
37  * if we really need one.
38  *
39  * CHUNK_ALLOC_LIMITED means to only try and allocate one
40  * if we have very few chunks already allocated.  This is
41  * used as part of the clustering code to help make sure
42  * we have a good pool of storage to cluster in, without
43  * filling the FS with empty chunks
44  *
45  * CHUNK_ALLOC_FORCE means it must try to allocate one
46  *
47  */
48 enum {
49         CHUNK_ALLOC_NO_FORCE = 0,
50         CHUNK_ALLOC_LIMITED = 1,
51         CHUNK_ALLOC_FORCE = 2,
52 };
53
54 /*
55  * Declare a helper function to detect underflow of various space info members
56  */
57 #define DECLARE_SPACE_INFO_UPDATE(name)                                 \
58 static inline void update_##name(struct btrfs_space_info *sinfo,        \
59                                  s64 bytes)                             \
60 {                                                                       \
61         if (bytes < 0 && sinfo->name < -bytes) {                        \
62                 WARN_ON(1);                                             \
63                 sinfo->name = 0;                                        \
64                 return;                                                 \
65         }                                                               \
66         sinfo->name += bytes;                                           \
67 }
68
69 DECLARE_SPACE_INFO_UPDATE(bytes_may_use);
70 DECLARE_SPACE_INFO_UPDATE(bytes_pinned);
71
72 static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
73                                struct btrfs_delayed_ref_node *node, u64 parent,
74                                u64 root_objectid, u64 owner_objectid,
75                                u64 owner_offset, int refs_to_drop,
76                                struct btrfs_delayed_extent_op *extra_op);
77 static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
78                                     struct extent_buffer *leaf,
79                                     struct btrfs_extent_item *ei);
80 static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
81                                       u64 parent, u64 root_objectid,
82                                       u64 flags, u64 owner, u64 offset,
83                                       struct btrfs_key *ins, int ref_mod);
84 static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
85                                      struct btrfs_delayed_ref_node *node,
86                                      struct btrfs_delayed_extent_op *extent_op);
87 static int do_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags,
88                           int force);
89 static int find_next_key(struct btrfs_path *path, int level,
90                          struct btrfs_key *key);
91 static void dump_space_info(struct btrfs_fs_info *fs_info,
92                             struct btrfs_space_info *info, u64 bytes,
93                             int dump_block_groups);
94 static int block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv,
95                                u64 num_bytes);
96 static void space_info_add_new_bytes(struct btrfs_fs_info *fs_info,
97                                      struct btrfs_space_info *space_info,
98                                      u64 num_bytes);
99 static void space_info_add_old_bytes(struct btrfs_fs_info *fs_info,
100                                      struct btrfs_space_info *space_info,
101                                      u64 num_bytes);
102
103 static noinline int
104 block_group_cache_done(struct btrfs_block_group_cache *cache)
105 {
106         smp_mb();
107         return cache->cached == BTRFS_CACHE_FINISHED ||
108                 cache->cached == BTRFS_CACHE_ERROR;
109 }
110
111 static int block_group_bits(struct btrfs_block_group_cache *cache, u64 bits)
112 {
113         return (cache->flags & bits) == bits;
114 }
115
116 void btrfs_get_block_group(struct btrfs_block_group_cache *cache)
117 {
118         atomic_inc(&cache->count);
119 }
120
121 void btrfs_put_block_group(struct btrfs_block_group_cache *cache)
122 {
123         if (atomic_dec_and_test(&cache->count)) {
124                 WARN_ON(cache->pinned > 0);
125                 WARN_ON(cache->reserved > 0);
126
127                 /*
128                  * If not empty, someone is still holding mutex of
129                  * full_stripe_lock, which can only be released by caller.
130                  * And it will definitely cause use-after-free when caller
131                  * tries to release full stripe lock.
132                  *
133                  * No better way to resolve, but only to warn.
134                  */
135                 WARN_ON(!RB_EMPTY_ROOT(&cache->full_stripe_locks_root.root));
136                 kfree(cache->free_space_ctl);
137                 kfree(cache);
138         }
139 }
140
141 /*
142  * this adds the block group to the fs_info rb tree for the block group
143  * cache
144  */
145 static int btrfs_add_block_group_cache(struct btrfs_fs_info *info,
146                                 struct btrfs_block_group_cache *block_group)
147 {
148         struct rb_node **p;
149         struct rb_node *parent = NULL;
150         struct btrfs_block_group_cache *cache;
151
152         spin_lock(&info->block_group_cache_lock);
153         p = &info->block_group_cache_tree.rb_node;
154
155         while (*p) {
156                 parent = *p;
157                 cache = rb_entry(parent, struct btrfs_block_group_cache,
158                                  cache_node);
159                 if (block_group->key.objectid < cache->key.objectid) {
160                         p = &(*p)->rb_left;
161                 } else if (block_group->key.objectid > cache->key.objectid) {
162                         p = &(*p)->rb_right;
163                 } else {
164                         spin_unlock(&info->block_group_cache_lock);
165                         return -EEXIST;
166                 }
167         }
168
169         rb_link_node(&block_group->cache_node, parent, p);
170         rb_insert_color(&block_group->cache_node,
171                         &info->block_group_cache_tree);
172
173         if (info->first_logical_byte > block_group->key.objectid)
174                 info->first_logical_byte = block_group->key.objectid;
175
176         spin_unlock(&info->block_group_cache_lock);
177
178         return 0;
179 }
180
181 /*
182  * This will return the block group at or after bytenr if contains is 0, else
183  * it will return the block group that contains the bytenr
184  */
185 static struct btrfs_block_group_cache *
186 block_group_cache_tree_search(struct btrfs_fs_info *info, u64 bytenr,
187                               int contains)
188 {
189         struct btrfs_block_group_cache *cache, *ret = NULL;
190         struct rb_node *n;
191         u64 end, start;
192
193         spin_lock(&info->block_group_cache_lock);
194         n = info->block_group_cache_tree.rb_node;
195
196         while (n) {
197                 cache = rb_entry(n, struct btrfs_block_group_cache,
198                                  cache_node);
199                 end = cache->key.objectid + cache->key.offset - 1;
200                 start = cache->key.objectid;
201
202                 if (bytenr < start) {
203                         if (!contains && (!ret || start < ret->key.objectid))
204                                 ret = cache;
205                         n = n->rb_left;
206                 } else if (bytenr > start) {
207                         if (contains && bytenr <= end) {
208                                 ret = cache;
209                                 break;
210                         }
211                         n = n->rb_right;
212                 } else {
213                         ret = cache;
214                         break;
215                 }
216         }
217         if (ret) {
218                 btrfs_get_block_group(ret);
219                 if (bytenr == 0 && info->first_logical_byte > ret->key.objectid)
220                         info->first_logical_byte = ret->key.objectid;
221         }
222         spin_unlock(&info->block_group_cache_lock);
223
224         return ret;
225 }
226
227 static int add_excluded_extent(struct btrfs_fs_info *fs_info,
228                                u64 start, u64 num_bytes)
229 {
230         u64 end = start + num_bytes - 1;
231         set_extent_bits(&fs_info->freed_extents[0],
232                         start, end, EXTENT_UPTODATE);
233         set_extent_bits(&fs_info->freed_extents[1],
234                         start, end, EXTENT_UPTODATE);
235         return 0;
236 }
237
238 static void free_excluded_extents(struct btrfs_block_group_cache *cache)
239 {
240         struct btrfs_fs_info *fs_info = cache->fs_info;
241         u64 start, end;
242
243         start = cache->key.objectid;
244         end = start + cache->key.offset - 1;
245
246         clear_extent_bits(&fs_info->freed_extents[0],
247                           start, end, EXTENT_UPTODATE);
248         clear_extent_bits(&fs_info->freed_extents[1],
249                           start, end, EXTENT_UPTODATE);
250 }
251
252 static int exclude_super_stripes(struct btrfs_block_group_cache *cache)
253 {
254         struct btrfs_fs_info *fs_info = cache->fs_info;
255         u64 bytenr;
256         u64 *logical;
257         int stripe_len;
258         int i, nr, ret;
259
260         if (cache->key.objectid < BTRFS_SUPER_INFO_OFFSET) {
261                 stripe_len = BTRFS_SUPER_INFO_OFFSET - cache->key.objectid;
262                 cache->bytes_super += stripe_len;
263                 ret = add_excluded_extent(fs_info, cache->key.objectid,
264                                           stripe_len);
265                 if (ret)
266                         return ret;
267         }
268
269         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
270                 bytenr = btrfs_sb_offset(i);
271                 ret = btrfs_rmap_block(fs_info, cache->key.objectid,
272                                        bytenr, &logical, &nr, &stripe_len);
273                 if (ret)
274                         return ret;
275
276                 while (nr--) {
277                         u64 start, len;
278
279                         if (logical[nr] > cache->key.objectid +
280                             cache->key.offset)
281                                 continue;
282
283                         if (logical[nr] + stripe_len <= cache->key.objectid)
284                                 continue;
285
286                         start = logical[nr];
287                         if (start < cache->key.objectid) {
288                                 start = cache->key.objectid;
289                                 len = (logical[nr] + stripe_len) - start;
290                         } else {
291                                 len = min_t(u64, stripe_len,
292                                             cache->key.objectid +
293                                             cache->key.offset - start);
294                         }
295
296                         cache->bytes_super += len;
297                         ret = add_excluded_extent(fs_info, start, len);
298                         if (ret) {
299                                 kfree(logical);
300                                 return ret;
301                         }
302                 }
303
304                 kfree(logical);
305         }
306         return 0;
307 }
308
309 static struct btrfs_caching_control *
310 get_caching_control(struct btrfs_block_group_cache *cache)
311 {
312         struct btrfs_caching_control *ctl;
313
314         spin_lock(&cache->lock);
315         if (!cache->caching_ctl) {
316                 spin_unlock(&cache->lock);
317                 return NULL;
318         }
319
320         ctl = cache->caching_ctl;
321         refcount_inc(&ctl->count);
322         spin_unlock(&cache->lock);
323         return ctl;
324 }
325
326 static void put_caching_control(struct btrfs_caching_control *ctl)
327 {
328         if (refcount_dec_and_test(&ctl->count))
329                 kfree(ctl);
330 }
331
332 #ifdef CONFIG_BTRFS_DEBUG
333 static void fragment_free_space(struct btrfs_block_group_cache *block_group)
334 {
335         struct btrfs_fs_info *fs_info = block_group->fs_info;
336         u64 start = block_group->key.objectid;
337         u64 len = block_group->key.offset;
338         u64 chunk = block_group->flags & BTRFS_BLOCK_GROUP_METADATA ?
339                 fs_info->nodesize : fs_info->sectorsize;
340         u64 step = chunk << 1;
341
342         while (len > chunk) {
343                 btrfs_remove_free_space(block_group, start, chunk);
344                 start += step;
345                 if (len < step)
346                         len = 0;
347                 else
348                         len -= step;
349         }
350 }
351 #endif
352
353 /*
354  * this is only called by cache_block_group, since we could have freed extents
355  * we need to check the pinned_extents for any extents that can't be used yet
356  * since their free space will be released as soon as the transaction commits.
357  */
358 u64 add_new_free_space(struct btrfs_block_group_cache *block_group,
359                        u64 start, u64 end)
360 {
361         struct btrfs_fs_info *info = block_group->fs_info;
362         u64 extent_start, extent_end, size, total_added = 0;
363         int ret;
364
365         while (start < end) {
366                 ret = find_first_extent_bit(info->pinned_extents, start,
367                                             &extent_start, &extent_end,
368                                             EXTENT_DIRTY | EXTENT_UPTODATE,
369                                             NULL);
370                 if (ret)
371                         break;
372
373                 if (extent_start <= start) {
374                         start = extent_end + 1;
375                 } else if (extent_start > start && extent_start < end) {
376                         size = extent_start - start;
377                         total_added += size;
378                         ret = btrfs_add_free_space(block_group, start,
379                                                    size);
380                         BUG_ON(ret); /* -ENOMEM or logic error */
381                         start = extent_end + 1;
382                 } else {
383                         break;
384                 }
385         }
386
387         if (start < end) {
388                 size = end - start;
389                 total_added += size;
390                 ret = btrfs_add_free_space(block_group, start, size);
391                 BUG_ON(ret); /* -ENOMEM or logic error */
392         }
393
394         return total_added;
395 }
396
397 static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl)
398 {
399         struct btrfs_block_group_cache *block_group = caching_ctl->block_group;
400         struct btrfs_fs_info *fs_info = block_group->fs_info;
401         struct btrfs_root *extent_root = fs_info->extent_root;
402         struct btrfs_path *path;
403         struct extent_buffer *leaf;
404         struct btrfs_key key;
405         u64 total_found = 0;
406         u64 last = 0;
407         u32 nritems;
408         int ret;
409         bool wakeup = true;
410
411         path = btrfs_alloc_path();
412         if (!path)
413                 return -ENOMEM;
414
415         last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
416
417 #ifdef CONFIG_BTRFS_DEBUG
418         /*
419          * If we're fragmenting we don't want to make anybody think we can
420          * allocate from this block group until we've had a chance to fragment
421          * the free space.
422          */
423         if (btrfs_should_fragment_free_space(block_group))
424                 wakeup = false;
425 #endif
426         /*
427          * We don't want to deadlock with somebody trying to allocate a new
428          * extent for the extent root while also trying to search the extent
429          * root to add free space.  So we skip locking and search the commit
430          * root, since its read-only
431          */
432         path->skip_locking = 1;
433         path->search_commit_root = 1;
434         path->reada = READA_FORWARD;
435
436         key.objectid = last;
437         key.offset = 0;
438         key.type = BTRFS_EXTENT_ITEM_KEY;
439
440 next:
441         ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
442         if (ret < 0)
443                 goto out;
444
445         leaf = path->nodes[0];
446         nritems = btrfs_header_nritems(leaf);
447
448         while (1) {
449                 if (btrfs_fs_closing(fs_info) > 1) {
450                         last = (u64)-1;
451                         break;
452                 }
453
454                 if (path->slots[0] < nritems) {
455                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
456                 } else {
457                         ret = find_next_key(path, 0, &key);
458                         if (ret)
459                                 break;
460
461                         if (need_resched() ||
462                             rwsem_is_contended(&fs_info->commit_root_sem)) {
463                                 if (wakeup)
464                                         caching_ctl->progress = last;
465                                 btrfs_release_path(path);
466                                 up_read(&fs_info->commit_root_sem);
467                                 mutex_unlock(&caching_ctl->mutex);
468                                 cond_resched();
469                                 mutex_lock(&caching_ctl->mutex);
470                                 down_read(&fs_info->commit_root_sem);
471                                 goto next;
472                         }
473
474                         ret = btrfs_next_leaf(extent_root, path);
475                         if (ret < 0)
476                                 goto out;
477                         if (ret)
478                                 break;
479                         leaf = path->nodes[0];
480                         nritems = btrfs_header_nritems(leaf);
481                         continue;
482                 }
483
484                 if (key.objectid < last) {
485                         key.objectid = last;
486                         key.offset = 0;
487                         key.type = BTRFS_EXTENT_ITEM_KEY;
488
489                         if (wakeup)
490                                 caching_ctl->progress = last;
491                         btrfs_release_path(path);
492                         goto next;
493                 }
494
495                 if (key.objectid < block_group->key.objectid) {
496                         path->slots[0]++;
497                         continue;
498                 }
499
500                 if (key.objectid >= block_group->key.objectid +
501                     block_group->key.offset)
502                         break;
503
504                 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
505                     key.type == BTRFS_METADATA_ITEM_KEY) {
506                         total_found += add_new_free_space(block_group, last,
507                                                           key.objectid);
508                         if (key.type == BTRFS_METADATA_ITEM_KEY)
509                                 last = key.objectid +
510                                         fs_info->nodesize;
511                         else
512                                 last = key.objectid + key.offset;
513
514                         if (total_found > CACHING_CTL_WAKE_UP) {
515                                 total_found = 0;
516                                 if (wakeup)
517                                         wake_up(&caching_ctl->wait);
518                         }
519                 }
520                 path->slots[0]++;
521         }
522         ret = 0;
523
524         total_found += add_new_free_space(block_group, last,
525                                           block_group->key.objectid +
526                                           block_group->key.offset);
527         caching_ctl->progress = (u64)-1;
528
529 out:
530         btrfs_free_path(path);
531         return ret;
532 }
533
534 static noinline void caching_thread(struct btrfs_work *work)
535 {
536         struct btrfs_block_group_cache *block_group;
537         struct btrfs_fs_info *fs_info;
538         struct btrfs_caching_control *caching_ctl;
539         int ret;
540
541         caching_ctl = container_of(work, struct btrfs_caching_control, work);
542         block_group = caching_ctl->block_group;
543         fs_info = block_group->fs_info;
544
545         mutex_lock(&caching_ctl->mutex);
546         down_read(&fs_info->commit_root_sem);
547
548         if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
549                 ret = load_free_space_tree(caching_ctl);
550         else
551                 ret = load_extent_tree_free(caching_ctl);
552
553         spin_lock(&block_group->lock);
554         block_group->caching_ctl = NULL;
555         block_group->cached = ret ? BTRFS_CACHE_ERROR : BTRFS_CACHE_FINISHED;
556         spin_unlock(&block_group->lock);
557
558 #ifdef CONFIG_BTRFS_DEBUG
559         if (btrfs_should_fragment_free_space(block_group)) {
560                 u64 bytes_used;
561
562                 spin_lock(&block_group->space_info->lock);
563                 spin_lock(&block_group->lock);
564                 bytes_used = block_group->key.offset -
565                         btrfs_block_group_used(&block_group->item);
566                 block_group->space_info->bytes_used += bytes_used >> 1;
567                 spin_unlock(&block_group->lock);
568                 spin_unlock(&block_group->space_info->lock);
569                 fragment_free_space(block_group);
570         }
571 #endif
572
573         caching_ctl->progress = (u64)-1;
574
575         up_read(&fs_info->commit_root_sem);
576         free_excluded_extents(block_group);
577         mutex_unlock(&caching_ctl->mutex);
578
579         wake_up(&caching_ctl->wait);
580
581         put_caching_control(caching_ctl);
582         btrfs_put_block_group(block_group);
583 }
584
585 static int cache_block_group(struct btrfs_block_group_cache *cache,
586                              int load_cache_only)
587 {
588         DEFINE_WAIT(wait);
589         struct btrfs_fs_info *fs_info = cache->fs_info;
590         struct btrfs_caching_control *caching_ctl;
591         int ret = 0;
592
593         caching_ctl = kzalloc(sizeof(*caching_ctl), GFP_NOFS);
594         if (!caching_ctl)
595                 return -ENOMEM;
596
597         INIT_LIST_HEAD(&caching_ctl->list);
598         mutex_init(&caching_ctl->mutex);
599         init_waitqueue_head(&caching_ctl->wait);
600         caching_ctl->block_group = cache;
601         caching_ctl->progress = cache->key.objectid;
602         refcount_set(&caching_ctl->count, 1);
603         btrfs_init_work(&caching_ctl->work, btrfs_cache_helper,
604                         caching_thread, NULL, NULL);
605
606         spin_lock(&cache->lock);
607         /*
608          * This should be a rare occasion, but this could happen I think in the
609          * case where one thread starts to load the space cache info, and then
610          * some other thread starts a transaction commit which tries to do an
611          * allocation while the other thread is still loading the space cache
612          * info.  The previous loop should have kept us from choosing this block
613          * group, but if we've moved to the state where we will wait on caching
614          * block groups we need to first check if we're doing a fast load here,
615          * so we can wait for it to finish, otherwise we could end up allocating
616          * from a block group who's cache gets evicted for one reason or
617          * another.
618          */
619         while (cache->cached == BTRFS_CACHE_FAST) {
620                 struct btrfs_caching_control *ctl;
621
622                 ctl = cache->caching_ctl;
623                 refcount_inc(&ctl->count);
624                 prepare_to_wait(&ctl->wait, &wait, TASK_UNINTERRUPTIBLE);
625                 spin_unlock(&cache->lock);
626
627                 schedule();
628
629                 finish_wait(&ctl->wait, &wait);
630                 put_caching_control(ctl);
631                 spin_lock(&cache->lock);
632         }
633
634         if (cache->cached != BTRFS_CACHE_NO) {
635                 spin_unlock(&cache->lock);
636                 kfree(caching_ctl);
637                 return 0;
638         }
639         WARN_ON(cache->caching_ctl);
640         cache->caching_ctl = caching_ctl;
641         cache->cached = BTRFS_CACHE_FAST;
642         spin_unlock(&cache->lock);
643
644         if (btrfs_test_opt(fs_info, SPACE_CACHE)) {
645                 mutex_lock(&caching_ctl->mutex);
646                 ret = load_free_space_cache(fs_info, cache);
647
648                 spin_lock(&cache->lock);
649                 if (ret == 1) {
650                         cache->caching_ctl = NULL;
651                         cache->cached = BTRFS_CACHE_FINISHED;
652                         cache->last_byte_to_unpin = (u64)-1;
653                         caching_ctl->progress = (u64)-1;
654                 } else {
655                         if (load_cache_only) {
656                                 cache->caching_ctl = NULL;
657                                 cache->cached = BTRFS_CACHE_NO;
658                         } else {
659                                 cache->cached = BTRFS_CACHE_STARTED;
660                                 cache->has_caching_ctl = 1;
661                         }
662                 }
663                 spin_unlock(&cache->lock);
664 #ifdef CONFIG_BTRFS_DEBUG
665                 if (ret == 1 &&
666                     btrfs_should_fragment_free_space(cache)) {
667                         u64 bytes_used;
668
669                         spin_lock(&cache->space_info->lock);
670                         spin_lock(&cache->lock);
671                         bytes_used = cache->key.offset -
672                                 btrfs_block_group_used(&cache->item);
673                         cache->space_info->bytes_used += bytes_used >> 1;
674                         spin_unlock(&cache->lock);
675                         spin_unlock(&cache->space_info->lock);
676                         fragment_free_space(cache);
677                 }
678 #endif
679                 mutex_unlock(&caching_ctl->mutex);
680
681                 wake_up(&caching_ctl->wait);
682                 if (ret == 1) {
683                         put_caching_control(caching_ctl);
684                         free_excluded_extents(cache);
685                         return 0;
686                 }
687         } else {
688                 /*
689                  * We're either using the free space tree or no caching at all.
690                  * Set cached to the appropriate value and wakeup any waiters.
691                  */
692                 spin_lock(&cache->lock);
693                 if (load_cache_only) {
694                         cache->caching_ctl = NULL;
695                         cache->cached = BTRFS_CACHE_NO;
696                 } else {
697                         cache->cached = BTRFS_CACHE_STARTED;
698                         cache->has_caching_ctl = 1;
699                 }
700                 spin_unlock(&cache->lock);
701                 wake_up(&caching_ctl->wait);
702         }
703
704         if (load_cache_only) {
705                 put_caching_control(caching_ctl);
706                 return 0;
707         }
708
709         down_write(&fs_info->commit_root_sem);
710         refcount_inc(&caching_ctl->count);
711         list_add_tail(&caching_ctl->list, &fs_info->caching_block_groups);
712         up_write(&fs_info->commit_root_sem);
713
714         btrfs_get_block_group(cache);
715
716         btrfs_queue_work(fs_info->caching_workers, &caching_ctl->work);
717
718         return ret;
719 }
720
721 /*
722  * return the block group that starts at or after bytenr
723  */
724 static struct btrfs_block_group_cache *
725 btrfs_lookup_first_block_group(struct btrfs_fs_info *info, u64 bytenr)
726 {
727         return block_group_cache_tree_search(info, bytenr, 0);
728 }
729
730 /*
731  * return the block group that contains the given bytenr
732  */
733 struct btrfs_block_group_cache *btrfs_lookup_block_group(
734                                                  struct btrfs_fs_info *info,
735                                                  u64 bytenr)
736 {
737         return block_group_cache_tree_search(info, bytenr, 1);
738 }
739
740 static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
741                                                   u64 flags)
742 {
743         struct list_head *head = &info->space_info;
744         struct btrfs_space_info *found;
745
746         flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
747
748         rcu_read_lock();
749         list_for_each_entry_rcu(found, head, list) {
750                 if (found->flags & flags) {
751                         rcu_read_unlock();
752                         return found;
753                 }
754         }
755         rcu_read_unlock();
756         return NULL;
757 }
758
759 static void add_pinned_bytes(struct btrfs_fs_info *fs_info, s64 num_bytes,
760                              bool metadata, u64 root_objectid)
761 {
762         struct btrfs_space_info *space_info;
763         u64 flags;
764
765         if (metadata) {
766                 if (root_objectid == BTRFS_CHUNK_TREE_OBJECTID)
767                         flags = BTRFS_BLOCK_GROUP_SYSTEM;
768                 else
769                         flags = BTRFS_BLOCK_GROUP_METADATA;
770         } else {
771                 flags = BTRFS_BLOCK_GROUP_DATA;
772         }
773
774         space_info = __find_space_info(fs_info, flags);
775         ASSERT(space_info);
776         percpu_counter_add_batch(&space_info->total_bytes_pinned, num_bytes,
777                     BTRFS_TOTAL_BYTES_PINNED_BATCH);
778 }
779
780 /*
781  * after adding space to the filesystem, we need to clear the full flags
782  * on all the space infos.
783  */
784 void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
785 {
786         struct list_head *head = &info->space_info;
787         struct btrfs_space_info *found;
788
789         rcu_read_lock();
790         list_for_each_entry_rcu(found, head, list)
791                 found->full = 0;
792         rcu_read_unlock();
793 }
794
795 /* simple helper to search for an existing data extent at a given offset */
796 int btrfs_lookup_data_extent(struct btrfs_fs_info *fs_info, u64 start, u64 len)
797 {
798         int ret;
799         struct btrfs_key key;
800         struct btrfs_path *path;
801
802         path = btrfs_alloc_path();
803         if (!path)
804                 return -ENOMEM;
805
806         key.objectid = start;
807         key.offset = len;
808         key.type = BTRFS_EXTENT_ITEM_KEY;
809         ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
810         btrfs_free_path(path);
811         return ret;
812 }
813
814 /*
815  * helper function to lookup reference count and flags of a tree block.
816  *
817  * the head node for delayed ref is used to store the sum of all the
818  * reference count modifications queued up in the rbtree. the head
819  * node may also store the extent flags to set. This way you can check
820  * to see what the reference count and extent flags would be if all of
821  * the delayed refs are not processed.
822  */
823 int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
824                              struct btrfs_fs_info *fs_info, u64 bytenr,
825                              u64 offset, int metadata, u64 *refs, u64 *flags)
826 {
827         struct btrfs_delayed_ref_head *head;
828         struct btrfs_delayed_ref_root *delayed_refs;
829         struct btrfs_path *path;
830         struct btrfs_extent_item *ei;
831         struct extent_buffer *leaf;
832         struct btrfs_key key;
833         u32 item_size;
834         u64 num_refs;
835         u64 extent_flags;
836         int ret;
837
838         /*
839          * If we don't have skinny metadata, don't bother doing anything
840          * different
841          */
842         if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA)) {
843                 offset = fs_info->nodesize;
844                 metadata = 0;
845         }
846
847         path = btrfs_alloc_path();
848         if (!path)
849                 return -ENOMEM;
850
851         if (!trans) {
852                 path->skip_locking = 1;
853                 path->search_commit_root = 1;
854         }
855
856 search_again:
857         key.objectid = bytenr;
858         key.offset = offset;
859         if (metadata)
860                 key.type = BTRFS_METADATA_ITEM_KEY;
861         else
862                 key.type = BTRFS_EXTENT_ITEM_KEY;
863
864         ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
865         if (ret < 0)
866                 goto out_free;
867
868         if (ret > 0 && metadata && key.type == BTRFS_METADATA_ITEM_KEY) {
869                 if (path->slots[0]) {
870                         path->slots[0]--;
871                         btrfs_item_key_to_cpu(path->nodes[0], &key,
872                                               path->slots[0]);
873                         if (key.objectid == bytenr &&
874                             key.type == BTRFS_EXTENT_ITEM_KEY &&
875                             key.offset == fs_info->nodesize)
876                                 ret = 0;
877                 }
878         }
879
880         if (ret == 0) {
881                 leaf = path->nodes[0];
882                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
883                 if (item_size >= sizeof(*ei)) {
884                         ei = btrfs_item_ptr(leaf, path->slots[0],
885                                             struct btrfs_extent_item);
886                         num_refs = btrfs_extent_refs(leaf, ei);
887                         extent_flags = btrfs_extent_flags(leaf, ei);
888                 } else {
889                         ret = -EINVAL;
890                         btrfs_print_v0_err(fs_info);
891                         if (trans)
892                                 btrfs_abort_transaction(trans, ret);
893                         else
894                                 btrfs_handle_fs_error(fs_info, ret, NULL);
895
896                         goto out_free;
897                 }
898
899                 BUG_ON(num_refs == 0);
900         } else {
901                 num_refs = 0;
902                 extent_flags = 0;
903                 ret = 0;
904         }
905
906         if (!trans)
907                 goto out;
908
909         delayed_refs = &trans->transaction->delayed_refs;
910         spin_lock(&delayed_refs->lock);
911         head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
912         if (head) {
913                 if (!mutex_trylock(&head->mutex)) {
914                         refcount_inc(&head->refs);
915                         spin_unlock(&delayed_refs->lock);
916
917                         btrfs_release_path(path);
918
919                         /*
920                          * Mutex was contended, block until it's released and try
921                          * again
922                          */
923                         mutex_lock(&head->mutex);
924                         mutex_unlock(&head->mutex);
925                         btrfs_put_delayed_ref_head(head);
926                         goto search_again;
927                 }
928                 spin_lock(&head->lock);
929                 if (head->extent_op && head->extent_op->update_flags)
930                         extent_flags |= head->extent_op->flags_to_set;
931                 else
932                         BUG_ON(num_refs == 0);
933
934                 num_refs += head->ref_mod;
935                 spin_unlock(&head->lock);
936                 mutex_unlock(&head->mutex);
937         }
938         spin_unlock(&delayed_refs->lock);
939 out:
940         WARN_ON(num_refs == 0);
941         if (refs)
942                 *refs = num_refs;
943         if (flags)
944                 *flags = extent_flags;
945 out_free:
946         btrfs_free_path(path);
947         return ret;
948 }
949
950 /*
951  * Back reference rules.  Back refs have three main goals:
952  *
953  * 1) differentiate between all holders of references to an extent so that
954  *    when a reference is dropped we can make sure it was a valid reference
955  *    before freeing the extent.
956  *
957  * 2) Provide enough information to quickly find the holders of an extent
958  *    if we notice a given block is corrupted or bad.
959  *
960  * 3) Make it easy to migrate blocks for FS shrinking or storage pool
961  *    maintenance.  This is actually the same as #2, but with a slightly
962  *    different use case.
963  *
964  * There are two kinds of back refs. The implicit back refs is optimized
965  * for pointers in non-shared tree blocks. For a given pointer in a block,
966  * back refs of this kind provide information about the block's owner tree
967  * and the pointer's key. These information allow us to find the block by
968  * b-tree searching. The full back refs is for pointers in tree blocks not
969  * referenced by their owner trees. The location of tree block is recorded
970  * in the back refs. Actually the full back refs is generic, and can be
971  * used in all cases the implicit back refs is used. The major shortcoming
972  * of the full back refs is its overhead. Every time a tree block gets
973  * COWed, we have to update back refs entry for all pointers in it.
974  *
975  * For a newly allocated tree block, we use implicit back refs for
976  * pointers in it. This means most tree related operations only involve
977  * implicit back refs. For a tree block created in old transaction, the
978  * only way to drop a reference to it is COW it. So we can detect the
979  * event that tree block loses its owner tree's reference and do the
980  * back refs conversion.
981  *
982  * When a tree block is COWed through a tree, there are four cases:
983  *
984  * The reference count of the block is one and the tree is the block's
985  * owner tree. Nothing to do in this case.
986  *
987  * The reference count of the block is one and the tree is not the
988  * block's owner tree. In this case, full back refs is used for pointers
989  * in the block. Remove these full back refs, add implicit back refs for
990  * every pointers in the new block.
991  *
992  * The reference count of the block is greater than one and the tree is
993  * the block's owner tree. In this case, implicit back refs is used for
994  * pointers in the block. Add full back refs for every pointers in the
995  * block, increase lower level extents' reference counts. The original
996  * implicit back refs are entailed to the new block.
997  *
998  * The reference count of the block is greater than one and the tree is
999  * not the block's owner tree. Add implicit back refs for every pointer in
1000  * the new block, increase lower level extents' reference count.
1001  *
1002  * Back Reference Key composing:
1003  *
1004  * The key objectid corresponds to the first byte in the extent,
1005  * The key type is used to differentiate between types of back refs.
1006  * There are different meanings of the key offset for different types
1007  * of back refs.
1008  *
1009  * File extents can be referenced by:
1010  *
1011  * - multiple snapshots, subvolumes, or different generations in one subvol
1012  * - different files inside a single subvolume
1013  * - different offsets inside a file (bookend extents in file.c)
1014  *
1015  * The extent ref structure for the implicit back refs has fields for:
1016  *
1017  * - Objectid of the subvolume root
1018  * - objectid of the file holding the reference
1019  * - original offset in the file
1020  * - how many bookend extents
1021  *
1022  * The key offset for the implicit back refs is hash of the first
1023  * three fields.
1024  *
1025  * The extent ref structure for the full back refs has field for:
1026  *
1027  * - number of pointers in the tree leaf
1028  *
1029  * The key offset for the implicit back refs is the first byte of
1030  * the tree leaf
1031  *
1032  * When a file extent is allocated, The implicit back refs is used.
1033  * the fields are filled in:
1034  *
1035  *     (root_key.objectid, inode objectid, offset in file, 1)
1036  *
1037  * When a file extent is removed file truncation, we find the
1038  * corresponding implicit back refs and check the following fields:
1039  *
1040  *     (btrfs_header_owner(leaf), inode objectid, offset in file)
1041  *
1042  * Btree extents can be referenced by:
1043  *
1044  * - Different subvolumes
1045  *
1046  * Both the implicit back refs and the full back refs for tree blocks
1047  * only consist of key. The key offset for the implicit back refs is
1048  * objectid of block's owner tree. The key offset for the full back refs
1049  * is the first byte of parent block.
1050  *
1051  * When implicit back refs is used, information about the lowest key and
1052  * level of the tree block are required. These information are stored in
1053  * tree block info structure.
1054  */
1055
1056 /*
1057  * is_data == BTRFS_REF_TYPE_BLOCK, tree block type is required,
1058  * is_data == BTRFS_REF_TYPE_DATA, data type is requried,
1059  * is_data == BTRFS_REF_TYPE_ANY, either type is OK.
1060  */
1061 int btrfs_get_extent_inline_ref_type(const struct extent_buffer *eb,
1062                                      struct btrfs_extent_inline_ref *iref,
1063                                      enum btrfs_inline_ref_type is_data)
1064 {
1065         int type = btrfs_extent_inline_ref_type(eb, iref);
1066         u64 offset = btrfs_extent_inline_ref_offset(eb, iref);
1067
1068         if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1069             type == BTRFS_SHARED_BLOCK_REF_KEY ||
1070             type == BTRFS_SHARED_DATA_REF_KEY ||
1071             type == BTRFS_EXTENT_DATA_REF_KEY) {
1072                 if (is_data == BTRFS_REF_TYPE_BLOCK) {
1073                         if (type == BTRFS_TREE_BLOCK_REF_KEY)
1074                                 return type;
1075                         if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
1076                                 ASSERT(eb->fs_info);
1077                                 /*
1078                                  * Every shared one has parent tree
1079                                  * block, which must be aligned to
1080                                  * nodesize.
1081                                  */
1082                                 if (offset &&
1083                                     IS_ALIGNED(offset, eb->fs_info->nodesize))
1084                                         return type;
1085                         }
1086                 } else if (is_data == BTRFS_REF_TYPE_DATA) {
1087                         if (type == BTRFS_EXTENT_DATA_REF_KEY)
1088                                 return type;
1089                         if (type == BTRFS_SHARED_DATA_REF_KEY) {
1090                                 ASSERT(eb->fs_info);
1091                                 /*
1092                                  * Every shared one has parent tree
1093                                  * block, which must be aligned to
1094                                  * nodesize.
1095                                  */
1096                                 if (offset &&
1097                                     IS_ALIGNED(offset, eb->fs_info->nodesize))
1098                                         return type;
1099                         }
1100                 } else {
1101                         ASSERT(is_data == BTRFS_REF_TYPE_ANY);
1102                         return type;
1103                 }
1104         }
1105
1106         btrfs_print_leaf((struct extent_buffer *)eb);
1107         btrfs_err(eb->fs_info, "eb %llu invalid extent inline ref type %d",
1108                   eb->start, type);
1109         WARN_ON(1);
1110
1111         return BTRFS_REF_TYPE_INVALID;
1112 }
1113
1114 static u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset)
1115 {
1116         u32 high_crc = ~(u32)0;
1117         u32 low_crc = ~(u32)0;
1118         __le64 lenum;
1119
1120         lenum = cpu_to_le64(root_objectid);
1121         high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
1122         lenum = cpu_to_le64(owner);
1123         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
1124         lenum = cpu_to_le64(offset);
1125         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
1126
1127         return ((u64)high_crc << 31) ^ (u64)low_crc;
1128 }
1129
1130 static u64 hash_extent_data_ref_item(struct extent_buffer *leaf,
1131                                      struct btrfs_extent_data_ref *ref)
1132 {
1133         return hash_extent_data_ref(btrfs_extent_data_ref_root(leaf, ref),
1134                                     btrfs_extent_data_ref_objectid(leaf, ref),
1135                                     btrfs_extent_data_ref_offset(leaf, ref));
1136 }
1137
1138 static int match_extent_data_ref(struct extent_buffer *leaf,
1139                                  struct btrfs_extent_data_ref *ref,
1140                                  u64 root_objectid, u64 owner, u64 offset)
1141 {
1142         if (btrfs_extent_data_ref_root(leaf, ref) != root_objectid ||
1143             btrfs_extent_data_ref_objectid(leaf, ref) != owner ||
1144             btrfs_extent_data_ref_offset(leaf, ref) != offset)
1145                 return 0;
1146         return 1;
1147 }
1148
1149 static noinline int lookup_extent_data_ref(struct btrfs_trans_handle *trans,
1150                                            struct btrfs_path *path,
1151                                            u64 bytenr, u64 parent,
1152                                            u64 root_objectid,
1153                                            u64 owner, u64 offset)
1154 {
1155         struct btrfs_root *root = trans->fs_info->extent_root;
1156         struct btrfs_key key;
1157         struct btrfs_extent_data_ref *ref;
1158         struct extent_buffer *leaf;
1159         u32 nritems;
1160         int ret;
1161         int recow;
1162         int err = -ENOENT;
1163
1164         key.objectid = bytenr;
1165         if (parent) {
1166                 key.type = BTRFS_SHARED_DATA_REF_KEY;
1167                 key.offset = parent;
1168         } else {
1169                 key.type = BTRFS_EXTENT_DATA_REF_KEY;
1170                 key.offset = hash_extent_data_ref(root_objectid,
1171                                                   owner, offset);
1172         }
1173 again:
1174         recow = 0;
1175         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1176         if (ret < 0) {
1177                 err = ret;
1178                 goto fail;
1179         }
1180
1181         if (parent) {
1182                 if (!ret)
1183                         return 0;
1184                 goto fail;
1185         }
1186
1187         leaf = path->nodes[0];
1188         nritems = btrfs_header_nritems(leaf);
1189         while (1) {
1190                 if (path->slots[0] >= nritems) {
1191                         ret = btrfs_next_leaf(root, path);
1192                         if (ret < 0)
1193                                 err = ret;
1194                         if (ret)
1195                                 goto fail;
1196
1197                         leaf = path->nodes[0];
1198                         nritems = btrfs_header_nritems(leaf);
1199                         recow = 1;
1200                 }
1201
1202                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1203                 if (key.objectid != bytenr ||
1204                     key.type != BTRFS_EXTENT_DATA_REF_KEY)
1205                         goto fail;
1206
1207                 ref = btrfs_item_ptr(leaf, path->slots[0],
1208                                      struct btrfs_extent_data_ref);
1209
1210                 if (match_extent_data_ref(leaf, ref, root_objectid,
1211                                           owner, offset)) {
1212                         if (recow) {
1213                                 btrfs_release_path(path);
1214                                 goto again;
1215                         }
1216                         err = 0;
1217                         break;
1218                 }
1219                 path->slots[0]++;
1220         }
1221 fail:
1222         return err;
1223 }
1224
1225 static noinline int insert_extent_data_ref(struct btrfs_trans_handle *trans,
1226                                            struct btrfs_path *path,
1227                                            u64 bytenr, u64 parent,
1228                                            u64 root_objectid, u64 owner,
1229                                            u64 offset, int refs_to_add)
1230 {
1231         struct btrfs_root *root = trans->fs_info->extent_root;
1232         struct btrfs_key key;
1233         struct extent_buffer *leaf;
1234         u32 size;
1235         u32 num_refs;
1236         int ret;
1237
1238         key.objectid = bytenr;
1239         if (parent) {
1240                 key.type = BTRFS_SHARED_DATA_REF_KEY;
1241                 key.offset = parent;
1242                 size = sizeof(struct btrfs_shared_data_ref);
1243         } else {
1244                 key.type = BTRFS_EXTENT_DATA_REF_KEY;
1245                 key.offset = hash_extent_data_ref(root_objectid,
1246                                                   owner, offset);
1247                 size = sizeof(struct btrfs_extent_data_ref);
1248         }
1249
1250         ret = btrfs_insert_empty_item(trans, root, path, &key, size);
1251         if (ret && ret != -EEXIST)
1252                 goto fail;
1253
1254         leaf = path->nodes[0];
1255         if (parent) {
1256                 struct btrfs_shared_data_ref *ref;
1257                 ref = btrfs_item_ptr(leaf, path->slots[0],
1258                                      struct btrfs_shared_data_ref);
1259                 if (ret == 0) {
1260                         btrfs_set_shared_data_ref_count(leaf, ref, refs_to_add);
1261                 } else {
1262                         num_refs = btrfs_shared_data_ref_count(leaf, ref);
1263                         num_refs += refs_to_add;
1264                         btrfs_set_shared_data_ref_count(leaf, ref, num_refs);
1265                 }
1266         } else {
1267                 struct btrfs_extent_data_ref *ref;
1268                 while (ret == -EEXIST) {
1269                         ref = btrfs_item_ptr(leaf, path->slots[0],
1270                                              struct btrfs_extent_data_ref);
1271                         if (match_extent_data_ref(leaf, ref, root_objectid,
1272                                                   owner, offset))
1273                                 break;
1274                         btrfs_release_path(path);
1275                         key.offset++;
1276                         ret = btrfs_insert_empty_item(trans, root, path, &key,
1277                                                       size);
1278                         if (ret && ret != -EEXIST)
1279                                 goto fail;
1280
1281                         leaf = path->nodes[0];
1282                 }
1283                 ref = btrfs_item_ptr(leaf, path->slots[0],
1284                                      struct btrfs_extent_data_ref);
1285                 if (ret == 0) {
1286                         btrfs_set_extent_data_ref_root(leaf, ref,
1287                                                        root_objectid);
1288                         btrfs_set_extent_data_ref_objectid(leaf, ref, owner);
1289                         btrfs_set_extent_data_ref_offset(leaf, ref, offset);
1290                         btrfs_set_extent_data_ref_count(leaf, ref, refs_to_add);
1291                 } else {
1292                         num_refs = btrfs_extent_data_ref_count(leaf, ref);
1293                         num_refs += refs_to_add;
1294                         btrfs_set_extent_data_ref_count(leaf, ref, num_refs);
1295                 }
1296         }
1297         btrfs_mark_buffer_dirty(leaf);
1298         ret = 0;
1299 fail:
1300         btrfs_release_path(path);
1301         return ret;
1302 }
1303
1304 static noinline int remove_extent_data_ref(struct btrfs_trans_handle *trans,
1305                                            struct btrfs_path *path,
1306                                            int refs_to_drop, int *last_ref)
1307 {
1308         struct btrfs_key key;
1309         struct btrfs_extent_data_ref *ref1 = NULL;
1310         struct btrfs_shared_data_ref *ref2 = NULL;
1311         struct extent_buffer *leaf;
1312         u32 num_refs = 0;
1313         int ret = 0;
1314
1315         leaf = path->nodes[0];
1316         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1317
1318         if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
1319                 ref1 = btrfs_item_ptr(leaf, path->slots[0],
1320                                       struct btrfs_extent_data_ref);
1321                 num_refs = btrfs_extent_data_ref_count(leaf, ref1);
1322         } else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
1323                 ref2 = btrfs_item_ptr(leaf, path->slots[0],
1324                                       struct btrfs_shared_data_ref);
1325                 num_refs = btrfs_shared_data_ref_count(leaf, ref2);
1326         } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
1327                 btrfs_print_v0_err(trans->fs_info);
1328                 btrfs_abort_transaction(trans, -EINVAL);
1329                 return -EINVAL;
1330         } else {
1331                 BUG();
1332         }
1333
1334         BUG_ON(num_refs < refs_to_drop);
1335         num_refs -= refs_to_drop;
1336
1337         if (num_refs == 0) {
1338                 ret = btrfs_del_item(trans, trans->fs_info->extent_root, path);
1339                 *last_ref = 1;
1340         } else {
1341                 if (key.type == BTRFS_EXTENT_DATA_REF_KEY)
1342                         btrfs_set_extent_data_ref_count(leaf, ref1, num_refs);
1343                 else if (key.type == BTRFS_SHARED_DATA_REF_KEY)
1344                         btrfs_set_shared_data_ref_count(leaf, ref2, num_refs);
1345                 btrfs_mark_buffer_dirty(leaf);
1346         }
1347         return ret;
1348 }
1349
1350 static noinline u32 extent_data_ref_count(struct btrfs_path *path,
1351                                           struct btrfs_extent_inline_ref *iref)
1352 {
1353         struct btrfs_key key;
1354         struct extent_buffer *leaf;
1355         struct btrfs_extent_data_ref *ref1;
1356         struct btrfs_shared_data_ref *ref2;
1357         u32 num_refs = 0;
1358         int type;
1359
1360         leaf = path->nodes[0];
1361         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1362
1363         BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
1364         if (iref) {
1365                 /*
1366                  * If type is invalid, we should have bailed out earlier than
1367                  * this call.
1368                  */
1369                 type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_DATA);
1370                 ASSERT(type != BTRFS_REF_TYPE_INVALID);
1371                 if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1372                         ref1 = (struct btrfs_extent_data_ref *)(&iref->offset);
1373                         num_refs = btrfs_extent_data_ref_count(leaf, ref1);
1374                 } else {
1375                         ref2 = (struct btrfs_shared_data_ref *)(iref + 1);
1376                         num_refs = btrfs_shared_data_ref_count(leaf, ref2);
1377                 }
1378         } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
1379                 ref1 = btrfs_item_ptr(leaf, path->slots[0],
1380                                       struct btrfs_extent_data_ref);
1381                 num_refs = btrfs_extent_data_ref_count(leaf, ref1);
1382         } else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
1383                 ref2 = btrfs_item_ptr(leaf, path->slots[0],
1384                                       struct btrfs_shared_data_ref);
1385                 num_refs = btrfs_shared_data_ref_count(leaf, ref2);
1386         } else {
1387                 WARN_ON(1);
1388         }
1389         return num_refs;
1390 }
1391
1392 static noinline int lookup_tree_block_ref(struct btrfs_trans_handle *trans,
1393                                           struct btrfs_path *path,
1394                                           u64 bytenr, u64 parent,
1395                                           u64 root_objectid)
1396 {
1397         struct btrfs_root *root = trans->fs_info->extent_root;
1398         struct btrfs_key key;
1399         int ret;
1400
1401         key.objectid = bytenr;
1402         if (parent) {
1403                 key.type = BTRFS_SHARED_BLOCK_REF_KEY;
1404                 key.offset = parent;
1405         } else {
1406                 key.type = BTRFS_TREE_BLOCK_REF_KEY;
1407                 key.offset = root_objectid;
1408         }
1409
1410         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1411         if (ret > 0)
1412                 ret = -ENOENT;
1413         return ret;
1414 }
1415
1416 static noinline int insert_tree_block_ref(struct btrfs_trans_handle *trans,
1417                                           struct btrfs_path *path,
1418                                           u64 bytenr, u64 parent,
1419                                           u64 root_objectid)
1420 {
1421         struct btrfs_key key;
1422         int ret;
1423
1424         key.objectid = bytenr;
1425         if (parent) {
1426                 key.type = BTRFS_SHARED_BLOCK_REF_KEY;
1427                 key.offset = parent;
1428         } else {
1429                 key.type = BTRFS_TREE_BLOCK_REF_KEY;
1430                 key.offset = root_objectid;
1431         }
1432
1433         ret = btrfs_insert_empty_item(trans, trans->fs_info->extent_root,
1434                                       path, &key, 0);
1435         btrfs_release_path(path);
1436         return ret;
1437 }
1438
1439 static inline int extent_ref_type(u64 parent, u64 owner)
1440 {
1441         int type;
1442         if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1443                 if (parent > 0)
1444                         type = BTRFS_SHARED_BLOCK_REF_KEY;
1445                 else
1446                         type = BTRFS_TREE_BLOCK_REF_KEY;
1447         } else {
1448                 if (parent > 0)
1449                         type = BTRFS_SHARED_DATA_REF_KEY;
1450                 else
1451                         type = BTRFS_EXTENT_DATA_REF_KEY;
1452         }
1453         return type;
1454 }
1455
1456 static int find_next_key(struct btrfs_path *path, int level,
1457                          struct btrfs_key *key)
1458
1459 {
1460         for (; level < BTRFS_MAX_LEVEL; level++) {
1461                 if (!path->nodes[level])
1462                         break;
1463                 if (path->slots[level] + 1 >=
1464                     btrfs_header_nritems(path->nodes[level]))
1465                         continue;
1466                 if (level == 0)
1467                         btrfs_item_key_to_cpu(path->nodes[level], key,
1468                                               path->slots[level] + 1);
1469                 else
1470                         btrfs_node_key_to_cpu(path->nodes[level], key,
1471                                               path->slots[level] + 1);
1472                 return 0;
1473         }
1474         return 1;
1475 }
1476
1477 /*
1478  * look for inline back ref. if back ref is found, *ref_ret is set
1479  * to the address of inline back ref, and 0 is returned.
1480  *
1481  * if back ref isn't found, *ref_ret is set to the address where it
1482  * should be inserted, and -ENOENT is returned.
1483  *
1484  * if insert is true and there are too many inline back refs, the path
1485  * points to the extent item, and -EAGAIN is returned.
1486  *
1487  * NOTE: inline back refs are ordered in the same way that back ref
1488  *       items in the tree are ordered.
1489  */
1490 static noinline_for_stack
1491 int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
1492                                  struct btrfs_path *path,
1493                                  struct btrfs_extent_inline_ref **ref_ret,
1494                                  u64 bytenr, u64 num_bytes,
1495                                  u64 parent, u64 root_objectid,
1496                                  u64 owner, u64 offset, int insert)
1497 {
1498         struct btrfs_fs_info *fs_info = trans->fs_info;
1499         struct btrfs_root *root = fs_info->extent_root;
1500         struct btrfs_key key;
1501         struct extent_buffer *leaf;
1502         struct btrfs_extent_item *ei;
1503         struct btrfs_extent_inline_ref *iref;
1504         u64 flags;
1505         u64 item_size;
1506         unsigned long ptr;
1507         unsigned long end;
1508         int extra_size;
1509         int type;
1510         int want;
1511         int ret;
1512         int err = 0;
1513         bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
1514         int needed;
1515
1516         key.objectid = bytenr;
1517         key.type = BTRFS_EXTENT_ITEM_KEY;
1518         key.offset = num_bytes;
1519
1520         want = extent_ref_type(parent, owner);
1521         if (insert) {
1522                 extra_size = btrfs_extent_inline_ref_size(want);
1523                 path->keep_locks = 1;
1524         } else
1525                 extra_size = -1;
1526
1527         /*
1528          * Owner is our level, so we can just add one to get the level for the
1529          * block we are interested in.
1530          */
1531         if (skinny_metadata && owner < BTRFS_FIRST_FREE_OBJECTID) {
1532                 key.type = BTRFS_METADATA_ITEM_KEY;
1533                 key.offset = owner;
1534         }
1535
1536 again:
1537         ret = btrfs_search_slot(trans, root, &key, path, extra_size, 1);
1538         if (ret < 0) {
1539                 err = ret;
1540                 goto out;
1541         }
1542
1543         /*
1544          * We may be a newly converted file system which still has the old fat
1545          * extent entries for metadata, so try and see if we have one of those.
1546          */
1547         if (ret > 0 && skinny_metadata) {
1548                 skinny_metadata = false;
1549                 if (path->slots[0]) {
1550                         path->slots[0]--;
1551                         btrfs_item_key_to_cpu(path->nodes[0], &key,
1552                                               path->slots[0]);
1553                         if (key.objectid == bytenr &&
1554                             key.type == BTRFS_EXTENT_ITEM_KEY &&
1555                             key.offset == num_bytes)
1556                                 ret = 0;
1557                 }
1558                 if (ret) {
1559                         key.objectid = bytenr;
1560                         key.type = BTRFS_EXTENT_ITEM_KEY;
1561                         key.offset = num_bytes;
1562                         btrfs_release_path(path);
1563                         goto again;
1564                 }
1565         }
1566
1567         if (ret && !insert) {
1568                 err = -ENOENT;
1569                 goto out;
1570         } else if (WARN_ON(ret)) {
1571                 err = -EIO;
1572                 goto out;
1573         }
1574
1575         leaf = path->nodes[0];
1576         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1577         if (unlikely(item_size < sizeof(*ei))) {
1578                 err = -EINVAL;
1579                 btrfs_print_v0_err(fs_info);
1580                 btrfs_abort_transaction(trans, err);
1581                 goto out;
1582         }
1583
1584         ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1585         flags = btrfs_extent_flags(leaf, ei);
1586
1587         ptr = (unsigned long)(ei + 1);
1588         end = (unsigned long)ei + item_size;
1589
1590         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK && !skinny_metadata) {
1591                 ptr += sizeof(struct btrfs_tree_block_info);
1592                 BUG_ON(ptr > end);
1593         }
1594
1595         if (owner >= BTRFS_FIRST_FREE_OBJECTID)
1596                 needed = BTRFS_REF_TYPE_DATA;
1597         else
1598                 needed = BTRFS_REF_TYPE_BLOCK;
1599
1600         err = -ENOENT;
1601         while (1) {
1602                 if (ptr >= end) {
1603                         WARN_ON(ptr > end);
1604                         break;
1605                 }
1606                 iref = (struct btrfs_extent_inline_ref *)ptr;
1607                 type = btrfs_get_extent_inline_ref_type(leaf, iref, needed);
1608                 if (type == BTRFS_REF_TYPE_INVALID) {
1609                         err = -EUCLEAN;
1610                         goto out;
1611                 }
1612
1613                 if (want < type)
1614                         break;
1615                 if (want > type) {
1616                         ptr += btrfs_extent_inline_ref_size(type);
1617                         continue;
1618                 }
1619
1620                 if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1621                         struct btrfs_extent_data_ref *dref;
1622                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1623                         if (match_extent_data_ref(leaf, dref, root_objectid,
1624                                                   owner, offset)) {
1625                                 err = 0;
1626                                 break;
1627                         }
1628                         if (hash_extent_data_ref_item(leaf, dref) <
1629                             hash_extent_data_ref(root_objectid, owner, offset))
1630                                 break;
1631                 } else {
1632                         u64 ref_offset;
1633                         ref_offset = btrfs_extent_inline_ref_offset(leaf, iref);
1634                         if (parent > 0) {
1635                                 if (parent == ref_offset) {
1636                                         err = 0;
1637                                         break;
1638                                 }
1639                                 if (ref_offset < parent)
1640                                         break;
1641                         } else {
1642                                 if (root_objectid == ref_offset) {
1643                                         err = 0;
1644                                         break;
1645                                 }
1646                                 if (ref_offset < root_objectid)
1647                                         break;
1648                         }
1649                 }
1650                 ptr += btrfs_extent_inline_ref_size(type);
1651         }
1652         if (err == -ENOENT && insert) {
1653                 if (item_size + extra_size >=
1654                     BTRFS_MAX_EXTENT_ITEM_SIZE(root)) {
1655                         err = -EAGAIN;
1656                         goto out;
1657                 }
1658                 /*
1659                  * To add new inline back ref, we have to make sure
1660                  * there is no corresponding back ref item.
1661                  * For simplicity, we just do not add new inline back
1662                  * ref if there is any kind of item for this block
1663                  */
1664                 if (find_next_key(path, 0, &key) == 0 &&
1665                     key.objectid == bytenr &&
1666                     key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
1667                         err = -EAGAIN;
1668                         goto out;
1669                 }
1670         }
1671         *ref_ret = (struct btrfs_extent_inline_ref *)ptr;
1672 out:
1673         if (insert) {
1674                 path->keep_locks = 0;
1675                 btrfs_unlock_up_safe(path, 1);
1676         }
1677         return err;
1678 }
1679
1680 /*
1681  * helper to add new inline back ref
1682  */
1683 static noinline_for_stack
1684 void setup_inline_extent_backref(struct btrfs_fs_info *fs_info,
1685                                  struct btrfs_path *path,
1686                                  struct btrfs_extent_inline_ref *iref,
1687                                  u64 parent, u64 root_objectid,
1688                                  u64 owner, u64 offset, int refs_to_add,
1689                                  struct btrfs_delayed_extent_op *extent_op)
1690 {
1691         struct extent_buffer *leaf;
1692         struct btrfs_extent_item *ei;
1693         unsigned long ptr;
1694         unsigned long end;
1695         unsigned long item_offset;
1696         u64 refs;
1697         int size;
1698         int type;
1699
1700         leaf = path->nodes[0];
1701         ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1702         item_offset = (unsigned long)iref - (unsigned long)ei;
1703
1704         type = extent_ref_type(parent, owner);
1705         size = btrfs_extent_inline_ref_size(type);
1706
1707         btrfs_extend_item(fs_info, path, size);
1708
1709         ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1710         refs = btrfs_extent_refs(leaf, ei);
1711         refs += refs_to_add;
1712         btrfs_set_extent_refs(leaf, ei, refs);
1713         if (extent_op)
1714                 __run_delayed_extent_op(extent_op, leaf, ei);
1715
1716         ptr = (unsigned long)ei + item_offset;
1717         end = (unsigned long)ei + btrfs_item_size_nr(leaf, path->slots[0]);
1718         if (ptr < end - size)
1719                 memmove_extent_buffer(leaf, ptr + size, ptr,
1720                                       end - size - ptr);
1721
1722         iref = (struct btrfs_extent_inline_ref *)ptr;
1723         btrfs_set_extent_inline_ref_type(leaf, iref, type);
1724         if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1725                 struct btrfs_extent_data_ref *dref;
1726                 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1727                 btrfs_set_extent_data_ref_root(leaf, dref, root_objectid);
1728                 btrfs_set_extent_data_ref_objectid(leaf, dref, owner);
1729                 btrfs_set_extent_data_ref_offset(leaf, dref, offset);
1730                 btrfs_set_extent_data_ref_count(leaf, dref, refs_to_add);
1731         } else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1732                 struct btrfs_shared_data_ref *sref;
1733                 sref = (struct btrfs_shared_data_ref *)(iref + 1);
1734                 btrfs_set_shared_data_ref_count(leaf, sref, refs_to_add);
1735                 btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
1736         } else if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
1737                 btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
1738         } else {
1739                 btrfs_set_extent_inline_ref_offset(leaf, iref, root_objectid);
1740         }
1741         btrfs_mark_buffer_dirty(leaf);
1742 }
1743
1744 static int lookup_extent_backref(struct btrfs_trans_handle *trans,
1745                                  struct btrfs_path *path,
1746                                  struct btrfs_extent_inline_ref **ref_ret,
1747                                  u64 bytenr, u64 num_bytes, u64 parent,
1748                                  u64 root_objectid, u64 owner, u64 offset)
1749 {
1750         int ret;
1751
1752         ret = lookup_inline_extent_backref(trans, path, ref_ret, bytenr,
1753                                            num_bytes, parent, root_objectid,
1754                                            owner, offset, 0);
1755         if (ret != -ENOENT)
1756                 return ret;
1757
1758         btrfs_release_path(path);
1759         *ref_ret = NULL;
1760
1761         if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1762                 ret = lookup_tree_block_ref(trans, path, bytenr, parent,
1763                                             root_objectid);
1764         } else {
1765                 ret = lookup_extent_data_ref(trans, path, bytenr, parent,
1766                                              root_objectid, owner, offset);
1767         }
1768         return ret;
1769 }
1770
1771 /*
1772  * helper to update/remove inline back ref
1773  */
1774 static noinline_for_stack
1775 void update_inline_extent_backref(struct btrfs_path *path,
1776                                   struct btrfs_extent_inline_ref *iref,
1777                                   int refs_to_mod,
1778                                   struct btrfs_delayed_extent_op *extent_op,
1779                                   int *last_ref)
1780 {
1781         struct extent_buffer *leaf = path->nodes[0];
1782         struct btrfs_fs_info *fs_info = leaf->fs_info;
1783         struct btrfs_extent_item *ei;
1784         struct btrfs_extent_data_ref *dref = NULL;
1785         struct btrfs_shared_data_ref *sref = NULL;
1786         unsigned long ptr;
1787         unsigned long end;
1788         u32 item_size;
1789         int size;
1790         int type;
1791         u64 refs;
1792
1793         ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1794         refs = btrfs_extent_refs(leaf, ei);
1795         WARN_ON(refs_to_mod < 0 && refs + refs_to_mod <= 0);
1796         refs += refs_to_mod;
1797         btrfs_set_extent_refs(leaf, ei, refs);
1798         if (extent_op)
1799                 __run_delayed_extent_op(extent_op, leaf, ei);
1800
1801         /*
1802          * If type is invalid, we should have bailed out after
1803          * lookup_inline_extent_backref().
1804          */
1805         type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_ANY);
1806         ASSERT(type != BTRFS_REF_TYPE_INVALID);
1807
1808         if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1809                 dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1810                 refs = btrfs_extent_data_ref_count(leaf, dref);
1811         } else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1812                 sref = (struct btrfs_shared_data_ref *)(iref + 1);
1813                 refs = btrfs_shared_data_ref_count(leaf, sref);
1814         } else {
1815                 refs = 1;
1816                 BUG_ON(refs_to_mod != -1);
1817         }
1818
1819         BUG_ON(refs_to_mod < 0 && refs < -refs_to_mod);
1820         refs += refs_to_mod;
1821
1822         if (refs > 0) {
1823                 if (type == BTRFS_EXTENT_DATA_REF_KEY)
1824                         btrfs_set_extent_data_ref_count(leaf, dref, refs);
1825                 else
1826                         btrfs_set_shared_data_ref_count(leaf, sref, refs);
1827         } else {
1828                 *last_ref = 1;
1829                 size =  btrfs_extent_inline_ref_size(type);
1830                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1831                 ptr = (unsigned long)iref;
1832                 end = (unsigned long)ei + item_size;
1833                 if (ptr + size < end)
1834                         memmove_extent_buffer(leaf, ptr, ptr + size,
1835                                               end - ptr - size);
1836                 item_size -= size;
1837                 btrfs_truncate_item(fs_info, path, item_size, 1);
1838         }
1839         btrfs_mark_buffer_dirty(leaf);
1840 }
1841
1842 static noinline_for_stack
1843 int insert_inline_extent_backref(struct btrfs_trans_handle *trans,
1844                                  struct btrfs_path *path,
1845                                  u64 bytenr, u64 num_bytes, u64 parent,
1846                                  u64 root_objectid, u64 owner,
1847                                  u64 offset, int refs_to_add,
1848                                  struct btrfs_delayed_extent_op *extent_op)
1849 {
1850         struct btrfs_extent_inline_ref *iref;
1851         int ret;
1852
1853         ret = lookup_inline_extent_backref(trans, path, &iref, bytenr,
1854                                            num_bytes, parent, root_objectid,
1855                                            owner, offset, 1);
1856         if (ret == 0) {
1857                 BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID);
1858                 update_inline_extent_backref(path, iref, refs_to_add,
1859                                              extent_op, NULL);
1860         } else if (ret == -ENOENT) {
1861                 setup_inline_extent_backref(trans->fs_info, path, iref, parent,
1862                                             root_objectid, owner, offset,
1863                                             refs_to_add, extent_op);
1864                 ret = 0;
1865         }
1866         return ret;
1867 }
1868
1869 static int insert_extent_backref(struct btrfs_trans_handle *trans,
1870                                  struct btrfs_path *path,
1871                                  u64 bytenr, u64 parent, u64 root_objectid,
1872                                  u64 owner, u64 offset, int refs_to_add)
1873 {
1874         int ret;
1875         if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1876                 BUG_ON(refs_to_add != 1);
1877                 ret = insert_tree_block_ref(trans, path, bytenr, parent,
1878                                             root_objectid);
1879         } else {
1880                 ret = insert_extent_data_ref(trans, path, bytenr, parent,
1881                                              root_objectid, owner, offset,
1882                                              refs_to_add);
1883         }
1884         return ret;
1885 }
1886
1887 static int remove_extent_backref(struct btrfs_trans_handle *trans,
1888                                  struct btrfs_path *path,
1889                                  struct btrfs_extent_inline_ref *iref,
1890                                  int refs_to_drop, int is_data, int *last_ref)
1891 {
1892         int ret = 0;
1893
1894         BUG_ON(!is_data && refs_to_drop != 1);
1895         if (iref) {
1896                 update_inline_extent_backref(path, iref, -refs_to_drop, NULL,
1897                                              last_ref);
1898         } else if (is_data) {
1899                 ret = remove_extent_data_ref(trans, path, refs_to_drop,
1900                                              last_ref);
1901         } else {
1902                 *last_ref = 1;
1903                 ret = btrfs_del_item(trans, trans->fs_info->extent_root, path);
1904         }
1905         return ret;
1906 }
1907
1908 #define in_range(b, first, len)        ((b) >= (first) && (b) < (first) + (len))
1909 static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len,
1910                                u64 *discarded_bytes)
1911 {
1912         int j, ret = 0;
1913         u64 bytes_left, end;
1914         u64 aligned_start = ALIGN(start, 1 << 9);
1915
1916         if (WARN_ON(start != aligned_start)) {
1917                 len -= aligned_start - start;
1918                 len = round_down(len, 1 << 9);
1919                 start = aligned_start;
1920         }
1921
1922         *discarded_bytes = 0;
1923
1924         if (!len)
1925                 return 0;
1926
1927         end = start + len;
1928         bytes_left = len;
1929
1930         /* Skip any superblocks on this device. */
1931         for (j = 0; j < BTRFS_SUPER_MIRROR_MAX; j++) {
1932                 u64 sb_start = btrfs_sb_offset(j);
1933                 u64 sb_end = sb_start + BTRFS_SUPER_INFO_SIZE;
1934                 u64 size = sb_start - start;
1935
1936                 if (!in_range(sb_start, start, bytes_left) &&
1937                     !in_range(sb_end, start, bytes_left) &&
1938                     !in_range(start, sb_start, BTRFS_SUPER_INFO_SIZE))
1939                         continue;
1940
1941                 /*
1942                  * Superblock spans beginning of range.  Adjust start and
1943                  * try again.
1944                  */
1945                 if (sb_start <= start) {
1946                         start += sb_end - start;
1947                         if (start > end) {
1948                                 bytes_left = 0;
1949                                 break;
1950                         }
1951                         bytes_left = end - start;
1952                         continue;
1953                 }
1954
1955                 if (size) {
1956                         ret = blkdev_issue_discard(bdev, start >> 9, size >> 9,
1957                                                    GFP_NOFS, 0);
1958                         if (!ret)
1959                                 *discarded_bytes += size;
1960                         else if (ret != -EOPNOTSUPP)
1961                                 return ret;
1962                 }
1963
1964                 start = sb_end;
1965                 if (start > end) {
1966                         bytes_left = 0;
1967                         break;
1968                 }
1969                 bytes_left = end - start;
1970         }
1971
1972         if (bytes_left) {
1973                 ret = blkdev_issue_discard(bdev, start >> 9, bytes_left >> 9,
1974                                            GFP_NOFS, 0);
1975                 if (!ret)
1976                         *discarded_bytes += bytes_left;
1977         }
1978         return ret;
1979 }
1980
1981 int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
1982                          u64 num_bytes, u64 *actual_bytes)
1983 {
1984         int ret;
1985         u64 discarded_bytes = 0;
1986         struct btrfs_bio *bbio = NULL;
1987
1988
1989         /*
1990          * Avoid races with device replace and make sure our bbio has devices
1991          * associated to its stripes that don't go away while we are discarding.
1992          */
1993         btrfs_bio_counter_inc_blocked(fs_info);
1994         /* Tell the block device(s) that the sectors can be discarded */
1995         ret = btrfs_map_block(fs_info, BTRFS_MAP_DISCARD, bytenr, &num_bytes,
1996                               &bbio, 0);
1997         /* Error condition is -ENOMEM */
1998         if (!ret) {
1999                 struct btrfs_bio_stripe *stripe = bbio->stripes;
2000                 int i;
2001
2002
2003                 for (i = 0; i < bbio->num_stripes; i++, stripe++) {
2004                         u64 bytes;
2005                         struct request_queue *req_q;
2006
2007                         if (!stripe->dev->bdev) {
2008                                 ASSERT(btrfs_test_opt(fs_info, DEGRADED));
2009                                 continue;
2010                         }
2011                         req_q = bdev_get_queue(stripe->dev->bdev);
2012                         if (!blk_queue_discard(req_q))
2013                                 continue;
2014
2015                         ret = btrfs_issue_discard(stripe->dev->bdev,
2016                                                   stripe->physical,
2017                                                   stripe->length,
2018                                                   &bytes);
2019                         if (!ret)
2020                                 discarded_bytes += bytes;
2021                         else if (ret != -EOPNOTSUPP)
2022                                 break; /* Logic errors or -ENOMEM, or -EIO but I don't know how that could happen JDM */
2023
2024                         /*
2025                          * Just in case we get back EOPNOTSUPP for some reason,
2026                          * just ignore the return value so we don't screw up
2027                          * people calling discard_extent.
2028                          */
2029                         ret = 0;
2030                 }
2031                 btrfs_put_bbio(bbio);
2032         }
2033         btrfs_bio_counter_dec(fs_info);
2034
2035         if (actual_bytes)
2036                 *actual_bytes = discarded_bytes;
2037
2038
2039         if (ret == -EOPNOTSUPP)
2040                 ret = 0;
2041         return ret;
2042 }
2043
2044 /* Can return -ENOMEM */
2045 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
2046                          struct btrfs_root *root,
2047                          u64 bytenr, u64 num_bytes, u64 parent,
2048                          u64 root_objectid, u64 owner, u64 offset)
2049 {
2050         struct btrfs_fs_info *fs_info = root->fs_info;
2051         int old_ref_mod, new_ref_mod;
2052         int ret;
2053
2054         BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID &&
2055                root_objectid == BTRFS_TREE_LOG_OBJECTID);
2056
2057         btrfs_ref_tree_mod(root, bytenr, num_bytes, parent, root_objectid,
2058                            owner, offset, BTRFS_ADD_DELAYED_REF);
2059
2060         if (owner < BTRFS_FIRST_FREE_OBJECTID) {
2061                 ret = btrfs_add_delayed_tree_ref(trans, bytenr,
2062                                                  num_bytes, parent,
2063                                                  root_objectid, (int)owner,
2064                                                  BTRFS_ADD_DELAYED_REF, NULL,
2065                                                  &old_ref_mod, &new_ref_mod);
2066         } else {
2067                 ret = btrfs_add_delayed_data_ref(trans, bytenr,
2068                                                  num_bytes, parent,
2069                                                  root_objectid, owner, offset,
2070                                                  0, BTRFS_ADD_DELAYED_REF,
2071                                                  &old_ref_mod, &new_ref_mod);
2072         }
2073
2074         if (ret == 0 && old_ref_mod < 0 && new_ref_mod >= 0) {
2075                 bool metadata = owner < BTRFS_FIRST_FREE_OBJECTID;
2076
2077                 add_pinned_bytes(fs_info, -num_bytes, metadata, root_objectid);
2078         }
2079
2080         return ret;
2081 }
2082
2083 /*
2084  * __btrfs_inc_extent_ref - insert backreference for a given extent
2085  *
2086  * @trans:          Handle of transaction
2087  *
2088  * @node:           The delayed ref node used to get the bytenr/length for
2089  *                  extent whose references are incremented.
2090  *
2091  * @parent:         If this is a shared extent (BTRFS_SHARED_DATA_REF_KEY/
2092  *                  BTRFS_SHARED_BLOCK_REF_KEY) then it holds the logical
2093  *                  bytenr of the parent block. Since new extents are always
2094  *                  created with indirect references, this will only be the case
2095  *                  when relocating a shared extent. In that case, root_objectid
2096  *                  will be BTRFS_TREE_RELOC_OBJECTID. Otheriwse, parent must
2097  *                  be 0
2098  *
2099  * @root_objectid:  The id of the root where this modification has originated,
2100  *                  this can be either one of the well-known metadata trees or
2101  *                  the subvolume id which references this extent.
2102  *
2103  * @owner:          For data extents it is the inode number of the owning file.
2104  *                  For metadata extents this parameter holds the level in the
2105  *                  tree of the extent.
2106  *
2107  * @offset:         For metadata extents the offset is ignored and is currently
2108  *                  always passed as 0. For data extents it is the fileoffset
2109  *                  this extent belongs to.
2110  *
2111  * @refs_to_add     Number of references to add
2112  *
2113  * @extent_op       Pointer to a structure, holding information necessary when
2114  *                  updating a tree block's flags
2115  *
2116  */
2117 static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
2118                                   struct btrfs_delayed_ref_node *node,
2119                                   u64 parent, u64 root_objectid,
2120                                   u64 owner, u64 offset, int refs_to_add,
2121                                   struct btrfs_delayed_extent_op *extent_op)
2122 {
2123         struct btrfs_path *path;
2124         struct extent_buffer *leaf;
2125         struct btrfs_extent_item *item;
2126         struct btrfs_key key;
2127         u64 bytenr = node->bytenr;
2128         u64 num_bytes = node->num_bytes;
2129         u64 refs;
2130         int ret;
2131
2132         path = btrfs_alloc_path();
2133         if (!path)
2134                 return -ENOMEM;
2135
2136         path->reada = READA_FORWARD;
2137         path->leave_spinning = 1;
2138         /* this will setup the path even if it fails to insert the back ref */
2139         ret = insert_inline_extent_backref(trans, path, bytenr, num_bytes,
2140                                            parent, root_objectid, owner,
2141                                            offset, refs_to_add, extent_op);
2142         if ((ret < 0 && ret != -EAGAIN) || !ret)
2143                 goto out;
2144
2145         /*
2146          * Ok we had -EAGAIN which means we didn't have space to insert and
2147          * inline extent ref, so just update the reference count and add a
2148          * normal backref.
2149          */
2150         leaf = path->nodes[0];
2151         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2152         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
2153         refs = btrfs_extent_refs(leaf, item);
2154         btrfs_set_extent_refs(leaf, item, refs + refs_to_add);
2155         if (extent_op)
2156                 __run_delayed_extent_op(extent_op, leaf, item);
2157
2158         btrfs_mark_buffer_dirty(leaf);
2159         btrfs_release_path(path);
2160
2161         path->reada = READA_FORWARD;
2162         path->leave_spinning = 1;
2163         /* now insert the actual backref */
2164         ret = insert_extent_backref(trans, path, bytenr, parent, root_objectid,
2165                                     owner, offset, refs_to_add);
2166         if (ret)
2167                 btrfs_abort_transaction(trans, ret);
2168 out:
2169         btrfs_free_path(path);
2170         return ret;
2171 }
2172
2173 static int run_delayed_data_ref(struct btrfs_trans_handle *trans,
2174                                 struct btrfs_delayed_ref_node *node,
2175                                 struct btrfs_delayed_extent_op *extent_op,
2176                                 int insert_reserved)
2177 {
2178         int ret = 0;
2179         struct btrfs_delayed_data_ref *ref;
2180         struct btrfs_key ins;
2181         u64 parent = 0;
2182         u64 ref_root = 0;
2183         u64 flags = 0;
2184
2185         ins.objectid = node->bytenr;
2186         ins.offset = node->num_bytes;
2187         ins.type = BTRFS_EXTENT_ITEM_KEY;
2188
2189         ref = btrfs_delayed_node_to_data_ref(node);
2190         trace_run_delayed_data_ref(trans->fs_info, node, ref, node->action);
2191
2192         if (node->type == BTRFS_SHARED_DATA_REF_KEY)
2193                 parent = ref->parent;
2194         ref_root = ref->root;
2195
2196         if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
2197                 if (extent_op)
2198                         flags |= extent_op->flags_to_set;
2199                 ret = alloc_reserved_file_extent(trans, parent, ref_root,
2200                                                  flags, ref->objectid,
2201                                                  ref->offset, &ins,
2202                                                  node->ref_mod);
2203         } else if (node->action == BTRFS_ADD_DELAYED_REF) {
2204                 ret = __btrfs_inc_extent_ref(trans, node, parent, ref_root,
2205                                              ref->objectid, ref->offset,
2206                                              node->ref_mod, extent_op);
2207         } else if (node->action == BTRFS_DROP_DELAYED_REF) {
2208                 ret = __btrfs_free_extent(trans, node, parent,
2209                                           ref_root, ref->objectid,
2210                                           ref->offset, node->ref_mod,
2211                                           extent_op);
2212         } else {
2213                 BUG();
2214         }
2215         return ret;
2216 }
2217
2218 static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
2219                                     struct extent_buffer *leaf,
2220                                     struct btrfs_extent_item *ei)
2221 {
2222         u64 flags = btrfs_extent_flags(leaf, ei);
2223         if (extent_op->update_flags) {
2224                 flags |= extent_op->flags_to_set;
2225                 btrfs_set_extent_flags(leaf, ei, flags);
2226         }
2227
2228         if (extent_op->update_key) {
2229                 struct btrfs_tree_block_info *bi;
2230                 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK));
2231                 bi = (struct btrfs_tree_block_info *)(ei + 1);
2232                 btrfs_set_tree_block_key(leaf, bi, &extent_op->key);
2233         }
2234 }
2235
2236 static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
2237                                  struct btrfs_delayed_ref_head *head,
2238                                  struct btrfs_delayed_extent_op *extent_op)
2239 {
2240         struct btrfs_fs_info *fs_info = trans->fs_info;
2241         struct btrfs_key key;
2242         struct btrfs_path *path;
2243         struct btrfs_extent_item *ei;
2244         struct extent_buffer *leaf;
2245         u32 item_size;
2246         int ret;
2247         int err = 0;
2248         int metadata = !extent_op->is_data;
2249
2250         if (trans->aborted)
2251                 return 0;
2252
2253         if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2254                 metadata = 0;
2255
2256         path = btrfs_alloc_path();
2257         if (!path)
2258                 return -ENOMEM;
2259
2260         key.objectid = head->bytenr;
2261
2262         if (metadata) {
2263                 key.type = BTRFS_METADATA_ITEM_KEY;
2264                 key.offset = extent_op->level;
2265         } else {
2266                 key.type = BTRFS_EXTENT_ITEM_KEY;
2267                 key.offset = head->num_bytes;
2268         }
2269
2270 again:
2271         path->reada = READA_FORWARD;
2272         path->leave_spinning = 1;
2273         ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 1);
2274         if (ret < 0) {
2275                 err = ret;
2276                 goto out;
2277         }
2278         if (ret > 0) {
2279                 if (metadata) {
2280                         if (path->slots[0] > 0) {
2281                                 path->slots[0]--;
2282                                 btrfs_item_key_to_cpu(path->nodes[0], &key,
2283                                                       path->slots[0]);
2284                                 if (key.objectid == head->bytenr &&
2285                                     key.type == BTRFS_EXTENT_ITEM_KEY &&
2286                                     key.offset == head->num_bytes)
2287                                         ret = 0;
2288                         }
2289                         if (ret > 0) {
2290                                 btrfs_release_path(path);
2291                                 metadata = 0;
2292
2293                                 key.objectid = head->bytenr;
2294                                 key.offset = head->num_bytes;
2295                                 key.type = BTRFS_EXTENT_ITEM_KEY;
2296                                 goto again;
2297                         }
2298                 } else {
2299                         err = -EIO;
2300                         goto out;
2301                 }
2302         }
2303
2304         leaf = path->nodes[0];
2305         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
2306
2307         if (unlikely(item_size < sizeof(*ei))) {
2308                 err = -EINVAL;
2309                 btrfs_print_v0_err(fs_info);
2310                 btrfs_abort_transaction(trans, err);
2311                 goto out;
2312         }
2313
2314         ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
2315         __run_delayed_extent_op(extent_op, leaf, ei);
2316
2317         btrfs_mark_buffer_dirty(leaf);
2318 out:
2319         btrfs_free_path(path);
2320         return err;
2321 }
2322
2323 static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
2324                                 struct btrfs_delayed_ref_node *node,
2325                                 struct btrfs_delayed_extent_op *extent_op,
2326                                 int insert_reserved)
2327 {
2328         int ret = 0;
2329         struct btrfs_delayed_tree_ref *ref;
2330         u64 parent = 0;
2331         u64 ref_root = 0;
2332
2333         ref = btrfs_delayed_node_to_tree_ref(node);
2334         trace_run_delayed_tree_ref(trans->fs_info, node, ref, node->action);
2335
2336         if (node->type == BTRFS_SHARED_BLOCK_REF_KEY)
2337                 parent = ref->parent;
2338         ref_root = ref->root;
2339
2340         if (node->ref_mod != 1) {
2341                 btrfs_err(trans->fs_info,
2342         "btree block(%llu) has %d references rather than 1: action %d ref_root %llu parent %llu",
2343                           node->bytenr, node->ref_mod, node->action, ref_root,
2344                           parent);
2345                 return -EIO;
2346         }
2347         if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
2348                 BUG_ON(!extent_op || !extent_op->update_flags);
2349                 ret = alloc_reserved_tree_block(trans, node, extent_op);
2350         } else if (node->action == BTRFS_ADD_DELAYED_REF) {
2351                 ret = __btrfs_inc_extent_ref(trans, node, parent, ref_root,
2352                                              ref->level, 0, 1, extent_op);
2353         } else if (node->action == BTRFS_DROP_DELAYED_REF) {
2354                 ret = __btrfs_free_extent(trans, node, parent, ref_root,
2355                                           ref->level, 0, 1, extent_op);
2356         } else {
2357                 BUG();
2358         }
2359         return ret;
2360 }
2361
2362 /* helper function to actually process a single delayed ref entry */
2363 static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
2364                                struct btrfs_delayed_ref_node *node,
2365                                struct btrfs_delayed_extent_op *extent_op,
2366                                int insert_reserved)
2367 {
2368         int ret = 0;
2369
2370         if (trans->aborted) {
2371                 if (insert_reserved)
2372                         btrfs_pin_extent(trans->fs_info, node->bytenr,
2373                                          node->num_bytes, 1);
2374                 return 0;
2375         }
2376
2377         if (node->type == BTRFS_TREE_BLOCK_REF_KEY ||
2378             node->type == BTRFS_SHARED_BLOCK_REF_KEY)
2379                 ret = run_delayed_tree_ref(trans, node, extent_op,
2380                                            insert_reserved);
2381         else if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
2382                  node->type == BTRFS_SHARED_DATA_REF_KEY)
2383                 ret = run_delayed_data_ref(trans, node, extent_op,
2384                                            insert_reserved);
2385         else
2386                 BUG();
2387         if (ret && insert_reserved)
2388                 btrfs_pin_extent(trans->fs_info, node->bytenr,
2389                                  node->num_bytes, 1);
2390         return ret;
2391 }
2392
2393 static inline struct btrfs_delayed_ref_node *
2394 select_delayed_ref(struct btrfs_delayed_ref_head *head)
2395 {
2396         struct btrfs_delayed_ref_node *ref;
2397
2398         if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
2399                 return NULL;
2400
2401         /*
2402          * Select a delayed ref of type BTRFS_ADD_DELAYED_REF first.
2403          * This is to prevent a ref count from going down to zero, which deletes
2404          * the extent item from the extent tree, when there still are references
2405          * to add, which would fail because they would not find the extent item.
2406          */
2407         if (!list_empty(&head->ref_add_list))
2408                 return list_first_entry(&head->ref_add_list,
2409                                 struct btrfs_delayed_ref_node, add_list);
2410
2411         ref = rb_entry(rb_first_cached(&head->ref_tree),
2412                        struct btrfs_delayed_ref_node, ref_node);
2413         ASSERT(list_empty(&ref->add_list));
2414         return ref;
2415 }
2416
2417 static void unselect_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
2418                                       struct btrfs_delayed_ref_head *head)
2419 {
2420         spin_lock(&delayed_refs->lock);
2421         head->processing = 0;
2422         delayed_refs->num_heads_ready++;
2423         spin_unlock(&delayed_refs->lock);
2424         btrfs_delayed_ref_unlock(head);
2425 }
2426
2427 static struct btrfs_delayed_extent_op *cleanup_extent_op(
2428                                 struct btrfs_delayed_ref_head *head)
2429 {
2430         struct btrfs_delayed_extent_op *extent_op = head->extent_op;
2431
2432         if (!extent_op)
2433                 return NULL;
2434
2435         if (head->must_insert_reserved) {
2436                 head->extent_op = NULL;
2437                 btrfs_free_delayed_extent_op(extent_op);
2438                 return NULL;
2439         }
2440         return extent_op;
2441 }
2442
2443 static int run_and_cleanup_extent_op(struct btrfs_trans_handle *trans,
2444                                      struct btrfs_delayed_ref_head *head)
2445 {
2446         struct btrfs_delayed_extent_op *extent_op;
2447         int ret;
2448
2449         extent_op = cleanup_extent_op(head);
2450         if (!extent_op)
2451                 return 0;
2452         head->extent_op = NULL;
2453         spin_unlock(&head->lock);
2454         ret = run_delayed_extent_op(trans, head, extent_op);
2455         btrfs_free_delayed_extent_op(extent_op);
2456         return ret ? ret : 1;
2457 }
2458
2459 static void cleanup_ref_head_accounting(struct btrfs_trans_handle *trans,
2460                                         struct btrfs_delayed_ref_head *head)
2461 {
2462         struct btrfs_fs_info *fs_info = trans->fs_info;
2463         struct btrfs_delayed_ref_root *delayed_refs =
2464                 &trans->transaction->delayed_refs;
2465         int nr_items = 1;       /* Dropping this ref head update. */
2466
2467         if (head->total_ref_mod < 0) {
2468                 struct btrfs_space_info *space_info;
2469                 u64 flags;
2470
2471                 if (head->is_data)
2472                         flags = BTRFS_BLOCK_GROUP_DATA;
2473                 else if (head->is_system)
2474                         flags = BTRFS_BLOCK_GROUP_SYSTEM;
2475                 else
2476                         flags = BTRFS_BLOCK_GROUP_METADATA;
2477                 space_info = __find_space_info(fs_info, flags);
2478                 ASSERT(space_info);
2479                 percpu_counter_add_batch(&space_info->total_bytes_pinned,
2480                                    -head->num_bytes,
2481                                    BTRFS_TOTAL_BYTES_PINNED_BATCH);
2482
2483                 /*
2484                  * We had csum deletions accounted for in our delayed refs rsv,
2485                  * we need to drop the csum leaves for this update from our
2486                  * delayed_refs_rsv.
2487                  */
2488                 if (head->is_data) {
2489                         spin_lock(&delayed_refs->lock);
2490                         delayed_refs->pending_csums -= head->num_bytes;
2491                         spin_unlock(&delayed_refs->lock);
2492                         nr_items += btrfs_csum_bytes_to_leaves(fs_info,
2493                                 head->num_bytes);
2494                 }
2495         }
2496
2497         /* Also free its reserved qgroup space */
2498         btrfs_qgroup_free_delayed_ref(fs_info, head->qgroup_ref_root,
2499                                       head->qgroup_reserved);
2500         btrfs_delayed_refs_rsv_release(fs_info, nr_items);
2501 }
2502
2503 static int cleanup_ref_head(struct btrfs_trans_handle *trans,
2504                             struct btrfs_delayed_ref_head *head)
2505 {
2506
2507         struct btrfs_fs_info *fs_info = trans->fs_info;
2508         struct btrfs_delayed_ref_root *delayed_refs;
2509         int ret;
2510
2511         delayed_refs = &trans->transaction->delayed_refs;
2512
2513         ret = run_and_cleanup_extent_op(trans, head);
2514         if (ret < 0) {
2515                 unselect_delayed_ref_head(delayed_refs, head);
2516                 btrfs_debug(fs_info, "run_delayed_extent_op returned %d", ret);
2517                 return ret;
2518         } else if (ret) {
2519                 return ret;
2520         }
2521
2522         /*
2523          * Need to drop our head ref lock and re-acquire the delayed ref lock
2524          * and then re-check to make sure nobody got added.
2525          */
2526         spin_unlock(&head->lock);
2527         spin_lock(&delayed_refs->lock);
2528         spin_lock(&head->lock);
2529         if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root) || head->extent_op) {
2530                 spin_unlock(&head->lock);
2531                 spin_unlock(&delayed_refs->lock);
2532                 return 1;
2533         }
2534         btrfs_delete_ref_head(delayed_refs, head);
2535         spin_unlock(&head->lock);
2536         spin_unlock(&delayed_refs->lock);
2537
2538         if (head->must_insert_reserved) {
2539                 btrfs_pin_extent(fs_info, head->bytenr,
2540                                  head->num_bytes, 1);
2541                 if (head->is_data) {
2542                         ret = btrfs_del_csums(trans, fs_info, head->bytenr,
2543                                               head->num_bytes);
2544                 }
2545         }
2546
2547         cleanup_ref_head_accounting(trans, head);
2548
2549         trace_run_delayed_ref_head(fs_info, head, 0);
2550         btrfs_delayed_ref_unlock(head);
2551         btrfs_put_delayed_ref_head(head);
2552         return 0;
2553 }
2554
2555 static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(
2556                                         struct btrfs_trans_handle *trans)
2557 {
2558         struct btrfs_delayed_ref_root *delayed_refs =
2559                 &trans->transaction->delayed_refs;
2560         struct btrfs_delayed_ref_head *head = NULL;
2561         int ret;
2562
2563         spin_lock(&delayed_refs->lock);
2564         head = btrfs_select_ref_head(delayed_refs);
2565         if (!head) {
2566                 spin_unlock(&delayed_refs->lock);
2567                 return head;
2568         }
2569
2570         /*
2571          * Grab the lock that says we are going to process all the refs for
2572          * this head
2573          */
2574         ret = btrfs_delayed_ref_lock(delayed_refs, head);
2575         spin_unlock(&delayed_refs->lock);
2576
2577         /*
2578          * We may have dropped the spin lock to get the head mutex lock, and
2579          * that might have given someone else time to free the head.  If that's
2580          * true, it has been removed from our list and we can move on.
2581          */
2582         if (ret == -EAGAIN)
2583                 head = ERR_PTR(-EAGAIN);
2584
2585         return head;
2586 }
2587
2588 static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,
2589                                     struct btrfs_delayed_ref_head *locked_ref,
2590                                     unsigned long *run_refs)
2591 {
2592         struct btrfs_fs_info *fs_info = trans->fs_info;
2593         struct btrfs_delayed_ref_root *delayed_refs;
2594         struct btrfs_delayed_extent_op *extent_op;
2595         struct btrfs_delayed_ref_node *ref;
2596         int must_insert_reserved = 0;
2597         int ret;
2598
2599         delayed_refs = &trans->transaction->delayed_refs;
2600
2601         lockdep_assert_held(&locked_ref->mutex);
2602         lockdep_assert_held(&locked_ref->lock);
2603
2604         while ((ref = select_delayed_ref(locked_ref))) {
2605                 if (ref->seq &&
2606                     btrfs_check_delayed_seq(fs_info, ref->seq)) {
2607                         spin_unlock(&locked_ref->lock);
2608                         unselect_delayed_ref_head(delayed_refs, locked_ref);
2609                         return -EAGAIN;
2610                 }
2611
2612                 (*run_refs)++;
2613                 ref->in_tree = 0;
2614                 rb_erase_cached(&ref->ref_node, &locked_ref->ref_tree);
2615                 RB_CLEAR_NODE(&ref->ref_node);
2616                 if (!list_empty(&ref->add_list))
2617                         list_del(&ref->add_list);
2618                 /*
2619                  * When we play the delayed ref, also correct the ref_mod on
2620                  * head
2621                  */
2622                 switch (ref->action) {
2623                 case BTRFS_ADD_DELAYED_REF:
2624                 case BTRFS_ADD_DELAYED_EXTENT:
2625                         locked_ref->ref_mod -= ref->ref_mod;
2626                         break;
2627                 case BTRFS_DROP_DELAYED_REF:
2628                         locked_ref->ref_mod += ref->ref_mod;
2629                         break;
2630                 default:
2631                         WARN_ON(1);
2632                 }
2633                 atomic_dec(&delayed_refs->num_entries);
2634
2635                 /*
2636                  * Record the must_insert_reserved flag before we drop the
2637                  * spin lock.
2638                  */
2639                 must_insert_reserved = locked_ref->must_insert_reserved;
2640                 locked_ref->must_insert_reserved = 0;
2641
2642                 extent_op = locked_ref->extent_op;
2643                 locked_ref->extent_op = NULL;
2644                 spin_unlock(&locked_ref->lock);
2645
2646                 ret = run_one_delayed_ref(trans, ref, extent_op,
2647                                           must_insert_reserved);
2648
2649                 btrfs_free_delayed_extent_op(extent_op);
2650                 if (ret) {
2651                         unselect_delayed_ref_head(delayed_refs, locked_ref);
2652                         btrfs_put_delayed_ref(ref);
2653                         btrfs_debug(fs_info, "run_one_delayed_ref returned %d",
2654                                     ret);
2655                         return ret;
2656                 }
2657
2658                 btrfs_put_delayed_ref(ref);
2659                 cond_resched();
2660
2661                 spin_lock(&locked_ref->lock);
2662                 btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);
2663         }
2664
2665         return 0;
2666 }
2667
2668 /*
2669  * Returns 0 on success or if called with an already aborted transaction.
2670  * Returns -ENOMEM or -EIO on failure and will abort the transaction.
2671  */
2672 static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
2673                                              unsigned long nr)
2674 {
2675         struct btrfs_fs_info *fs_info = trans->fs_info;
2676         struct btrfs_delayed_ref_root *delayed_refs;
2677         struct btrfs_delayed_ref_head *locked_ref = NULL;
2678         ktime_t start = ktime_get();
2679         int ret;
2680         unsigned long count = 0;
2681         unsigned long actual_count = 0;
2682
2683         delayed_refs = &trans->transaction->delayed_refs;
2684         do {
2685                 if (!locked_ref) {
2686                         locked_ref = btrfs_obtain_ref_head(trans);
2687                         if (IS_ERR_OR_NULL(locked_ref)) {
2688                                 if (PTR_ERR(locked_ref) == -EAGAIN) {
2689                                         continue;
2690                                 } else {
2691                                         break;
2692                                 }
2693                         }
2694                         count++;
2695                 }
2696                 /*
2697                  * We need to try and merge add/drops of the same ref since we
2698                  * can run into issues with relocate dropping the implicit ref
2699                  * and then it being added back again before the drop can
2700                  * finish.  If we merged anything we need to re-loop so we can
2701                  * get a good ref.
2702                  * Or we can get node references of the same type that weren't
2703                  * merged when created due to bumps in the tree mod seq, and
2704                  * we need to merge them to prevent adding an inline extent
2705                  * backref before dropping it (triggering a BUG_ON at
2706                  * insert_inline_extent_backref()).
2707                  */
2708                 spin_lock(&locked_ref->lock);
2709                 btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);
2710
2711                 ret = btrfs_run_delayed_refs_for_head(trans, locked_ref,
2712                                                       &actual_count);
2713                 if (ret < 0 && ret != -EAGAIN) {
2714                         /*
2715                          * Error, btrfs_run_delayed_refs_for_head already
2716                          * unlocked everything so just bail out
2717                          */
2718                         return ret;
2719                 } else if (!ret) {
2720                         /*
2721                          * Success, perform the usual cleanup of a processed
2722                          * head
2723                          */
2724                         ret = cleanup_ref_head(trans, locked_ref);
2725                         if (ret > 0 ) {
2726                                 /* We dropped our lock, we need to loop. */
2727                                 ret = 0;
2728                                 continue;
2729                         } else if (ret) {
2730                                 return ret;
2731                         }
2732                 }
2733
2734                 /*
2735                  * Either success case or btrfs_run_delayed_refs_for_head
2736                  * returned -EAGAIN, meaning we need to select another head
2737                  */
2738
2739                 locked_ref = NULL;
2740                 cond_resched();
2741         } while ((nr != -1 && count < nr) || locked_ref);
2742
2743         /*
2744          * We don't want to include ref heads since we can have empty ref heads
2745          * and those will drastically skew our runtime down since we just do
2746          * accounting, no actual extent tree updates.
2747          */
2748         if (actual_count > 0) {
2749                 u64 runtime = ktime_to_ns(ktime_sub(ktime_get(), start));
2750                 u64 avg;
2751
2752                 /*
2753                  * We weigh the current average higher than our current runtime
2754                  * to avoid large swings in the average.
2755                  */
2756                 spin_lock(&delayed_refs->lock);
2757                 avg = fs_info->avg_delayed_ref_runtime * 3 + runtime;
2758                 fs_info->avg_delayed_ref_runtime = avg >> 2;    /* div by 4 */
2759                 spin_unlock(&delayed_refs->lock);
2760         }
2761         return 0;
2762 }
2763
2764 #ifdef SCRAMBLE_DELAYED_REFS
2765 /*
2766  * Normally delayed refs get processed in ascending bytenr order. This
2767  * correlates in most cases to the order added. To expose dependencies on this
2768  * order, we start to process the tree in the middle instead of the beginning
2769  */
2770 static u64 find_middle(struct rb_root *root)
2771 {
2772         struct rb_node *n = root->rb_node;
2773         struct btrfs_delayed_ref_node *entry;
2774         int alt = 1;
2775         u64 middle;
2776         u64 first = 0, last = 0;
2777
2778         n = rb_first(root);
2779         if (n) {
2780                 entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2781                 first = entry->bytenr;
2782         }
2783         n = rb_last(root);
2784         if (n) {
2785                 entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2786                 last = entry->bytenr;
2787         }
2788         n = root->rb_node;
2789
2790         while (n) {
2791                 entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2792                 WARN_ON(!entry->in_tree);
2793
2794                 middle = entry->bytenr;
2795
2796                 if (alt)
2797                         n = n->rb_left;
2798                 else
2799                         n = n->rb_right;
2800
2801                 alt = 1 - alt;
2802         }
2803         return middle;
2804 }
2805 #endif
2806
2807 static inline u64 heads_to_leaves(struct btrfs_fs_info *fs_info, u64 heads)
2808 {
2809         u64 num_bytes;
2810
2811         num_bytes = heads * (sizeof(struct btrfs_extent_item) +
2812                              sizeof(struct btrfs_extent_inline_ref));
2813         if (!btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2814                 num_bytes += heads * sizeof(struct btrfs_tree_block_info);
2815
2816         /*
2817          * We don't ever fill up leaves all the way so multiply by 2 just to be
2818          * closer to what we're really going to want to use.
2819          */
2820         return div_u64(num_bytes, BTRFS_LEAF_DATA_SIZE(fs_info));
2821 }
2822
2823 /*
2824  * Takes the number of bytes to be csumm'ed and figures out how many leaves it
2825  * would require to store the csums for that many bytes.
2826  */
2827 u64 btrfs_csum_bytes_to_leaves(struct btrfs_fs_info *fs_info, u64 csum_bytes)
2828 {
2829         u64 csum_size;
2830         u64 num_csums_per_leaf;
2831         u64 num_csums;
2832
2833         csum_size = BTRFS_MAX_ITEM_SIZE(fs_info);
2834         num_csums_per_leaf = div64_u64(csum_size,
2835                         (u64)btrfs_super_csum_size(fs_info->super_copy));
2836         num_csums = div64_u64(csum_bytes, fs_info->sectorsize);
2837         num_csums += num_csums_per_leaf - 1;
2838         num_csums = div64_u64(num_csums, num_csums_per_leaf);
2839         return num_csums;
2840 }
2841
2842 bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info)
2843 {
2844         struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
2845         struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
2846         bool ret = false;
2847         u64 reserved;
2848
2849         spin_lock(&global_rsv->lock);
2850         reserved = global_rsv->reserved;
2851         spin_unlock(&global_rsv->lock);
2852
2853         /*
2854          * Since the global reserve is just kind of magic we don't really want
2855          * to rely on it to save our bacon, so if our size is more than the
2856          * delayed_refs_rsv and the global rsv then it's time to think about
2857          * bailing.
2858          */
2859         spin_lock(&delayed_refs_rsv->lock);
2860         reserved += delayed_refs_rsv->reserved;
2861         if (delayed_refs_rsv->size >= reserved)
2862                 ret = true;
2863         spin_unlock(&delayed_refs_rsv->lock);
2864         return ret;
2865 }
2866
2867 int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans)
2868 {
2869         u64 num_entries =
2870                 atomic_read(&trans->transaction->delayed_refs.num_entries);
2871         u64 avg_runtime;
2872         u64 val;
2873
2874         smp_mb();
2875         avg_runtime = trans->fs_info->avg_delayed_ref_runtime;
2876         val = num_entries * avg_runtime;
2877         if (val >= NSEC_PER_SEC)
2878                 return 1;
2879         if (val >= NSEC_PER_SEC / 2)
2880                 return 2;
2881
2882         return btrfs_check_space_for_delayed_refs(trans->fs_info);
2883 }
2884
2885 struct async_delayed_refs {
2886         struct btrfs_root *root;
2887         u64 transid;
2888         int count;
2889         int error;
2890         int sync;
2891         struct completion wait;
2892         struct btrfs_work work;
2893 };
2894
2895 static inline struct async_delayed_refs *
2896 to_async_delayed_refs(struct btrfs_work *work)
2897 {
2898         return container_of(work, struct async_delayed_refs, work);
2899 }
2900
2901 static void delayed_ref_async_start(struct btrfs_work *work)
2902 {
2903         struct async_delayed_refs *async = to_async_delayed_refs(work);
2904         struct btrfs_trans_handle *trans;
2905         struct btrfs_fs_info *fs_info = async->root->fs_info;
2906         int ret;
2907
2908         /* if the commit is already started, we don't need to wait here */
2909         if (btrfs_transaction_blocked(fs_info))
2910                 goto done;
2911
2912         trans = btrfs_join_transaction(async->root);
2913         if (IS_ERR(trans)) {
2914                 async->error = PTR_ERR(trans);
2915                 goto done;
2916         }
2917
2918         /*
2919          * trans->sync means that when we call end_transaction, we won't
2920          * wait on delayed refs
2921          */
2922         trans->sync = true;
2923
2924         /* Don't bother flushing if we got into a different transaction */
2925         if (trans->transid > async->transid)
2926                 goto end;
2927
2928         ret = btrfs_run_delayed_refs(trans, async->count);
2929         if (ret)
2930                 async->error = ret;
2931 end:
2932         ret = btrfs_end_transaction(trans);
2933         if (ret && !async->error)
2934                 async->error = ret;
2935 done:
2936         if (async->sync)
2937                 complete(&async->wait);
2938         else
2939                 kfree(async);
2940 }
2941
2942 int btrfs_async_run_delayed_refs(struct btrfs_fs_info *fs_info,
2943                                  unsigned long count, u64 transid, int wait)
2944 {
2945         struct async_delayed_refs *async;
2946         int ret;
2947
2948         async = kmalloc(sizeof(*async), GFP_NOFS);
2949         if (!async)
2950                 return -ENOMEM;
2951
2952         async->root = fs_info->tree_root;
2953         async->count = count;
2954         async->error = 0;
2955         async->transid = transid;
2956         if (wait)
2957                 async->sync = 1;
2958         else
2959                 async->sync = 0;
2960         init_completion(&async->wait);
2961
2962         btrfs_init_work(&async->work, btrfs_extent_refs_helper,
2963                         delayed_ref_async_start, NULL, NULL);
2964
2965         btrfs_queue_work(fs_info->extent_workers, &async->work);
2966
2967         if (wait) {
2968                 wait_for_completion(&async->wait);
2969                 ret = async->error;
2970                 kfree(async);
2971                 return ret;
2972         }
2973         return 0;
2974 }
2975
2976 /*
2977  * this starts processing the delayed reference count updates and
2978  * extent insertions we have queued up so far.  count can be
2979  * 0, which means to process everything in the tree at the start
2980  * of the run (but not newly added entries), or it can be some target
2981  * number you'd like to process.
2982  *
2983  * Returns 0 on success or if called with an aborted transaction
2984  * Returns <0 on error and aborts the transaction
2985  */
2986 int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
2987                            unsigned long count)
2988 {
2989         struct btrfs_fs_info *fs_info = trans->fs_info;
2990         struct rb_node *node;
2991         struct btrfs_delayed_ref_root *delayed_refs;
2992         struct btrfs_delayed_ref_head *head;
2993         int ret;
2994         int run_all = count == (unsigned long)-1;
2995
2996         /* We'll clean this up in btrfs_cleanup_transaction */
2997         if (trans->aborted)
2998                 return 0;
2999
3000         if (test_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags))
3001                 return 0;
3002
3003         delayed_refs = &trans->transaction->delayed_refs;
3004         if (count == 0)
3005                 count = atomic_read(&delayed_refs->num_entries) * 2;
3006
3007 again:
3008 #ifdef SCRAMBLE_DELAYED_REFS
3009         delayed_refs->run_delayed_start = find_middle(&delayed_refs->root);
3010 #endif
3011         ret = __btrfs_run_delayed_refs(trans, count);
3012         if (ret < 0) {
3013                 btrfs_abort_transaction(trans, ret);
3014                 return ret;
3015         }
3016
3017         if (run_all) {
3018                 if (!list_empty(&trans->new_bgs))
3019                         btrfs_create_pending_block_groups(trans);
3020
3021                 spin_lock(&delayed_refs->lock);
3022                 node = rb_first_cached(&delayed_refs->href_root);
3023                 if (!node) {
3024                         spin_unlock(&delayed_refs->lock);
3025                         goto out;
3026                 }
3027                 head = rb_entry(node, struct btrfs_delayed_ref_head,
3028                                 href_node);
3029                 refcount_inc(&head->refs);
3030                 spin_unlock(&delayed_refs->lock);
3031
3032                 /* Mutex was contended, block until it's released and retry. */
3033                 mutex_lock(&head->mutex);
3034                 mutex_unlock(&head->mutex);
3035
3036                 btrfs_put_delayed_ref_head(head);
3037                 cond_resched();
3038                 goto again;
3039         }
3040 out:
3041         return 0;
3042 }
3043
3044 int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
3045                                 struct btrfs_fs_info *fs_info,
3046                                 u64 bytenr, u64 num_bytes, u64 flags,
3047                                 int level, int is_data)
3048 {
3049         struct btrfs_delayed_extent_op *extent_op;
3050         int ret;
3051
3052         extent_op = btrfs_alloc_delayed_extent_op();
3053         if (!extent_op)
3054                 return -ENOMEM;
3055
3056         extent_op->flags_to_set = flags;
3057         extent_op->update_flags = true;
3058         extent_op->update_key = false;
3059         extent_op->is_data = is_data ? true : false;
3060         extent_op->level = level;
3061
3062         ret = btrfs_add_delayed_extent_op(fs_info, trans, bytenr,
3063                                           num_bytes, extent_op);
3064         if (ret)
3065                 btrfs_free_delayed_extent_op(extent_op);
3066         return ret;
3067 }
3068
3069 static noinline int check_delayed_ref(struct btrfs_root *root,
3070                                       struct btrfs_path *path,
3071                                       u64 objectid, u64 offset, u64 bytenr)
3072 {
3073         struct btrfs_delayed_ref_head *head;
3074         struct btrfs_delayed_ref_node *ref;
3075         struct btrfs_delayed_data_ref *data_ref;
3076         struct btrfs_delayed_ref_root *delayed_refs;
3077         struct btrfs_transaction *cur_trans;
3078         struct rb_node *node;
3079         int ret = 0;
3080
3081         spin_lock(&root->fs_info->trans_lock);
3082         cur_trans = root->fs_info->running_transaction;
3083         if (cur_trans)
3084                 refcount_inc(&cur_trans->use_count);
3085         spin_unlock(&root->fs_info->trans_lock);
3086         if (!cur_trans)
3087                 return 0;
3088
3089         delayed_refs = &cur_trans->delayed_refs;
3090         spin_lock(&delayed_refs->lock);
3091         head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
3092         if (!head) {
3093                 spin_unlock(&delayed_refs->lock);
3094                 btrfs_put_transaction(cur_trans);
3095                 return 0;
3096         }
3097
3098         if (!mutex_trylock(&head->mutex)) {
3099                 refcount_inc(&head->refs);
3100                 spin_unlock(&delayed_refs->lock);
3101
3102                 btrfs_release_path(path);
3103
3104                 /*
3105                  * Mutex was contended, block until it's released and let
3106                  * caller try again
3107                  */
3108                 mutex_lock(&head->mutex);
3109                 mutex_unlock(&head->mutex);
3110                 btrfs_put_delayed_ref_head(head);
3111                 btrfs_put_transaction(cur_trans);
3112                 return -EAGAIN;
3113         }
3114         spin_unlock(&delayed_refs->lock);
3115
3116         spin_lock(&head->lock);
3117         /*
3118          * XXX: We should replace this with a proper search function in the
3119          * future.
3120          */
3121         for (node = rb_first_cached(&head->ref_tree); node;
3122              node = rb_next(node)) {
3123                 ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
3124                 /* If it's a shared ref we know a cross reference exists */
3125                 if (ref->type != BTRFS_EXTENT_DATA_REF_KEY) {
3126                         ret = 1;
3127                         break;
3128                 }
3129
3130                 data_ref = btrfs_delayed_node_to_data_ref(ref);
3131
3132                 /*
3133                  * If our ref doesn't match the one we're currently looking at
3134                  * then we have a cross reference.
3135                  */
3136                 if (data_ref->root != root->root_key.objectid ||
3137                     data_ref->objectid != objectid ||
3138                     data_ref->offset != offset) {
3139                         ret = 1;
3140                         break;
3141                 }
3142         }
3143         spin_unlock(&head->lock);
3144         mutex_unlock(&head->mutex);
3145         btrfs_put_transaction(cur_trans);
3146         return ret;
3147 }
3148
3149 static noinline int check_committed_ref(struct btrfs_root *root,
3150                                         struct btrfs_path *path,
3151                                         u64 objectid, u64 offset, u64 bytenr)
3152 {
3153         struct btrfs_fs_info *fs_info = root->fs_info;
3154         struct btrfs_root *extent_root = fs_info->extent_root;
3155         struct extent_buffer *leaf;
3156         struct btrfs_extent_data_ref *ref;
3157         struct btrfs_extent_inline_ref *iref;
3158         struct btrfs_extent_item *ei;
3159         struct btrfs_key key;
3160         u32 item_size;
3161         int type;
3162         int ret;
3163
3164         key.objectid = bytenr;
3165         key.offset = (u64)-1;
3166         key.type = BTRFS_EXTENT_ITEM_KEY;
3167
3168         ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
3169         if (ret < 0)
3170                 goto out;
3171         BUG_ON(ret == 0); /* Corruption */
3172
3173         ret = -ENOENT;
3174         if (path->slots[0] == 0)
3175                 goto out;
3176
3177         path->slots[0]--;
3178         leaf = path->nodes[0];
3179         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3180
3181         if (key.objectid != bytenr || key.type != BTRFS_EXTENT_ITEM_KEY)
3182                 goto out;
3183
3184         ret = 1;
3185         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3186         ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
3187
3188         if (item_size != sizeof(*ei) +
3189             btrfs_extent_inline_ref_size(BTRFS_EXTENT_DATA_REF_KEY))
3190                 goto out;
3191
3192         if (btrfs_extent_generation(leaf, ei) <=
3193             btrfs_root_last_snapshot(&root->root_item))
3194                 goto out;
3195
3196         iref = (struct btrfs_extent_inline_ref *)(ei + 1);
3197
3198         type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_DATA);
3199         if (type != BTRFS_EXTENT_DATA_REF_KEY)
3200                 goto out;
3201
3202         ref = (struct btrfs_extent_data_ref *)(&iref->offset);
3203         if (btrfs_extent_refs(leaf, ei) !=
3204             btrfs_extent_data_ref_count(leaf, ref) ||
3205             btrfs_extent_data_ref_root(leaf, ref) !=
3206             root->root_key.objectid ||
3207             btrfs_extent_data_ref_objectid(leaf, ref) != objectid ||
3208             btrfs_extent_data_ref_offset(leaf, ref) != offset)
3209                 goto out;
3210
3211         ret = 0;
3212 out:
3213         return ret;
3214 }
3215
3216 int btrfs_cross_ref_exist(struct btrfs_root *root, u64 objectid, u64 offset,
3217                           u64 bytenr)
3218 {
3219         struct btrfs_path *path;
3220         int ret;
3221
3222         path = btrfs_alloc_path();
3223         if (!path)
3224                 return -ENOMEM;
3225
3226         do {
3227                 ret = check_committed_ref(root, path, objectid,
3228                                           offset, bytenr);
3229                 if (ret && ret != -ENOENT)
3230                         goto out;
3231
3232                 ret = check_delayed_ref(root, path, objectid, offset, bytenr);
3233         } while (ret == -EAGAIN);
3234
3235 out:
3236         btrfs_free_path(path);
3237         if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
3238                 WARN_ON(ret > 0);
3239         return ret;
3240 }
3241
3242 static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
3243                            struct btrfs_root *root,
3244                            struct extent_buffer *buf,
3245                            int full_backref, int inc)
3246 {
3247         struct btrfs_fs_info *fs_info = root->fs_info;
3248         u64 bytenr;
3249         u64 num_bytes;
3250         u64 parent;
3251         u64 ref_root;
3252         u32 nritems;
3253         struct btrfs_key key;
3254         struct btrfs_file_extent_item *fi;
3255         int i;
3256         int level;
3257         int ret = 0;
3258         int (*process_func)(struct btrfs_trans_handle *,
3259                             struct btrfs_root *,
3260                             u64, u64, u64, u64, u64, u64);
3261
3262
3263         if (btrfs_is_testing(fs_info))
3264                 return 0;
3265
3266         ref_root = btrfs_header_owner(buf);
3267         nritems = btrfs_header_nritems(buf);
3268         level = btrfs_header_level(buf);
3269
3270         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state) && level == 0)
3271                 return 0;
3272
3273         if (inc)
3274                 process_func = btrfs_inc_extent_ref;
3275         else
3276                 process_func = btrfs_free_extent;
3277
3278         if (full_backref)
3279                 parent = buf->start;
3280         else
3281                 parent = 0;
3282
3283         for (i = 0; i < nritems; i++) {
3284                 if (level == 0) {
3285                         btrfs_item_key_to_cpu(buf, &key, i);
3286                         if (key.type != BTRFS_EXTENT_DATA_KEY)
3287                                 continue;
3288                         fi = btrfs_item_ptr(buf, i,
3289                                             struct btrfs_file_extent_item);
3290                         if (btrfs_file_extent_type(buf, fi) ==
3291                             BTRFS_FILE_EXTENT_INLINE)
3292                                 continue;
3293                         bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
3294                         if (bytenr == 0)
3295                                 continue;
3296
3297                         num_bytes = btrfs_file_extent_disk_num_bytes(buf, fi);
3298                         key.offset -= btrfs_file_extent_offset(buf, fi);
3299                         ret = process_func(trans, root, bytenr, num_bytes,
3300                                            parent, ref_root, key.objectid,
3301                                            key.offset);
3302                         if (ret)
3303                                 goto fail;
3304                 } else {
3305                         bytenr = btrfs_node_blockptr(buf, i);
3306                         num_bytes = fs_info->nodesize;
3307                         ret = process_func(trans, root, bytenr, num_bytes,
3308                                            parent, ref_root, level - 1, 0);
3309                         if (ret)
3310                                 goto fail;
3311                 }
3312         }
3313         return 0;
3314 fail:
3315         return ret;
3316 }
3317
3318 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3319                   struct extent_buffer *buf, int full_backref)
3320 {
3321         return __btrfs_mod_ref(trans, root, buf, full_backref, 1);
3322 }
3323
3324 int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3325                   struct extent_buffer *buf, int full_backref)
3326 {
3327         return __btrfs_mod_ref(trans, root, buf, full_backref, 0);
3328 }
3329
3330 static int write_one_cache_group(struct btrfs_trans_handle *trans,
3331                                  struct btrfs_fs_info *fs_info,
3332                                  struct btrfs_path *path,
3333                                  struct btrfs_block_group_cache *cache)
3334 {
3335         int ret;
3336         struct btrfs_root *extent_root = fs_info->extent_root;
3337         unsigned long bi;
3338         struct extent_buffer *leaf;
3339
3340         ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
3341         if (ret) {
3342                 if (ret > 0)
3343                         ret = -ENOENT;
3344                 goto fail;
3345         }
3346
3347         leaf = path->nodes[0];
3348         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
3349         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
3350         btrfs_mark_buffer_dirty(leaf);
3351 fail:
3352         btrfs_release_path(path);
3353         return ret;
3354
3355 }
3356
3357 static struct btrfs_block_group_cache *
3358 next_block_group(struct btrfs_fs_info *fs_info,
3359                  struct btrfs_block_group_cache *cache)
3360 {
3361         struct rb_node *node;
3362
3363         spin_lock(&fs_info->block_group_cache_lock);
3364
3365         /* If our block group was removed, we need a full search. */
3366         if (RB_EMPTY_NODE(&cache->cache_node)) {
3367                 const u64 next_bytenr = cache->key.objectid + cache->key.offset;
3368
3369                 spin_unlock(&fs_info->block_group_cache_lock);
3370                 btrfs_put_block_group(cache);
3371                 cache = btrfs_lookup_first_block_group(fs_info, next_bytenr); return cache;
3372         }
3373         node = rb_next(&cache->cache_node);
3374         btrfs_put_block_group(cache);
3375         if (node) {
3376                 cache = rb_entry(node, struct btrfs_block_group_cache,
3377                                  cache_node);
3378                 btrfs_get_block_group(cache);
3379         } else
3380                 cache = NULL;
3381         spin_unlock(&fs_info->block_group_cache_lock);
3382         return cache;
3383 }
3384
3385 static int cache_save_setup(struct btrfs_block_group_cache *block_group,
3386                             struct btrfs_trans_handle *trans,
3387                             struct btrfs_path *path)
3388 {
3389         struct btrfs_fs_info *fs_info = block_group->fs_info;
3390         struct btrfs_root *root = fs_info->tree_root;
3391         struct inode *inode = NULL;
3392         struct extent_changeset *data_reserved = NULL;
3393         u64 alloc_hint = 0;
3394         int dcs = BTRFS_DC_ERROR;
3395         u64 num_pages = 0;
3396         int retries = 0;
3397         int ret = 0;
3398
3399         /*
3400          * If this block group is smaller than 100 megs don't bother caching the
3401          * block group.
3402          */
3403         if (block_group->key.offset < (100 * SZ_1M)) {
3404                 spin_lock(&block_group->lock);
3405                 block_group->disk_cache_state = BTRFS_DC_WRITTEN;
3406                 spin_unlock(&block_group->lock);
3407                 return 0;
3408         }
3409
3410         if (trans->aborted)
3411                 return 0;
3412 again:
3413         inode = lookup_free_space_inode(fs_info, block_group, path);
3414         if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
3415                 ret = PTR_ERR(inode);
3416                 btrfs_release_path(path);
3417                 goto out;
3418         }
3419
3420         if (IS_ERR(inode)) {
3421                 BUG_ON(retries);
3422                 retries++;
3423
3424                 if (block_group->ro)
3425                         goto out_free;
3426
3427                 ret = create_free_space_inode(fs_info, trans, block_group,
3428                                               path);
3429                 if (ret)
3430                         goto out_free;
3431                 goto again;
3432         }
3433
3434         /*
3435          * We want to set the generation to 0, that way if anything goes wrong
3436          * from here on out we know not to trust this cache when we load up next
3437          * time.
3438          */
3439         BTRFS_I(inode)->generation = 0;
3440         ret = btrfs_update_inode(trans, root, inode);
3441         if (ret) {
3442                 /*
3443                  * So theoretically we could recover from this, simply set the
3444                  * super cache generation to 0 so we know to invalidate the
3445                  * cache, but then we'd have to keep track of the block groups
3446                  * that fail this way so we know we _have_ to reset this cache
3447                  * before the next commit or risk reading stale cache.  So to
3448                  * limit our exposure to horrible edge cases lets just abort the
3449                  * transaction, this only happens in really bad situations
3450                  * anyway.
3451                  */
3452                 btrfs_abort_transaction(trans, ret);
3453                 goto out_put;
3454         }
3455         WARN_ON(ret);
3456
3457         /* We've already setup this transaction, go ahead and exit */
3458         if (block_group->cache_generation == trans->transid &&
3459             i_size_read(inode)) {
3460                 dcs = BTRFS_DC_SETUP;
3461                 goto out_put;
3462         }
3463
3464         if (i_size_read(inode) > 0) {
3465                 ret = btrfs_check_trunc_cache_free_space(fs_info,
3466                                         &fs_info->global_block_rsv);
3467                 if (ret)
3468                         goto out_put;
3469
3470                 ret = btrfs_truncate_free_space_cache(trans, NULL, inode);
3471                 if (ret)
3472                         goto out_put;
3473         }
3474
3475         spin_lock(&block_group->lock);
3476         if (block_group->cached != BTRFS_CACHE_FINISHED ||
3477             !btrfs_test_opt(fs_info, SPACE_CACHE)) {
3478                 /*
3479                  * don't bother trying to write stuff out _if_
3480                  * a) we're not cached,
3481                  * b) we're with nospace_cache mount option,
3482                  * c) we're with v2 space_cache (FREE_SPACE_TREE).
3483                  */
3484                 dcs = BTRFS_DC_WRITTEN;
3485                 spin_unlock(&block_group->lock);
3486                 goto out_put;
3487         }
3488         spin_unlock(&block_group->lock);
3489
3490         /*
3491          * We hit an ENOSPC when setting up the cache in this transaction, just
3492          * skip doing the setup, we've already cleared the cache so we're safe.
3493          */
3494         if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) {
3495                 ret = -ENOSPC;
3496                 goto out_put;
3497         }
3498
3499         /*
3500          * Try to preallocate enough space based on how big the block group is.
3501          * Keep in mind this has to include any pinned space which could end up
3502          * taking up quite a bit since it's not folded into the other space
3503          * cache.
3504          */
3505         num_pages = div_u64(block_group->key.offset, SZ_256M);
3506         if (!num_pages)
3507                 num_pages = 1;
3508
3509         num_pages *= 16;
3510         num_pages *= PAGE_SIZE;
3511
3512         ret = btrfs_check_data_free_space(inode, &data_reserved, 0, num_pages);
3513         if (ret)
3514                 goto out_put;
3515
3516         ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages,
3517                                               num_pages, num_pages,
3518                                               &alloc_hint);
3519         /*
3520          * Our cache requires contiguous chunks so that we don't modify a bunch
3521          * of metadata or split extents when writing the cache out, which means
3522          * we can enospc if we are heavily fragmented in addition to just normal
3523          * out of space conditions.  So if we hit this just skip setting up any
3524          * other block groups for this transaction, maybe we'll unpin enough
3525          * space the next time around.
3526          */
3527         if (!ret)
3528                 dcs = BTRFS_DC_SETUP;
3529         else if (ret == -ENOSPC)
3530                 set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags);
3531
3532 out_put:
3533         iput(inode);
3534 out_free:
3535         btrfs_release_path(path);
3536 out:
3537         spin_lock(&block_group->lock);
3538         if (!ret && dcs == BTRFS_DC_SETUP)
3539                 block_group->cache_generation = trans->transid;
3540         block_group->disk_cache_state = dcs;
3541         spin_unlock(&block_group->lock);
3542
3543         extent_changeset_free(data_reserved);
3544         return ret;
3545 }
3546
3547 int btrfs_setup_space_cache(struct btrfs_trans_handle *trans,
3548                             struct btrfs_fs_info *fs_info)
3549 {
3550         struct btrfs_block_group_cache *cache, *tmp;
3551         struct btrfs_transaction *cur_trans = trans->transaction;
3552         struct btrfs_path *path;
3553
3554         if (list_empty(&cur_trans->dirty_bgs) ||
3555             !btrfs_test_opt(fs_info, SPACE_CACHE))
3556                 return 0;
3557
3558         path = btrfs_alloc_path();
3559         if (!path)
3560                 return -ENOMEM;
3561
3562         /* Could add new block groups, use _safe just in case */
3563         list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs,
3564                                  dirty_list) {
3565                 if (cache->disk_cache_state == BTRFS_DC_CLEAR)
3566                         cache_save_setup(cache, trans, path);
3567         }
3568