interconnect: qcom: icc-rpm: Fix peak rate calculation
[linux-2.6-microblaze.git] / fs / btrfs / transaction.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2007 Oracle.  All rights reserved.
4  */
5
6 #include <linux/fs.h>
7 #include <linux/slab.h>
8 #include <linux/sched.h>
9 #include <linux/sched/mm.h>
10 #include <linux/writeback.h>
11 #include <linux/pagemap.h>
12 #include <linux/blkdev.h>
13 #include <linux/uuid.h>
14 #include <linux/timekeeping.h>
15 #include "misc.h"
16 #include "ctree.h"
17 #include "disk-io.h"
18 #include "transaction.h"
19 #include "locking.h"
20 #include "tree-log.h"
21 #include "volumes.h"
22 #include "dev-replace.h"
23 #include "qgroup.h"
24 #include "block-group.h"
25 #include "space-info.h"
26 #include "zoned.h"
27 #include "fs.h"
28 #include "accessors.h"
29 #include "extent-tree.h"
30 #include "root-tree.h"
31 #include "defrag.h"
32 #include "dir-item.h"
33 #include "uuid-tree.h"
34 #include "ioctl.h"
35 #include "relocation.h"
36 #include "scrub.h"
37
38 static struct kmem_cache *btrfs_trans_handle_cachep;
39
40 #define BTRFS_ROOT_TRANS_TAG 0
41
42 /*
43  * Transaction states and transitions
44  *
45  * No running transaction (fs tree blocks are not modified)
46  * |
47  * | To next stage:
48  * |  Call start_transaction() variants. Except btrfs_join_transaction_nostart().
49  * V
50  * Transaction N [[TRANS_STATE_RUNNING]]
51  * |
52  * | New trans handles can be attached to transaction N by calling all
53  * | start_transaction() variants.
54  * |
55  * | To next stage:
56  * |  Call btrfs_commit_transaction() on any trans handle attached to
57  * |  transaction N
58  * V
59  * Transaction N [[TRANS_STATE_COMMIT_PREP]]
60  * |
61  * | If there are simultaneous calls to btrfs_commit_transaction() one will win
62  * | the race and the rest will wait for the winner to commit the transaction.
63  * |
64  * | The winner will wait for previous running transaction to completely finish
65  * | if there is one.
66  * |
67  * Transaction N [[TRANS_STATE_COMMIT_START]]
68  * |
69  * | Then one of the following happens:
70  * | - Wait for all other trans handle holders to release.
71  * |   The btrfs_commit_transaction() caller will do the commit work.
72  * | - Wait for current transaction to be committed by others.
73  * |   Other btrfs_commit_transaction() caller will do the commit work.
74  * |
75  * | At this stage, only btrfs_join_transaction*() variants can attach
76  * | to this running transaction.
77  * | All other variants will wait for current one to finish and attach to
78  * | transaction N+1.
79  * |
80  * | To next stage:
81  * |  Caller is chosen to commit transaction N, and all other trans handle
82  * |  haven been released.
83  * V
84  * Transaction N [[TRANS_STATE_COMMIT_DOING]]
85  * |
86  * | The heavy lifting transaction work is started.
87  * | From running delayed refs (modifying extent tree) to creating pending
88  * | snapshots, running qgroups.
89  * | In short, modify supporting trees to reflect modifications of subvolume
90  * | trees.
91  * |
92  * | At this stage, all start_transaction() calls will wait for this
93  * | transaction to finish and attach to transaction N+1.
94  * |
95  * | To next stage:
96  * |  Until all supporting trees are updated.
97  * V
98  * Transaction N [[TRANS_STATE_UNBLOCKED]]
99  * |                                                Transaction N+1
100  * | All needed trees are modified, thus we only    [[TRANS_STATE_RUNNING]]
101  * | need to write them back to disk and update     |
102  * | super blocks.                                  |
103  * |                                                |
104  * | At this stage, new transaction is allowed to   |
105  * | start.                                         |
106  * | All new start_transaction() calls will be      |
107  * | attached to transid N+1.                       |
108  * |                                                |
109  * | To next stage:                                 |
110  * |  Until all tree blocks are super blocks are    |
111  * |  written to block devices                      |
112  * V                                                |
113  * Transaction N [[TRANS_STATE_COMPLETED]]          V
114  *   All tree blocks and super blocks are written.  Transaction N+1
115  *   This transaction is finished and all its       [[TRANS_STATE_COMMIT_START]]
116  *   data structures will be cleaned up.            | Life goes on
117  */
118 static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
119         [TRANS_STATE_RUNNING]           = 0U,
120         [TRANS_STATE_COMMIT_PREP]       = 0U,
121         [TRANS_STATE_COMMIT_START]      = (__TRANS_START | __TRANS_ATTACH),
122         [TRANS_STATE_COMMIT_DOING]      = (__TRANS_START |
123                                            __TRANS_ATTACH |
124                                            __TRANS_JOIN |
125                                            __TRANS_JOIN_NOSTART),
126         [TRANS_STATE_UNBLOCKED]         = (__TRANS_START |
127                                            __TRANS_ATTACH |
128                                            __TRANS_JOIN |
129                                            __TRANS_JOIN_NOLOCK |
130                                            __TRANS_JOIN_NOSTART),
131         [TRANS_STATE_SUPER_COMMITTED]   = (__TRANS_START |
132                                            __TRANS_ATTACH |
133                                            __TRANS_JOIN |
134                                            __TRANS_JOIN_NOLOCK |
135                                            __TRANS_JOIN_NOSTART),
136         [TRANS_STATE_COMPLETED]         = (__TRANS_START |
137                                            __TRANS_ATTACH |
138                                            __TRANS_JOIN |
139                                            __TRANS_JOIN_NOLOCK |
140                                            __TRANS_JOIN_NOSTART),
141 };
142
143 void btrfs_put_transaction(struct btrfs_transaction *transaction)
144 {
145         WARN_ON(refcount_read(&transaction->use_count) == 0);
146         if (refcount_dec_and_test(&transaction->use_count)) {
147                 BUG_ON(!list_empty(&transaction->list));
148                 WARN_ON(!RB_EMPTY_ROOT(
149                                 &transaction->delayed_refs.href_root.rb_root));
150                 WARN_ON(!RB_EMPTY_ROOT(
151                                 &transaction->delayed_refs.dirty_extent_root));
152                 if (transaction->delayed_refs.pending_csums)
153                         btrfs_err(transaction->fs_info,
154                                   "pending csums is %llu",
155                                   transaction->delayed_refs.pending_csums);
156                 /*
157                  * If any block groups are found in ->deleted_bgs then it's
158                  * because the transaction was aborted and a commit did not
159                  * happen (things failed before writing the new superblock
160                  * and calling btrfs_finish_extent_commit()), so we can not
161                  * discard the physical locations of the block groups.
162                  */
163                 while (!list_empty(&transaction->deleted_bgs)) {
164                         struct btrfs_block_group *cache;
165
166                         cache = list_first_entry(&transaction->deleted_bgs,
167                                                  struct btrfs_block_group,
168                                                  bg_list);
169                         list_del_init(&cache->bg_list);
170                         btrfs_unfreeze_block_group(cache);
171                         btrfs_put_block_group(cache);
172                 }
173                 WARN_ON(!list_empty(&transaction->dev_update_list));
174                 kfree(transaction);
175         }
176 }
177
178 static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
179 {
180         struct btrfs_transaction *cur_trans = trans->transaction;
181         struct btrfs_fs_info *fs_info = trans->fs_info;
182         struct btrfs_root *root, *tmp;
183
184         /*
185          * At this point no one can be using this transaction to modify any tree
186          * and no one can start another transaction to modify any tree either.
187          */
188         ASSERT(cur_trans->state == TRANS_STATE_COMMIT_DOING);
189
190         down_write(&fs_info->commit_root_sem);
191
192         if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
193                 fs_info->last_reloc_trans = trans->transid;
194
195         list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
196                                  dirty_list) {
197                 list_del_init(&root->dirty_list);
198                 free_extent_buffer(root->commit_root);
199                 root->commit_root = btrfs_root_node(root);
200                 extent_io_tree_release(&root->dirty_log_pages);
201                 btrfs_qgroup_clean_swapped_blocks(root);
202         }
203
204         /* We can free old roots now. */
205         spin_lock(&cur_trans->dropped_roots_lock);
206         while (!list_empty(&cur_trans->dropped_roots)) {
207                 root = list_first_entry(&cur_trans->dropped_roots,
208                                         struct btrfs_root, root_list);
209                 list_del_init(&root->root_list);
210                 spin_unlock(&cur_trans->dropped_roots_lock);
211                 btrfs_free_log(trans, root);
212                 btrfs_drop_and_free_fs_root(fs_info, root);
213                 spin_lock(&cur_trans->dropped_roots_lock);
214         }
215         spin_unlock(&cur_trans->dropped_roots_lock);
216
217         up_write(&fs_info->commit_root_sem);
218 }
219
220 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
221                                          unsigned int type)
222 {
223         if (type & TRANS_EXTWRITERS)
224                 atomic_inc(&trans->num_extwriters);
225 }
226
227 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
228                                          unsigned int type)
229 {
230         if (type & TRANS_EXTWRITERS)
231                 atomic_dec(&trans->num_extwriters);
232 }
233
234 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
235                                           unsigned int type)
236 {
237         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
238 }
239
240 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
241 {
242         return atomic_read(&trans->num_extwriters);
243 }
244
245 /*
246  * To be called after doing the chunk btree updates right after allocating a new
247  * chunk (after btrfs_chunk_alloc_add_chunk_item() is called), when removing a
248  * chunk after all chunk btree updates and after finishing the second phase of
249  * chunk allocation (btrfs_create_pending_block_groups()) in case some block
250  * group had its chunk item insertion delayed to the second phase.
251  */
252 void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans)
253 {
254         struct btrfs_fs_info *fs_info = trans->fs_info;
255
256         if (!trans->chunk_bytes_reserved)
257                 return;
258
259         btrfs_block_rsv_release(fs_info, &fs_info->chunk_block_rsv,
260                                 trans->chunk_bytes_reserved, NULL);
261         trans->chunk_bytes_reserved = 0;
262 }
263
264 /*
265  * either allocate a new transaction or hop into the existing one
266  */
267 static noinline int join_transaction(struct btrfs_fs_info *fs_info,
268                                      unsigned int type)
269 {
270         struct btrfs_transaction *cur_trans;
271
272         spin_lock(&fs_info->trans_lock);
273 loop:
274         /* The file system has been taken offline. No new transactions. */
275         if (BTRFS_FS_ERROR(fs_info)) {
276                 spin_unlock(&fs_info->trans_lock);
277                 return -EROFS;
278         }
279
280         cur_trans = fs_info->running_transaction;
281         if (cur_trans) {
282                 if (TRANS_ABORTED(cur_trans)) {
283                         spin_unlock(&fs_info->trans_lock);
284                         return cur_trans->aborted;
285                 }
286                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
287                         spin_unlock(&fs_info->trans_lock);
288                         return -EBUSY;
289                 }
290                 refcount_inc(&cur_trans->use_count);
291                 atomic_inc(&cur_trans->num_writers);
292                 extwriter_counter_inc(cur_trans, type);
293                 spin_unlock(&fs_info->trans_lock);
294                 btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);
295                 btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);
296                 return 0;
297         }
298         spin_unlock(&fs_info->trans_lock);
299
300         /*
301          * If we are ATTACH or TRANS_JOIN_NOSTART, we just want to catch the
302          * current transaction, and commit it. If there is no transaction, just
303          * return ENOENT.
304          */
305         if (type == TRANS_ATTACH || type == TRANS_JOIN_NOSTART)
306                 return -ENOENT;
307
308         /*
309          * JOIN_NOLOCK only happens during the transaction commit, so
310          * it is impossible that ->running_transaction is NULL
311          */
312         BUG_ON(type == TRANS_JOIN_NOLOCK);
313
314         cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
315         if (!cur_trans)
316                 return -ENOMEM;
317
318         btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);
319         btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);
320
321         spin_lock(&fs_info->trans_lock);
322         if (fs_info->running_transaction) {
323                 /*
324                  * someone started a transaction after we unlocked.  Make sure
325                  * to redo the checks above
326                  */
327                 btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
328                 btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
329                 kfree(cur_trans);
330                 goto loop;
331         } else if (BTRFS_FS_ERROR(fs_info)) {
332                 spin_unlock(&fs_info->trans_lock);
333                 btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
334                 btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
335                 kfree(cur_trans);
336                 return -EROFS;
337         }
338
339         cur_trans->fs_info = fs_info;
340         atomic_set(&cur_trans->pending_ordered, 0);
341         init_waitqueue_head(&cur_trans->pending_wait);
342         atomic_set(&cur_trans->num_writers, 1);
343         extwriter_counter_init(cur_trans, type);
344         init_waitqueue_head(&cur_trans->writer_wait);
345         init_waitqueue_head(&cur_trans->commit_wait);
346         cur_trans->state = TRANS_STATE_RUNNING;
347         /*
348          * One for this trans handle, one so it will live on until we
349          * commit the transaction.
350          */
351         refcount_set(&cur_trans->use_count, 2);
352         cur_trans->flags = 0;
353         cur_trans->start_time = ktime_get_seconds();
354
355         memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
356
357         cur_trans->delayed_refs.href_root = RB_ROOT_CACHED;
358         cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
359         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
360
361         /*
362          * although the tree mod log is per file system and not per transaction,
363          * the log must never go across transaction boundaries.
364          */
365         smp_mb();
366         if (!list_empty(&fs_info->tree_mod_seq_list))
367                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
368         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
369                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
370         atomic64_set(&fs_info->tree_mod_seq, 0);
371
372         spin_lock_init(&cur_trans->delayed_refs.lock);
373
374         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
375         INIT_LIST_HEAD(&cur_trans->dev_update_list);
376         INIT_LIST_HEAD(&cur_trans->switch_commits);
377         INIT_LIST_HEAD(&cur_trans->dirty_bgs);
378         INIT_LIST_HEAD(&cur_trans->io_bgs);
379         INIT_LIST_HEAD(&cur_trans->dropped_roots);
380         mutex_init(&cur_trans->cache_write_mutex);
381         spin_lock_init(&cur_trans->dirty_bgs_lock);
382         INIT_LIST_HEAD(&cur_trans->deleted_bgs);
383         spin_lock_init(&cur_trans->dropped_roots_lock);
384         list_add_tail(&cur_trans->list, &fs_info->trans_list);
385         extent_io_tree_init(fs_info, &cur_trans->dirty_pages,
386                         IO_TREE_TRANS_DIRTY_PAGES);
387         extent_io_tree_init(fs_info, &cur_trans->pinned_extents,
388                         IO_TREE_FS_PINNED_EXTENTS);
389         btrfs_set_fs_generation(fs_info, fs_info->generation + 1);
390         cur_trans->transid = fs_info->generation;
391         fs_info->running_transaction = cur_trans;
392         cur_trans->aborted = 0;
393         spin_unlock(&fs_info->trans_lock);
394
395         return 0;
396 }
397
398 /*
399  * This does all the record keeping required to make sure that a shareable root
400  * is properly recorded in a given transaction.  This is required to make sure
401  * the old root from before we joined the transaction is deleted when the
402  * transaction commits.
403  */
404 static int record_root_in_trans(struct btrfs_trans_handle *trans,
405                                struct btrfs_root *root,
406                                int force)
407 {
408         struct btrfs_fs_info *fs_info = root->fs_info;
409         int ret = 0;
410
411         if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
412             root->last_trans < trans->transid) || force) {
413                 WARN_ON(!force && root->commit_root != root->node);
414
415                 /*
416                  * see below for IN_TRANS_SETUP usage rules
417                  * we have the reloc mutex held now, so there
418                  * is only one writer in this function
419                  */
420                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
421
422                 /* make sure readers find IN_TRANS_SETUP before
423                  * they find our root->last_trans update
424                  */
425                 smp_wmb();
426
427                 spin_lock(&fs_info->fs_roots_radix_lock);
428                 if (root->last_trans == trans->transid && !force) {
429                         spin_unlock(&fs_info->fs_roots_radix_lock);
430                         return 0;
431                 }
432                 radix_tree_tag_set(&fs_info->fs_roots_radix,
433                                    (unsigned long)root->root_key.objectid,
434                                    BTRFS_ROOT_TRANS_TAG);
435                 spin_unlock(&fs_info->fs_roots_radix_lock);
436                 root->last_trans = trans->transid;
437
438                 /* this is pretty tricky.  We don't want to
439                  * take the relocation lock in btrfs_record_root_in_trans
440                  * unless we're really doing the first setup for this root in
441                  * this transaction.
442                  *
443                  * Normally we'd use root->last_trans as a flag to decide
444                  * if we want to take the expensive mutex.
445                  *
446                  * But, we have to set root->last_trans before we
447                  * init the relocation root, otherwise, we trip over warnings
448                  * in ctree.c.  The solution used here is to flag ourselves
449                  * with root IN_TRANS_SETUP.  When this is 1, we're still
450                  * fixing up the reloc trees and everyone must wait.
451                  *
452                  * When this is zero, they can trust root->last_trans and fly
453                  * through btrfs_record_root_in_trans without having to take the
454                  * lock.  smp_wmb() makes sure that all the writes above are
455                  * done before we pop in the zero below
456                  */
457                 ret = btrfs_init_reloc_root(trans, root);
458                 smp_mb__before_atomic();
459                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
460         }
461         return ret;
462 }
463
464
465 void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
466                             struct btrfs_root *root)
467 {
468         struct btrfs_fs_info *fs_info = root->fs_info;
469         struct btrfs_transaction *cur_trans = trans->transaction;
470
471         /* Add ourselves to the transaction dropped list */
472         spin_lock(&cur_trans->dropped_roots_lock);
473         list_add_tail(&root->root_list, &cur_trans->dropped_roots);
474         spin_unlock(&cur_trans->dropped_roots_lock);
475
476         /* Make sure we don't try to update the root at commit time */
477         spin_lock(&fs_info->fs_roots_radix_lock);
478         radix_tree_tag_clear(&fs_info->fs_roots_radix,
479                              (unsigned long)root->root_key.objectid,
480                              BTRFS_ROOT_TRANS_TAG);
481         spin_unlock(&fs_info->fs_roots_radix_lock);
482 }
483
484 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
485                                struct btrfs_root *root)
486 {
487         struct btrfs_fs_info *fs_info = root->fs_info;
488         int ret;
489
490         if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
491                 return 0;
492
493         /*
494          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
495          * and barriers
496          */
497         smp_rmb();
498         if (root->last_trans == trans->transid &&
499             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
500                 return 0;
501
502         mutex_lock(&fs_info->reloc_mutex);
503         ret = record_root_in_trans(trans, root, 0);
504         mutex_unlock(&fs_info->reloc_mutex);
505
506         return ret;
507 }
508
509 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
510 {
511         return (trans->state >= TRANS_STATE_COMMIT_START &&
512                 trans->state < TRANS_STATE_UNBLOCKED &&
513                 !TRANS_ABORTED(trans));
514 }
515
516 /* wait for commit against the current transaction to become unblocked
517  * when this is done, it is safe to start a new transaction, but the current
518  * transaction might not be fully on disk.
519  */
520 static void wait_current_trans(struct btrfs_fs_info *fs_info)
521 {
522         struct btrfs_transaction *cur_trans;
523
524         spin_lock(&fs_info->trans_lock);
525         cur_trans = fs_info->running_transaction;
526         if (cur_trans && is_transaction_blocked(cur_trans)) {
527                 refcount_inc(&cur_trans->use_count);
528                 spin_unlock(&fs_info->trans_lock);
529
530                 btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
531                 wait_event(fs_info->transaction_wait,
532                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
533                            TRANS_ABORTED(cur_trans));
534                 btrfs_put_transaction(cur_trans);
535         } else {
536                 spin_unlock(&fs_info->trans_lock);
537         }
538 }
539
540 static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
541 {
542         if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
543                 return 0;
544
545         if (type == TRANS_START)
546                 return 1;
547
548         return 0;
549 }
550
551 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
552 {
553         struct btrfs_fs_info *fs_info = root->fs_info;
554
555         if (!fs_info->reloc_ctl ||
556             !test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
557             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
558             root->reloc_root)
559                 return false;
560
561         return true;
562 }
563
564 static int btrfs_reserve_trans_metadata(struct btrfs_fs_info *fs_info,
565                                         enum btrfs_reserve_flush_enum flush,
566                                         u64 num_bytes,
567                                         u64 *delayed_refs_bytes)
568 {
569         struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
570         struct btrfs_space_info *si = fs_info->trans_block_rsv.space_info;
571         u64 extra_delayed_refs_bytes = 0;
572         u64 bytes;
573         int ret;
574
575         /*
576          * If there's a gap between the size of the delayed refs reserve and
577          * its reserved space, than some tasks have added delayed refs or bumped
578          * its size otherwise (due to block group creation or removal, or block
579          * group item update). Also try to allocate that gap in order to prevent
580          * using (and possibly abusing) the global reserve when committing the
581          * transaction.
582          */
583         if (flush == BTRFS_RESERVE_FLUSH_ALL &&
584             !btrfs_block_rsv_full(delayed_refs_rsv)) {
585                 spin_lock(&delayed_refs_rsv->lock);
586                 if (delayed_refs_rsv->size > delayed_refs_rsv->reserved)
587                         extra_delayed_refs_bytes = delayed_refs_rsv->size -
588                                 delayed_refs_rsv->reserved;
589                 spin_unlock(&delayed_refs_rsv->lock);
590         }
591
592         bytes = num_bytes + *delayed_refs_bytes + extra_delayed_refs_bytes;
593
594         /*
595          * We want to reserve all the bytes we may need all at once, so we only
596          * do 1 enospc flushing cycle per transaction start.
597          */
598         ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);
599         if (ret == 0) {
600                 if (extra_delayed_refs_bytes > 0)
601                         btrfs_migrate_to_delayed_refs_rsv(fs_info,
602                                                           extra_delayed_refs_bytes);
603                 return 0;
604         }
605
606         if (extra_delayed_refs_bytes > 0) {
607                 bytes -= extra_delayed_refs_bytes;
608                 ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);
609                 if (ret == 0)
610                         return 0;
611         }
612
613         /*
614          * If we are an emergency flush, which can steal from the global block
615          * reserve, then attempt to not reserve space for the delayed refs, as
616          * we will consume space for them from the global block reserve.
617          */
618         if (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL) {
619                 bytes -= *delayed_refs_bytes;
620                 *delayed_refs_bytes = 0;
621                 ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);
622         }
623
624         return ret;
625 }
626
627 static struct btrfs_trans_handle *
628 start_transaction(struct btrfs_root *root, unsigned int num_items,
629                   unsigned int type, enum btrfs_reserve_flush_enum flush,
630                   bool enforce_qgroups)
631 {
632         struct btrfs_fs_info *fs_info = root->fs_info;
633         struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
634         struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv;
635         struct btrfs_trans_handle *h;
636         struct btrfs_transaction *cur_trans;
637         u64 num_bytes = 0;
638         u64 qgroup_reserved = 0;
639         u64 delayed_refs_bytes = 0;
640         bool reloc_reserved = false;
641         bool do_chunk_alloc = false;
642         int ret;
643
644         if (BTRFS_FS_ERROR(fs_info))
645                 return ERR_PTR(-EROFS);
646
647         if (current->journal_info) {
648                 WARN_ON(type & TRANS_EXTWRITERS);
649                 h = current->journal_info;
650                 refcount_inc(&h->use_count);
651                 WARN_ON(refcount_read(&h->use_count) > 2);
652                 h->orig_rsv = h->block_rsv;
653                 h->block_rsv = NULL;
654                 goto got_it;
655         }
656
657         /*
658          * Do the reservation before we join the transaction so we can do all
659          * the appropriate flushing if need be.
660          */
661         if (num_items && root != fs_info->chunk_root) {
662                 qgroup_reserved = num_items * fs_info->nodesize;
663                 /*
664                  * Use prealloc for now, as there might be a currently running
665                  * transaction that could free this reserved space prematurely
666                  * by committing.
667                  */
668                 ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserved,
669                                                          enforce_qgroups, false);
670                 if (ret)
671                         return ERR_PTR(ret);
672
673                 num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_items);
674                 /*
675                  * If we plan to insert/update/delete "num_items" from a btree,
676                  * we will also generate delayed refs for extent buffers in the
677                  * respective btree paths, so reserve space for the delayed refs
678                  * that will be generated by the caller as it modifies btrees.
679                  * Try to reserve them to avoid excessive use of the global
680                  * block reserve.
681                  */
682                 delayed_refs_bytes = btrfs_calc_delayed_ref_bytes(fs_info, num_items);
683
684                 /*
685                  * Do the reservation for the relocation root creation
686                  */
687                 if (need_reserve_reloc_root(root)) {
688                         num_bytes += fs_info->nodesize;
689                         reloc_reserved = true;
690                 }
691
692                 ret = btrfs_reserve_trans_metadata(fs_info, flush, num_bytes,
693                                                    &delayed_refs_bytes);
694                 if (ret)
695                         goto reserve_fail;
696
697                 btrfs_block_rsv_add_bytes(trans_rsv, num_bytes, true);
698
699                 if (trans_rsv->space_info->force_alloc)
700                         do_chunk_alloc = true;
701         } else if (num_items == 0 && flush == BTRFS_RESERVE_FLUSH_ALL &&
702                    !btrfs_block_rsv_full(delayed_refs_rsv)) {
703                 /*
704                  * Some people call with btrfs_start_transaction(root, 0)
705                  * because they can be throttled, but have some other mechanism
706                  * for reserving space.  We still want these guys to refill the
707                  * delayed block_rsv so just add 1 items worth of reservation
708                  * here.
709                  */
710                 ret = btrfs_delayed_refs_rsv_refill(fs_info, flush);
711                 if (ret)
712                         goto reserve_fail;
713         }
714 again:
715         h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
716         if (!h) {
717                 ret = -ENOMEM;
718                 goto alloc_fail;
719         }
720
721         /*
722          * If we are JOIN_NOLOCK we're already committing a transaction and
723          * waiting on this guy, so we don't need to do the sb_start_intwrite
724          * because we're already holding a ref.  We need this because we could
725          * have raced in and did an fsync() on a file which can kick a commit
726          * and then we deadlock with somebody doing a freeze.
727          *
728          * If we are ATTACH, it means we just want to catch the current
729          * transaction and commit it, so we needn't do sb_start_intwrite(). 
730          */
731         if (type & __TRANS_FREEZABLE)
732                 sb_start_intwrite(fs_info->sb);
733
734         if (may_wait_transaction(fs_info, type))
735                 wait_current_trans(fs_info);
736
737         do {
738                 ret = join_transaction(fs_info, type);
739                 if (ret == -EBUSY) {
740                         wait_current_trans(fs_info);
741                         if (unlikely(type == TRANS_ATTACH ||
742                                      type == TRANS_JOIN_NOSTART))
743                                 ret = -ENOENT;
744                 }
745         } while (ret == -EBUSY);
746
747         if (ret < 0)
748                 goto join_fail;
749
750         cur_trans = fs_info->running_transaction;
751
752         h->transid = cur_trans->transid;
753         h->transaction = cur_trans;
754         refcount_set(&h->use_count, 1);
755         h->fs_info = root->fs_info;
756
757         h->type = type;
758         INIT_LIST_HEAD(&h->new_bgs);
759         btrfs_init_metadata_block_rsv(fs_info, &h->delayed_rsv, BTRFS_BLOCK_RSV_DELOPS);
760
761         smp_mb();
762         if (cur_trans->state >= TRANS_STATE_COMMIT_START &&
763             may_wait_transaction(fs_info, type)) {
764                 current->journal_info = h;
765                 btrfs_commit_transaction(h);
766                 goto again;
767         }
768
769         if (num_bytes) {
770                 trace_btrfs_space_reservation(fs_info, "transaction",
771                                               h->transid, num_bytes, 1);
772                 h->block_rsv = trans_rsv;
773                 h->bytes_reserved = num_bytes;
774                 if (delayed_refs_bytes > 0) {
775                         trace_btrfs_space_reservation(fs_info,
776                                                       "local_delayed_refs_rsv",
777                                                       h->transid,
778                                                       delayed_refs_bytes, 1);
779                         h->delayed_refs_bytes_reserved = delayed_refs_bytes;
780                         btrfs_block_rsv_add_bytes(&h->delayed_rsv, delayed_refs_bytes, true);
781                         delayed_refs_bytes = 0;
782                 }
783                 h->reloc_reserved = reloc_reserved;
784         }
785
786         /*
787          * Now that we have found a transaction to be a part of, convert the
788          * qgroup reservation from prealloc to pertrans. A different transaction
789          * can't race in and free our pertrans out from under us.
790          */
791         if (qgroup_reserved)
792                 btrfs_qgroup_convert_reserved_meta(root, qgroup_reserved);
793
794 got_it:
795         if (!current->journal_info)
796                 current->journal_info = h;
797
798         /*
799          * If the space_info is marked ALLOC_FORCE then we'll get upgraded to
800          * ALLOC_FORCE the first run through, and then we won't allocate for
801          * anybody else who races in later.  We don't care about the return
802          * value here.
803          */
804         if (do_chunk_alloc && num_bytes) {
805                 u64 flags = h->block_rsv->space_info->flags;
806
807                 btrfs_chunk_alloc(h, btrfs_get_alloc_profile(fs_info, flags),
808                                   CHUNK_ALLOC_NO_FORCE);
809         }
810
811         /*
812          * btrfs_record_root_in_trans() needs to alloc new extents, and may
813          * call btrfs_join_transaction() while we're also starting a
814          * transaction.
815          *
816          * Thus it need to be called after current->journal_info initialized,
817          * or we can deadlock.
818          */
819         ret = btrfs_record_root_in_trans(h, root);
820         if (ret) {
821                 /*
822                  * The transaction handle is fully initialized and linked with
823                  * other structures so it needs to be ended in case of errors,
824                  * not just freed.
825                  */
826                 btrfs_end_transaction(h);
827                 return ERR_PTR(ret);
828         }
829
830         return h;
831
832 join_fail:
833         if (type & __TRANS_FREEZABLE)
834                 sb_end_intwrite(fs_info->sb);
835         kmem_cache_free(btrfs_trans_handle_cachep, h);
836 alloc_fail:
837         if (num_bytes)
838                 btrfs_block_rsv_release(fs_info, trans_rsv, num_bytes, NULL);
839         if (delayed_refs_bytes)
840                 btrfs_space_info_free_bytes_may_use(fs_info, trans_rsv->space_info,
841                                                     delayed_refs_bytes);
842 reserve_fail:
843         btrfs_qgroup_free_meta_prealloc(root, qgroup_reserved);
844         return ERR_PTR(ret);
845 }
846
847 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
848                                                    unsigned int num_items)
849 {
850         return start_transaction(root, num_items, TRANS_START,
851                                  BTRFS_RESERVE_FLUSH_ALL, true);
852 }
853
854 struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
855                                         struct btrfs_root *root,
856                                         unsigned int num_items)
857 {
858         return start_transaction(root, num_items, TRANS_START,
859                                  BTRFS_RESERVE_FLUSH_ALL_STEAL, false);
860 }
861
862 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
863 {
864         return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,
865                                  true);
866 }
867
868 struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root)
869 {
870         return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
871                                  BTRFS_RESERVE_NO_FLUSH, true);
872 }
873
874 /*
875  * Similar to regular join but it never starts a transaction when none is
876  * running or when there's a running one at a state >= TRANS_STATE_UNBLOCKED.
877  * This is similar to btrfs_attach_transaction() but it allows the join to
878  * happen if the transaction commit already started but it's not yet in the
879  * "doing" phase (the state is < TRANS_STATE_COMMIT_DOING).
880  */
881 struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root)
882 {
883         return start_transaction(root, 0, TRANS_JOIN_NOSTART,
884                                  BTRFS_RESERVE_NO_FLUSH, true);
885 }
886
887 /*
888  * Catch the running transaction.
889  *
890  * It is used when we want to commit the current the transaction, but
891  * don't want to start a new one.
892  *
893  * Note: If this function return -ENOENT, it just means there is no
894  * running transaction. But it is possible that the inactive transaction
895  * is still in the memory, not fully on disk. If you hope there is no
896  * inactive transaction in the fs when -ENOENT is returned, you should
897  * invoke
898  *     btrfs_attach_transaction_barrier()
899  */
900 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
901 {
902         return start_transaction(root, 0, TRANS_ATTACH,
903                                  BTRFS_RESERVE_NO_FLUSH, true);
904 }
905
906 /*
907  * Catch the running transaction.
908  *
909  * It is similar to the above function, the difference is this one
910  * will wait for all the inactive transactions until they fully
911  * complete.
912  */
913 struct btrfs_trans_handle *
914 btrfs_attach_transaction_barrier(struct btrfs_root *root)
915 {
916         struct btrfs_trans_handle *trans;
917
918         trans = start_transaction(root, 0, TRANS_ATTACH,
919                                   BTRFS_RESERVE_NO_FLUSH, true);
920         if (trans == ERR_PTR(-ENOENT)) {
921                 int ret;
922
923                 ret = btrfs_wait_for_commit(root->fs_info, 0);
924                 if (ret)
925                         return ERR_PTR(ret);
926         }
927
928         return trans;
929 }
930
931 /* Wait for a transaction commit to reach at least the given state. */
932 static noinline void wait_for_commit(struct btrfs_transaction *commit,
933                                      const enum btrfs_trans_state min_state)
934 {
935         struct btrfs_fs_info *fs_info = commit->fs_info;
936         u64 transid = commit->transid;
937         bool put = false;
938
939         /*
940          * At the moment this function is called with min_state either being
941          * TRANS_STATE_COMPLETED or TRANS_STATE_SUPER_COMMITTED.
942          */
943         if (min_state == TRANS_STATE_COMPLETED)
944                 btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
945         else
946                 btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
947
948         while (1) {
949                 wait_event(commit->commit_wait, commit->state >= min_state);
950                 if (put)
951                         btrfs_put_transaction(commit);
952
953                 if (min_state < TRANS_STATE_COMPLETED)
954                         break;
955
956                 /*
957                  * A transaction isn't really completed until all of the
958                  * previous transactions are completed, but with fsync we can
959                  * end up with SUPER_COMMITTED transactions before a COMPLETED
960                  * transaction. Wait for those.
961                  */
962
963                 spin_lock(&fs_info->trans_lock);
964                 commit = list_first_entry_or_null(&fs_info->trans_list,
965                                                   struct btrfs_transaction,
966                                                   list);
967                 if (!commit || commit->transid > transid) {
968                         spin_unlock(&fs_info->trans_lock);
969                         break;
970                 }
971                 refcount_inc(&commit->use_count);
972                 put = true;
973                 spin_unlock(&fs_info->trans_lock);
974         }
975 }
976
977 int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
978 {
979         struct btrfs_transaction *cur_trans = NULL, *t;
980         int ret = 0;
981
982         if (transid) {
983                 if (transid <= btrfs_get_last_trans_committed(fs_info))
984                         goto out;
985
986                 /* find specified transaction */
987                 spin_lock(&fs_info->trans_lock);
988                 list_for_each_entry(t, &fs_info->trans_list, list) {
989                         if (t->transid == transid) {
990                                 cur_trans = t;
991                                 refcount_inc(&cur_trans->use_count);
992                                 ret = 0;
993                                 break;
994                         }
995                         if (t->transid > transid) {
996                                 ret = 0;
997                                 break;
998                         }
999                 }
1000                 spin_unlock(&fs_info->trans_lock);
1001
1002                 /*
1003                  * The specified transaction doesn't exist, or we
1004                  * raced with btrfs_commit_transaction
1005                  */
1006                 if (!cur_trans) {
1007                         if (transid > btrfs_get_last_trans_committed(fs_info))
1008                                 ret = -EINVAL;
1009                         goto out;
1010                 }
1011         } else {
1012                 /* find newest transaction that is committing | committed */
1013                 spin_lock(&fs_info->trans_lock);
1014                 list_for_each_entry_reverse(t, &fs_info->trans_list,
1015                                             list) {
1016                         if (t->state >= TRANS_STATE_COMMIT_START) {
1017                                 if (t->state == TRANS_STATE_COMPLETED)
1018                                         break;
1019                                 cur_trans = t;
1020                                 refcount_inc(&cur_trans->use_count);
1021                                 break;
1022                         }
1023                 }
1024                 spin_unlock(&fs_info->trans_lock);
1025                 if (!cur_trans)
1026                         goto out;  /* nothing committing|committed */
1027         }
1028
1029         wait_for_commit(cur_trans, TRANS_STATE_COMPLETED);
1030         ret = cur_trans->aborted;
1031         btrfs_put_transaction(cur_trans);
1032 out:
1033         return ret;
1034 }
1035
1036 void btrfs_throttle(struct btrfs_fs_info *fs_info)
1037 {
1038         wait_current_trans(fs_info);
1039 }
1040
1041 bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
1042 {
1043         struct btrfs_transaction *cur_trans = trans->transaction;
1044
1045         if (cur_trans->state >= TRANS_STATE_COMMIT_START ||
1046             test_bit(BTRFS_DELAYED_REFS_FLUSHING, &cur_trans->delayed_refs.flags))
1047                 return true;
1048
1049         if (btrfs_check_space_for_delayed_refs(trans->fs_info))
1050                 return true;
1051
1052         return !!btrfs_block_rsv_check(&trans->fs_info->global_block_rsv, 50);
1053 }
1054
1055 static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans)
1056
1057 {
1058         struct btrfs_fs_info *fs_info = trans->fs_info;
1059
1060         if (!trans->block_rsv) {
1061                 ASSERT(!trans->bytes_reserved);
1062                 ASSERT(!trans->delayed_refs_bytes_reserved);
1063                 return;
1064         }
1065
1066         if (!trans->bytes_reserved) {
1067                 ASSERT(!trans->delayed_refs_bytes_reserved);
1068                 return;
1069         }
1070
1071         ASSERT(trans->block_rsv == &fs_info->trans_block_rsv);
1072         trace_btrfs_space_reservation(fs_info, "transaction",
1073                                       trans->transid, trans->bytes_reserved, 0);
1074         btrfs_block_rsv_release(fs_info, trans->block_rsv,
1075                                 trans->bytes_reserved, NULL);
1076         trans->bytes_reserved = 0;
1077
1078         if (!trans->delayed_refs_bytes_reserved)
1079                 return;
1080
1081         trace_btrfs_space_reservation(fs_info, "local_delayed_refs_rsv",
1082                                       trans->transid,
1083                                       trans->delayed_refs_bytes_reserved, 0);
1084         btrfs_block_rsv_release(fs_info, &trans->delayed_rsv,
1085                                 trans->delayed_refs_bytes_reserved, NULL);
1086         trans->delayed_refs_bytes_reserved = 0;
1087 }
1088
1089 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
1090                                    int throttle)
1091 {
1092         struct btrfs_fs_info *info = trans->fs_info;
1093         struct btrfs_transaction *cur_trans = trans->transaction;
1094         int err = 0;
1095
1096         if (refcount_read(&trans->use_count) > 1) {
1097                 refcount_dec(&trans->use_count);
1098                 trans->block_rsv = trans->orig_rsv;
1099                 return 0;
1100         }
1101
1102         btrfs_trans_release_metadata(trans);
1103         trans->block_rsv = NULL;
1104
1105         btrfs_create_pending_block_groups(trans);
1106
1107         btrfs_trans_release_chunk_metadata(trans);
1108
1109         if (trans->type & __TRANS_FREEZABLE)
1110                 sb_end_intwrite(info->sb);
1111
1112         WARN_ON(cur_trans != info->running_transaction);
1113         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
1114         atomic_dec(&cur_trans->num_writers);
1115         extwriter_counter_dec(cur_trans, trans->type);
1116
1117         cond_wake_up(&cur_trans->writer_wait);
1118
1119         btrfs_lockdep_release(info, btrfs_trans_num_extwriters);
1120         btrfs_lockdep_release(info, btrfs_trans_num_writers);
1121
1122         btrfs_put_transaction(cur_trans);
1123
1124         if (current->journal_info == trans)
1125                 current->journal_info = NULL;
1126
1127         if (throttle)
1128                 btrfs_run_delayed_iputs(info);
1129
1130         if (TRANS_ABORTED(trans) || BTRFS_FS_ERROR(info)) {
1131                 wake_up_process(info->transaction_kthread);
1132                 if (TRANS_ABORTED(trans))
1133                         err = trans->aborted;
1134                 else
1135                         err = -EROFS;
1136         }
1137
1138         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1139         return err;
1140 }
1141
1142 int btrfs_end_transaction(struct btrfs_trans_handle *trans)
1143 {
1144         return __btrfs_end_transaction(trans, 0);
1145 }
1146
1147 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
1148 {
1149         return __btrfs_end_transaction(trans, 1);
1150 }
1151
1152 /*
1153  * when btree blocks are allocated, they have some corresponding bits set for
1154  * them in one of two extent_io trees.  This is used to make sure all of
1155  * those extents are sent to disk but does not wait on them
1156  */
1157 int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
1158                                struct extent_io_tree *dirty_pages, int mark)
1159 {
1160         int err = 0;
1161         int werr = 0;
1162         struct address_space *mapping = fs_info->btree_inode->i_mapping;
1163         struct extent_state *cached_state = NULL;
1164         u64 start = 0;
1165         u64 end;
1166
1167         while (find_first_extent_bit(dirty_pages, start, &start, &end,
1168                                      mark, &cached_state)) {
1169                 bool wait_writeback = false;
1170
1171                 err = convert_extent_bit(dirty_pages, start, end,
1172                                          EXTENT_NEED_WAIT,
1173                                          mark, &cached_state);
1174                 /*
1175                  * convert_extent_bit can return -ENOMEM, which is most of the
1176                  * time a temporary error. So when it happens, ignore the error
1177                  * and wait for writeback of this range to finish - because we
1178                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
1179                  * to __btrfs_wait_marked_extents() would not know that
1180                  * writeback for this range started and therefore wouldn't
1181                  * wait for it to finish - we don't want to commit a
1182                  * superblock that points to btree nodes/leafs for which
1183                  * writeback hasn't finished yet (and without errors).
1184                  * We cleanup any entries left in the io tree when committing
1185                  * the transaction (through extent_io_tree_release()).
1186                  */
1187                 if (err == -ENOMEM) {
1188                         err = 0;
1189                         wait_writeback = true;
1190                 }
1191                 if (!err)
1192                         err = filemap_fdatawrite_range(mapping, start, end);
1193                 if (err)
1194                         werr = err;
1195                 else if (wait_writeback)
1196                         werr = filemap_fdatawait_range(mapping, start, end);
1197                 free_extent_state(cached_state);
1198                 cached_state = NULL;
1199                 cond_resched();
1200                 start = end + 1;
1201         }
1202         return werr;
1203 }
1204
1205 /*
1206  * when btree blocks are allocated, they have some corresponding bits set for
1207  * them in one of two extent_io trees.  This is used to make sure all of
1208  * those extents are on disk for transaction or log commit.  We wait
1209  * on all the pages and clear them from the dirty pages state tree
1210  */
1211 static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
1212                                        struct extent_io_tree *dirty_pages)
1213 {
1214         int err = 0;
1215         int werr = 0;
1216         struct address_space *mapping = fs_info->btree_inode->i_mapping;
1217         struct extent_state *cached_state = NULL;
1218         u64 start = 0;
1219         u64 end;
1220
1221         while (find_first_extent_bit(dirty_pages, start, &start, &end,
1222                                      EXTENT_NEED_WAIT, &cached_state)) {
1223                 /*
1224                  * Ignore -ENOMEM errors returned by clear_extent_bit().
1225                  * When committing the transaction, we'll remove any entries
1226                  * left in the io tree. For a log commit, we don't remove them
1227                  * after committing the log because the tree can be accessed
1228                  * concurrently - we do it only at transaction commit time when
1229                  * it's safe to do it (through extent_io_tree_release()).
1230                  */
1231                 err = clear_extent_bit(dirty_pages, start, end,
1232                                        EXTENT_NEED_WAIT, &cached_state);
1233                 if (err == -ENOMEM)
1234                         err = 0;
1235                 if (!err)
1236                         err = filemap_fdatawait_range(mapping, start, end);
1237                 if (err)
1238                         werr = err;
1239                 free_extent_state(cached_state);
1240                 cached_state = NULL;
1241                 cond_resched();
1242                 start = end + 1;
1243         }
1244         if (err)
1245                 werr = err;
1246         return werr;
1247 }
1248
1249 static int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1250                        struct extent_io_tree *dirty_pages)
1251 {
1252         bool errors = false;
1253         int err;
1254
1255         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1256         if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1257                 errors = true;
1258
1259         if (errors && !err)
1260                 err = -EIO;
1261         return err;
1262 }
1263
1264 int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1265 {
1266         struct btrfs_fs_info *fs_info = log_root->fs_info;
1267         struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1268         bool errors = false;
1269         int err;
1270
1271         ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
1272
1273         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1274         if ((mark & EXTENT_DIRTY) &&
1275             test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1276                 errors = true;
1277
1278         if ((mark & EXTENT_NEW) &&
1279             test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1280                 errors = true;
1281
1282         if (errors && !err)
1283                 err = -EIO;
1284         return err;
1285 }
1286
1287 /*
1288  * When btree blocks are allocated the corresponding extents are marked dirty.
1289  * This function ensures such extents are persisted on disk for transaction or
1290  * log commit.
1291  *
1292  * @trans: transaction whose dirty pages we'd like to write
1293  */
1294 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)
1295 {
1296         int ret;
1297         int ret2;
1298         struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;
1299         struct btrfs_fs_info *fs_info = trans->fs_info;
1300         struct blk_plug plug;
1301
1302         blk_start_plug(&plug);
1303         ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);
1304         blk_finish_plug(&plug);
1305         ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1306
1307         extent_io_tree_release(&trans->transaction->dirty_pages);
1308
1309         if (ret)
1310                 return ret;
1311         else if (ret2)
1312                 return ret2;
1313         else
1314                 return 0;
1315 }
1316
1317 /*
1318  * this is used to update the root pointer in the tree of tree roots.
1319  *
1320  * But, in the case of the extent allocation tree, updating the root
1321  * pointer may allocate blocks which may change the root of the extent
1322  * allocation tree.
1323  *
1324  * So, this loops and repeats and makes sure the cowonly root didn't
1325  * change while the root pointer was being updated in the metadata.
1326  */
1327 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1328                                struct btrfs_root *root)
1329 {
1330         int ret;
1331         u64 old_root_bytenr;
1332         u64 old_root_used;
1333         struct btrfs_fs_info *fs_info = root->fs_info;
1334         struct btrfs_root *tree_root = fs_info->tree_root;
1335
1336         old_root_used = btrfs_root_used(&root->root_item);
1337
1338         while (1) {
1339                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1340                 if (old_root_bytenr == root->node->start &&
1341                     old_root_used == btrfs_root_used(&root->root_item))
1342                         break;
1343
1344                 btrfs_set_root_node(&root->root_item, root->node);
1345                 ret = btrfs_update_root(trans, tree_root,
1346                                         &root->root_key,
1347                                         &root->root_item);
1348                 if (ret)
1349                         return ret;
1350
1351                 old_root_used = btrfs_root_used(&root->root_item);
1352         }
1353
1354         return 0;
1355 }
1356
1357 /*
1358  * update all the cowonly tree roots on disk
1359  *
1360  * The error handling in this function may not be obvious. Any of the
1361  * failures will cause the file system to go offline. We still need
1362  * to clean up the delayed refs.
1363  */
1364 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)
1365 {
1366         struct btrfs_fs_info *fs_info = trans->fs_info;
1367         struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1368         struct list_head *io_bgs = &trans->transaction->io_bgs;
1369         struct list_head *next;
1370         struct extent_buffer *eb;
1371         int ret;
1372
1373         /*
1374          * At this point no one can be using this transaction to modify any tree
1375          * and no one can start another transaction to modify any tree either.
1376          */
1377         ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);
1378
1379         eb = btrfs_lock_root_node(fs_info->tree_root);
1380         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1381                               0, &eb, BTRFS_NESTING_COW);
1382         btrfs_tree_unlock(eb);
1383         free_extent_buffer(eb);
1384
1385         if (ret)
1386                 return ret;
1387
1388         ret = btrfs_run_dev_stats(trans);
1389         if (ret)
1390                 return ret;
1391         ret = btrfs_run_dev_replace(trans);
1392         if (ret)
1393                 return ret;
1394         ret = btrfs_run_qgroups(trans);
1395         if (ret)
1396                 return ret;
1397
1398         ret = btrfs_setup_space_cache(trans);
1399         if (ret)
1400                 return ret;
1401
1402 again:
1403         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1404                 struct btrfs_root *root;
1405                 next = fs_info->dirty_cowonly_roots.next;
1406                 list_del_init(next);
1407                 root = list_entry(next, struct btrfs_root, dirty_list);
1408                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1409
1410                 list_add_tail(&root->dirty_list,
1411                               &trans->transaction->switch_commits);
1412                 ret = update_cowonly_root(trans, root);
1413                 if (ret)
1414                         return ret;
1415         }
1416
1417         /* Now flush any delayed refs generated by updating all of the roots */
1418         ret = btrfs_run_delayed_refs(trans, U64_MAX);
1419         if (ret)
1420                 return ret;
1421
1422         while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1423                 ret = btrfs_write_dirty_block_groups(trans);
1424                 if (ret)
1425                         return ret;
1426
1427                 /*
1428                  * We're writing the dirty block groups, which could generate
1429                  * delayed refs, which could generate more dirty block groups,
1430                  * so we want to keep this flushing in this loop to make sure
1431                  * everything gets run.
1432                  */
1433                 ret = btrfs_run_delayed_refs(trans, U64_MAX);
1434                 if (ret)
1435                         return ret;
1436         }
1437
1438         if (!list_empty(&fs_info->dirty_cowonly_roots))
1439                 goto again;
1440
1441         /* Update dev-replace pointer once everything is committed */
1442         fs_info->dev_replace.committed_cursor_left =
1443                 fs_info->dev_replace.cursor_left_last_write_of_item;
1444
1445         return 0;
1446 }
1447
1448 /*
1449  * If we had a pending drop we need to see if there are any others left in our
1450  * dead roots list, and if not clear our bit and wake any waiters.
1451  */
1452 void btrfs_maybe_wake_unfinished_drop(struct btrfs_fs_info *fs_info)
1453 {
1454         /*
1455          * We put the drop in progress roots at the front of the list, so if the
1456          * first entry doesn't have UNFINISHED_DROP set we can wake everybody
1457          * up.
1458          */
1459         spin_lock(&fs_info->trans_lock);
1460         if (!list_empty(&fs_info->dead_roots)) {
1461                 struct btrfs_root *root = list_first_entry(&fs_info->dead_roots,
1462                                                            struct btrfs_root,
1463                                                            root_list);
1464                 if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state)) {
1465                         spin_unlock(&fs_info->trans_lock);
1466                         return;
1467                 }
1468         }
1469         spin_unlock(&fs_info->trans_lock);
1470
1471         btrfs_wake_unfinished_drop(fs_info);
1472 }
1473
1474 /*
1475  * dead roots are old snapshots that need to be deleted.  This allocates
1476  * a dirty root struct and adds it into the list of dead roots that need to
1477  * be deleted
1478  */
1479 void btrfs_add_dead_root(struct btrfs_root *root)
1480 {
1481         struct btrfs_fs_info *fs_info = root->fs_info;
1482
1483         spin_lock(&fs_info->trans_lock);
1484         if (list_empty(&root->root_list)) {
1485                 btrfs_grab_root(root);
1486
1487                 /* We want to process the partially complete drops first. */
1488                 if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state))
1489                         list_add(&root->root_list, &fs_info->dead_roots);
1490                 else
1491                         list_add_tail(&root->root_list, &fs_info->dead_roots);
1492         }
1493         spin_unlock(&fs_info->trans_lock);
1494 }
1495
1496 /*
1497  * Update each subvolume root and its relocation root, if it exists, in the tree
1498  * of tree roots. Also free log roots if they exist.
1499  */
1500 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
1501 {
1502         struct btrfs_fs_info *fs_info = trans->fs_info;
1503         struct btrfs_root *gang[8];
1504         int i;
1505         int ret;
1506
1507         /*
1508          * At this point no one can be using this transaction to modify any tree
1509          * and no one can start another transaction to modify any tree either.
1510          */
1511         ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);
1512
1513         spin_lock(&fs_info->fs_roots_radix_lock);
1514         while (1) {
1515                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1516                                                  (void **)gang, 0,
1517                                                  ARRAY_SIZE(gang),
1518                                                  BTRFS_ROOT_TRANS_TAG);
1519                 if (ret == 0)
1520                         break;
1521                 for (i = 0; i < ret; i++) {
1522                         struct btrfs_root *root = gang[i];
1523                         int ret2;
1524
1525                         /*
1526                          * At this point we can neither have tasks logging inodes
1527                          * from a root nor trying to commit a log tree.
1528                          */
1529                         ASSERT(atomic_read(&root->log_writers) == 0);
1530                         ASSERT(atomic_read(&root->log_commit[0]) == 0);
1531                         ASSERT(atomic_read(&root->log_commit[1]) == 0);
1532
1533                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1534                                         (unsigned long)root->root_key.objectid,
1535                                         BTRFS_ROOT_TRANS_TAG);
1536                         spin_unlock(&fs_info->fs_roots_radix_lock);
1537
1538                         btrfs_free_log(trans, root);
1539                         ret2 = btrfs_update_reloc_root(trans, root);
1540                         if (ret2)
1541                                 return ret2;
1542
1543                         /* see comments in should_cow_block() */
1544                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1545                         smp_mb__after_atomic();
1546
1547                         if (root->commit_root != root->node) {
1548                                 list_add_tail(&root->dirty_list,
1549                                         &trans->transaction->switch_commits);
1550                                 btrfs_set_root_node(&root->root_item,
1551                                                     root->node);
1552                         }
1553
1554                         ret2 = btrfs_update_root(trans, fs_info->tree_root,
1555                                                 &root->root_key,
1556                                                 &root->root_item);
1557                         if (ret2)
1558                                 return ret2;
1559                         spin_lock(&fs_info->fs_roots_radix_lock);
1560                         btrfs_qgroup_free_meta_all_pertrans(root);
1561                 }
1562         }
1563         spin_unlock(&fs_info->fs_roots_radix_lock);
1564         return 0;
1565 }
1566
1567 /*
1568  * Do all special snapshot related qgroup dirty hack.
1569  *
1570  * Will do all needed qgroup inherit and dirty hack like switch commit
1571  * roots inside one transaction and write all btree into disk, to make
1572  * qgroup works.
1573  */
1574 static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1575                                    struct btrfs_root *src,
1576                                    struct btrfs_root *parent,
1577                                    struct btrfs_qgroup_inherit *inherit,
1578                                    u64 dst_objectid)
1579 {
1580         struct btrfs_fs_info *fs_info = src->fs_info;
1581         int ret;
1582
1583         /*
1584          * Save some performance in the case that qgroups are not enabled. If
1585          * this check races with the ioctl, rescan will kick in anyway.
1586          */
1587         if (!btrfs_qgroup_full_accounting(fs_info))
1588                 return 0;
1589
1590         /*
1591          * Ensure dirty @src will be committed.  Or, after coming
1592          * commit_fs_roots() and switch_commit_roots(), any dirty but not
1593          * recorded root will never be updated again, causing an outdated root
1594          * item.
1595          */
1596         ret = record_root_in_trans(trans, src, 1);
1597         if (ret)
1598                 return ret;
1599
1600         /*
1601          * btrfs_qgroup_inherit relies on a consistent view of the usage for the
1602          * src root, so we must run the delayed refs here.
1603          *
1604          * However this isn't particularly fool proof, because there's no
1605          * synchronization keeping us from changing the tree after this point
1606          * before we do the qgroup_inherit, or even from making changes while
1607          * we're doing the qgroup_inherit.  But that's a problem for the future,
1608          * for now flush the delayed refs to narrow the race window where the
1609          * qgroup counters could end up wrong.
1610          */
1611         ret = btrfs_run_delayed_refs(trans, U64_MAX);
1612         if (ret) {
1613                 btrfs_abort_transaction(trans, ret);
1614                 return ret;
1615         }
1616
1617         ret = commit_fs_roots(trans);
1618         if (ret)
1619                 goto out;
1620         ret = btrfs_qgroup_account_extents(trans);
1621         if (ret < 0)
1622                 goto out;
1623
1624         /* Now qgroup are all updated, we can inherit it to new qgroups */
1625         ret = btrfs_qgroup_inherit(trans, src->root_key.objectid, dst_objectid,
1626                                    parent->root_key.objectid, inherit);
1627         if (ret < 0)
1628                 goto out;
1629
1630         /*
1631          * Now we do a simplified commit transaction, which will:
1632          * 1) commit all subvolume and extent tree
1633          *    To ensure all subvolume and extent tree have a valid
1634          *    commit_root to accounting later insert_dir_item()
1635          * 2) write all btree blocks onto disk
1636          *    This is to make sure later btree modification will be cowed
1637          *    Or commit_root can be populated and cause wrong qgroup numbers
1638          * In this simplified commit, we don't really care about other trees
1639          * like chunk and root tree, as they won't affect qgroup.
1640          * And we don't write super to avoid half committed status.
1641          */
1642         ret = commit_cowonly_roots(trans);
1643         if (ret)
1644                 goto out;
1645         switch_commit_roots(trans);
1646         ret = btrfs_write_and_wait_transaction(trans);
1647         if (ret)
1648                 btrfs_handle_fs_error(fs_info, ret,
1649                         "Error while writing out transaction for qgroup");
1650
1651 out:
1652         /*
1653          * Force parent root to be updated, as we recorded it before so its
1654          * last_trans == cur_transid.
1655          * Or it won't be committed again onto disk after later
1656          * insert_dir_item()
1657          */
1658         if (!ret)
1659                 ret = record_root_in_trans(trans, parent, 1);
1660         return ret;
1661 }
1662
1663 /*
1664  * new snapshots need to be created at a very specific time in the
1665  * transaction commit.  This does the actual creation.
1666  *
1667  * Note:
1668  * If the error which may affect the commitment of the current transaction
1669  * happens, we should return the error number. If the error which just affect
1670  * the creation of the pending snapshots, just return 0.
1671  */
1672 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1673                                    struct btrfs_pending_snapshot *pending)
1674 {
1675
1676         struct btrfs_fs_info *fs_info = trans->fs_info;
1677         struct btrfs_key key;
1678         struct btrfs_root_item *new_root_item;
1679         struct btrfs_root *tree_root = fs_info->tree_root;
1680         struct btrfs_root *root = pending->root;
1681         struct btrfs_root *parent_root;
1682         struct btrfs_block_rsv *rsv;
1683         struct inode *parent_inode = pending->dir;
1684         struct btrfs_path *path;
1685         struct btrfs_dir_item *dir_item;
1686         struct extent_buffer *tmp;
1687         struct extent_buffer *old;
1688         struct timespec64 cur_time;
1689         int ret = 0;
1690         u64 to_reserve = 0;
1691         u64 index = 0;
1692         u64 objectid;
1693         u64 root_flags;
1694         unsigned int nofs_flags;
1695         struct fscrypt_name fname;
1696
1697         ASSERT(pending->path);
1698         path = pending->path;
1699
1700         ASSERT(pending->root_item);
1701         new_root_item = pending->root_item;
1702
1703         /*
1704          * We're inside a transaction and must make sure that any potential
1705          * allocations with GFP_KERNEL in fscrypt won't recurse back to
1706          * filesystem.
1707          */
1708         nofs_flags = memalloc_nofs_save();
1709         pending->error = fscrypt_setup_filename(parent_inode,
1710                                                 &pending->dentry->d_name, 0,
1711                                                 &fname);
1712         memalloc_nofs_restore(nofs_flags);
1713         if (pending->error)
1714                 goto free_pending;
1715
1716         pending->error = btrfs_get_free_objectid(tree_root, &objectid);
1717         if (pending->error)
1718                 goto free_fname;
1719
1720         /*
1721          * Make qgroup to skip current new snapshot's qgroupid, as it is
1722          * accounted by later btrfs_qgroup_inherit().
1723          */
1724         btrfs_set_skip_qgroup(trans, objectid);
1725
1726         btrfs_reloc_pre_snapshot(pending, &to_reserve);
1727
1728         if (to_reserve > 0) {
1729                 pending->error = btrfs_block_rsv_add(fs_info,
1730                                                      &pending->block_rsv,
1731                                                      to_reserve,
1732                                                      BTRFS_RESERVE_NO_FLUSH);
1733                 if (pending->error)
1734                         goto clear_skip_qgroup;
1735         }
1736
1737         key.objectid = objectid;
1738         key.offset = (u64)-1;
1739         key.type = BTRFS_ROOT_ITEM_KEY;
1740
1741         rsv = trans->block_rsv;
1742         trans->block_rsv = &pending->block_rsv;
1743         trans->bytes_reserved = trans->block_rsv->reserved;
1744         trace_btrfs_space_reservation(fs_info, "transaction",
1745                                       trans->transid,
1746                                       trans->bytes_reserved, 1);
1747         parent_root = BTRFS_I(parent_inode)->root;
1748         ret = record_root_in_trans(trans, parent_root, 0);
1749         if (ret)
1750                 goto fail;
1751         cur_time = current_time(parent_inode);
1752
1753         /*
1754          * insert the directory item
1755          */
1756         ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);
1757         if (ret) {
1758                 btrfs_abort_transaction(trans, ret);
1759                 goto fail;
1760         }
1761
1762         /* check if there is a file/dir which has the same name. */
1763         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1764                                          btrfs_ino(BTRFS_I(parent_inode)),
1765                                          &fname.disk_name, 0);
1766         if (dir_item != NULL && !IS_ERR(dir_item)) {
1767                 pending->error = -EEXIST;
1768                 goto dir_item_existed;
1769         } else if (IS_ERR(dir_item)) {
1770                 ret = PTR_ERR(dir_item);
1771                 btrfs_abort_transaction(trans, ret);
1772                 goto fail;
1773         }
1774         btrfs_release_path(path);
1775
1776         ret = btrfs_create_qgroup(trans, objectid);
1777         if (ret) {
1778                 btrfs_abort_transaction(trans, ret);
1779                 goto fail;
1780         }
1781
1782         /*
1783          * pull in the delayed directory update
1784          * and the delayed inode item
1785          * otherwise we corrupt the FS during
1786          * snapshot
1787          */
1788         ret = btrfs_run_delayed_items(trans);
1789         if (ret) {      /* Transaction aborted */
1790                 btrfs_abort_transaction(trans, ret);
1791                 goto fail;
1792         }
1793
1794         ret = record_root_in_trans(trans, root, 0);
1795         if (ret) {
1796                 btrfs_abort_transaction(trans, ret);
1797                 goto fail;
1798         }
1799         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1800         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1801         btrfs_check_and_init_root_item(new_root_item);
1802
1803         root_flags = btrfs_root_flags(new_root_item);
1804         if (pending->readonly)
1805                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1806         else
1807                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1808         btrfs_set_root_flags(new_root_item, root_flags);
1809
1810         btrfs_set_root_generation_v2(new_root_item,
1811                         trans->transid);
1812         generate_random_guid(new_root_item->uuid);
1813         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1814                         BTRFS_UUID_SIZE);
1815         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1816                 memset(new_root_item->received_uuid, 0,
1817                        sizeof(new_root_item->received_uuid));
1818                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1819                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1820                 btrfs_set_root_stransid(new_root_item, 0);
1821                 btrfs_set_root_rtransid(new_root_item, 0);
1822         }
1823         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1824         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1825         btrfs_set_root_otransid(new_root_item, trans->transid);
1826
1827         old = btrfs_lock_root_node(root);
1828         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old,
1829                               BTRFS_NESTING_COW);
1830         if (ret) {
1831                 btrfs_tree_unlock(old);
1832                 free_extent_buffer(old);
1833                 btrfs_abort_transaction(trans, ret);
1834                 goto fail;
1835         }
1836
1837         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1838         /* clean up in any case */
1839         btrfs_tree_unlock(old);
1840         free_extent_buffer(old);
1841         if (ret) {
1842                 btrfs_abort_transaction(trans, ret);
1843                 goto fail;
1844         }
1845         /* see comments in should_cow_block() */
1846         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1847         smp_wmb();
1848
1849         btrfs_set_root_node(new_root_item, tmp);
1850         /* record when the snapshot was created in key.offset */
1851         key.offset = trans->transid;
1852         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1853         btrfs_tree_unlock(tmp);
1854         free_extent_buffer(tmp);
1855         if (ret) {
1856                 btrfs_abort_transaction(trans, ret);
1857                 goto fail;
1858         }
1859
1860         /*
1861          * insert root back/forward references
1862          */
1863         ret = btrfs_add_root_ref(trans, objectid,
1864                                  parent_root->root_key.objectid,
1865                                  btrfs_ino(BTRFS_I(parent_inode)), index,
1866                                  &fname.disk_name);
1867         if (ret) {
1868                 btrfs_abort_transaction(trans, ret);
1869                 goto fail;
1870         }
1871
1872         key.offset = (u64)-1;
1873         pending->snap = btrfs_get_new_fs_root(fs_info, objectid, pending->anon_dev);
1874         if (IS_ERR(pending->snap)) {
1875                 ret = PTR_ERR(pending->snap);
1876                 pending->snap = NULL;
1877                 btrfs_abort_transaction(trans, ret);
1878                 goto fail;
1879         }
1880
1881         ret = btrfs_reloc_post_snapshot(trans, pending);
1882         if (ret) {
1883                 btrfs_abort_transaction(trans, ret);
1884                 goto fail;
1885         }
1886
1887         /*
1888          * Do special qgroup accounting for snapshot, as we do some qgroup
1889          * snapshot hack to do fast snapshot.
1890          * To co-operate with that hack, we do hack again.
1891          * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1892          */
1893         if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_FULL)
1894                 ret = qgroup_account_snapshot(trans, root, parent_root,
1895                                               pending->inherit, objectid);
1896         else if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_SIMPLE)
1897                 ret = btrfs_qgroup_inherit(trans, root->root_key.objectid, objectid,
1898                                            parent_root->root_key.objectid, pending->inherit);
1899         if (ret < 0)
1900                 goto fail;
1901
1902         ret = btrfs_insert_dir_item(trans, &fname.disk_name,
1903                                     BTRFS_I(parent_inode), &key, BTRFS_FT_DIR,
1904                                     index);
1905         /* We have check then name at the beginning, so it is impossible. */
1906         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1907         if (ret) {
1908                 btrfs_abort_transaction(trans, ret);
1909                 goto fail;
1910         }
1911
1912         btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +
1913                                                   fname.disk_name.len * 2);
1914         inode_set_mtime_to_ts(parent_inode,
1915                               inode_set_ctime_current(parent_inode));
1916         ret = btrfs_update_inode_fallback(trans, BTRFS_I(parent_inode));
1917         if (ret) {
1918                 btrfs_abort_transaction(trans, ret);
1919                 goto fail;
1920         }
1921         ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,
1922                                   BTRFS_UUID_KEY_SUBVOL,
1923                                   objectid);
1924         if (ret) {
1925                 btrfs_abort_transaction(trans, ret);
1926                 goto fail;
1927         }
1928         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1929                 ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid,
1930                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1931                                           objectid);
1932                 if (ret && ret != -EEXIST) {
1933                         btrfs_abort_transaction(trans, ret);
1934                         goto fail;
1935                 }
1936         }
1937
1938 fail:
1939         pending->error = ret;
1940 dir_item_existed:
1941         trans->block_rsv = rsv;
1942         trans->bytes_reserved = 0;
1943 clear_skip_qgroup:
1944         btrfs_clear_skip_qgroup(trans);
1945 free_fname:
1946         fscrypt_free_filename(&fname);
1947 free_pending:
1948         kfree(new_root_item);
1949         pending->root_item = NULL;
1950         btrfs_free_path(path);
1951         pending->path = NULL;
1952
1953         return ret;
1954 }
1955
1956 /*
1957  * create all the snapshots we've scheduled for creation
1958  */
1959 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)
1960 {
1961         struct btrfs_pending_snapshot *pending, *next;
1962         struct list_head *head = &trans->transaction->pending_snapshots;
1963         int ret = 0;
1964
1965         list_for_each_entry_safe(pending, next, head, list) {
1966                 list_del(&pending->list);
1967                 ret = create_pending_snapshot(trans, pending);
1968                 if (ret)
1969                         break;
1970         }
1971         return ret;
1972 }
1973
1974 static void update_super_roots(struct btrfs_fs_info *fs_info)
1975 {
1976         struct btrfs_root_item *root_item;
1977         struct btrfs_super_block *super;
1978
1979         super = fs_info->super_copy;
1980
1981         root_item = &fs_info->chunk_root->root_item;
1982         super->chunk_root = root_item->bytenr;
1983         super->chunk_root_generation = root_item->generation;
1984         super->chunk_root_level = root_item->level;
1985
1986         root_item = &fs_info->tree_root->root_item;
1987         super->root = root_item->bytenr;
1988         super->generation = root_item->generation;
1989         super->root_level = root_item->level;
1990         if (btrfs_test_opt(fs_info, SPACE_CACHE))
1991                 super->cache_generation = root_item->generation;
1992         else if (test_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags))
1993                 super->cache_generation = 0;
1994         if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1995                 super->uuid_tree_generation = root_item->generation;
1996 }
1997
1998 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1999 {
2000         struct btrfs_transaction *trans;
2001         int ret = 0;
2002
2003         spin_lock(&info->trans_lock);
2004         trans = info->running_transaction;
2005         if (trans)
2006                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
2007         spin_unlock(&info->trans_lock);
2008         return ret;
2009 }
2010
2011 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
2012 {
2013         struct btrfs_transaction *trans;
2014         int ret = 0;
2015
2016         spin_lock(&info->trans_lock);
2017         trans = info->running_transaction;
2018         if (trans)
2019                 ret = is_transaction_blocked(trans);
2020         spin_unlock(&info->trans_lock);
2021         return ret;
2022 }
2023
2024 void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
2025 {
2026         struct btrfs_fs_info *fs_info = trans->fs_info;
2027         struct btrfs_transaction *cur_trans;
2028
2029         /* Kick the transaction kthread. */
2030         set_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
2031         wake_up_process(fs_info->transaction_kthread);
2032
2033         /* take transaction reference */
2034         cur_trans = trans->transaction;
2035         refcount_inc(&cur_trans->use_count);
2036
2037         btrfs_end_transaction(trans);
2038
2039         /*
2040          * Wait for the current transaction commit to start and block
2041          * subsequent transaction joins
2042          */
2043         btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2044         wait_event(fs_info->transaction_blocked_wait,
2045                    cur_trans->state >= TRANS_STATE_COMMIT_START ||
2046                    TRANS_ABORTED(cur_trans));
2047         btrfs_put_transaction(cur_trans);
2048 }
2049
2050 static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
2051 {
2052         struct btrfs_fs_info *fs_info = trans->fs_info;
2053         struct btrfs_transaction *cur_trans = trans->transaction;
2054
2055         WARN_ON(refcount_read(&trans->use_count) > 1);
2056
2057         btrfs_abort_transaction(trans, err);
2058
2059         spin_lock(&fs_info->trans_lock);
2060
2061         /*
2062          * If the transaction is removed from the list, it means this
2063          * transaction has been committed successfully, so it is impossible
2064          * to call the cleanup function.
2065          */
2066         BUG_ON(list_empty(&cur_trans->list));
2067
2068         if (cur_trans == fs_info->running_transaction) {
2069                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
2070                 spin_unlock(&fs_info->trans_lock);
2071
2072                 /*
2073                  * The thread has already released the lockdep map as reader
2074                  * already in btrfs_commit_transaction().
2075                  */
2076                 btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);
2077                 wait_event(cur_trans->writer_wait,
2078                            atomic_read(&cur_trans->num_writers) == 1);
2079
2080                 spin_lock(&fs_info->trans_lock);
2081         }
2082
2083         /*
2084          * Now that we know no one else is still using the transaction we can
2085          * remove the transaction from the list of transactions. This avoids
2086          * the transaction kthread from cleaning up the transaction while some
2087          * other task is still using it, which could result in a use-after-free
2088          * on things like log trees, as it forces the transaction kthread to
2089          * wait for this transaction to be cleaned up by us.
2090          */
2091         list_del_init(&cur_trans->list);
2092
2093         spin_unlock(&fs_info->trans_lock);
2094
2095         btrfs_cleanup_one_transaction(trans->transaction, fs_info);
2096
2097         spin_lock(&fs_info->trans_lock);
2098         if (cur_trans == fs_info->running_transaction)
2099                 fs_info->running_transaction = NULL;
2100         spin_unlock(&fs_info->trans_lock);
2101
2102         if (trans->type & __TRANS_FREEZABLE)
2103                 sb_end_intwrite(fs_info->sb);
2104         btrfs_put_transaction(cur_trans);
2105         btrfs_put_transaction(cur_trans);
2106
2107         trace_btrfs_transaction_commit(fs_info);
2108
2109         if (current->journal_info == trans)
2110                 current->journal_info = NULL;
2111
2112         /*
2113          * If relocation is running, we can't cancel scrub because that will
2114          * result in a deadlock. Before relocating a block group, relocation
2115          * pauses scrub, then starts and commits a transaction before unpausing
2116          * scrub. If the transaction commit is being done by the relocation
2117          * task or triggered by another task and the relocation task is waiting
2118          * for the commit, and we end up here due to an error in the commit
2119          * path, then calling btrfs_scrub_cancel() will deadlock, as we are
2120          * asking for scrub to stop while having it asked to be paused higher
2121          * above in relocation code.
2122          */
2123         if (!test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
2124                 btrfs_scrub_cancel(fs_info);
2125
2126         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2127 }
2128
2129 /*
2130  * Release reserved delayed ref space of all pending block groups of the
2131  * transaction and remove them from the list
2132  */
2133 static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)
2134 {
2135        struct btrfs_fs_info *fs_info = trans->fs_info;
2136        struct btrfs_block_group *block_group, *tmp;
2137
2138        list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {
2139                btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info);
2140                list_del_init(&block_group->bg_list);
2141        }
2142 }
2143
2144 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
2145 {
2146         /*
2147          * We use try_to_writeback_inodes_sb() here because if we used
2148          * btrfs_start_delalloc_roots we would deadlock with fs freeze.
2149          * Currently are holding the fs freeze lock, if we do an async flush
2150          * we'll do btrfs_join_transaction() and deadlock because we need to
2151          * wait for the fs freeze lock.  Using the direct flushing we benefit
2152          * from already being in a transaction and our join_transaction doesn't
2153          * have to re-take the fs freeze lock.
2154          *
2155          * Note that try_to_writeback_inodes_sb() will only trigger writeback
2156          * if it can read lock sb->s_umount. It will always be able to lock it,
2157          * except when the filesystem is being unmounted or being frozen, but in
2158          * those cases sync_filesystem() is called, which results in calling
2159          * writeback_inodes_sb() while holding a write lock on sb->s_umount.
2160          * Note that we don't call writeback_inodes_sb() directly, because it
2161          * will emit a warning if sb->s_umount is not locked.
2162          */
2163         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
2164                 try_to_writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
2165         return 0;
2166 }
2167
2168 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
2169 {
2170         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
2171                 btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
2172 }
2173
2174 /*
2175  * Add a pending snapshot associated with the given transaction handle to the
2176  * respective handle. This must be called after the transaction commit started
2177  * and while holding fs_info->trans_lock.
2178  * This serves to guarantee a caller of btrfs_commit_transaction() that it can
2179  * safely free the pending snapshot pointer in case btrfs_commit_transaction()
2180  * returns an error.
2181  */
2182 static void add_pending_snapshot(struct btrfs_trans_handle *trans)
2183 {
2184         struct btrfs_transaction *cur_trans = trans->transaction;
2185
2186         if (!trans->pending_snapshot)
2187                 return;
2188
2189         lockdep_assert_held(&trans->fs_info->trans_lock);
2190         ASSERT(cur_trans->state >= TRANS_STATE_COMMIT_PREP);
2191
2192         list_add(&trans->pending_snapshot->list, &cur_trans->pending_snapshots);
2193 }
2194
2195 static void update_commit_stats(struct btrfs_fs_info *fs_info, ktime_t interval)
2196 {
2197         fs_info->commit_stats.commit_count++;
2198         fs_info->commit_stats.last_commit_dur = interval;
2199         fs_info->commit_stats.max_commit_dur =
2200                         max_t(u64, fs_info->commit_stats.max_commit_dur, interval);
2201         fs_info->commit_stats.total_commit_dur += interval;
2202 }
2203
2204 int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
2205 {
2206         struct btrfs_fs_info *fs_info = trans->fs_info;
2207         struct btrfs_transaction *cur_trans = trans->transaction;
2208         struct btrfs_transaction *prev_trans = NULL;
2209         int ret;
2210         ktime_t start_time;
2211         ktime_t interval;
2212
2213         ASSERT(refcount_read(&trans->use_count) == 1);
2214         btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2215
2216         clear_bit(BTRFS_FS_NEED_TRANS_COMMIT, &fs_info->flags);
2217
2218         /* Stop the commit early if ->aborted is set */
2219         if (TRANS_ABORTED(cur_trans)) {
2220                 ret = cur_trans->aborted;
2221                 goto lockdep_trans_commit_start_release;
2222         }
2223
2224         btrfs_trans_release_metadata(trans);
2225         trans->block_rsv = NULL;
2226
2227         /*
2228          * We only want one transaction commit doing the flushing so we do not
2229          * waste a bunch of time on lock contention on the extent root node.
2230          */
2231         if (!test_and_set_bit(BTRFS_DELAYED_REFS_FLUSHING,
2232                               &cur_trans->delayed_refs.flags)) {
2233                 /*
2234                  * Make a pass through all the delayed refs we have so far.
2235                  * Any running threads may add more while we are here.
2236                  */
2237                 ret = btrfs_run_delayed_refs(trans, 0);
2238                 if (ret)
2239                         goto lockdep_trans_commit_start_release;
2240         }
2241
2242         btrfs_create_pending_block_groups(trans);
2243
2244         if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
2245                 int run_it = 0;
2246
2247                 /* this mutex is also taken before trying to set
2248                  * block groups readonly.  We need to make sure
2249                  * that nobody has set a block group readonly
2250                  * after a extents from that block group have been
2251                  * allocated for cache files.  btrfs_set_block_group_ro
2252                  * will wait for the transaction to commit if it
2253                  * finds BTRFS_TRANS_DIRTY_BG_RUN set.
2254                  *
2255                  * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
2256                  * only one process starts all the block group IO.  It wouldn't
2257                  * hurt to have more than one go through, but there's no
2258                  * real advantage to it either.
2259                  */
2260                 mutex_lock(&fs_info->ro_block_group_mutex);
2261                 if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
2262                                       &cur_trans->flags))
2263                         run_it = 1;
2264                 mutex_unlock(&fs_info->ro_block_group_mutex);
2265
2266                 if (run_it) {
2267                         ret = btrfs_start_dirty_block_groups(trans);
2268                         if (ret)
2269                                 goto lockdep_trans_commit_start_release;
2270                 }
2271         }
2272
2273         spin_lock(&fs_info->trans_lock);
2274         if (cur_trans->state >= TRANS_STATE_COMMIT_PREP) {
2275                 enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
2276
2277                 add_pending_snapshot(trans);
2278
2279                 spin_unlock(&fs_info->trans_lock);
2280                 refcount_inc(&cur_trans->use_count);
2281
2282                 if (trans->in_fsync)
2283                         want_state = TRANS_STATE_SUPER_COMMITTED;
2284
2285                 btrfs_trans_state_lockdep_release(fs_info,
2286                                                   BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2287                 ret = btrfs_end_transaction(trans);
2288                 wait_for_commit(cur_trans, want_state);
2289
2290                 if (TRANS_ABORTED(cur_trans))
2291                         ret = cur_trans->aborted;
2292
2293                 btrfs_put_transaction(cur_trans);
2294
2295                 return ret;
2296         }
2297
2298         cur_trans->state = TRANS_STATE_COMMIT_PREP;
2299         wake_up(&fs_info->transaction_blocked_wait);
2300         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2301
2302         if (cur_trans->list.prev != &fs_info->trans_list) {
2303                 enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
2304
2305                 if (trans->in_fsync)
2306                         want_state = TRANS_STATE_SUPER_COMMITTED;
2307
2308                 prev_trans = list_entry(cur_trans->list.prev,
2309                                         struct btrfs_transaction, list);
2310                 if (prev_trans->state < want_state) {
2311                         refcount_inc(&prev_trans->use_count);
2312                         spin_unlock(&fs_info->trans_lock);
2313
2314                         wait_for_commit(prev_trans, want_state);
2315
2316                         ret = READ_ONCE(prev_trans->aborted);
2317
2318                         btrfs_put_transaction(prev_trans);
2319                         if (ret)
2320                                 goto lockdep_release;
2321                         spin_lock(&fs_info->trans_lock);
2322                 }
2323         } else {
2324                 /*
2325                  * The previous transaction was aborted and was already removed
2326                  * from the list of transactions at fs_info->trans_list. So we
2327                  * abort to prevent writing a new superblock that reflects a
2328                  * corrupt state (pointing to trees with unwritten nodes/leafs).
2329                  */
2330                 if (BTRFS_FS_ERROR(fs_info)) {
2331                         spin_unlock(&fs_info->trans_lock);
2332                         ret = -EROFS;
2333                         goto lockdep_release;
2334                 }
2335         }
2336
2337         cur_trans->state = TRANS_STATE_COMMIT_START;
2338         wake_up(&fs_info->transaction_blocked_wait);
2339         spin_unlock(&fs_info->trans_lock);
2340
2341         /*
2342          * Get the time spent on the work done by the commit thread and not
2343          * the time spent waiting on a previous commit
2344          */
2345         start_time = ktime_get_ns();
2346
2347         extwriter_counter_dec(cur_trans, trans->type);
2348
2349         ret = btrfs_start_delalloc_flush(fs_info);
2350         if (ret)
2351                 goto lockdep_release;
2352
2353         ret = btrfs_run_delayed_items(trans);
2354         if (ret)
2355                 goto lockdep_release;
2356
2357         /*
2358          * The thread has started/joined the transaction thus it holds the
2359          * lockdep map as a reader. It has to release it before acquiring the
2360          * lockdep map as a writer.
2361          */
2362         btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
2363         btrfs_might_wait_for_event(fs_info, btrfs_trans_num_extwriters);
2364         wait_event(cur_trans->writer_wait,
2365                    extwriter_counter_read(cur_trans) == 0);
2366
2367         /* some pending stuffs might be added after the previous flush. */
2368         ret = btrfs_run_delayed_items(trans);
2369         if (ret) {
2370                 btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
2371                 goto cleanup_transaction;
2372         }
2373
2374         btrfs_wait_delalloc_flush(fs_info);
2375
2376         /*
2377          * Wait for all ordered extents started by a fast fsync that joined this
2378          * transaction. Otherwise if this transaction commits before the ordered
2379          * extents complete we lose logged data after a power failure.
2380          */
2381         btrfs_might_wait_for_event(fs_info, btrfs_trans_pending_ordered);
2382         wait_event(cur_trans->pending_wait,
2383                    atomic_read(&cur_trans->pending_ordered) == 0);
2384
2385         btrfs_scrub_pause(fs_info);
2386         /*
2387          * Ok now we need to make sure to block out any other joins while we
2388          * commit the transaction.  We could have started a join before setting
2389          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2390          */
2391         spin_lock(&fs_info->trans_lock);
2392         add_pending_snapshot(trans);
2393         cur_trans->state = TRANS_STATE_COMMIT_DOING;
2394         spin_unlock(&fs_info->trans_lock);
2395
2396         /*
2397          * The thread has started/joined the transaction thus it holds the
2398          * lockdep map as a reader. It has to release it before acquiring the
2399          * lockdep map as a writer.
2400          */
2401         btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
2402         btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);
2403         wait_event(cur_trans->writer_wait,
2404                    atomic_read(&cur_trans->num_writers) == 1);
2405
2406         /*
2407          * Make lockdep happy by acquiring the state locks after
2408          * btrfs_trans_num_writers is released. If we acquired the state locks
2409          * before releasing the btrfs_trans_num_writers lock then lockdep would
2410          * complain because we did not follow the reverse order unlocking rule.
2411          */
2412         btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
2413         btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
2414         btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2415
2416         /*
2417          * We've started the commit, clear the flag in case we were triggered to
2418          * do an async commit but somebody else started before the transaction
2419          * kthread could do the work.
2420          */
2421         clear_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
2422
2423         if (TRANS_ABORTED(cur_trans)) {
2424                 ret = cur_trans->aborted;
2425                 btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2426                 goto scrub_continue;
2427         }
2428         /*
2429          * the reloc mutex makes sure that we stop
2430          * the balancing code from coming in and moving
2431          * extents around in the middle of the commit
2432          */
2433         mutex_lock(&fs_info->reloc_mutex);
2434
2435         /*
2436          * We needn't worry about the delayed items because we will
2437          * deal with them in create_pending_snapshot(), which is the
2438          * core function of the snapshot creation.
2439          */
2440         ret = create_pending_snapshots(trans);
2441         if (ret)
2442                 goto unlock_reloc;
2443
2444         /*
2445          * We insert the dir indexes of the snapshots and update the inode
2446          * of the snapshots' parents after the snapshot creation, so there
2447          * are some delayed items which are not dealt with. Now deal with
2448          * them.
2449          *
2450          * We needn't worry that this operation will corrupt the snapshots,
2451          * because all the tree which are snapshoted will be forced to COW
2452          * the nodes and leaves.
2453          */
2454         ret = btrfs_run_delayed_items(trans);
2455         if (ret)
2456                 goto unlock_reloc;
2457
2458         ret = btrfs_run_delayed_refs(trans, U64_MAX);
2459         if (ret)
2460                 goto unlock_reloc;
2461
2462         /*
2463          * make sure none of the code above managed to slip in a
2464          * delayed item
2465          */
2466         btrfs_assert_delayed_root_empty(fs_info);
2467
2468         WARN_ON(cur_trans != trans->transaction);
2469
2470         ret = commit_fs_roots(trans);
2471         if (ret)
2472                 goto unlock_reloc;
2473
2474         /* commit_fs_roots gets rid of all the tree log roots, it is now
2475          * safe to free the root of tree log roots
2476          */
2477         btrfs_free_log_root_tree(trans, fs_info);
2478
2479         /*
2480          * Since fs roots are all committed, we can get a quite accurate
2481          * new_roots. So let's do quota accounting.
2482          */
2483         ret = btrfs_qgroup_account_extents(trans);
2484         if (ret < 0)
2485                 goto unlock_reloc;
2486
2487         ret = commit_cowonly_roots(trans);
2488         if (ret)
2489                 goto unlock_reloc;
2490
2491         /*
2492          * The tasks which save the space cache and inode cache may also
2493          * update ->aborted, check it.
2494          */
2495         if (TRANS_ABORTED(cur_trans)) {
2496                 ret = cur_trans->aborted;
2497                 goto unlock_reloc;
2498         }
2499
2500         cur_trans = fs_info->running_transaction;
2501
2502         btrfs_set_root_node(&fs_info->tree_root->root_item,
2503                             fs_info->tree_root->node);
2504         list_add_tail(&fs_info->tree_root->dirty_list,
2505                       &cur_trans->switch_commits);
2506
2507         btrfs_set_root_node(&fs_info->chunk_root->root_item,
2508                             fs_info->chunk_root->node);
2509         list_add_tail(&fs_info->chunk_root->dirty_list,
2510                       &cur_trans->switch_commits);
2511
2512         if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
2513                 btrfs_set_root_node(&fs_info->block_group_root->root_item,
2514                                     fs_info->block_group_root->node);
2515                 list_add_tail(&fs_info->block_group_root->dirty_list,
2516                               &cur_trans->switch_commits);
2517         }
2518
2519         switch_commit_roots(trans);
2520
2521         ASSERT(list_empty(&cur_trans->dirty_bgs));
2522         ASSERT(list_empty(&cur_trans->io_bgs));
2523         update_super_roots(fs_info);
2524
2525         btrfs_set_super_log_root(fs_info->super_copy, 0);
2526         btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2527         memcpy(fs_info->super_for_commit, fs_info->super_copy,
2528                sizeof(*fs_info->super_copy));
2529
2530         btrfs_commit_device_sizes(cur_trans);
2531
2532         clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2533         clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2534
2535         btrfs_trans_release_chunk_metadata(trans);
2536
2537         /*
2538          * Before changing the transaction state to TRANS_STATE_UNBLOCKED and
2539          * setting fs_info->running_transaction to NULL, lock tree_log_mutex to
2540          * make sure that before we commit our superblock, no other task can
2541          * start a new transaction and commit a log tree before we commit our
2542          * superblock. Anyone trying to commit a log tree locks this mutex before
2543          * writing its superblock.
2544          */
2545         mutex_lock(&fs_info->tree_log_mutex);
2546
2547         spin_lock(&fs_info->trans_lock);
2548         cur_trans->state = TRANS_STATE_UNBLOCKED;
2549         fs_info->running_transaction = NULL;
2550         spin_unlock(&fs_info->trans_lock);
2551         mutex_unlock(&fs_info->reloc_mutex);
2552
2553         wake_up(&fs_info->transaction_wait);
2554         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2555
2556         /* If we have features changed, wake up the cleaner to update sysfs. */
2557         if (test_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags) &&
2558             fs_info->cleaner_kthread)
2559                 wake_up_process(fs_info->cleaner_kthread);
2560
2561         ret = btrfs_write_and_wait_transaction(trans);
2562         if (ret) {
2563                 btrfs_handle_fs_error(fs_info, ret,
2564                                       "Error while writing out transaction");
2565                 mutex_unlock(&fs_info->tree_log_mutex);
2566                 goto scrub_continue;
2567         }
2568
2569         ret = write_all_supers(fs_info, 0);
2570         /*
2571          * the super is written, we can safely allow the tree-loggers
2572          * to go about their business
2573          */
2574         mutex_unlock(&fs_info->tree_log_mutex);
2575         if (ret)
2576                 goto scrub_continue;
2577
2578         /*
2579          * We needn't acquire the lock here because there is no other task
2580          * which can change it.
2581          */
2582         cur_trans->state = TRANS_STATE_SUPER_COMMITTED;
2583         wake_up(&cur_trans->commit_wait);
2584         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
2585
2586         btrfs_finish_extent_commit(trans);
2587
2588         if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2589                 btrfs_clear_space_info_full(fs_info);
2590
2591         btrfs_set_last_trans_committed(fs_info, cur_trans->transid);
2592         /*
2593          * We needn't acquire the lock here because there is no other task
2594          * which can change it.
2595          */
2596         cur_trans->state = TRANS_STATE_COMPLETED;
2597         wake_up(&cur_trans->commit_wait);
2598         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
2599
2600         spin_lock(&fs_info->trans_lock);
2601         list_del_init(&cur_trans->list);
2602         spin_unlock(&fs_info->trans_lock);
2603
2604         btrfs_put_transaction(cur_trans);
2605         btrfs_put_transaction(cur_trans);
2606
2607         if (trans->type & __TRANS_FREEZABLE)
2608                 sb_end_intwrite(fs_info->sb);
2609
2610         trace_btrfs_transaction_commit(fs_info);
2611
2612         interval = ktime_get_ns() - start_time;
2613
2614         btrfs_scrub_continue(fs_info);
2615
2616         if (current->journal_info == trans)
2617                 current->journal_info = NULL;
2618
2619         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2620
2621         update_commit_stats(fs_info, interval);
2622
2623         return ret;
2624
2625 unlock_reloc:
2626         mutex_unlock(&fs_info->reloc_mutex);
2627         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2628 scrub_continue:
2629         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
2630         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
2631         btrfs_scrub_continue(fs_info);
2632 cleanup_transaction:
2633         btrfs_trans_release_metadata(trans);
2634         btrfs_cleanup_pending_block_groups(trans);
2635         btrfs_trans_release_chunk_metadata(trans);
2636         trans->block_rsv = NULL;
2637         btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2638         if (current->journal_info == trans)
2639                 current->journal_info = NULL;
2640         cleanup_transaction(trans, ret);
2641
2642         return ret;
2643
2644 lockdep_release:
2645         btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
2646         btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
2647         goto cleanup_transaction;
2648
2649 lockdep_trans_commit_start_release:
2650         btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2651         btrfs_end_transaction(trans);
2652         return ret;
2653 }
2654
2655 /*
2656  * return < 0 if error
2657  * 0 if there are no more dead_roots at the time of call
2658  * 1 there are more to be processed, call me again
2659  *
2660  * The return value indicates there are certainly more snapshots to delete, but
2661  * if there comes a new one during processing, it may return 0. We don't mind,
2662  * because btrfs_commit_super will poke cleaner thread and it will process it a
2663  * few seconds later.
2664  */
2665 int btrfs_clean_one_deleted_snapshot(struct btrfs_fs_info *fs_info)
2666 {
2667         struct btrfs_root *root;
2668         int ret;
2669
2670         spin_lock(&fs_info->trans_lock);
2671         if (list_empty(&fs_info->dead_roots)) {
2672                 spin_unlock(&fs_info->trans_lock);
2673                 return 0;
2674         }
2675         root = list_first_entry(&fs_info->dead_roots,
2676                         struct btrfs_root, root_list);
2677         list_del_init(&root->root_list);
2678         spin_unlock(&fs_info->trans_lock);
2679
2680         btrfs_debug(fs_info, "cleaner removing %llu", root->root_key.objectid);
2681
2682         btrfs_kill_all_delayed_nodes(root);
2683
2684         if (btrfs_header_backref_rev(root->node) <
2685                         BTRFS_MIXED_BACKREF_REV)
2686                 ret = btrfs_drop_snapshot(root, 0, 0);
2687         else
2688                 ret = btrfs_drop_snapshot(root, 1, 0);
2689
2690         btrfs_put_root(root);
2691         return (ret < 0) ? 0 : 1;
2692 }
2693
2694 /*
2695  * We only mark the transaction aborted and then set the file system read-only.
2696  * This will prevent new transactions from starting or trying to join this
2697  * one.
2698  *
2699  * This means that error recovery at the call site is limited to freeing
2700  * any local memory allocations and passing the error code up without
2701  * further cleanup. The transaction should complete as it normally would
2702  * in the call path but will return -EIO.
2703  *
2704  * We'll complete the cleanup in btrfs_end_transaction and
2705  * btrfs_commit_transaction.
2706  */
2707 void __cold __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
2708                                       const char *function,
2709                                       unsigned int line, int error, bool first_hit)
2710 {
2711         struct btrfs_fs_info *fs_info = trans->fs_info;
2712
2713         WRITE_ONCE(trans->aborted, error);
2714         WRITE_ONCE(trans->transaction->aborted, error);
2715         if (first_hit && error == -ENOSPC)
2716                 btrfs_dump_space_info_for_trans_abort(fs_info);
2717         /* Wake up anybody who may be waiting on this transaction */
2718         wake_up(&fs_info->transaction_wait);
2719         wake_up(&fs_info->transaction_blocked_wait);
2720         __btrfs_handle_fs_error(fs_info, function, line, error, NULL);
2721 }
2722
2723 int __init btrfs_transaction_init(void)
2724 {
2725         btrfs_trans_handle_cachep = kmem_cache_create("btrfs_trans_handle",
2726                         sizeof(struct btrfs_trans_handle), 0,
2727                         SLAB_TEMPORARY | SLAB_MEM_SPREAD, NULL);
2728         if (!btrfs_trans_handle_cachep)
2729                 return -ENOMEM;
2730         return 0;
2731 }
2732
2733 void __cold btrfs_transaction_exit(void)
2734 {
2735         kmem_cache_destroy(btrfs_trans_handle_cachep);
2736 }