17978fd731f65f8403107d09b7cef94aa170a4dc
[sfrench/cifs-2.6.git] / fs / btrfs / transaction.c
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/fs.h>
20 #include <linux/slab.h>
21 #include <linux/sched.h>
22 #include <linux/writeback.h>
23 #include <linux/pagemap.h>
24 #include <linux/blkdev.h>
25 #include <linux/uuid.h>
26 #include "ctree.h"
27 #include "disk-io.h"
28 #include "transaction.h"
29 #include "locking.h"
30 #include "tree-log.h"
31 #include "inode-map.h"
32 #include "volumes.h"
33 #include "dev-replace.h"
34 #include "qgroup.h"
35
36 #define BTRFS_ROOT_TRANS_TAG 0
37
38 static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
39         [TRANS_STATE_RUNNING]           = 0U,
40         [TRANS_STATE_BLOCKED]           = (__TRANS_USERSPACE |
41                                            __TRANS_START),
42         [TRANS_STATE_COMMIT_START]      = (__TRANS_USERSPACE |
43                                            __TRANS_START |
44                                            __TRANS_ATTACH),
45         [TRANS_STATE_COMMIT_DOING]      = (__TRANS_USERSPACE |
46                                            __TRANS_START |
47                                            __TRANS_ATTACH |
48                                            __TRANS_JOIN),
49         [TRANS_STATE_UNBLOCKED]         = (__TRANS_USERSPACE |
50                                            __TRANS_START |
51                                            __TRANS_ATTACH |
52                                            __TRANS_JOIN |
53                                            __TRANS_JOIN_NOLOCK),
54         [TRANS_STATE_COMPLETED]         = (__TRANS_USERSPACE |
55                                            __TRANS_START |
56                                            __TRANS_ATTACH |
57                                            __TRANS_JOIN |
58                                            __TRANS_JOIN_NOLOCK),
59 };
60
61 void btrfs_put_transaction(struct btrfs_transaction *transaction)
62 {
63         WARN_ON(refcount_read(&transaction->use_count) == 0);
64         if (refcount_dec_and_test(&transaction->use_count)) {
65                 BUG_ON(!list_empty(&transaction->list));
66                 WARN_ON(!RB_EMPTY_ROOT(&transaction->delayed_refs.href_root));
67                 if (transaction->delayed_refs.pending_csums)
68                         btrfs_err(transaction->fs_info,
69                                   "pending csums is %llu",
70                                   transaction->delayed_refs.pending_csums);
71                 while (!list_empty(&transaction->pending_chunks)) {
72                         struct extent_map *em;
73
74                         em = list_first_entry(&transaction->pending_chunks,
75                                               struct extent_map, list);
76                         list_del_init(&em->list);
77                         free_extent_map(em);
78                 }
79                 /*
80                  * If any block groups are found in ->deleted_bgs then it's
81                  * because the transaction was aborted and a commit did not
82                  * happen (things failed before writing the new superblock
83                  * and calling btrfs_finish_extent_commit()), so we can not
84                  * discard the physical locations of the block groups.
85                  */
86                 while (!list_empty(&transaction->deleted_bgs)) {
87                         struct btrfs_block_group_cache *cache;
88
89                         cache = list_first_entry(&transaction->deleted_bgs,
90                                                  struct btrfs_block_group_cache,
91                                                  bg_list);
92                         list_del_init(&cache->bg_list);
93                         btrfs_put_block_group_trimming(cache);
94                         btrfs_put_block_group(cache);
95                 }
96                 kfree(transaction);
97         }
98 }
99
100 static void clear_btree_io_tree(struct extent_io_tree *tree)
101 {
102         spin_lock(&tree->lock);
103         /*
104          * Do a single barrier for the waitqueue_active check here, the state
105          * of the waitqueue should not change once clear_btree_io_tree is
106          * called.
107          */
108         smp_mb();
109         while (!RB_EMPTY_ROOT(&tree->state)) {
110                 struct rb_node *node;
111                 struct extent_state *state;
112
113                 node = rb_first(&tree->state);
114                 state = rb_entry(node, struct extent_state, rb_node);
115                 rb_erase(&state->rb_node, &tree->state);
116                 RB_CLEAR_NODE(&state->rb_node);
117                 /*
118                  * btree io trees aren't supposed to have tasks waiting for
119                  * changes in the flags of extent states ever.
120                  */
121                 ASSERT(!waitqueue_active(&state->wq));
122                 free_extent_state(state);
123
124                 cond_resched_lock(&tree->lock);
125         }
126         spin_unlock(&tree->lock);
127 }
128
129 static noinline void switch_commit_roots(struct btrfs_transaction *trans)
130 {
131         struct btrfs_fs_info *fs_info = trans->fs_info;
132         struct btrfs_root *root, *tmp;
133
134         down_write(&fs_info->commit_root_sem);
135         list_for_each_entry_safe(root, tmp, &trans->switch_commits,
136                                  dirty_list) {
137                 list_del_init(&root->dirty_list);
138                 free_extent_buffer(root->commit_root);
139                 root->commit_root = btrfs_root_node(root);
140                 if (is_fstree(root->objectid))
141                         btrfs_unpin_free_ino(root);
142                 clear_btree_io_tree(&root->dirty_log_pages);
143         }
144
145         /* We can free old roots now. */
146         spin_lock(&trans->dropped_roots_lock);
147         while (!list_empty(&trans->dropped_roots)) {
148                 root = list_first_entry(&trans->dropped_roots,
149                                         struct btrfs_root, root_list);
150                 list_del_init(&root->root_list);
151                 spin_unlock(&trans->dropped_roots_lock);
152                 btrfs_drop_and_free_fs_root(fs_info, root);
153                 spin_lock(&trans->dropped_roots_lock);
154         }
155         spin_unlock(&trans->dropped_roots_lock);
156         up_write(&fs_info->commit_root_sem);
157 }
158
159 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
160                                          unsigned int type)
161 {
162         if (type & TRANS_EXTWRITERS)
163                 atomic_inc(&trans->num_extwriters);
164 }
165
166 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
167                                          unsigned int type)
168 {
169         if (type & TRANS_EXTWRITERS)
170                 atomic_dec(&trans->num_extwriters);
171 }
172
173 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
174                                           unsigned int type)
175 {
176         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
177 }
178
179 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
180 {
181         return atomic_read(&trans->num_extwriters);
182 }
183
184 /*
185  * either allocate a new transaction or hop into the existing one
186  */
187 static noinline int join_transaction(struct btrfs_fs_info *fs_info,
188                                      unsigned int type)
189 {
190         struct btrfs_transaction *cur_trans;
191
192         spin_lock(&fs_info->trans_lock);
193 loop:
194         /* The file system has been taken offline. No new transactions. */
195         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
196                 spin_unlock(&fs_info->trans_lock);
197                 return -EROFS;
198         }
199
200         cur_trans = fs_info->running_transaction;
201         if (cur_trans) {
202                 if (cur_trans->aborted) {
203                         spin_unlock(&fs_info->trans_lock);
204                         return cur_trans->aborted;
205                 }
206                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
207                         spin_unlock(&fs_info->trans_lock);
208                         return -EBUSY;
209                 }
210                 refcount_inc(&cur_trans->use_count);
211                 atomic_inc(&cur_trans->num_writers);
212                 extwriter_counter_inc(cur_trans, type);
213                 spin_unlock(&fs_info->trans_lock);
214                 return 0;
215         }
216         spin_unlock(&fs_info->trans_lock);
217
218         /*
219          * If we are ATTACH, we just want to catch the current transaction,
220          * and commit it. If there is no transaction, just return ENOENT.
221          */
222         if (type == TRANS_ATTACH)
223                 return -ENOENT;
224
225         /*
226          * JOIN_NOLOCK only happens during the transaction commit, so
227          * it is impossible that ->running_transaction is NULL
228          */
229         BUG_ON(type == TRANS_JOIN_NOLOCK);
230
231         cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
232         if (!cur_trans)
233                 return -ENOMEM;
234
235         spin_lock(&fs_info->trans_lock);
236         if (fs_info->running_transaction) {
237                 /*
238                  * someone started a transaction after we unlocked.  Make sure
239                  * to redo the checks above
240                  */
241                 kfree(cur_trans);
242                 goto loop;
243         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
244                 spin_unlock(&fs_info->trans_lock);
245                 kfree(cur_trans);
246                 return -EROFS;
247         }
248
249         cur_trans->fs_info = fs_info;
250         atomic_set(&cur_trans->num_writers, 1);
251         extwriter_counter_init(cur_trans, type);
252         init_waitqueue_head(&cur_trans->writer_wait);
253         init_waitqueue_head(&cur_trans->commit_wait);
254         init_waitqueue_head(&cur_trans->pending_wait);
255         cur_trans->state = TRANS_STATE_RUNNING;
256         /*
257          * One for this trans handle, one so it will live on until we
258          * commit the transaction.
259          */
260         refcount_set(&cur_trans->use_count, 2);
261         atomic_set(&cur_trans->pending_ordered, 0);
262         cur_trans->flags = 0;
263         cur_trans->start_time = get_seconds();
264
265         memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
266
267         cur_trans->delayed_refs.href_root = RB_ROOT;
268         cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
269         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
270
271         /*
272          * although the tree mod log is per file system and not per transaction,
273          * the log must never go across transaction boundaries.
274          */
275         smp_mb();
276         if (!list_empty(&fs_info->tree_mod_seq_list))
277                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
278         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
279                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
280         atomic64_set(&fs_info->tree_mod_seq, 0);
281
282         spin_lock_init(&cur_trans->delayed_refs.lock);
283
284         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
285         INIT_LIST_HEAD(&cur_trans->pending_chunks);
286         INIT_LIST_HEAD(&cur_trans->switch_commits);
287         INIT_LIST_HEAD(&cur_trans->dirty_bgs);
288         INIT_LIST_HEAD(&cur_trans->io_bgs);
289         INIT_LIST_HEAD(&cur_trans->dropped_roots);
290         mutex_init(&cur_trans->cache_write_mutex);
291         cur_trans->num_dirty_bgs = 0;
292         spin_lock_init(&cur_trans->dirty_bgs_lock);
293         INIT_LIST_HEAD(&cur_trans->deleted_bgs);
294         spin_lock_init(&cur_trans->dropped_roots_lock);
295         list_add_tail(&cur_trans->list, &fs_info->trans_list);
296         extent_io_tree_init(&cur_trans->dirty_pages,
297                              fs_info->btree_inode);
298         fs_info->generation++;
299         cur_trans->transid = fs_info->generation;
300         fs_info->running_transaction = cur_trans;
301         cur_trans->aborted = 0;
302         spin_unlock(&fs_info->trans_lock);
303
304         return 0;
305 }
306
307 /*
308  * this does all the record keeping required to make sure that a reference
309  * counted root is properly recorded in a given transaction.  This is required
310  * to make sure the old root from before we joined the transaction is deleted
311  * when the transaction commits
312  */
313 static int record_root_in_trans(struct btrfs_trans_handle *trans,
314                                struct btrfs_root *root,
315                                int force)
316 {
317         struct btrfs_fs_info *fs_info = root->fs_info;
318
319         if ((test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
320             root->last_trans < trans->transid) || force) {
321                 WARN_ON(root == fs_info->extent_root);
322                 WARN_ON(!force && root->commit_root != root->node);
323
324                 /*
325                  * see below for IN_TRANS_SETUP usage rules
326                  * we have the reloc mutex held now, so there
327                  * is only one writer in this function
328                  */
329                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
330
331                 /* make sure readers find IN_TRANS_SETUP before
332                  * they find our root->last_trans update
333                  */
334                 smp_wmb();
335
336                 spin_lock(&fs_info->fs_roots_radix_lock);
337                 if (root->last_trans == trans->transid && !force) {
338                         spin_unlock(&fs_info->fs_roots_radix_lock);
339                         return 0;
340                 }
341                 radix_tree_tag_set(&fs_info->fs_roots_radix,
342                                    (unsigned long)root->root_key.objectid,
343                                    BTRFS_ROOT_TRANS_TAG);
344                 spin_unlock(&fs_info->fs_roots_radix_lock);
345                 root->last_trans = trans->transid;
346
347                 /* this is pretty tricky.  We don't want to
348                  * take the relocation lock in btrfs_record_root_in_trans
349                  * unless we're really doing the first setup for this root in
350                  * this transaction.
351                  *
352                  * Normally we'd use root->last_trans as a flag to decide
353                  * if we want to take the expensive mutex.
354                  *
355                  * But, we have to set root->last_trans before we
356                  * init the relocation root, otherwise, we trip over warnings
357                  * in ctree.c.  The solution used here is to flag ourselves
358                  * with root IN_TRANS_SETUP.  When this is 1, we're still
359                  * fixing up the reloc trees and everyone must wait.
360                  *
361                  * When this is zero, they can trust root->last_trans and fly
362                  * through btrfs_record_root_in_trans without having to take the
363                  * lock.  smp_wmb() makes sure that all the writes above are
364                  * done before we pop in the zero below
365                  */
366                 btrfs_init_reloc_root(trans, root);
367                 smp_mb__before_atomic();
368                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
369         }
370         return 0;
371 }
372
373
374 void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
375                             struct btrfs_root *root)
376 {
377         struct btrfs_fs_info *fs_info = root->fs_info;
378         struct btrfs_transaction *cur_trans = trans->transaction;
379
380         /* Add ourselves to the transaction dropped list */
381         spin_lock(&cur_trans->dropped_roots_lock);
382         list_add_tail(&root->root_list, &cur_trans->dropped_roots);
383         spin_unlock(&cur_trans->dropped_roots_lock);
384
385         /* Make sure we don't try to update the root at commit time */
386         spin_lock(&fs_info->fs_roots_radix_lock);
387         radix_tree_tag_clear(&fs_info->fs_roots_radix,
388                              (unsigned long)root->root_key.objectid,
389                              BTRFS_ROOT_TRANS_TAG);
390         spin_unlock(&fs_info->fs_roots_radix_lock);
391 }
392
393 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
394                                struct btrfs_root *root)
395 {
396         struct btrfs_fs_info *fs_info = root->fs_info;
397
398         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
399                 return 0;
400
401         /*
402          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
403          * and barriers
404          */
405         smp_rmb();
406         if (root->last_trans == trans->transid &&
407             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
408                 return 0;
409
410         mutex_lock(&fs_info->reloc_mutex);
411         record_root_in_trans(trans, root, 0);
412         mutex_unlock(&fs_info->reloc_mutex);
413
414         return 0;
415 }
416
417 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
418 {
419         return (trans->state >= TRANS_STATE_BLOCKED &&
420                 trans->state < TRANS_STATE_UNBLOCKED &&
421                 !trans->aborted);
422 }
423
424 /* wait for commit against the current transaction to become unblocked
425  * when this is done, it is safe to start a new transaction, but the current
426  * transaction might not be fully on disk.
427  */
428 static void wait_current_trans(struct btrfs_fs_info *fs_info)
429 {
430         struct btrfs_transaction *cur_trans;
431
432         spin_lock(&fs_info->trans_lock);
433         cur_trans = fs_info->running_transaction;
434         if (cur_trans && is_transaction_blocked(cur_trans)) {
435                 refcount_inc(&cur_trans->use_count);
436                 spin_unlock(&fs_info->trans_lock);
437
438                 wait_event(fs_info->transaction_wait,
439                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
440                            cur_trans->aborted);
441                 btrfs_put_transaction(cur_trans);
442         } else {
443                 spin_unlock(&fs_info->trans_lock);
444         }
445 }
446
447 static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
448 {
449         if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
450                 return 0;
451
452         if (type == TRANS_USERSPACE)
453                 return 1;
454
455         if (type == TRANS_START &&
456             !atomic_read(&fs_info->open_ioctl_trans))
457                 return 1;
458
459         return 0;
460 }
461
462 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
463 {
464         struct btrfs_fs_info *fs_info = root->fs_info;
465
466         if (!fs_info->reloc_ctl ||
467             !test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
468             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
469             root->reloc_root)
470                 return false;
471
472         return true;
473 }
474
475 static struct btrfs_trans_handle *
476 start_transaction(struct btrfs_root *root, unsigned int num_items,
477                   unsigned int type, enum btrfs_reserve_flush_enum flush,
478                   bool enforce_qgroups)
479 {
480         struct btrfs_fs_info *fs_info = root->fs_info;
481
482         struct btrfs_trans_handle *h;
483         struct btrfs_transaction *cur_trans;
484         u64 num_bytes = 0;
485         u64 qgroup_reserved = 0;
486         bool reloc_reserved = false;
487         int ret;
488
489         /* Send isn't supposed to start transactions. */
490         ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
491
492         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
493                 return ERR_PTR(-EROFS);
494
495         if (current->journal_info) {
496                 WARN_ON(type & TRANS_EXTWRITERS);
497                 h = current->journal_info;
498                 refcount_inc(&h->use_count);
499                 WARN_ON(refcount_read(&h->use_count) > 2);
500                 h->orig_rsv = h->block_rsv;
501                 h->block_rsv = NULL;
502                 goto got_it;
503         }
504
505         /*
506          * Do the reservation before we join the transaction so we can do all
507          * the appropriate flushing if need be.
508          */
509         if (num_items && root != fs_info->chunk_root) {
510                 qgroup_reserved = num_items * fs_info->nodesize;
511                 ret = btrfs_qgroup_reserve_meta(root, qgroup_reserved,
512                                                 enforce_qgroups);
513                 if (ret)
514                         return ERR_PTR(ret);
515
516                 num_bytes = btrfs_calc_trans_metadata_size(fs_info, num_items);
517                 /*
518                  * Do the reservation for the relocation root creation
519                  */
520                 if (need_reserve_reloc_root(root)) {
521                         num_bytes += fs_info->nodesize;
522                         reloc_reserved = true;
523                 }
524
525                 ret = btrfs_block_rsv_add(root, &fs_info->trans_block_rsv,
526                                           num_bytes, flush);
527                 if (ret)
528                         goto reserve_fail;
529         }
530 again:
531         h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
532         if (!h) {
533                 ret = -ENOMEM;
534                 goto alloc_fail;
535         }
536
537         /*
538          * If we are JOIN_NOLOCK we're already committing a transaction and
539          * waiting on this guy, so we don't need to do the sb_start_intwrite
540          * because we're already holding a ref.  We need this because we could
541          * have raced in and did an fsync() on a file which can kick a commit
542          * and then we deadlock with somebody doing a freeze.
543          *
544          * If we are ATTACH, it means we just want to catch the current
545          * transaction and commit it, so we needn't do sb_start_intwrite(). 
546          */
547         if (type & __TRANS_FREEZABLE)
548                 sb_start_intwrite(fs_info->sb);
549
550         if (may_wait_transaction(fs_info, type))
551                 wait_current_trans(fs_info);
552
553         do {
554                 ret = join_transaction(fs_info, type);
555                 if (ret == -EBUSY) {
556                         wait_current_trans(fs_info);
557                         if (unlikely(type == TRANS_ATTACH))
558                                 ret = -ENOENT;
559                 }
560         } while (ret == -EBUSY);
561
562         if (ret < 0)
563                 goto join_fail;
564
565         cur_trans = fs_info->running_transaction;
566
567         h->transid = cur_trans->transid;
568         h->transaction = cur_trans;
569         h->root = root;
570         refcount_set(&h->use_count, 1);
571         h->fs_info = root->fs_info;
572
573         h->type = type;
574         h->can_flush_pending_bgs = true;
575         INIT_LIST_HEAD(&h->new_bgs);
576
577         smp_mb();
578         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
579             may_wait_transaction(fs_info, type)) {
580                 current->journal_info = h;
581                 btrfs_commit_transaction(h);
582                 goto again;
583         }
584
585         if (num_bytes) {
586                 trace_btrfs_space_reservation(fs_info, "transaction",
587                                               h->transid, num_bytes, 1);
588                 h->block_rsv = &fs_info->trans_block_rsv;
589                 h->bytes_reserved = num_bytes;
590                 h->reloc_reserved = reloc_reserved;
591         }
592
593 got_it:
594         btrfs_record_root_in_trans(h, root);
595
596         if (!current->journal_info && type != TRANS_USERSPACE)
597                 current->journal_info = h;
598         return h;
599
600 join_fail:
601         if (type & __TRANS_FREEZABLE)
602                 sb_end_intwrite(fs_info->sb);
603         kmem_cache_free(btrfs_trans_handle_cachep, h);
604 alloc_fail:
605         if (num_bytes)
606                 btrfs_block_rsv_release(fs_info, &fs_info->trans_block_rsv,
607                                         num_bytes);
608 reserve_fail:
609         btrfs_qgroup_free_meta(root, qgroup_reserved);
610         return ERR_PTR(ret);
611 }
612
613 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
614                                                    unsigned int num_items)
615 {
616         return start_transaction(root, num_items, TRANS_START,
617                                  BTRFS_RESERVE_FLUSH_ALL, true);
618 }
619
620 struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
621                                         struct btrfs_root *root,
622                                         unsigned int num_items,
623                                         int min_factor)
624 {
625         struct btrfs_fs_info *fs_info = root->fs_info;
626         struct btrfs_trans_handle *trans;
627         u64 num_bytes;
628         int ret;
629
630         /*
631          * We have two callers: unlink and block group removal.  The
632          * former should succeed even if we will temporarily exceed
633          * quota and the latter operates on the extent root so
634          * qgroup enforcement is ignored anyway.
635          */
636         trans = start_transaction(root, num_items, TRANS_START,
637                                   BTRFS_RESERVE_FLUSH_ALL, false);
638         if (!IS_ERR(trans) || PTR_ERR(trans) != -ENOSPC)
639                 return trans;
640
641         trans = btrfs_start_transaction(root, 0);
642         if (IS_ERR(trans))
643                 return trans;
644
645         num_bytes = btrfs_calc_trans_metadata_size(fs_info, num_items);
646         ret = btrfs_cond_migrate_bytes(fs_info, &fs_info->trans_block_rsv,
647                                        num_bytes, min_factor);
648         if (ret) {
649                 btrfs_end_transaction(trans);
650                 return ERR_PTR(ret);
651         }
652
653         trans->block_rsv = &fs_info->trans_block_rsv;
654         trans->bytes_reserved = num_bytes;
655         trace_btrfs_space_reservation(fs_info, "transaction",
656                                       trans->transid, num_bytes, 1);
657
658         return trans;
659 }
660
661 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
662 {
663         return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,
664                                  true);
665 }
666
667 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
668 {
669         return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
670                                  BTRFS_RESERVE_NO_FLUSH, true);
671 }
672
673 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
674 {
675         return start_transaction(root, 0, TRANS_USERSPACE,
676                                  BTRFS_RESERVE_NO_FLUSH, true);
677 }
678
679 /*
680  * btrfs_attach_transaction() - catch the running transaction
681  *
682  * It is used when we want to commit the current the transaction, but
683  * don't want to start a new one.
684  *
685  * Note: If this function return -ENOENT, it just means there is no
686  * running transaction. But it is possible that the inactive transaction
687  * is still in the memory, not fully on disk. If you hope there is no
688  * inactive transaction in the fs when -ENOENT is returned, you should
689  * invoke
690  *     btrfs_attach_transaction_barrier()
691  */
692 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
693 {
694         return start_transaction(root, 0, TRANS_ATTACH,
695                                  BTRFS_RESERVE_NO_FLUSH, true);
696 }
697
698 /*
699  * btrfs_attach_transaction_barrier() - catch the running transaction
700  *
701  * It is similar to the above function, the differentia is this one
702  * will wait for all the inactive transactions until they fully
703  * complete.
704  */
705 struct btrfs_trans_handle *
706 btrfs_attach_transaction_barrier(struct btrfs_root *root)
707 {
708         struct btrfs_trans_handle *trans;
709
710         trans = start_transaction(root, 0, TRANS_ATTACH,
711                                   BTRFS_RESERVE_NO_FLUSH, true);
712         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
713                 btrfs_wait_for_commit(root->fs_info, 0);
714
715         return trans;
716 }
717
718 /* wait for a transaction commit to be fully complete */
719 static noinline void wait_for_commit(struct btrfs_transaction *commit)
720 {
721         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
722 }
723
724 int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
725 {
726         struct btrfs_transaction *cur_trans = NULL, *t;
727         int ret = 0;
728
729         if (transid) {
730                 if (transid <= fs_info->last_trans_committed)
731                         goto out;
732
733                 /* find specified transaction */
734                 spin_lock(&fs_info->trans_lock);
735                 list_for_each_entry(t, &fs_info->trans_list, list) {
736                         if (t->transid == transid) {
737                                 cur_trans = t;
738                                 refcount_inc(&cur_trans->use_count);
739                                 ret = 0;
740                                 break;
741                         }
742                         if (t->transid > transid) {
743                                 ret = 0;
744                                 break;
745                         }
746                 }
747                 spin_unlock(&fs_info->trans_lock);
748
749                 /*
750                  * The specified transaction doesn't exist, or we
751                  * raced with btrfs_commit_transaction
752                  */
753                 if (!cur_trans) {
754                         if (transid > fs_info->last_trans_committed)
755                                 ret = -EINVAL;
756                         goto out;
757                 }
758         } else {
759                 /* find newest transaction that is committing | committed */
760                 spin_lock(&fs_info->trans_lock);
761                 list_for_each_entry_reverse(t, &fs_info->trans_list,
762                                             list) {
763                         if (t->state >= TRANS_STATE_COMMIT_START) {
764                                 if (t->state == TRANS_STATE_COMPLETED)
765                                         break;
766                                 cur_trans = t;
767                                 refcount_inc(&cur_trans->use_count);
768                                 break;
769                         }
770                 }
771                 spin_unlock(&fs_info->trans_lock);
772                 if (!cur_trans)
773                         goto out;  /* nothing committing|committed */
774         }
775
776         wait_for_commit(cur_trans);
777         btrfs_put_transaction(cur_trans);
778 out:
779         return ret;
780 }
781
782 void btrfs_throttle(struct btrfs_fs_info *fs_info)
783 {
784         if (!atomic_read(&fs_info->open_ioctl_trans))
785                 wait_current_trans(fs_info);
786 }
787
788 static int should_end_transaction(struct btrfs_trans_handle *trans)
789 {
790         struct btrfs_fs_info *fs_info = trans->fs_info;
791
792         if (btrfs_check_space_for_delayed_refs(trans, fs_info))
793                 return 1;
794
795         return !!btrfs_block_rsv_check(&fs_info->global_block_rsv, 5);
796 }
797
798 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
799 {
800         struct btrfs_transaction *cur_trans = trans->transaction;
801         struct btrfs_fs_info *fs_info = trans->fs_info;
802         int updates;
803         int err;
804
805         smp_mb();
806         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
807             cur_trans->delayed_refs.flushing)
808                 return 1;
809
810         updates = trans->delayed_ref_updates;
811         trans->delayed_ref_updates = 0;
812         if (updates) {
813                 err = btrfs_run_delayed_refs(trans, fs_info, updates * 2);
814                 if (err) /* Error code will also eval true */
815                         return err;
816         }
817
818         return should_end_transaction(trans);
819 }
820
821 static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans)
822
823 {
824         struct btrfs_fs_info *fs_info = trans->fs_info;
825
826         if (!trans->block_rsv) {
827                 ASSERT(!trans->bytes_reserved);
828                 return;
829         }
830
831         if (!trans->bytes_reserved)
832                 return;
833
834         ASSERT(trans->block_rsv == &fs_info->trans_block_rsv);
835         trace_btrfs_space_reservation(fs_info, "transaction",
836                                       trans->transid, trans->bytes_reserved, 0);
837         btrfs_block_rsv_release(fs_info, trans->block_rsv,
838                                 trans->bytes_reserved);
839         trans->bytes_reserved = 0;
840 }
841
842 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
843                                    int throttle)
844 {
845         struct btrfs_fs_info *info = trans->fs_info;
846         struct btrfs_transaction *cur_trans = trans->transaction;
847         u64 transid = trans->transid;
848         unsigned long cur = trans->delayed_ref_updates;
849         int lock = (trans->type != TRANS_JOIN_NOLOCK);
850         int err = 0;
851         int must_run_delayed_refs = 0;
852
853         if (refcount_read(&trans->use_count) > 1) {
854                 refcount_dec(&trans->use_count);
855                 trans->block_rsv = trans->orig_rsv;
856                 return 0;
857         }
858
859         btrfs_trans_release_metadata(trans);
860         trans->block_rsv = NULL;
861
862         if (!list_empty(&trans->new_bgs))
863                 btrfs_create_pending_block_groups(trans);
864
865         trans->delayed_ref_updates = 0;
866         if (!trans->sync) {
867                 must_run_delayed_refs =
868                         btrfs_should_throttle_delayed_refs(trans, info);
869                 cur = max_t(unsigned long, cur, 32);
870
871                 /*
872                  * don't make the caller wait if they are from a NOLOCK
873                  * or ATTACH transaction, it will deadlock with commit
874                  */
875                 if (must_run_delayed_refs == 1 &&
876                     (trans->type & (__TRANS_JOIN_NOLOCK | __TRANS_ATTACH)))
877                         must_run_delayed_refs = 2;
878         }
879
880         btrfs_trans_release_metadata(trans);
881         trans->block_rsv = NULL;
882
883         if (!list_empty(&trans->new_bgs))
884                 btrfs_create_pending_block_groups(trans);
885
886         btrfs_trans_release_chunk_metadata(trans);
887
888         if (lock && !atomic_read(&info->open_ioctl_trans) &&
889             should_end_transaction(trans) &&
890             READ_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
891                 spin_lock(&info->trans_lock);
892                 if (cur_trans->state == TRANS_STATE_RUNNING)
893                         cur_trans->state = TRANS_STATE_BLOCKED;
894                 spin_unlock(&info->trans_lock);
895         }
896
897         if (lock && READ_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
898                 if (throttle)
899                         return btrfs_commit_transaction(trans);
900                 else
901                         wake_up_process(info->transaction_kthread);
902         }
903
904         if (trans->type & __TRANS_FREEZABLE)
905                 sb_end_intwrite(info->sb);
906
907         WARN_ON(cur_trans != info->running_transaction);
908         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
909         atomic_dec(&cur_trans->num_writers);
910         extwriter_counter_dec(cur_trans, trans->type);
911
912         /*
913          * Make sure counter is updated before we wake up waiters.
914          */
915         smp_mb();
916         if (waitqueue_active(&cur_trans->writer_wait))
917                 wake_up(&cur_trans->writer_wait);
918         btrfs_put_transaction(cur_trans);
919
920         if (current->journal_info == trans)
921                 current->journal_info = NULL;
922
923         if (throttle)
924                 btrfs_run_delayed_iputs(info);
925
926         if (trans->aborted ||
927             test_bit(BTRFS_FS_STATE_ERROR, &info->fs_state)) {
928                 wake_up_process(info->transaction_kthread);
929                 err = -EIO;
930         }
931
932         kmem_cache_free(btrfs_trans_handle_cachep, trans);
933         if (must_run_delayed_refs) {
934                 btrfs_async_run_delayed_refs(info, cur, transid,
935                                              must_run_delayed_refs == 1);
936         }
937         return err;
938 }
939
940 int btrfs_end_transaction(struct btrfs_trans_handle *trans)
941 {
942         return __btrfs_end_transaction(trans, 0);
943 }
944
945 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
946 {
947         return __btrfs_end_transaction(trans, 1);
948 }
949
950 /*
951  * when btree blocks are allocated, they have some corresponding bits set for
952  * them in one of two extent_io trees.  This is used to make sure all of
953  * those extents are sent to disk but does not wait on them
954  */
955 int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
956                                struct extent_io_tree *dirty_pages, int mark)
957 {
958         int err = 0;
959         int werr = 0;
960         struct address_space *mapping = fs_info->btree_inode->i_mapping;
961         struct extent_state *cached_state = NULL;
962         u64 start = 0;
963         u64 end;
964
965         atomic_inc(&BTRFS_I(fs_info->btree_inode)->sync_writers);
966         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
967                                       mark, &cached_state)) {
968                 bool wait_writeback = false;
969
970                 err = convert_extent_bit(dirty_pages, start, end,
971                                          EXTENT_NEED_WAIT,
972                                          mark, &cached_state);
973                 /*
974                  * convert_extent_bit can return -ENOMEM, which is most of the
975                  * time a temporary error. So when it happens, ignore the error
976                  * and wait for writeback of this range to finish - because we
977                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
978                  * to __btrfs_wait_marked_extents() would not know that
979                  * writeback for this range started and therefore wouldn't
980                  * wait for it to finish - we don't want to commit a
981                  * superblock that points to btree nodes/leafs for which
982                  * writeback hasn't finished yet (and without errors).
983                  * We cleanup any entries left in the io tree when committing
984                  * the transaction (through clear_btree_io_tree()).
985                  */
986                 if (err == -ENOMEM) {
987                         err = 0;
988                         wait_writeback = true;
989                 }
990                 if (!err)
991                         err = filemap_fdatawrite_range(mapping, start, end);
992                 if (err)
993                         werr = err;
994                 else if (wait_writeback)
995                         werr = filemap_fdatawait_range(mapping, start, end);
996                 free_extent_state(cached_state);
997                 cached_state = NULL;
998                 cond_resched();
999                 start = end + 1;
1000         }
1001         atomic_dec(&BTRFS_I(fs_info->btree_inode)->sync_writers);
1002         return werr;
1003 }
1004
1005 /*
1006  * when btree blocks are allocated, they have some corresponding bits set for
1007  * them in one of two extent_io trees.  This is used to make sure all of
1008  * those extents are on disk for transaction or log commit.  We wait
1009  * on all the pages and clear them from the dirty pages state tree
1010  */
1011 static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
1012                                        struct extent_io_tree *dirty_pages)
1013 {
1014         int err = 0;
1015         int werr = 0;
1016         struct address_space *mapping = fs_info->btree_inode->i_mapping;
1017         struct extent_state *cached_state = NULL;
1018         u64 start = 0;
1019         u64 end;
1020
1021         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
1022                                       EXTENT_NEED_WAIT, &cached_state)) {
1023                 /*
1024                  * Ignore -ENOMEM errors returned by clear_extent_bit().
1025                  * When committing the transaction, we'll remove any entries
1026                  * left in the io tree. For a log commit, we don't remove them
1027                  * after committing the log because the tree can be accessed
1028                  * concurrently - we do it only at transaction commit time when
1029                  * it's safe to do it (through clear_btree_io_tree()).
1030                  */
1031                 err = clear_extent_bit(dirty_pages, start, end,
1032                                        EXTENT_NEED_WAIT, 0, 0, &cached_state);
1033                 if (err == -ENOMEM)
1034                         err = 0;
1035                 if (!err)
1036                         err = filemap_fdatawait_range(mapping, start, end);
1037                 if (err)
1038                         werr = err;
1039                 free_extent_state(cached_state);
1040                 cached_state = NULL;
1041                 cond_resched();
1042                 start = end + 1;
1043         }
1044         if (err)
1045                 werr = err;
1046         return werr;
1047 }
1048
1049 int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1050                        struct extent_io_tree *dirty_pages)
1051 {
1052         bool errors = false;
1053         int err;
1054
1055         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1056         if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1057                 errors = true;
1058
1059         if (errors && !err)
1060                 err = -EIO;
1061         return err;
1062 }
1063
1064 int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1065 {
1066         struct btrfs_fs_info *fs_info = log_root->fs_info;
1067         struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1068         bool errors = false;
1069         int err;
1070
1071         ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
1072
1073         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1074         if ((mark & EXTENT_DIRTY) &&
1075             test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1076                 errors = true;
1077
1078         if ((mark & EXTENT_NEW) &&
1079             test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1080                 errors = true;
1081
1082         if (errors && !err)
1083                 err = -EIO;
1084         return err;
1085 }
1086
1087 /*
1088  * When btree blocks are allocated the corresponding extents are marked dirty.
1089  * This function ensures such extents are persisted on disk for transaction or
1090  * log commit.
1091  *
1092  * @trans: transaction whose dirty pages we'd like to write
1093  */
1094 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)
1095 {
1096         int ret;
1097         int ret2;
1098         struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;
1099         struct btrfs_fs_info *fs_info = trans->fs_info;
1100         struct blk_plug plug;
1101
1102         blk_start_plug(&plug);
1103         ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);
1104         blk_finish_plug(&plug);
1105         ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1106
1107         clear_btree_io_tree(&trans->transaction->dirty_pages);
1108
1109         if (ret)
1110                 return ret;
1111         else if (ret2)
1112                 return ret2;
1113         else
1114                 return 0;
1115 }
1116
1117 /*
1118  * this is used to update the root pointer in the tree of tree roots.
1119  *
1120  * But, in the case of the extent allocation tree, updating the root
1121  * pointer may allocate blocks which may change the root of the extent
1122  * allocation tree.
1123  *
1124  * So, this loops and repeats and makes sure the cowonly root didn't
1125  * change while the root pointer was being updated in the metadata.
1126  */
1127 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1128                                struct btrfs_root *root)
1129 {
1130         int ret;
1131         u64 old_root_bytenr;
1132         u64 old_root_used;
1133         struct btrfs_fs_info *fs_info = root->fs_info;
1134         struct btrfs_root *tree_root = fs_info->tree_root;
1135
1136         old_root_used = btrfs_root_used(&root->root_item);
1137
1138         while (1) {
1139                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1140                 if (old_root_bytenr == root->node->start &&
1141                     old_root_used == btrfs_root_used(&root->root_item))
1142                         break;
1143
1144                 btrfs_set_root_node(&root->root_item, root->node);
1145                 ret = btrfs_update_root(trans, tree_root,
1146                                         &root->root_key,
1147                                         &root->root_item);
1148                 if (ret)
1149                         return ret;
1150
1151                 old_root_used = btrfs_root_used(&root->root_item);
1152         }
1153
1154         return 0;
1155 }
1156
1157 /*
1158  * update all the cowonly tree roots on disk
1159  *
1160  * The error handling in this function may not be obvious. Any of the
1161  * failures will cause the file system to go offline. We still need
1162  * to clean up the delayed refs.
1163  */
1164 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)
1165 {
1166         struct btrfs_fs_info *fs_info = trans->fs_info;
1167         struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1168         struct list_head *io_bgs = &trans->transaction->io_bgs;
1169         struct list_head *next;
1170         struct extent_buffer *eb;
1171         int ret;
1172
1173         eb = btrfs_lock_root_node(fs_info->tree_root);
1174         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1175                               0, &eb);
1176         btrfs_tree_unlock(eb);
1177         free_extent_buffer(eb);
1178
1179         if (ret)
1180                 return ret;
1181
1182         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1183         if (ret)
1184                 return ret;
1185
1186         ret = btrfs_run_dev_stats(trans, fs_info);
1187         if (ret)
1188                 return ret;
1189         ret = btrfs_run_dev_replace(trans, fs_info);
1190         if (ret)
1191                 return ret;
1192         ret = btrfs_run_qgroups(trans, fs_info);
1193         if (ret)
1194                 return ret;
1195
1196         ret = btrfs_setup_space_cache(trans, fs_info);
1197         if (ret)
1198                 return ret;
1199
1200         /* run_qgroups might have added some more refs */
1201         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1202         if (ret)
1203                 return ret;
1204 again:
1205         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1206                 struct btrfs_root *root;
1207                 next = fs_info->dirty_cowonly_roots.next;
1208                 list_del_init(next);
1209                 root = list_entry(next, struct btrfs_root, dirty_list);
1210                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1211
1212                 if (root != fs_info->extent_root)
1213                         list_add_tail(&root->dirty_list,
1214                                       &trans->transaction->switch_commits);
1215                 ret = update_cowonly_root(trans, root);
1216                 if (ret)
1217                         return ret;
1218                 ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1219                 if (ret)
1220                         return ret;
1221         }
1222
1223         while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1224                 ret = btrfs_write_dirty_block_groups(trans, fs_info);
1225                 if (ret)
1226                         return ret;
1227                 ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1228                 if (ret)
1229                         return ret;
1230         }
1231
1232         if (!list_empty(&fs_info->dirty_cowonly_roots))
1233                 goto again;
1234
1235         list_add_tail(&fs_info->extent_root->dirty_list,
1236                       &trans->transaction->switch_commits);
1237         btrfs_after_dev_replace_commit(fs_info);
1238
1239         return 0;
1240 }
1241
1242 /*
1243  * dead roots are old snapshots that need to be deleted.  This allocates
1244  * a dirty root struct and adds it into the list of dead roots that need to
1245  * be deleted
1246  */
1247 void btrfs_add_dead_root(struct btrfs_root *root)
1248 {
1249         struct btrfs_fs_info *fs_info = root->fs_info;
1250
1251         spin_lock(&fs_info->trans_lock);
1252         if (list_empty(&root->root_list))
1253                 list_add_tail(&root->root_list, &fs_info->dead_roots);
1254         spin_unlock(&fs_info->trans_lock);
1255 }
1256
1257 /*
1258  * update all the cowonly tree roots on disk
1259  */
1260 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
1261 {
1262         struct btrfs_fs_info *fs_info = trans->fs_info;
1263         struct btrfs_root *gang[8];
1264         int i;
1265         int ret;
1266         int err = 0;
1267
1268         spin_lock(&fs_info->fs_roots_radix_lock);
1269         while (1) {
1270                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1271                                                  (void **)gang, 0,
1272                                                  ARRAY_SIZE(gang),
1273                                                  BTRFS_ROOT_TRANS_TAG);
1274                 if (ret == 0)
1275                         break;
1276                 for (i = 0; i < ret; i++) {
1277                         struct btrfs_root *root = gang[i];
1278                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1279                                         (unsigned long)root->root_key.objectid,
1280                                         BTRFS_ROOT_TRANS_TAG);
1281                         spin_unlock(&fs_info->fs_roots_radix_lock);
1282
1283                         btrfs_free_log(trans, root);
1284                         btrfs_update_reloc_root(trans, root);
1285                         btrfs_orphan_commit_root(trans, root);
1286
1287                         btrfs_save_ino_cache(root, trans);
1288
1289                         /* see comments in should_cow_block() */
1290                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1291                         smp_mb__after_atomic();
1292
1293                         if (root->commit_root != root->node) {
1294                                 list_add_tail(&root->dirty_list,
1295                                         &trans->transaction->switch_commits);
1296                                 btrfs_set_root_node(&root->root_item,
1297                                                     root->node);
1298                         }
1299
1300                         err = btrfs_update_root(trans, fs_info->tree_root,
1301                                                 &root->root_key,
1302                                                 &root->root_item);
1303                         spin_lock(&fs_info->fs_roots_radix_lock);
1304                         if (err)
1305                                 break;
1306                         btrfs_qgroup_free_meta_all(root);
1307                 }
1308         }
1309         spin_unlock(&fs_info->fs_roots_radix_lock);
1310         return err;
1311 }
1312
1313 /*
1314  * defrag a given btree.
1315  * Every leaf in the btree is read and defragged.
1316  */
1317 int btrfs_defrag_root(struct btrfs_root *root)
1318 {
1319         struct btrfs_fs_info *info = root->fs_info;
1320         struct btrfs_trans_handle *trans;
1321         int ret;
1322
1323         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1324                 return 0;
1325
1326         while (1) {
1327                 trans = btrfs_start_transaction(root, 0);
1328                 if (IS_ERR(trans))
1329                         return PTR_ERR(trans);
1330
1331                 ret = btrfs_defrag_leaves(trans, root);
1332
1333                 btrfs_end_transaction(trans);
1334                 btrfs_btree_balance_dirty(info);
1335                 cond_resched();
1336
1337                 if (btrfs_fs_closing(info) || ret != -EAGAIN)
1338                         break;
1339
1340                 if (btrfs_defrag_cancelled(info)) {
1341                         btrfs_debug(info, "defrag_root cancelled");
1342                         ret = -EAGAIN;
1343                         break;
1344                 }
1345         }
1346         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1347         return ret;
1348 }
1349
1350 /*
1351  * Do all special snapshot related qgroup dirty hack.
1352  *
1353  * Will do all needed qgroup inherit and dirty hack like switch commit
1354  * roots inside one transaction and write all btree into disk, to make
1355  * qgroup works.
1356  */
1357 static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1358                                    struct btrfs_root *src,
1359                                    struct btrfs_root *parent,
1360                                    struct btrfs_qgroup_inherit *inherit,
1361                                    u64 dst_objectid)
1362 {
1363         struct btrfs_fs_info *fs_info = src->fs_info;
1364         int ret;
1365
1366         /*
1367          * Save some performance in the case that qgroups are not
1368          * enabled. If this check races with the ioctl, rescan will
1369          * kick in anyway.
1370          */
1371         if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
1372                 return 0;
1373
1374         /*
1375          * Ensure dirty @src will be commited.  Or, after comming
1376          * commit_fs_roots() and switch_commit_roots(), any dirty but not
1377          * recorded root will never be updated again, causing an outdated root
1378          * item.
1379          */
1380         record_root_in_trans(trans, src, 1);
1381
1382         /*
1383          * We are going to commit transaction, see btrfs_commit_transaction()
1384          * comment for reason locking tree_log_mutex
1385          */
1386         mutex_lock(&fs_info->tree_log_mutex);
1387
1388         ret = commit_fs_roots(trans);
1389         if (ret)
1390                 goto out;
1391         ret = btrfs_qgroup_account_extents(trans, fs_info);
1392         if (ret < 0)
1393                 goto out;
1394
1395         /* Now qgroup are all updated, we can inherit it to new qgroups */
1396         ret = btrfs_qgroup_inherit(trans, fs_info,
1397                                    src->root_key.objectid, dst_objectid,
1398                                    inherit);
1399         if (ret < 0)
1400                 goto out;
1401
1402         /*
1403          * Now we do a simplified commit transaction, which will:
1404          * 1) commit all subvolume and extent tree
1405          *    To ensure all subvolume and extent tree have a valid
1406          *    commit_root to accounting later insert_dir_item()
1407          * 2) write all btree blocks onto disk
1408          *    This is to make sure later btree modification will be cowed
1409          *    Or commit_root can be populated and cause wrong qgroup numbers
1410          * In this simplified commit, we don't really care about other trees
1411          * like chunk and root tree, as they won't affect qgroup.
1412          * And we don't write super to avoid half committed status.
1413          */
1414         ret = commit_cowonly_roots(trans);
1415         if (ret)
1416                 goto out;
1417         switch_commit_roots(trans->transaction);
1418         ret = btrfs_write_and_wait_transaction(trans);
1419         if (ret)
1420                 btrfs_handle_fs_error(fs_info, ret,
1421                         "Error while writing out transaction for qgroup");
1422
1423 out:
1424         mutex_unlock(&fs_info->tree_log_mutex);
1425
1426         /*
1427          * Force parent root to be updated, as we recorded it before so its
1428          * last_trans == cur_transid.
1429          * Or it won't be committed again onto disk after later
1430          * insert_dir_item()
1431          */
1432         if (!ret)
1433                 record_root_in_trans(trans, parent, 1);
1434         return ret;
1435 }
1436
1437 /*
1438  * new snapshots need to be created at a very specific time in the
1439  * transaction commit.  This does the actual creation.
1440  *
1441  * Note:
1442  * If the error which may affect the commitment of the current transaction
1443  * happens, we should return the error number. If the error which just affect
1444  * the creation of the pending snapshots, just return 0.
1445  */
1446 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1447                                    struct btrfs_pending_snapshot *pending)
1448 {
1449
1450         struct btrfs_fs_info *fs_info = trans->fs_info;
1451         struct btrfs_key key;
1452         struct btrfs_root_item *new_root_item;
1453         struct btrfs_root *tree_root = fs_info->tree_root;
1454         struct btrfs_root *root = pending->root;
1455         struct btrfs_root *parent_root;
1456         struct btrfs_block_rsv *rsv;
1457         struct inode *parent_inode;
1458         struct btrfs_path *path;
1459         struct btrfs_dir_item *dir_item;
1460         struct dentry *dentry;
1461         struct extent_buffer *tmp;
1462         struct extent_buffer *old;
1463         struct timespec cur_time;
1464         int ret = 0;
1465         u64 to_reserve = 0;
1466         u64 index = 0;
1467         u64 objectid;
1468         u64 root_flags;
1469         uuid_le new_uuid;
1470
1471         ASSERT(pending->path);
1472         path = pending->path;
1473
1474         ASSERT(pending->root_item);
1475         new_root_item = pending->root_item;
1476
1477         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1478         if (pending->error)
1479                 goto no_free_objectid;
1480
1481         /*
1482          * Make qgroup to skip current new snapshot's qgroupid, as it is
1483          * accounted by later btrfs_qgroup_inherit().
1484          */
1485         btrfs_set_skip_qgroup(trans, objectid);
1486
1487         btrfs_reloc_pre_snapshot(pending, &to_reserve);
1488
1489         if (to_reserve > 0) {
1490                 pending->error = btrfs_block_rsv_add(root,
1491                                                      &pending->block_rsv,
1492                                                      to_reserve,
1493                                                      BTRFS_RESERVE_NO_FLUSH);
1494                 if (pending->error)
1495                         goto clear_skip_qgroup;
1496         }
1497
1498         key.objectid = objectid;
1499         key.offset = (u64)-1;
1500         key.type = BTRFS_ROOT_ITEM_KEY;
1501
1502         rsv = trans->block_rsv;
1503         trans->block_rsv = &pending->block_rsv;
1504         trans->bytes_reserved = trans->block_rsv->reserved;
1505         trace_btrfs_space_reservation(fs_info, "transaction",
1506                                       trans->transid,
1507                                       trans->bytes_reserved, 1);
1508         dentry = pending->dentry;
1509         parent_inode = pending->dir;
1510         parent_root = BTRFS_I(parent_inode)->root;
1511         record_root_in_trans(trans, parent_root, 0);
1512
1513         cur_time = current_time(parent_inode);
1514
1515         /*
1516          * insert the directory item
1517          */
1518         ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);
1519         BUG_ON(ret); /* -ENOMEM */
1520
1521         /* check if there is a file/dir which has the same name. */
1522         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1523                                          btrfs_ino(BTRFS_I(parent_inode)),
1524                                          dentry->d_name.name,
1525                                          dentry->d_name.len, 0);
1526         if (dir_item != NULL && !IS_ERR(dir_item)) {
1527                 pending->error = -EEXIST;
1528                 goto dir_item_existed;
1529         } else if (IS_ERR(dir_item)) {
1530                 ret = PTR_ERR(dir_item);
1531                 btrfs_abort_transaction(trans, ret);
1532                 goto fail;
1533         }
1534         btrfs_release_path(path);
1535
1536         /*
1537          * pull in the delayed directory update
1538          * and the delayed inode item
1539          * otherwise we corrupt the FS during
1540          * snapshot
1541          */
1542         ret = btrfs_run_delayed_items(trans);
1543         if (ret) {      /* Transaction aborted */
1544                 btrfs_abort_transaction(trans, ret);
1545                 goto fail;
1546         }
1547
1548         record_root_in_trans(trans, root, 0);
1549         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1550         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1551         btrfs_check_and_init_root_item(new_root_item);
1552
1553         root_flags = btrfs_root_flags(new_root_item);
1554         if (pending->readonly)
1555                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1556         else
1557                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1558         btrfs_set_root_flags(new_root_item, root_flags);
1559
1560         btrfs_set_root_generation_v2(new_root_item,
1561                         trans->transid);
1562         uuid_le_gen(&new_uuid);
1563         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1564         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1565                         BTRFS_UUID_SIZE);
1566         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1567                 memset(new_root_item->received_uuid, 0,
1568                        sizeof(new_root_item->received_uuid));
1569                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1570                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1571                 btrfs_set_root_stransid(new_root_item, 0);
1572                 btrfs_set_root_rtransid(new_root_item, 0);
1573         }
1574         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1575         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1576         btrfs_set_root_otransid(new_root_item, trans->transid);
1577
1578         old = btrfs_lock_root_node(root);
1579         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1580         if (ret) {
1581                 btrfs_tree_unlock(old);
1582                 free_extent_buffer(old);
1583                 btrfs_abort_transaction(trans, ret);
1584                 goto fail;
1585         }
1586
1587         btrfs_set_lock_blocking(old);
1588
1589         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1590         /* clean up in any case */
1591         btrfs_tree_unlock(old);
1592         free_extent_buffer(old);
1593         if (ret) {
1594                 btrfs_abort_transaction(trans, ret);
1595                 goto fail;
1596         }
1597         /* see comments in should_cow_block() */
1598         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1599         smp_wmb();
1600
1601         btrfs_set_root_node(new_root_item, tmp);
1602         /* record when the snapshot was created in key.offset */
1603         key.offset = trans->transid;
1604         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1605         btrfs_tree_unlock(tmp);
1606         free_extent_buffer(tmp);
1607         if (ret) {
1608                 btrfs_abort_transaction(trans, ret);
1609                 goto fail;
1610         }
1611
1612         /*
1613          * insert root back/forward references
1614          */
1615         ret = btrfs_add_root_ref(trans, fs_info, objectid,
1616                                  parent_root->root_key.objectid,
1617                                  btrfs_ino(BTRFS_I(parent_inode)), index,
1618                                  dentry->d_name.name, dentry->d_name.len);
1619         if (ret) {
1620                 btrfs_abort_transaction(trans, ret);
1621                 goto fail;
1622         }
1623
1624         key.offset = (u64)-1;
1625         pending->snap = btrfs_read_fs_root_no_name(fs_info, &key);
1626         if (IS_ERR(pending->snap)) {
1627                 ret = PTR_ERR(pending->snap);
1628                 btrfs_abort_transaction(trans, ret);
1629                 goto fail;
1630         }
1631
1632         ret = btrfs_reloc_post_snapshot(trans, pending);
1633         if (ret) {
1634                 btrfs_abort_transaction(trans, ret);
1635                 goto fail;
1636         }
1637
1638         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1639         if (ret) {
1640                 btrfs_abort_transaction(trans, ret);
1641                 goto fail;
1642         }
1643
1644         /*
1645          * Do special qgroup accounting for snapshot, as we do some qgroup
1646          * snapshot hack to do fast snapshot.
1647          * To co-operate with that hack, we do hack again.
1648          * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1649          */
1650         ret = qgroup_account_snapshot(trans, root, parent_root,
1651                                       pending->inherit, objectid);
1652         if (ret < 0)
1653                 goto fail;
1654
1655         ret = btrfs_insert_dir_item(trans, parent_root,
1656                                     dentry->d_name.name, dentry->d_name.len,
1657                                     BTRFS_I(parent_inode), &key,
1658                                     BTRFS_FT_DIR, index);
1659         /* We have check then name at the beginning, so it is impossible. */
1660         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1661         if (ret) {
1662                 btrfs_abort_transaction(trans, ret);
1663                 goto fail;
1664         }
1665
1666         btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +
1667                                          dentry->d_name.len * 2);
1668         parent_inode->i_mtime = parent_inode->i_ctime =
1669                 current_time(parent_inode);
1670         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1671         if (ret) {
1672                 btrfs_abort_transaction(trans, ret);
1673                 goto fail;
1674         }
1675         ret = btrfs_uuid_tree_add(trans, fs_info, new_uuid.b,
1676                                   BTRFS_UUID_KEY_SUBVOL, objectid);
1677         if (ret) {
1678                 btrfs_abort_transaction(trans, ret);
1679                 goto fail;
1680         }
1681         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1682                 ret = btrfs_uuid_tree_add(trans, fs_info,
1683                                           new_root_item->received_uuid,
1684                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1685                                           objectid);
1686                 if (ret && ret != -EEXIST) {
1687                         btrfs_abort_transaction(trans, ret);
1688                         goto fail;
1689                 }
1690         }
1691
1692         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1693         if (ret) {
1694                 btrfs_abort_transaction(trans, ret);
1695                 goto fail;
1696         }
1697
1698 fail:
1699         pending->error = ret;
1700 dir_item_existed:
1701         trans->block_rsv = rsv;
1702         trans->bytes_reserved = 0;
1703 clear_skip_qgroup:
1704         btrfs_clear_skip_qgroup(trans);
1705 no_free_objectid:
1706         kfree(new_root_item);
1707         pending->root_item = NULL;
1708         btrfs_free_path(path);
1709         pending->path = NULL;
1710
1711         return ret;
1712 }
1713
1714 /*
1715  * create all the snapshots we've scheduled for creation
1716  */
1717 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)
1718 {
1719         struct btrfs_pending_snapshot *pending, *next;
1720         struct list_head *head = &trans->transaction->pending_snapshots;
1721         int ret = 0;
1722
1723         list_for_each_entry_safe(pending, next, head, list) {
1724                 list_del(&pending->list);
1725                 ret = create_pending_snapshot(trans, pending);
1726                 if (ret)
1727                         break;
1728         }
1729         return ret;
1730 }
1731
1732 static void update_super_roots(struct btrfs_fs_info *fs_info)
1733 {
1734         struct btrfs_root_item *root_item;
1735         struct btrfs_super_block *super;
1736
1737         super = fs_info->super_copy;
1738
1739         root_item = &fs_info->chunk_root->root_item;
1740         super->chunk_root = root_item->bytenr;
1741         super->chunk_root_generation = root_item->generation;
1742         super->chunk_root_level = root_item->level;
1743
1744         root_item = &fs_info->tree_root->root_item;
1745         super->root = root_item->bytenr;
1746         super->generation = root_item->generation;
1747         super->root_level = root_item->level;
1748         if (btrfs_test_opt(fs_info, SPACE_CACHE))
1749                 super->cache_generation = root_item->generation;
1750         if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1751                 super->uuid_tree_generation = root_item->generation;
1752 }
1753
1754 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1755 {
1756         struct btrfs_transaction *trans;
1757         int ret = 0;
1758
1759         spin_lock(&info->trans_lock);
1760         trans = info->running_transaction;
1761         if (trans)
1762                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1763         spin_unlock(&info->trans_lock);
1764         return ret;
1765 }
1766
1767 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1768 {
1769         struct btrfs_transaction *trans;
1770         int ret = 0;
1771
1772         spin_lock(&info->trans_lock);
1773         trans = info->running_transaction;
1774         if (trans)
1775                 ret = is_transaction_blocked(trans);
1776         spin_unlock(&info->trans_lock);
1777         return ret;
1778 }
1779
1780 /*
1781  * wait for the current transaction commit to start and block subsequent
1782  * transaction joins
1783  */
1784 static void wait_current_trans_commit_start(struct btrfs_fs_info *fs_info,
1785                                             struct btrfs_transaction *trans)
1786 {
1787         wait_event(fs_info->transaction_blocked_wait,
1788                    trans->state >= TRANS_STATE_COMMIT_START || trans->aborted);
1789 }
1790
1791 /*
1792  * wait for the current transaction to start and then become unblocked.
1793  * caller holds ref.
1794  */
1795 static void wait_current_trans_commit_start_and_unblock(
1796                                         struct btrfs_fs_info *fs_info,
1797                                         struct btrfs_transaction *trans)
1798 {
1799         wait_event(fs_info->transaction_wait,
1800                    trans->state >= TRANS_STATE_UNBLOCKED || trans->aborted);
1801 }
1802
1803 /*
1804  * commit transactions asynchronously. once btrfs_commit_transaction_async
1805  * returns, any subsequent transaction will not be allowed to join.
1806  */
1807 struct btrfs_async_commit {
1808         struct btrfs_trans_handle *newtrans;
1809         struct work_struct work;
1810 };
1811
1812 static void do_async_commit(struct work_struct *work)
1813 {
1814         struct btrfs_async_commit *ac =
1815                 container_of(work, struct btrfs_async_commit, work);
1816
1817         /*
1818          * We've got freeze protection passed with the transaction.
1819          * Tell lockdep about it.
1820          */
1821         if (ac->newtrans->type & __TRANS_FREEZABLE)
1822                 __sb_writers_acquired(ac->newtrans->fs_info->sb, SB_FREEZE_FS);
1823
1824         current->journal_info = ac->newtrans;
1825
1826         btrfs_commit_transaction(ac->newtrans);
1827         kfree(ac);
1828 }
1829
1830 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1831                                    int wait_for_unblock)
1832 {
1833         struct btrfs_fs_info *fs_info = trans->fs_info;
1834         struct btrfs_async_commit *ac;
1835         struct btrfs_transaction *cur_trans;
1836
1837         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1838         if (!ac)
1839                 return -ENOMEM;
1840
1841         INIT_WORK(&ac->work, do_async_commit);
1842         ac->newtrans = btrfs_join_transaction(trans->root);
1843         if (IS_ERR(ac->newtrans)) {
1844                 int err = PTR_ERR(ac->newtrans);
1845                 kfree(ac);
1846                 return err;
1847         }
1848
1849         /* take transaction reference */
1850         cur_trans = trans->transaction;
1851         refcount_inc(&cur_trans->use_count);
1852
1853         btrfs_end_transaction(trans);
1854
1855         /*
1856          * Tell lockdep we've released the freeze rwsem, since the
1857          * async commit thread will be the one to unlock it.
1858          */
1859         if (ac->newtrans->type & __TRANS_FREEZABLE)
1860                 __sb_writers_release(fs_info->sb, SB_FREEZE_FS);
1861
1862         schedule_work(&ac->work);
1863
1864         /* wait for transaction to start and unblock */
1865         if (wait_for_unblock)
1866                 wait_current_trans_commit_start_and_unblock(fs_info, cur_trans);
1867         else
1868                 wait_current_trans_commit_start(fs_info, cur_trans);
1869
1870         if (current->journal_info == trans)
1871                 current->journal_info = NULL;
1872
1873         btrfs_put_transaction(cur_trans);
1874         return 0;
1875 }
1876
1877
1878 static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
1879 {
1880         struct btrfs_fs_info *fs_info = trans->fs_info;
1881         struct btrfs_transaction *cur_trans = trans->transaction;
1882         DEFINE_WAIT(wait);
1883
1884         WARN_ON(refcount_read(&trans->use_count) > 1);
1885
1886         btrfs_abort_transaction(trans, err);
1887
1888         spin_lock(&fs_info->trans_lock);
1889
1890         /*
1891          * If the transaction is removed from the list, it means this
1892          * transaction has been committed successfully, so it is impossible
1893          * to call the cleanup function.
1894          */
1895         BUG_ON(list_empty(&cur_trans->list));
1896
1897         list_del_init(&cur_trans->list);
1898         if (cur_trans == fs_info->running_transaction) {
1899                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1900                 spin_unlock(&fs_info->trans_lock);
1901                 wait_event(cur_trans->writer_wait,
1902                            atomic_read(&cur_trans->num_writers) == 1);
1903
1904                 spin_lock(&fs_info->trans_lock);
1905         }
1906         spin_unlock(&fs_info->trans_lock);
1907
1908         btrfs_cleanup_one_transaction(trans->transaction, fs_info);
1909
1910         spin_lock(&fs_info->trans_lock);
1911         if (cur_trans == fs_info->running_transaction)
1912                 fs_info->running_transaction = NULL;
1913         spin_unlock(&fs_info->trans_lock);
1914
1915         if (trans->type & __TRANS_FREEZABLE)
1916                 sb_end_intwrite(fs_info->sb);
1917         btrfs_put_transaction(cur_trans);
1918         btrfs_put_transaction(cur_trans);
1919
1920         trace_btrfs_transaction_commit(trans->root);
1921
1922         if (current->journal_info == trans)
1923                 current->journal_info = NULL;
1924         btrfs_scrub_cancel(fs_info);
1925
1926         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1927 }
1928
1929 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1930 {
1931         /*
1932          * We use writeback_inodes_sb here because if we used
1933          * btrfs_start_delalloc_roots we would deadlock with fs freeze.
1934          * Currently are holding the fs freeze lock, if we do an async flush
1935          * we'll do btrfs_join_transaction() and deadlock because we need to
1936          * wait for the fs freeze lock.  Using the direct flushing we benefit
1937          * from already being in a transaction and our join_transaction doesn't
1938          * have to re-take the fs freeze lock.
1939          */
1940         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1941                 writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
1942         return 0;
1943 }
1944
1945 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1946 {
1947         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1948                 btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1949 }
1950
1951 static inline void
1952 btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans)
1953 {
1954         wait_event(cur_trans->pending_wait,
1955                    atomic_read(&cur_trans->pending_ordered) == 0);
1956 }
1957
1958 int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
1959 {
1960         struct btrfs_fs_info *fs_info = trans->fs_info;
1961         struct btrfs_transaction *cur_trans = trans->transaction;
1962         struct btrfs_transaction *prev_trans = NULL;
1963         int ret;
1964
1965         /* Stop the commit early if ->aborted is set */
1966         if (unlikely(READ_ONCE(cur_trans->aborted))) {
1967                 ret = cur_trans->aborted;
1968                 btrfs_end_transaction(trans);
1969                 return ret;
1970         }
1971
1972         /* make a pass through all the delayed refs we have so far
1973          * any runnings procs may add more while we are here
1974          */
1975         ret = btrfs_run_delayed_refs(trans, fs_info, 0);
1976         if (ret) {
1977                 btrfs_end_transaction(trans);
1978                 return ret;
1979         }
1980
1981         btrfs_trans_release_metadata(trans);
1982         trans->block_rsv = NULL;
1983
1984         cur_trans = trans->transaction;
1985
1986         /*
1987          * set the flushing flag so procs in this transaction have to
1988          * start sending their work down.
1989          */
1990         cur_trans->delayed_refs.flushing = 1;
1991         smp_wmb();
1992
1993         if (!list_empty(&trans->new_bgs))
1994                 btrfs_create_pending_block_groups(trans);
1995
1996         ret = btrfs_run_delayed_refs(trans, fs_info, 0);
1997         if (ret) {
1998                 btrfs_end_transaction(trans);
1999                 return ret;
2000         }
2001
2002         if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
2003                 int run_it = 0;
2004
2005                 /* this mutex is also taken before trying to set
2006                  * block groups readonly.  We need to make sure
2007                  * that nobody has set a block group readonly
2008                  * after a extents from that block group have been
2009                  * allocated for cache files.  btrfs_set_block_group_ro
2010                  * will wait for the transaction to commit if it
2011                  * finds BTRFS_TRANS_DIRTY_BG_RUN set.
2012                  *
2013                  * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
2014                  * only one process starts all the block group IO.  It wouldn't
2015                  * hurt to have more than one go through, but there's no
2016                  * real advantage to it either.
2017                  */
2018                 mutex_lock(&fs_info->ro_block_group_mutex);
2019                 if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
2020                                       &cur_trans->flags))
2021                         run_it = 1;
2022                 mutex_unlock(&fs_info->ro_block_group_mutex);
2023
2024                 if (run_it) {
2025                         ret = btrfs_start_dirty_block_groups(trans);
2026                         if (ret) {
2027                                 btrfs_end_transaction(trans);
2028                                 return ret;
2029                         }
2030                 }
2031         }
2032
2033         spin_lock(&fs_info->trans_lock);
2034         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
2035                 spin_unlock(&fs_info->trans_lock);
2036                 refcount_inc(&cur_trans->use_count);
2037                 ret = btrfs_end_transaction(trans);
2038
2039                 wait_for_commit(cur_trans);
2040
2041                 if (unlikely(cur_trans->aborted))
2042                         ret = cur_trans->aborted;
2043
2044                 btrfs_put_transaction(cur_trans);
2045
2046                 return ret;
2047         }
2048
2049         cur_trans->state = TRANS_STATE_COMMIT_START;
2050         wake_up(&fs_info->transaction_blocked_wait);
2051
2052         if (cur_trans->list.prev != &fs_info->trans_list) {
2053                 prev_trans = list_entry(cur_trans->list.prev,
2054                                         struct btrfs_transaction, list);
2055                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
2056                         refcount_inc(&prev_trans->use_count);
2057                         spin_unlock(&fs_info->trans_lock);
2058
2059                         wait_for_commit(prev_trans);
2060                         ret = prev_trans->aborted;
2061
2062                         btrfs_put_transaction(prev_trans);
2063                         if (ret)
2064                                 goto cleanup_transaction;
2065                 } else {
2066                         spin_unlock(&fs_info->trans_lock);
2067                 }
2068         } else {
2069                 spin_unlock(&fs_info->trans_lock);
2070         }
2071
2072         extwriter_counter_dec(cur_trans, trans->type);
2073
2074         ret = btrfs_start_delalloc_flush(fs_info);
2075         if (ret)
2076                 goto cleanup_transaction;
2077
2078         ret = btrfs_run_delayed_items(trans);
2079         if (ret)
2080                 goto cleanup_transaction;
2081
2082         wait_event(cur_trans->writer_wait,
2083                    extwriter_counter_read(cur_trans) == 0);
2084
2085         /* some pending stuffs might be added after the previous flush. */
2086         ret = btrfs_run_delayed_items(trans);
2087         if (ret)
2088                 goto cleanup_transaction;
2089
2090         btrfs_wait_delalloc_flush(fs_info);
2091
2092         btrfs_wait_pending_ordered(cur_trans);
2093
2094         btrfs_scrub_pause(fs_info);
2095         /*
2096          * Ok now we need to make sure to block out any other joins while we
2097          * commit the transaction.  We could have started a join before setting
2098          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2099          */
2100         spin_lock(&fs_info->trans_lock);
2101         cur_trans->state = TRANS_STATE_COMMIT_DOING;
2102         spin_unlock(&fs_info->trans_lock);
2103         wait_event(cur_trans->writer_wait,
2104                    atomic_read(&cur_trans->num_writers) == 1);
2105
2106         /* ->aborted might be set after the previous check, so check it */
2107         if (unlikely(READ_ONCE(cur_trans->aborted))) {
2108                 ret = cur_trans->aborted;
2109                 goto scrub_continue;
2110         }
2111         /*
2112          * the reloc mutex makes sure that we stop
2113          * the balancing code from coming in and moving
2114          * extents around in the middle of the commit
2115          */
2116         mutex_lock(&fs_info->reloc_mutex);
2117
2118         /*
2119          * We needn't worry about the delayed items because we will
2120          * deal with them in create_pending_snapshot(), which is the
2121          * core function of the snapshot creation.
2122          */
2123         ret = create_pending_snapshots(trans);
2124         if (ret) {
2125                 mutex_unlock(&fs_info->reloc_mutex);
2126                 goto scrub_continue;
2127         }
2128
2129         /*
2130          * We insert the dir indexes of the snapshots and update the inode
2131          * of the snapshots' parents after the snapshot creation, so there
2132          * are some delayed items which are not dealt with. Now deal with
2133          * them.
2134          *
2135          * We needn't worry that this operation will corrupt the snapshots,
2136          * because all the tree which are snapshoted will be forced to COW
2137          * the nodes and leaves.
2138          */
2139         ret = btrfs_run_delayed_items(trans);
2140         if (ret) {
2141                 mutex_unlock(&fs_info->reloc_mutex);
2142                 goto scrub_continue;
2143         }
2144
2145         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
2146         if (ret) {
2147                 mutex_unlock(&fs_info->reloc_mutex);
2148                 goto scrub_continue;
2149         }
2150
2151         /*
2152          * make sure none of the code above managed to slip in a
2153          * delayed item
2154          */
2155         btrfs_assert_delayed_root_empty(fs_info);
2156
2157         WARN_ON(cur_trans != trans->transaction);
2158
2159         /* btrfs_commit_tree_roots is responsible for getting the
2160          * various roots consistent with each other.  Every pointer
2161          * in the tree of tree roots has to point to the most up to date
2162          * root for every subvolume and other tree.  So, we have to keep
2163          * the tree logging code from jumping in and changing any
2164          * of the trees.
2165          *
2166          * At this point in the commit, there can't be any tree-log
2167          * writers, but a little lower down we drop the trans mutex
2168          * and let new people in.  By holding the tree_log_mutex
2169          * from now until after the super is written, we avoid races
2170          * with the tree-log code.
2171          */
2172         mutex_lock(&fs_info->tree_log_mutex);
2173
2174         ret = commit_fs_roots(trans);
2175         if (ret) {
2176                 mutex_unlock(&fs_info->tree_log_mutex);
2177                 mutex_unlock(&fs_info->reloc_mutex);
2178                 goto scrub_continue;
2179         }
2180
2181         /*
2182          * Since the transaction is done, we can apply the pending changes
2183          * before the next transaction.
2184          */
2185         btrfs_apply_pending_changes(fs_info);
2186
2187         /* commit_fs_roots gets rid of all the tree log roots, it is now
2188          * safe to free the root of tree log roots
2189          */
2190         btrfs_free_log_root_tree(trans, fs_info);
2191
2192         /*
2193          * commit_fs_roots() can call btrfs_save_ino_cache(), which generates
2194          * new delayed refs. Must handle them or qgroup can be wrong.
2195          */
2196         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
2197         if (ret) {
2198                 mutex_unlock(&fs_info->tree_log_mutex);
2199                 mutex_unlock(&fs_info->reloc_mutex);
2200                 goto scrub_continue;
2201         }
2202
2203         /*
2204          * Since fs roots are all committed, we can get a quite accurate
2205          * new_roots. So let's do quota accounting.
2206          */
2207         ret = btrfs_qgroup_account_extents(trans, fs_info);
2208         if (ret < 0) {
2209                 mutex_unlock(&fs_info->tree_log_mutex);
2210                 mutex_unlock(&fs_info->reloc_mutex);
2211                 goto scrub_continue;
2212         }
2213
2214         ret = commit_cowonly_roots(trans);
2215         if (ret) {
2216                 mutex_unlock(&fs_info->tree_log_mutex);
2217                 mutex_unlock(&fs_info->reloc_mutex);
2218                 goto scrub_continue;
2219         }
2220
2221         /*
2222          * The tasks which save the space cache and inode cache may also
2223          * update ->aborted, check it.
2224          */
2225         if (unlikely(READ_ONCE(cur_trans->aborted))) {
2226                 ret = cur_trans->aborted;
2227                 mutex_unlock(&fs_info->tree_log_mutex);
2228                 mutex_unlock(&fs_info->reloc_mutex);
2229                 goto scrub_continue;
2230         }
2231
2232         btrfs_prepare_extent_commit(fs_info);
2233
2234         cur_trans = fs_info->running_transaction;
2235
2236         btrfs_set_root_node(&fs_info->tree_root->root_item,
2237                             fs_info->tree_root->node);
2238         list_add_tail(&fs_info->tree_root->dirty_list,
2239                       &cur_trans->switch_commits);
2240
2241         btrfs_set_root_node(&fs_info->chunk_root->root_item,
2242                             fs_info->chunk_root->node);
2243         list_add_tail(&fs_info->chunk_root->dirty_list,
2244                       &cur_trans->switch_commits);
2245
2246         switch_commit_roots(cur_trans);
2247
2248         ASSERT(list_empty(&cur_trans->dirty_bgs));
2249         ASSERT(list_empty(&cur_trans->io_bgs));
2250         update_super_roots(fs_info);
2251
2252         btrfs_set_super_log_root(fs_info->super_copy, 0);
2253         btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2254         memcpy(fs_info->super_for_commit, fs_info->super_copy,
2255                sizeof(*fs_info->super_copy));
2256
2257         btrfs_update_commit_device_size(fs_info);
2258         btrfs_update_commit_device_bytes_used(cur_trans);
2259
2260         clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2261         clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2262
2263         btrfs_trans_release_chunk_metadata(trans);
2264
2265         spin_lock(&fs_info->trans_lock);
2266         cur_trans->state = TRANS_STATE_UNBLOCKED;
2267         fs_info->running_transaction = NULL;
2268         spin_unlock(&fs_info->trans_lock);
2269         mutex_unlock(&fs_info->reloc_mutex);
2270
2271         wake_up(&fs_info->transaction_wait);
2272
2273         ret = btrfs_write_and_wait_transaction(trans);
2274         if (ret) {
2275                 btrfs_handle_fs_error(fs_info, ret,
2276                                       "Error while writing out transaction");
2277                 mutex_unlock(&fs_info->tree_log_mutex);
2278                 goto scrub_continue;
2279         }
2280
2281         ret = write_all_supers(fs_info, 0);
2282         /*
2283          * the super is written, we can safely allow the tree-loggers
2284          * to go about their business
2285          */
2286         mutex_unlock(&fs_info->tree_log_mutex);
2287         if (ret)
2288                 goto scrub_continue;
2289
2290         btrfs_finish_extent_commit(trans, fs_info);
2291
2292         if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2293                 btrfs_clear_space_info_full(fs_info);
2294
2295         fs_info->last_trans_committed = cur_trans->transid;
2296         /*
2297          * We needn't acquire the lock here because there is no other task
2298          * which can change it.
2299          */
2300         cur_trans->state = TRANS_STATE_COMPLETED;
2301         wake_up(&cur_trans->commit_wait);
2302
2303         spin_lock(&fs_info->trans_lock);
2304         list_del_init(&cur_trans->list);
2305         spin_unlock(&fs_info->trans_lock);
2306
2307         btrfs_put_transaction(cur_trans);
2308         btrfs_put_transaction(cur_trans);
2309
2310         if (trans->type & __TRANS_FREEZABLE)
2311                 sb_end_intwrite(fs_info->sb);
2312
2313         trace_btrfs_transaction_commit(trans->root);
2314
2315         btrfs_scrub_continue(fs_info);
2316
2317         if (current->journal_info == trans)
2318                 current->journal_info = NULL;
2319
2320         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2321
2322         /*
2323          * If fs has been frozen, we can not handle delayed iputs, otherwise
2324          * it'll result in deadlock about SB_FREEZE_FS.
2325          */
2326         if (current != fs_info->transaction_kthread &&
2327             current != fs_info->cleaner_kthread &&
2328             !test_bit(BTRFS_FS_FROZEN, &fs_info->flags))
2329                 btrfs_run_delayed_iputs(fs_info);
2330
2331         return ret;
2332
2333 scrub_continue:
2334         btrfs_scrub_continue(fs_info);
2335 cleanup_transaction:
2336         btrfs_trans_release_metadata(trans);
2337         btrfs_trans_release_chunk_metadata(trans);
2338         trans->block_rsv = NULL;
2339         btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2340         if (current->journal_info == trans)
2341                 current->journal_info = NULL;
2342         cleanup_transaction(trans, ret);
2343
2344         return ret;
2345 }
2346
2347 /*
2348  * return < 0 if error
2349  * 0 if there are no more dead_roots at the time of call
2350  * 1 there are more to be processed, call me again
2351  *
2352  * The return value indicates there are certainly more snapshots to delete, but
2353  * if there comes a new one during processing, it may return 0. We don't mind,
2354  * because btrfs_commit_super will poke cleaner thread and it will process it a
2355  * few seconds later.
2356  */
2357 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2358 {
2359         int ret;
2360         struct btrfs_fs_info *fs_info = root->fs_info;
2361
2362         spin_lock(&fs_info->trans_lock);
2363         if (list_empty(&fs_info->dead_roots)) {
2364                 spin_unlock(&fs_info->trans_lock);
2365                 return 0;
2366         }
2367         root = list_first_entry(&fs_info->dead_roots,
2368                         struct btrfs_root, root_list);
2369         list_del_init(&root->root_list);
2370         spin_unlock(&fs_info->trans_lock);
2371
2372         btrfs_debug(fs_info, "cleaner removing %llu", root->objectid);
2373
2374         btrfs_kill_all_delayed_nodes(root);
2375
2376         if (btrfs_header_backref_rev(root->node) <
2377                         BTRFS_MIXED_BACKREF_REV)
2378                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2379         else
2380                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2381
2382         return (ret < 0) ? 0 : 1;
2383 }
2384
2385 void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2386 {
2387         unsigned long prev;
2388         unsigned long bit;
2389
2390         prev = xchg(&fs_info->pending_changes, 0);
2391         if (!prev)
2392                 return;
2393
2394         bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2395         if (prev & bit)
2396                 btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2397         prev &= ~bit;
2398
2399         bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2400         if (prev & bit)
2401                 btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2402         prev &= ~bit;
2403
2404         bit = 1 << BTRFS_PENDING_COMMIT;
2405         if (prev & bit)
2406                 btrfs_debug(fs_info, "pending commit done");
2407         prev &= ~bit;
2408
2409         if (prev)
2410                 btrfs_warn(fs_info,
2411                         "unknown pending changes left 0x%lx, ignoring", prev);
2412 }