a2d6f7bcef6cf39ccdc0664d5c1cce6ef4d0789d
[muen/linux.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(atomic_read(&transaction->use_count) == 0);
64         if (atomic_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                         printk(KERN_ERR "pending csums is %llu\n",
69                                transaction->delayed_refs.pending_csums);
70                 while (!list_empty(&transaction->pending_chunks)) {
71                         struct extent_map *em;
72
73                         em = list_first_entry(&transaction->pending_chunks,
74                                               struct extent_map, list);
75                         list_del_init(&em->list);
76                         free_extent_map(em);
77                 }
78                 kmem_cache_free(btrfs_transaction_cachep, transaction);
79         }
80 }
81
82 static void clear_btree_io_tree(struct extent_io_tree *tree)
83 {
84         spin_lock(&tree->lock);
85         while (!RB_EMPTY_ROOT(&tree->state)) {
86                 struct rb_node *node;
87                 struct extent_state *state;
88
89                 node = rb_first(&tree->state);
90                 state = rb_entry(node, struct extent_state, rb_node);
91                 rb_erase(&state->rb_node, &tree->state);
92                 RB_CLEAR_NODE(&state->rb_node);
93                 /*
94                  * btree io trees aren't supposed to have tasks waiting for
95                  * changes in the flags of extent states ever.
96                  */
97                 ASSERT(!waitqueue_active(&state->wq));
98                 free_extent_state(state);
99
100                 cond_resched_lock(&tree->lock);
101         }
102         spin_unlock(&tree->lock);
103 }
104
105 static noinline void switch_commit_roots(struct btrfs_transaction *trans,
106                                          struct btrfs_fs_info *fs_info)
107 {
108         struct btrfs_root *root, *tmp;
109
110         down_write(&fs_info->commit_root_sem);
111         list_for_each_entry_safe(root, tmp, &trans->switch_commits,
112                                  dirty_list) {
113                 list_del_init(&root->dirty_list);
114                 free_extent_buffer(root->commit_root);
115                 root->commit_root = btrfs_root_node(root);
116                 if (is_fstree(root->objectid))
117                         btrfs_unpin_free_ino(root);
118                 clear_btree_io_tree(&root->dirty_log_pages);
119         }
120
121         /* We can free old roots now. */
122         spin_lock(&trans->dropped_roots_lock);
123         while (!list_empty(&trans->dropped_roots)) {
124                 root = list_first_entry(&trans->dropped_roots,
125                                         struct btrfs_root, root_list);
126                 list_del_init(&root->root_list);
127                 spin_unlock(&trans->dropped_roots_lock);
128                 btrfs_drop_and_free_fs_root(fs_info, root);
129                 spin_lock(&trans->dropped_roots_lock);
130         }
131         spin_unlock(&trans->dropped_roots_lock);
132         up_write(&fs_info->commit_root_sem);
133 }
134
135 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
136                                          unsigned int type)
137 {
138         if (type & TRANS_EXTWRITERS)
139                 atomic_inc(&trans->num_extwriters);
140 }
141
142 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
143                                          unsigned int type)
144 {
145         if (type & TRANS_EXTWRITERS)
146                 atomic_dec(&trans->num_extwriters);
147 }
148
149 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
150                                           unsigned int type)
151 {
152         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
153 }
154
155 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
156 {
157         return atomic_read(&trans->num_extwriters);
158 }
159
160 /*
161  * either allocate a new transaction or hop into the existing one
162  */
163 static noinline int join_transaction(struct btrfs_root *root, unsigned int type)
164 {
165         struct btrfs_transaction *cur_trans;
166         struct btrfs_fs_info *fs_info = root->fs_info;
167
168         spin_lock(&fs_info->trans_lock);
169 loop:
170         /* The file system has been taken offline. No new transactions. */
171         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
172                 spin_unlock(&fs_info->trans_lock);
173                 return -EROFS;
174         }
175
176         cur_trans = fs_info->running_transaction;
177         if (cur_trans) {
178                 if (cur_trans->aborted) {
179                         spin_unlock(&fs_info->trans_lock);
180                         return cur_trans->aborted;
181                 }
182                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
183                         spin_unlock(&fs_info->trans_lock);
184                         return -EBUSY;
185                 }
186                 atomic_inc(&cur_trans->use_count);
187                 atomic_inc(&cur_trans->num_writers);
188                 extwriter_counter_inc(cur_trans, type);
189                 spin_unlock(&fs_info->trans_lock);
190                 return 0;
191         }
192         spin_unlock(&fs_info->trans_lock);
193
194         /*
195          * If we are ATTACH, we just want to catch the current transaction,
196          * and commit it. If there is no transaction, just return ENOENT.
197          */
198         if (type == TRANS_ATTACH)
199                 return -ENOENT;
200
201         /*
202          * JOIN_NOLOCK only happens during the transaction commit, so
203          * it is impossible that ->running_transaction is NULL
204          */
205         BUG_ON(type == TRANS_JOIN_NOLOCK);
206
207         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
208         if (!cur_trans)
209                 return -ENOMEM;
210
211         spin_lock(&fs_info->trans_lock);
212         if (fs_info->running_transaction) {
213                 /*
214                  * someone started a transaction after we unlocked.  Make sure
215                  * to redo the checks above
216                  */
217                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
218                 goto loop;
219         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
220                 spin_unlock(&fs_info->trans_lock);
221                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
222                 return -EROFS;
223         }
224
225         atomic_set(&cur_trans->num_writers, 1);
226         extwriter_counter_init(cur_trans, type);
227         init_waitqueue_head(&cur_trans->writer_wait);
228         init_waitqueue_head(&cur_trans->commit_wait);
229         cur_trans->state = TRANS_STATE_RUNNING;
230         /*
231          * One for this trans handle, one so it will live on until we
232          * commit the transaction.
233          */
234         atomic_set(&cur_trans->use_count, 2);
235         cur_trans->have_free_bgs = 0;
236         cur_trans->start_time = get_seconds();
237         cur_trans->dirty_bg_run = 0;
238
239         cur_trans->delayed_refs.href_root = RB_ROOT;
240         cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
241         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
242         cur_trans->delayed_refs.num_heads_ready = 0;
243         cur_trans->delayed_refs.pending_csums = 0;
244         cur_trans->delayed_refs.num_heads = 0;
245         cur_trans->delayed_refs.flushing = 0;
246         cur_trans->delayed_refs.run_delayed_start = 0;
247         cur_trans->delayed_refs.qgroup_to_skip = 0;
248
249         /*
250          * although the tree mod log is per file system and not per transaction,
251          * the log must never go across transaction boundaries.
252          */
253         smp_mb();
254         if (!list_empty(&fs_info->tree_mod_seq_list))
255                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when "
256                         "creating a fresh transaction\n");
257         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
258                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when "
259                         "creating a fresh transaction\n");
260         atomic64_set(&fs_info->tree_mod_seq, 0);
261
262         spin_lock_init(&cur_trans->delayed_refs.lock);
263
264         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
265         INIT_LIST_HEAD(&cur_trans->pending_chunks);
266         INIT_LIST_HEAD(&cur_trans->switch_commits);
267         INIT_LIST_HEAD(&cur_trans->pending_ordered);
268         INIT_LIST_HEAD(&cur_trans->dirty_bgs);
269         INIT_LIST_HEAD(&cur_trans->io_bgs);
270         INIT_LIST_HEAD(&cur_trans->dropped_roots);
271         mutex_init(&cur_trans->cache_write_mutex);
272         cur_trans->num_dirty_bgs = 0;
273         spin_lock_init(&cur_trans->dirty_bgs_lock);
274         INIT_LIST_HEAD(&cur_trans->deleted_bgs);
275         spin_lock_init(&cur_trans->deleted_bgs_lock);
276         spin_lock_init(&cur_trans->dropped_roots_lock);
277         list_add_tail(&cur_trans->list, &fs_info->trans_list);
278         extent_io_tree_init(&cur_trans->dirty_pages,
279                              fs_info->btree_inode->i_mapping);
280         fs_info->generation++;
281         cur_trans->transid = fs_info->generation;
282         fs_info->running_transaction = cur_trans;
283         cur_trans->aborted = 0;
284         spin_unlock(&fs_info->trans_lock);
285
286         return 0;
287 }
288
289 /*
290  * this does all the record keeping required to make sure that a reference
291  * counted root is properly recorded in a given transaction.  This is required
292  * to make sure the old root from before we joined the transaction is deleted
293  * when the transaction commits
294  */
295 static int record_root_in_trans(struct btrfs_trans_handle *trans,
296                                struct btrfs_root *root)
297 {
298         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
299             root->last_trans < trans->transid) {
300                 WARN_ON(root == root->fs_info->extent_root);
301                 WARN_ON(root->commit_root != root->node);
302
303                 /*
304                  * see below for IN_TRANS_SETUP usage rules
305                  * we have the reloc mutex held now, so there
306                  * is only one writer in this function
307                  */
308                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
309
310                 /* make sure readers find IN_TRANS_SETUP before
311                  * they find our root->last_trans update
312                  */
313                 smp_wmb();
314
315                 spin_lock(&root->fs_info->fs_roots_radix_lock);
316                 if (root->last_trans == trans->transid) {
317                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
318                         return 0;
319                 }
320                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
321                            (unsigned long)root->root_key.objectid,
322                            BTRFS_ROOT_TRANS_TAG);
323                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
324                 root->last_trans = trans->transid;
325
326                 /* this is pretty tricky.  We don't want to
327                  * take the relocation lock in btrfs_record_root_in_trans
328                  * unless we're really doing the first setup for this root in
329                  * this transaction.
330                  *
331                  * Normally we'd use root->last_trans as a flag to decide
332                  * if we want to take the expensive mutex.
333                  *
334                  * But, we have to set root->last_trans before we
335                  * init the relocation root, otherwise, we trip over warnings
336                  * in ctree.c.  The solution used here is to flag ourselves
337                  * with root IN_TRANS_SETUP.  When this is 1, we're still
338                  * fixing up the reloc trees and everyone must wait.
339                  *
340                  * When this is zero, they can trust root->last_trans and fly
341                  * through btrfs_record_root_in_trans without having to take the
342                  * lock.  smp_wmb() makes sure that all the writes above are
343                  * done before we pop in the zero below
344                  */
345                 btrfs_init_reloc_root(trans, root);
346                 smp_mb__before_atomic();
347                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
348         }
349         return 0;
350 }
351
352
353 void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
354                             struct btrfs_root *root)
355 {
356         struct btrfs_transaction *cur_trans = trans->transaction;
357
358         /* Add ourselves to the transaction dropped list */
359         spin_lock(&cur_trans->dropped_roots_lock);
360         list_add_tail(&root->root_list, &cur_trans->dropped_roots);
361         spin_unlock(&cur_trans->dropped_roots_lock);
362
363         /* Make sure we don't try to update the root at commit time */
364         spin_lock(&root->fs_info->fs_roots_radix_lock);
365         radix_tree_tag_clear(&root->fs_info->fs_roots_radix,
366                              (unsigned long)root->root_key.objectid,
367                              BTRFS_ROOT_TRANS_TAG);
368         spin_unlock(&root->fs_info->fs_roots_radix_lock);
369 }
370
371 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
372                                struct btrfs_root *root)
373 {
374         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
375                 return 0;
376
377         /*
378          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
379          * and barriers
380          */
381         smp_rmb();
382         if (root->last_trans == trans->transid &&
383             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
384                 return 0;
385
386         mutex_lock(&root->fs_info->reloc_mutex);
387         record_root_in_trans(trans, root);
388         mutex_unlock(&root->fs_info->reloc_mutex);
389
390         return 0;
391 }
392
393 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
394 {
395         return (trans->state >= TRANS_STATE_BLOCKED &&
396                 trans->state < TRANS_STATE_UNBLOCKED &&
397                 !trans->aborted);
398 }
399
400 /* wait for commit against the current transaction to become unblocked
401  * when this is done, it is safe to start a new transaction, but the current
402  * transaction might not be fully on disk.
403  */
404 static void wait_current_trans(struct btrfs_root *root)
405 {
406         struct btrfs_transaction *cur_trans;
407
408         spin_lock(&root->fs_info->trans_lock);
409         cur_trans = root->fs_info->running_transaction;
410         if (cur_trans && is_transaction_blocked(cur_trans)) {
411                 atomic_inc(&cur_trans->use_count);
412                 spin_unlock(&root->fs_info->trans_lock);
413
414                 wait_event(root->fs_info->transaction_wait,
415                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
416                            cur_trans->aborted);
417                 btrfs_put_transaction(cur_trans);
418         } else {
419                 spin_unlock(&root->fs_info->trans_lock);
420         }
421 }
422
423 static int may_wait_transaction(struct btrfs_root *root, int type)
424 {
425         if (root->fs_info->log_root_recovering)
426                 return 0;
427
428         if (type == TRANS_USERSPACE)
429                 return 1;
430
431         if (type == TRANS_START &&
432             !atomic_read(&root->fs_info->open_ioctl_trans))
433                 return 1;
434
435         return 0;
436 }
437
438 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
439 {
440         if (!root->fs_info->reloc_ctl ||
441             !test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
442             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
443             root->reloc_root)
444                 return false;
445
446         return true;
447 }
448
449 static struct btrfs_trans_handle *
450 start_transaction(struct btrfs_root *root, u64 num_items, unsigned int type,
451                   enum btrfs_reserve_flush_enum flush)
452 {
453         struct btrfs_trans_handle *h;
454         struct btrfs_transaction *cur_trans;
455         u64 num_bytes = 0;
456         u64 qgroup_reserved = 0;
457         bool reloc_reserved = false;
458         int ret;
459
460         /* Send isn't supposed to start transactions. */
461         ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
462
463         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
464                 return ERR_PTR(-EROFS);
465
466         if (current->journal_info) {
467                 WARN_ON(type & TRANS_EXTWRITERS);
468                 h = current->journal_info;
469                 h->use_count++;
470                 WARN_ON(h->use_count > 2);
471                 h->orig_rsv = h->block_rsv;
472                 h->block_rsv = NULL;
473                 goto got_it;
474         }
475
476         /*
477          * Do the reservation before we join the transaction so we can do all
478          * the appropriate flushing if need be.
479          */
480         if (num_items > 0 && root != root->fs_info->chunk_root) {
481                 if (root->fs_info->quota_enabled &&
482                     is_fstree(root->root_key.objectid)) {
483                         qgroup_reserved = num_items * root->nodesize;
484                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
485                         if (ret)
486                                 return ERR_PTR(ret);
487                 }
488
489                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
490                 /*
491                  * Do the reservation for the relocation root creation
492                  */
493                 if (need_reserve_reloc_root(root)) {
494                         num_bytes += root->nodesize;
495                         reloc_reserved = true;
496                 }
497
498                 ret = btrfs_block_rsv_add(root,
499                                           &root->fs_info->trans_block_rsv,
500                                           num_bytes, flush);
501                 if (ret)
502                         goto reserve_fail;
503         }
504 again:
505         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
506         if (!h) {
507                 ret = -ENOMEM;
508                 goto alloc_fail;
509         }
510
511         /*
512          * If we are JOIN_NOLOCK we're already committing a transaction and
513          * waiting on this guy, so we don't need to do the sb_start_intwrite
514          * because we're already holding a ref.  We need this because we could
515          * have raced in and did an fsync() on a file which can kick a commit
516          * and then we deadlock with somebody doing a freeze.
517          *
518          * If we are ATTACH, it means we just want to catch the current
519          * transaction and commit it, so we needn't do sb_start_intwrite(). 
520          */
521         if (type & __TRANS_FREEZABLE)
522                 sb_start_intwrite(root->fs_info->sb);
523
524         if (may_wait_transaction(root, type))
525                 wait_current_trans(root);
526
527         do {
528                 ret = join_transaction(root, type);
529                 if (ret == -EBUSY) {
530                         wait_current_trans(root);
531                         if (unlikely(type == TRANS_ATTACH))
532                                 ret = -ENOENT;
533                 }
534         } while (ret == -EBUSY);
535
536         if (ret < 0) {
537                 /* We must get the transaction if we are JOIN_NOLOCK. */
538                 BUG_ON(type == TRANS_JOIN_NOLOCK);
539                 goto join_fail;
540         }
541
542         cur_trans = root->fs_info->running_transaction;
543
544         h->transid = cur_trans->transid;
545         h->transaction = cur_trans;
546         h->blocks_used = 0;
547         h->bytes_reserved = 0;
548         h->chunk_bytes_reserved = 0;
549         h->root = root;
550         h->delayed_ref_updates = 0;
551         h->use_count = 1;
552         h->adding_csums = 0;
553         h->block_rsv = NULL;
554         h->orig_rsv = NULL;
555         h->aborted = 0;
556         h->qgroup_reserved = 0;
557         h->delayed_ref_elem.seq = 0;
558         h->type = type;
559         h->allocating_chunk = false;
560         h->reloc_reserved = false;
561         h->sync = false;
562         INIT_LIST_HEAD(&h->qgroup_ref_list);
563         INIT_LIST_HEAD(&h->new_bgs);
564         INIT_LIST_HEAD(&h->ordered);
565
566         smp_mb();
567         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
568             may_wait_transaction(root, type)) {
569                 current->journal_info = h;
570                 btrfs_commit_transaction(h, root);
571                 goto again;
572         }
573
574         if (num_bytes) {
575                 trace_btrfs_space_reservation(root->fs_info, "transaction",
576                                               h->transid, num_bytes, 1);
577                 h->block_rsv = &root->fs_info->trans_block_rsv;
578                 h->bytes_reserved = num_bytes;
579                 h->reloc_reserved = reloc_reserved;
580         }
581         h->qgroup_reserved = qgroup_reserved;
582
583 got_it:
584         btrfs_record_root_in_trans(h, root);
585
586         if (!current->journal_info && type != TRANS_USERSPACE)
587                 current->journal_info = h;
588         return h;
589
590 join_fail:
591         if (type & __TRANS_FREEZABLE)
592                 sb_end_intwrite(root->fs_info->sb);
593         kmem_cache_free(btrfs_trans_handle_cachep, h);
594 alloc_fail:
595         if (num_bytes)
596                 btrfs_block_rsv_release(root, &root->fs_info->trans_block_rsv,
597                                         num_bytes);
598 reserve_fail:
599         if (qgroup_reserved)
600                 btrfs_qgroup_free(root, qgroup_reserved);
601         return ERR_PTR(ret);
602 }
603
604 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
605                                                    int num_items)
606 {
607         return start_transaction(root, num_items, TRANS_START,
608                                  BTRFS_RESERVE_FLUSH_ALL);
609 }
610
611 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
612                                         struct btrfs_root *root, int num_items)
613 {
614         return start_transaction(root, num_items, TRANS_START,
615                                  BTRFS_RESERVE_FLUSH_LIMIT);
616 }
617
618 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
619 {
620         return start_transaction(root, 0, TRANS_JOIN, 0);
621 }
622
623 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
624 {
625         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
626 }
627
628 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
629 {
630         return start_transaction(root, 0, TRANS_USERSPACE, 0);
631 }
632
633 /*
634  * btrfs_attach_transaction() - catch the running transaction
635  *
636  * It is used when we want to commit the current the transaction, but
637  * don't want to start a new one.
638  *
639  * Note: If this function return -ENOENT, it just means there is no
640  * running transaction. But it is possible that the inactive transaction
641  * is still in the memory, not fully on disk. If you hope there is no
642  * inactive transaction in the fs when -ENOENT is returned, you should
643  * invoke
644  *     btrfs_attach_transaction_barrier()
645  */
646 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
647 {
648         return start_transaction(root, 0, TRANS_ATTACH, 0);
649 }
650
651 /*
652  * btrfs_attach_transaction_barrier() - catch the running transaction
653  *
654  * It is similar to the above function, the differentia is this one
655  * will wait for all the inactive transactions until they fully
656  * complete.
657  */
658 struct btrfs_trans_handle *
659 btrfs_attach_transaction_barrier(struct btrfs_root *root)
660 {
661         struct btrfs_trans_handle *trans;
662
663         trans = start_transaction(root, 0, TRANS_ATTACH, 0);
664         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
665                 btrfs_wait_for_commit(root, 0);
666
667         return trans;
668 }
669
670 /* wait for a transaction commit to be fully complete */
671 static noinline void wait_for_commit(struct btrfs_root *root,
672                                     struct btrfs_transaction *commit)
673 {
674         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
675 }
676
677 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
678 {
679         struct btrfs_transaction *cur_trans = NULL, *t;
680         int ret = 0;
681
682         if (transid) {
683                 if (transid <= root->fs_info->last_trans_committed)
684                         goto out;
685
686                 /* find specified transaction */
687                 spin_lock(&root->fs_info->trans_lock);
688                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
689                         if (t->transid == transid) {
690                                 cur_trans = t;
691                                 atomic_inc(&cur_trans->use_count);
692                                 ret = 0;
693                                 break;
694                         }
695                         if (t->transid > transid) {
696                                 ret = 0;
697                                 break;
698                         }
699                 }
700                 spin_unlock(&root->fs_info->trans_lock);
701
702                 /*
703                  * The specified transaction doesn't exist, or we
704                  * raced with btrfs_commit_transaction
705                  */
706                 if (!cur_trans) {
707                         if (transid > root->fs_info->last_trans_committed)
708                                 ret = -EINVAL;
709                         goto out;
710                 }
711         } else {
712                 /* find newest transaction that is committing | committed */
713                 spin_lock(&root->fs_info->trans_lock);
714                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
715                                             list) {
716                         if (t->state >= TRANS_STATE_COMMIT_START) {
717                                 if (t->state == TRANS_STATE_COMPLETED)
718                                         break;
719                                 cur_trans = t;
720                                 atomic_inc(&cur_trans->use_count);
721                                 break;
722                         }
723                 }
724                 spin_unlock(&root->fs_info->trans_lock);
725                 if (!cur_trans)
726                         goto out;  /* nothing committing|committed */
727         }
728
729         wait_for_commit(root, cur_trans);
730         btrfs_put_transaction(cur_trans);
731 out:
732         return ret;
733 }
734
735 void btrfs_throttle(struct btrfs_root *root)
736 {
737         if (!atomic_read(&root->fs_info->open_ioctl_trans))
738                 wait_current_trans(root);
739 }
740
741 static int should_end_transaction(struct btrfs_trans_handle *trans,
742                                   struct btrfs_root *root)
743 {
744         if (root->fs_info->global_block_rsv.space_info->full &&
745             btrfs_check_space_for_delayed_refs(trans, root))
746                 return 1;
747
748         return !!btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
749 }
750
751 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
752                                  struct btrfs_root *root)
753 {
754         struct btrfs_transaction *cur_trans = trans->transaction;
755         int updates;
756         int err;
757
758         smp_mb();
759         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
760             cur_trans->delayed_refs.flushing)
761                 return 1;
762
763         updates = trans->delayed_ref_updates;
764         trans->delayed_ref_updates = 0;
765         if (updates) {
766                 err = btrfs_run_delayed_refs(trans, root, updates * 2);
767                 if (err) /* Error code will also eval true */
768                         return err;
769         }
770
771         return should_end_transaction(trans, root);
772 }
773
774 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
775                           struct btrfs_root *root, int throttle)
776 {
777         struct btrfs_transaction *cur_trans = trans->transaction;
778         struct btrfs_fs_info *info = root->fs_info;
779         unsigned long cur = trans->delayed_ref_updates;
780         int lock = (trans->type != TRANS_JOIN_NOLOCK);
781         int err = 0;
782         int must_run_delayed_refs = 0;
783
784         if (trans->use_count > 1) {
785                 trans->use_count--;
786                 trans->block_rsv = trans->orig_rsv;
787                 return 0;
788         }
789
790         btrfs_trans_release_metadata(trans, root);
791         trans->block_rsv = NULL;
792
793         if (!list_empty(&trans->new_bgs))
794                 btrfs_create_pending_block_groups(trans, root);
795
796         if (!list_empty(&trans->ordered)) {
797                 spin_lock(&info->trans_lock);
798                 list_splice_init(&trans->ordered, &cur_trans->pending_ordered);
799                 spin_unlock(&info->trans_lock);
800         }
801
802         trans->delayed_ref_updates = 0;
803         if (!trans->sync) {
804                 must_run_delayed_refs =
805                         btrfs_should_throttle_delayed_refs(trans, root);
806                 cur = max_t(unsigned long, cur, 32);
807
808                 /*
809                  * don't make the caller wait if they are from a NOLOCK
810                  * or ATTACH transaction, it will deadlock with commit
811                  */
812                 if (must_run_delayed_refs == 1 &&
813                     (trans->type & (__TRANS_JOIN_NOLOCK | __TRANS_ATTACH)))
814                         must_run_delayed_refs = 2;
815         }
816
817         if (trans->qgroup_reserved) {
818                 /*
819                  * the same root has to be passed here between start_transaction
820                  * and end_transaction. Subvolume quota depends on this.
821                  */
822                 btrfs_qgroup_free(trans->root, trans->qgroup_reserved);
823                 trans->qgroup_reserved = 0;
824         }
825
826         btrfs_trans_release_metadata(trans, root);
827         trans->block_rsv = NULL;
828
829         if (!list_empty(&trans->new_bgs))
830                 btrfs_create_pending_block_groups(trans, root);
831
832         btrfs_trans_release_chunk_metadata(trans);
833
834         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
835             should_end_transaction(trans, root) &&
836             ACCESS_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
837                 spin_lock(&info->trans_lock);
838                 if (cur_trans->state == TRANS_STATE_RUNNING)
839                         cur_trans->state = TRANS_STATE_BLOCKED;
840                 spin_unlock(&info->trans_lock);
841         }
842
843         if (lock && ACCESS_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
844                 if (throttle)
845                         return btrfs_commit_transaction(trans, root);
846                 else
847                         wake_up_process(info->transaction_kthread);
848         }
849
850         if (trans->type & __TRANS_FREEZABLE)
851                 sb_end_intwrite(root->fs_info->sb);
852
853         WARN_ON(cur_trans != info->running_transaction);
854         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
855         atomic_dec(&cur_trans->num_writers);
856         extwriter_counter_dec(cur_trans, trans->type);
857
858         smp_mb();
859         if (waitqueue_active(&cur_trans->writer_wait))
860                 wake_up(&cur_trans->writer_wait);
861         btrfs_put_transaction(cur_trans);
862
863         if (current->journal_info == trans)
864                 current->journal_info = NULL;
865
866         if (throttle)
867                 btrfs_run_delayed_iputs(root);
868
869         if (trans->aborted ||
870             test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
871                 wake_up_process(info->transaction_kthread);
872                 err = -EIO;
873         }
874         assert_qgroups_uptodate(trans);
875
876         kmem_cache_free(btrfs_trans_handle_cachep, trans);
877         if (must_run_delayed_refs) {
878                 btrfs_async_run_delayed_refs(root, cur,
879                                              must_run_delayed_refs == 1);
880         }
881         return err;
882 }
883
884 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
885                           struct btrfs_root *root)
886 {
887         return __btrfs_end_transaction(trans, root, 0);
888 }
889
890 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
891                                    struct btrfs_root *root)
892 {
893         return __btrfs_end_transaction(trans, root, 1);
894 }
895
896 /*
897  * when btree blocks are allocated, they have some corresponding bits set for
898  * them in one of two extent_io trees.  This is used to make sure all of
899  * those extents are sent to disk but does not wait on them
900  */
901 int btrfs_write_marked_extents(struct btrfs_root *root,
902                                struct extent_io_tree *dirty_pages, int mark)
903 {
904         int err = 0;
905         int werr = 0;
906         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
907         struct extent_state *cached_state = NULL;
908         u64 start = 0;
909         u64 end;
910
911         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
912                                       mark, &cached_state)) {
913                 bool wait_writeback = false;
914
915                 err = convert_extent_bit(dirty_pages, start, end,
916                                          EXTENT_NEED_WAIT,
917                                          mark, &cached_state, GFP_NOFS);
918                 /*
919                  * convert_extent_bit can return -ENOMEM, which is most of the
920                  * time a temporary error. So when it happens, ignore the error
921                  * and wait for writeback of this range to finish - because we
922                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
923                  * to btrfs_wait_marked_extents() would not know that writeback
924                  * for this range started and therefore wouldn't wait for it to
925                  * finish - we don't want to commit a superblock that points to
926                  * btree nodes/leafs for which writeback hasn't finished yet
927                  * (and without errors).
928                  * We cleanup any entries left in the io tree when committing
929                  * the transaction (through clear_btree_io_tree()).
930                  */
931                 if (err == -ENOMEM) {
932                         err = 0;
933                         wait_writeback = true;
934                 }
935                 if (!err)
936                         err = filemap_fdatawrite_range(mapping, start, end);
937                 if (err)
938                         werr = err;
939                 else if (wait_writeback)
940                         werr = filemap_fdatawait_range(mapping, start, end);
941                 free_extent_state(cached_state);
942                 cached_state = NULL;
943                 cond_resched();
944                 start = end + 1;
945         }
946         return werr;
947 }
948
949 /*
950  * when btree blocks are allocated, they have some corresponding bits set for
951  * them in one of two extent_io trees.  This is used to make sure all of
952  * those extents are on disk for transaction or log commit.  We wait
953  * on all the pages and clear them from the dirty pages state tree
954  */
955 int btrfs_wait_marked_extents(struct btrfs_root *root,
956                               struct extent_io_tree *dirty_pages, int mark)
957 {
958         int err = 0;
959         int werr = 0;
960         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
961         struct extent_state *cached_state = NULL;
962         u64 start = 0;
963         u64 end;
964         struct btrfs_inode *btree_ino = BTRFS_I(root->fs_info->btree_inode);
965         bool errors = false;
966
967         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
968                                       EXTENT_NEED_WAIT, &cached_state)) {
969                 /*
970                  * Ignore -ENOMEM errors returned by clear_extent_bit().
971                  * When committing the transaction, we'll remove any entries
972                  * left in the io tree. For a log commit, we don't remove them
973                  * after committing the log because the tree can be accessed
974                  * concurrently - we do it only at transaction commit time when
975                  * it's safe to do it (through clear_btree_io_tree()).
976                  */
977                 err = clear_extent_bit(dirty_pages, start, end,
978                                        EXTENT_NEED_WAIT,
979                                        0, 0, &cached_state, GFP_NOFS);
980                 if (err == -ENOMEM)
981                         err = 0;
982                 if (!err)
983                         err = filemap_fdatawait_range(mapping, start, end);
984                 if (err)
985                         werr = err;
986                 free_extent_state(cached_state);
987                 cached_state = NULL;
988                 cond_resched();
989                 start = end + 1;
990         }
991         if (err)
992                 werr = err;
993
994         if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
995                 if ((mark & EXTENT_DIRTY) &&
996                     test_and_clear_bit(BTRFS_INODE_BTREE_LOG1_ERR,
997                                        &btree_ino->runtime_flags))
998                         errors = true;
999
1000                 if ((mark & EXTENT_NEW) &&
1001                     test_and_clear_bit(BTRFS_INODE_BTREE_LOG2_ERR,
1002                                        &btree_ino->runtime_flags))
1003                         errors = true;
1004         } else {
1005                 if (test_and_clear_bit(BTRFS_INODE_BTREE_ERR,
1006                                        &btree_ino->runtime_flags))
1007                         errors = true;
1008         }
1009
1010         if (errors && !werr)
1011                 werr = -EIO;
1012
1013         return werr;
1014 }
1015
1016 /*
1017  * when btree blocks are allocated, they have some corresponding bits set for
1018  * them in one of two extent_io trees.  This is used to make sure all of
1019  * those extents are on disk for transaction or log commit
1020  */
1021 static int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
1022                                 struct extent_io_tree *dirty_pages, int mark)
1023 {
1024         int ret;
1025         int ret2;
1026         struct blk_plug plug;
1027
1028         blk_start_plug(&plug);
1029         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
1030         blk_finish_plug(&plug);
1031         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
1032
1033         if (ret)
1034                 return ret;
1035         if (ret2)
1036                 return ret2;
1037         return 0;
1038 }
1039
1040 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
1041                                      struct btrfs_root *root)
1042 {
1043         int ret;
1044
1045         ret = btrfs_write_and_wait_marked_extents(root,
1046                                            &trans->transaction->dirty_pages,
1047                                            EXTENT_DIRTY);
1048         clear_btree_io_tree(&trans->transaction->dirty_pages);
1049
1050         return ret;
1051 }
1052
1053 /*
1054  * this is used to update the root pointer in the tree of tree roots.
1055  *
1056  * But, in the case of the extent allocation tree, updating the root
1057  * pointer may allocate blocks which may change the root of the extent
1058  * allocation tree.
1059  *
1060  * So, this loops and repeats and makes sure the cowonly root didn't
1061  * change while the root pointer was being updated in the metadata.
1062  */
1063 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1064                                struct btrfs_root *root)
1065 {
1066         int ret;
1067         u64 old_root_bytenr;
1068         u64 old_root_used;
1069         struct btrfs_root *tree_root = root->fs_info->tree_root;
1070
1071         old_root_used = btrfs_root_used(&root->root_item);
1072
1073         while (1) {
1074                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1075                 if (old_root_bytenr == root->node->start &&
1076                     old_root_used == btrfs_root_used(&root->root_item))
1077                         break;
1078
1079                 btrfs_set_root_node(&root->root_item, root->node);
1080                 ret = btrfs_update_root(trans, tree_root,
1081                                         &root->root_key,
1082                                         &root->root_item);
1083                 if (ret)
1084                         return ret;
1085
1086                 old_root_used = btrfs_root_used(&root->root_item);
1087         }
1088
1089         return 0;
1090 }
1091
1092 /*
1093  * update all the cowonly tree roots on disk
1094  *
1095  * The error handling in this function may not be obvious. Any of the
1096  * failures will cause the file system to go offline. We still need
1097  * to clean up the delayed refs.
1098  */
1099 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
1100                                          struct btrfs_root *root)
1101 {
1102         struct btrfs_fs_info *fs_info = root->fs_info;
1103         struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1104         struct list_head *io_bgs = &trans->transaction->io_bgs;
1105         struct list_head *next;
1106         struct extent_buffer *eb;
1107         int ret;
1108
1109         eb = btrfs_lock_root_node(fs_info->tree_root);
1110         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1111                               0, &eb);
1112         btrfs_tree_unlock(eb);
1113         free_extent_buffer(eb);
1114
1115         if (ret)
1116                 return ret;
1117
1118         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1119         if (ret)
1120                 return ret;
1121
1122         ret = btrfs_run_dev_stats(trans, root->fs_info);
1123         if (ret)
1124                 return ret;
1125         ret = btrfs_run_dev_replace(trans, root->fs_info);
1126         if (ret)
1127                 return ret;
1128         ret = btrfs_run_qgroups(trans, root->fs_info);
1129         if (ret)
1130                 return ret;
1131
1132         ret = btrfs_setup_space_cache(trans, root);
1133         if (ret)
1134                 return ret;
1135
1136         /* run_qgroups might have added some more refs */
1137         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1138         if (ret)
1139                 return ret;
1140 again:
1141         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1142                 next = fs_info->dirty_cowonly_roots.next;
1143                 list_del_init(next);
1144                 root = list_entry(next, struct btrfs_root, dirty_list);
1145                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1146
1147                 if (root != fs_info->extent_root)
1148                         list_add_tail(&root->dirty_list,
1149                                       &trans->transaction->switch_commits);
1150                 ret = update_cowonly_root(trans, root);
1151                 if (ret)
1152                         return ret;
1153                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1154                 if (ret)
1155                         return ret;
1156         }
1157
1158         while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1159                 ret = btrfs_write_dirty_block_groups(trans, root);
1160                 if (ret)
1161                         return ret;
1162                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1163                 if (ret)
1164                         return ret;
1165         }
1166
1167         if (!list_empty(&fs_info->dirty_cowonly_roots))
1168                 goto again;
1169
1170         list_add_tail(&fs_info->extent_root->dirty_list,
1171                       &trans->transaction->switch_commits);
1172         btrfs_after_dev_replace_commit(fs_info);
1173
1174         return 0;
1175 }
1176
1177 /*
1178  * dead roots are old snapshots that need to be deleted.  This allocates
1179  * a dirty root struct and adds it into the list of dead roots that need to
1180  * be deleted
1181  */
1182 void btrfs_add_dead_root(struct btrfs_root *root)
1183 {
1184         spin_lock(&root->fs_info->trans_lock);
1185         if (list_empty(&root->root_list))
1186                 list_add_tail(&root->root_list, &root->fs_info->dead_roots);
1187         spin_unlock(&root->fs_info->trans_lock);
1188 }
1189
1190 /*
1191  * update all the cowonly tree roots on disk
1192  */
1193 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
1194                                     struct btrfs_root *root)
1195 {
1196         struct btrfs_root *gang[8];
1197         struct btrfs_fs_info *fs_info = root->fs_info;
1198         int i;
1199         int ret;
1200         int err = 0;
1201
1202         spin_lock(&fs_info->fs_roots_radix_lock);
1203         while (1) {
1204                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1205                                                  (void **)gang, 0,
1206                                                  ARRAY_SIZE(gang),
1207                                                  BTRFS_ROOT_TRANS_TAG);
1208                 if (ret == 0)
1209                         break;
1210                 for (i = 0; i < ret; i++) {
1211                         root = gang[i];
1212                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1213                                         (unsigned long)root->root_key.objectid,
1214                                         BTRFS_ROOT_TRANS_TAG);
1215                         spin_unlock(&fs_info->fs_roots_radix_lock);
1216
1217                         btrfs_free_log(trans, root);
1218                         btrfs_update_reloc_root(trans, root);
1219                         btrfs_orphan_commit_root(trans, root);
1220
1221                         btrfs_save_ino_cache(root, trans);
1222
1223                         /* see comments in should_cow_block() */
1224                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1225                         smp_mb__after_atomic();
1226
1227                         if (root->commit_root != root->node) {
1228                                 list_add_tail(&root->dirty_list,
1229                                         &trans->transaction->switch_commits);
1230                                 btrfs_set_root_node(&root->root_item,
1231                                                     root->node);
1232                         }
1233
1234                         err = btrfs_update_root(trans, fs_info->tree_root,
1235                                                 &root->root_key,
1236                                                 &root->root_item);
1237                         spin_lock(&fs_info->fs_roots_radix_lock);
1238                         if (err)
1239                                 break;
1240                 }
1241         }
1242         spin_unlock(&fs_info->fs_roots_radix_lock);
1243         return err;
1244 }
1245
1246 /*
1247  * defrag a given btree.
1248  * Every leaf in the btree is read and defragged.
1249  */
1250 int btrfs_defrag_root(struct btrfs_root *root)
1251 {
1252         struct btrfs_fs_info *info = root->fs_info;
1253         struct btrfs_trans_handle *trans;
1254         int ret;
1255
1256         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1257                 return 0;
1258
1259         while (1) {
1260                 trans = btrfs_start_transaction(root, 0);
1261                 if (IS_ERR(trans))
1262                         return PTR_ERR(trans);
1263
1264                 ret = btrfs_defrag_leaves(trans, root);
1265
1266                 btrfs_end_transaction(trans, root);
1267                 btrfs_btree_balance_dirty(info->tree_root);
1268                 cond_resched();
1269
1270                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
1271                         break;
1272
1273                 if (btrfs_defrag_cancelled(root->fs_info)) {
1274                         pr_debug("BTRFS: defrag_root cancelled\n");
1275                         ret = -EAGAIN;
1276                         break;
1277                 }
1278         }
1279         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1280         return ret;
1281 }
1282
1283 /*
1284  * new snapshots need to be created at a very specific time in the
1285  * transaction commit.  This does the actual creation.
1286  *
1287  * Note:
1288  * If the error which may affect the commitment of the current transaction
1289  * happens, we should return the error number. If the error which just affect
1290  * the creation of the pending snapshots, just return 0.
1291  */
1292 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1293                                    struct btrfs_fs_info *fs_info,
1294                                    struct btrfs_pending_snapshot *pending)
1295 {
1296         struct btrfs_key key;
1297         struct btrfs_root_item *new_root_item;
1298         struct btrfs_root *tree_root = fs_info->tree_root;
1299         struct btrfs_root *root = pending->root;
1300         struct btrfs_root *parent_root;
1301         struct btrfs_block_rsv *rsv;
1302         struct inode *parent_inode;
1303         struct btrfs_path *path;
1304         struct btrfs_dir_item *dir_item;
1305         struct dentry *dentry;
1306         struct extent_buffer *tmp;
1307         struct extent_buffer *old;
1308         struct timespec cur_time = CURRENT_TIME;
1309         int ret = 0;
1310         u64 to_reserve = 0;
1311         u64 index = 0;
1312         u64 objectid;
1313         u64 root_flags;
1314         uuid_le new_uuid;
1315
1316         path = btrfs_alloc_path();
1317         if (!path) {
1318                 pending->error = -ENOMEM;
1319                 return 0;
1320         }
1321
1322         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1323         if (!new_root_item) {
1324                 pending->error = -ENOMEM;
1325                 goto root_item_alloc_fail;
1326         }
1327
1328         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1329         if (pending->error)
1330                 goto no_free_objectid;
1331
1332         /*
1333          * Make qgroup to skip current new snapshot's qgroupid, as it is
1334          * accounted by later btrfs_qgroup_inherit().
1335          */
1336         btrfs_set_skip_qgroup(trans, objectid);
1337
1338         btrfs_reloc_pre_snapshot(pending, &to_reserve);
1339
1340         if (to_reserve > 0) {
1341                 pending->error = btrfs_block_rsv_add(root,
1342                                                      &pending->block_rsv,
1343                                                      to_reserve,
1344                                                      BTRFS_RESERVE_NO_FLUSH);
1345                 if (pending->error)
1346                         goto clear_skip_qgroup;
1347         }
1348
1349         key.objectid = objectid;
1350         key.offset = (u64)-1;
1351         key.type = BTRFS_ROOT_ITEM_KEY;
1352
1353         rsv = trans->block_rsv;
1354         trans->block_rsv = &pending->block_rsv;
1355         trans->bytes_reserved = trans->block_rsv->reserved;
1356
1357         dentry = pending->dentry;
1358         parent_inode = pending->dir;
1359         parent_root = BTRFS_I(parent_inode)->root;
1360         record_root_in_trans(trans, parent_root);
1361
1362         /*
1363          * insert the directory item
1364          */
1365         ret = btrfs_set_inode_index(parent_inode, &index);
1366         BUG_ON(ret); /* -ENOMEM */
1367
1368         /* check if there is a file/dir which has the same name. */
1369         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1370                                          btrfs_ino(parent_inode),
1371                                          dentry->d_name.name,
1372                                          dentry->d_name.len, 0);
1373         if (dir_item != NULL && !IS_ERR(dir_item)) {
1374                 pending->error = -EEXIST;
1375                 goto dir_item_existed;
1376         } else if (IS_ERR(dir_item)) {
1377                 ret = PTR_ERR(dir_item);
1378                 btrfs_abort_transaction(trans, root, ret);
1379                 goto fail;
1380         }
1381         btrfs_release_path(path);
1382
1383         /*
1384          * pull in the delayed directory update
1385          * and the delayed inode item
1386          * otherwise we corrupt the FS during
1387          * snapshot
1388          */
1389         ret = btrfs_run_delayed_items(trans, root);
1390         if (ret) {      /* Transaction aborted */
1391                 btrfs_abort_transaction(trans, root, ret);
1392                 goto fail;
1393         }
1394
1395         record_root_in_trans(trans, root);
1396         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1397         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1398         btrfs_check_and_init_root_item(new_root_item);
1399
1400         root_flags = btrfs_root_flags(new_root_item);
1401         if (pending->readonly)
1402                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1403         else
1404                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1405         btrfs_set_root_flags(new_root_item, root_flags);
1406
1407         btrfs_set_root_generation_v2(new_root_item,
1408                         trans->transid);
1409         uuid_le_gen(&new_uuid);
1410         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1411         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1412                         BTRFS_UUID_SIZE);
1413         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1414                 memset(new_root_item->received_uuid, 0,
1415                        sizeof(new_root_item->received_uuid));
1416                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1417                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1418                 btrfs_set_root_stransid(new_root_item, 0);
1419                 btrfs_set_root_rtransid(new_root_item, 0);
1420         }
1421         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1422         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1423         btrfs_set_root_otransid(new_root_item, trans->transid);
1424
1425         old = btrfs_lock_root_node(root);
1426         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1427         if (ret) {
1428                 btrfs_tree_unlock(old);
1429                 free_extent_buffer(old);
1430                 btrfs_abort_transaction(trans, root, ret);
1431                 goto fail;
1432         }
1433
1434         btrfs_set_lock_blocking(old);
1435
1436         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1437         /* clean up in any case */
1438         btrfs_tree_unlock(old);
1439         free_extent_buffer(old);
1440         if (ret) {
1441                 btrfs_abort_transaction(trans, root, ret);
1442                 goto fail;
1443         }
1444         /* see comments in should_cow_block() */
1445         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1446         smp_wmb();
1447
1448         btrfs_set_root_node(new_root_item, tmp);
1449         /* record when the snapshot was created in key.offset */
1450         key.offset = trans->transid;
1451         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1452         btrfs_tree_unlock(tmp);
1453         free_extent_buffer(tmp);
1454         if (ret) {
1455                 btrfs_abort_transaction(trans, root, ret);
1456                 goto fail;
1457         }
1458
1459         /*
1460          * insert root back/forward references
1461          */
1462         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1463                                  parent_root->root_key.objectid,
1464                                  btrfs_ino(parent_inode), index,
1465                                  dentry->d_name.name, dentry->d_name.len);
1466         if (ret) {
1467                 btrfs_abort_transaction(trans, root, ret);
1468                 goto fail;
1469         }
1470
1471         key.offset = (u64)-1;
1472         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1473         if (IS_ERR(pending->snap)) {
1474                 ret = PTR_ERR(pending->snap);
1475                 btrfs_abort_transaction(trans, root, ret);
1476                 goto fail;
1477         }
1478
1479         ret = btrfs_reloc_post_snapshot(trans, pending);
1480         if (ret) {
1481                 btrfs_abort_transaction(trans, root, ret);
1482                 goto fail;
1483         }
1484
1485         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1486         if (ret) {
1487                 btrfs_abort_transaction(trans, root, ret);
1488                 goto fail;
1489         }
1490
1491         ret = btrfs_insert_dir_item(trans, parent_root,
1492                                     dentry->d_name.name, dentry->d_name.len,
1493                                     parent_inode, &key,
1494                                     BTRFS_FT_DIR, index);
1495         /* We have check then name at the beginning, so it is impossible. */
1496         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1497         if (ret) {
1498                 btrfs_abort_transaction(trans, root, ret);
1499                 goto fail;
1500         }
1501
1502         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1503                                          dentry->d_name.len * 2);
1504         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1505         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1506         if (ret) {
1507                 btrfs_abort_transaction(trans, root, ret);
1508                 goto fail;
1509         }
1510         ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root, new_uuid.b,
1511                                   BTRFS_UUID_KEY_SUBVOL, objectid);
1512         if (ret) {
1513                 btrfs_abort_transaction(trans, root, ret);
1514                 goto fail;
1515         }
1516         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1517                 ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
1518                                           new_root_item->received_uuid,
1519                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1520                                           objectid);
1521                 if (ret && ret != -EEXIST) {
1522                         btrfs_abort_transaction(trans, root, ret);
1523                         goto fail;
1524                 }
1525         }
1526
1527         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1528         if (ret) {
1529                 btrfs_abort_transaction(trans, root, ret);
1530                 goto fail;
1531         }
1532
1533         /*
1534          * account qgroup counters before qgroup_inherit()
1535          */
1536         ret = btrfs_qgroup_prepare_account_extents(trans, fs_info);
1537         if (ret)
1538                 goto fail;
1539         ret = btrfs_qgroup_account_extents(trans, fs_info);
1540         if (ret)
1541                 goto fail;
1542         ret = btrfs_qgroup_inherit(trans, fs_info,
1543                                    root->root_key.objectid,
1544                                    objectid, pending->inherit);
1545         if (ret) {
1546                 btrfs_abort_transaction(trans, root, ret);
1547                 goto fail;
1548         }
1549
1550 fail:
1551         pending->error = ret;
1552 dir_item_existed:
1553         trans->block_rsv = rsv;
1554         trans->bytes_reserved = 0;
1555 clear_skip_qgroup:
1556         btrfs_clear_skip_qgroup(trans);
1557 no_free_objectid:
1558         kfree(new_root_item);
1559 root_item_alloc_fail:
1560         btrfs_free_path(path);
1561         return ret;
1562 }
1563
1564 /*
1565  * create all the snapshots we've scheduled for creation
1566  */
1567 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1568                                              struct btrfs_fs_info *fs_info)
1569 {
1570         struct btrfs_pending_snapshot *pending, *next;
1571         struct list_head *head = &trans->transaction->pending_snapshots;
1572         int ret = 0;
1573
1574         list_for_each_entry_safe(pending, next, head, list) {
1575                 list_del(&pending->list);
1576                 ret = create_pending_snapshot(trans, fs_info, pending);
1577                 if (ret)
1578                         break;
1579         }
1580         return ret;
1581 }
1582
1583 static void update_super_roots(struct btrfs_root *root)
1584 {
1585         struct btrfs_root_item *root_item;
1586         struct btrfs_super_block *super;
1587
1588         super = root->fs_info->super_copy;
1589
1590         root_item = &root->fs_info->chunk_root->root_item;
1591         super->chunk_root = root_item->bytenr;
1592         super->chunk_root_generation = root_item->generation;
1593         super->chunk_root_level = root_item->level;
1594
1595         root_item = &root->fs_info->tree_root->root_item;
1596         super->root = root_item->bytenr;
1597         super->generation = root_item->generation;
1598         super->root_level = root_item->level;
1599         if (btrfs_test_opt(root, SPACE_CACHE))
1600                 super->cache_generation = root_item->generation;
1601         if (root->fs_info->update_uuid_tree_gen)
1602                 super->uuid_tree_generation = root_item->generation;
1603 }
1604
1605 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1606 {
1607         struct btrfs_transaction *trans;
1608         int ret = 0;
1609
1610         spin_lock(&info->trans_lock);
1611         trans = info->running_transaction;
1612         if (trans)
1613                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1614         spin_unlock(&info->trans_lock);
1615         return ret;
1616 }
1617
1618 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1619 {
1620         struct btrfs_transaction *trans;
1621         int ret = 0;
1622
1623         spin_lock(&info->trans_lock);
1624         trans = info->running_transaction;
1625         if (trans)
1626                 ret = is_transaction_blocked(trans);
1627         spin_unlock(&info->trans_lock);
1628         return ret;
1629 }
1630
1631 /*
1632  * wait for the current transaction commit to start and block subsequent
1633  * transaction joins
1634  */
1635 static void wait_current_trans_commit_start(struct btrfs_root *root,
1636                                             struct btrfs_transaction *trans)
1637 {
1638         wait_event(root->fs_info->transaction_blocked_wait,
1639                    trans->state >= TRANS_STATE_COMMIT_START ||
1640                    trans->aborted);
1641 }
1642
1643 /*
1644  * wait for the current transaction to start and then become unblocked.
1645  * caller holds ref.
1646  */
1647 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1648                                          struct btrfs_transaction *trans)
1649 {
1650         wait_event(root->fs_info->transaction_wait,
1651                    trans->state >= TRANS_STATE_UNBLOCKED ||
1652                    trans->aborted);
1653 }
1654
1655 /*
1656  * commit transactions asynchronously. once btrfs_commit_transaction_async
1657  * returns, any subsequent transaction will not be allowed to join.
1658  */
1659 struct btrfs_async_commit {
1660         struct btrfs_trans_handle *newtrans;
1661         struct btrfs_root *root;
1662         struct work_struct work;
1663 };
1664
1665 static void do_async_commit(struct work_struct *work)
1666 {
1667         struct btrfs_async_commit *ac =
1668                 container_of(work, struct btrfs_async_commit, work);
1669
1670         /*
1671          * We've got freeze protection passed with the transaction.
1672          * Tell lockdep about it.
1673          */
1674         if (ac->newtrans->type & __TRANS_FREEZABLE)
1675                 rwsem_acquire_read(
1676                      &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1677                      0, 1, _THIS_IP_);
1678
1679         current->journal_info = ac->newtrans;
1680
1681         btrfs_commit_transaction(ac->newtrans, ac->root);
1682         kfree(ac);
1683 }
1684
1685 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1686                                    struct btrfs_root *root,
1687                                    int wait_for_unblock)
1688 {
1689         struct btrfs_async_commit *ac;
1690         struct btrfs_transaction *cur_trans;
1691
1692         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1693         if (!ac)
1694                 return -ENOMEM;
1695
1696         INIT_WORK(&ac->work, do_async_commit);
1697         ac->root = root;
1698         ac->newtrans = btrfs_join_transaction(root);
1699         if (IS_ERR(ac->newtrans)) {
1700                 int err = PTR_ERR(ac->newtrans);
1701                 kfree(ac);
1702                 return err;
1703         }
1704
1705         /* take transaction reference */
1706         cur_trans = trans->transaction;
1707         atomic_inc(&cur_trans->use_count);
1708
1709         btrfs_end_transaction(trans, root);
1710
1711         /*
1712          * Tell lockdep we've released the freeze rwsem, since the
1713          * async commit thread will be the one to unlock it.
1714          */
1715         if (ac->newtrans->type & __TRANS_FREEZABLE)
1716                 rwsem_release(
1717                         &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1718                         1, _THIS_IP_);
1719
1720         schedule_work(&ac->work);
1721
1722         /* wait for transaction to start and unblock */
1723         if (wait_for_unblock)
1724                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1725         else
1726                 wait_current_trans_commit_start(root, cur_trans);
1727
1728         if (current->journal_info == trans)
1729                 current->journal_info = NULL;
1730
1731         btrfs_put_transaction(cur_trans);
1732         return 0;
1733 }
1734
1735
1736 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1737                                 struct btrfs_root *root, int err)
1738 {
1739         struct btrfs_transaction *cur_trans = trans->transaction;
1740         DEFINE_WAIT(wait);
1741
1742         WARN_ON(trans->use_count > 1);
1743
1744         btrfs_abort_transaction(trans, root, err);
1745
1746         spin_lock(&root->fs_info->trans_lock);
1747
1748         /*
1749          * If the transaction is removed from the list, it means this
1750          * transaction has been committed successfully, so it is impossible
1751          * to call the cleanup function.
1752          */
1753         BUG_ON(list_empty(&cur_trans->list));
1754
1755         list_del_init(&cur_trans->list);
1756         if (cur_trans == root->fs_info->running_transaction) {
1757                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1758                 spin_unlock(&root->fs_info->trans_lock);
1759                 wait_event(cur_trans->writer_wait,
1760                            atomic_read(&cur_trans->num_writers) == 1);
1761
1762                 spin_lock(&root->fs_info->trans_lock);
1763         }
1764         spin_unlock(&root->fs_info->trans_lock);
1765
1766         btrfs_cleanup_one_transaction(trans->transaction, root);
1767
1768         spin_lock(&root->fs_info->trans_lock);
1769         if (cur_trans == root->fs_info->running_transaction)
1770                 root->fs_info->running_transaction = NULL;
1771         spin_unlock(&root->fs_info->trans_lock);
1772
1773         if (trans->type & __TRANS_FREEZABLE)
1774                 sb_end_intwrite(root->fs_info->sb);
1775         btrfs_put_transaction(cur_trans);
1776         btrfs_put_transaction(cur_trans);
1777
1778         trace_btrfs_transaction_commit(root);
1779
1780         if (current->journal_info == trans)
1781                 current->journal_info = NULL;
1782         btrfs_scrub_cancel(root->fs_info);
1783
1784         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1785 }
1786
1787 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1788 {
1789         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1790                 return btrfs_start_delalloc_roots(fs_info, 1, -1);
1791         return 0;
1792 }
1793
1794 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1795 {
1796         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1797                 btrfs_wait_ordered_roots(fs_info, -1);
1798 }
1799
1800 static inline void
1801 btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans,
1802                            struct btrfs_fs_info *fs_info)
1803 {
1804         struct btrfs_ordered_extent *ordered;
1805
1806         spin_lock(&fs_info->trans_lock);
1807         while (!list_empty(&cur_trans->pending_ordered)) {
1808                 ordered = list_first_entry(&cur_trans->pending_ordered,
1809                                            struct btrfs_ordered_extent,
1810                                            trans_list);
1811                 list_del_init(&ordered->trans_list);
1812                 spin_unlock(&fs_info->trans_lock);
1813
1814                 wait_event(ordered->wait, test_bit(BTRFS_ORDERED_COMPLETE,
1815                                                    &ordered->flags));
1816                 btrfs_put_ordered_extent(ordered);
1817                 spin_lock(&fs_info->trans_lock);
1818         }
1819         spin_unlock(&fs_info->trans_lock);
1820 }
1821
1822 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1823                              struct btrfs_root *root)
1824 {
1825         struct btrfs_transaction *cur_trans = trans->transaction;
1826         struct btrfs_transaction *prev_trans = NULL;
1827         struct btrfs_inode *btree_ino = BTRFS_I(root->fs_info->btree_inode);
1828         int ret;
1829
1830         /* Stop the commit early if ->aborted is set */
1831         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1832                 ret = cur_trans->aborted;
1833                 btrfs_end_transaction(trans, root);
1834                 return ret;
1835         }
1836
1837         /* make a pass through all the delayed refs we have so far
1838          * any runnings procs may add more while we are here
1839          */
1840         ret = btrfs_run_delayed_refs(trans, root, 0);
1841         if (ret) {
1842                 btrfs_end_transaction(trans, root);
1843                 return ret;
1844         }
1845
1846         btrfs_trans_release_metadata(trans, root);
1847         trans->block_rsv = NULL;
1848         if (trans->qgroup_reserved) {
1849                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1850                 trans->qgroup_reserved = 0;
1851         }
1852
1853         cur_trans = trans->transaction;
1854
1855         /*
1856          * set the flushing flag so procs in this transaction have to
1857          * start sending their work down.
1858          */
1859         cur_trans->delayed_refs.flushing = 1;
1860         smp_wmb();
1861
1862         if (!list_empty(&trans->new_bgs))
1863                 btrfs_create_pending_block_groups(trans, root);
1864
1865         ret = btrfs_run_delayed_refs(trans, root, 0);
1866         if (ret) {
1867                 btrfs_end_transaction(trans, root);
1868                 return ret;
1869         }
1870
1871         if (!cur_trans->dirty_bg_run) {
1872                 int run_it = 0;
1873
1874                 /* this mutex is also taken before trying to set
1875                  * block groups readonly.  We need to make sure
1876                  * that nobody has set a block group readonly
1877                  * after a extents from that block group have been
1878                  * allocated for cache files.  btrfs_set_block_group_ro
1879                  * will wait for the transaction to commit if it
1880                  * finds dirty_bg_run = 1
1881                  *
1882                  * The dirty_bg_run flag is also used to make sure only
1883                  * one process starts all the block group IO.  It wouldn't
1884                  * hurt to have more than one go through, but there's no
1885                  * real advantage to it either.
1886                  */
1887                 mutex_lock(&root->fs_info->ro_block_group_mutex);
1888                 if (!cur_trans->dirty_bg_run) {
1889                         run_it = 1;
1890                         cur_trans->dirty_bg_run = 1;
1891                 }
1892                 mutex_unlock(&root->fs_info->ro_block_group_mutex);
1893
1894                 if (run_it)
1895                         ret = btrfs_start_dirty_block_groups(trans, root);
1896         }
1897         if (ret) {
1898                 btrfs_end_transaction(trans, root);
1899                 return ret;
1900         }
1901
1902         spin_lock(&root->fs_info->trans_lock);
1903         list_splice_init(&trans->ordered, &cur_trans->pending_ordered);
1904         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
1905                 spin_unlock(&root->fs_info->trans_lock);
1906                 atomic_inc(&cur_trans->use_count);
1907                 ret = btrfs_end_transaction(trans, root);
1908
1909                 wait_for_commit(root, cur_trans);
1910
1911                 if (unlikely(cur_trans->aborted))
1912                         ret = cur_trans->aborted;
1913
1914                 btrfs_put_transaction(cur_trans);
1915
1916                 return ret;
1917         }
1918
1919         cur_trans->state = TRANS_STATE_COMMIT_START;
1920         wake_up(&root->fs_info->transaction_blocked_wait);
1921
1922         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1923                 prev_trans = list_entry(cur_trans->list.prev,
1924                                         struct btrfs_transaction, list);
1925                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
1926                         atomic_inc(&prev_trans->use_count);
1927                         spin_unlock(&root->fs_info->trans_lock);
1928
1929                         wait_for_commit(root, prev_trans);
1930                         ret = prev_trans->aborted;
1931
1932                         btrfs_put_transaction(prev_trans);
1933                         if (ret)
1934                                 goto cleanup_transaction;
1935                 } else {
1936                         spin_unlock(&root->fs_info->trans_lock);
1937                 }
1938         } else {
1939                 spin_unlock(&root->fs_info->trans_lock);
1940         }
1941
1942         extwriter_counter_dec(cur_trans, trans->type);
1943
1944         ret = btrfs_start_delalloc_flush(root->fs_info);
1945         if (ret)
1946                 goto cleanup_transaction;
1947
1948         ret = btrfs_run_delayed_items(trans, root);
1949         if (ret)
1950                 goto cleanup_transaction;
1951
1952         wait_event(cur_trans->writer_wait,
1953                    extwriter_counter_read(cur_trans) == 0);
1954
1955         /* some pending stuffs might be added after the previous flush. */
1956         ret = btrfs_run_delayed_items(trans, root);
1957         if (ret)
1958                 goto cleanup_transaction;
1959
1960         btrfs_wait_delalloc_flush(root->fs_info);
1961
1962         btrfs_wait_pending_ordered(cur_trans, root->fs_info);
1963
1964         btrfs_scrub_pause(root);
1965         /*
1966          * Ok now we need to make sure to block out any other joins while we
1967          * commit the transaction.  We could have started a join before setting
1968          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
1969          */
1970         spin_lock(&root->fs_info->trans_lock);
1971         cur_trans->state = TRANS_STATE_COMMIT_DOING;
1972         spin_unlock(&root->fs_info->trans_lock);
1973         wait_event(cur_trans->writer_wait,
1974                    atomic_read(&cur_trans->num_writers) == 1);
1975
1976         /* ->aborted might be set after the previous check, so check it */
1977         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1978                 ret = cur_trans->aborted;
1979                 goto scrub_continue;
1980         }
1981         /*
1982          * the reloc mutex makes sure that we stop
1983          * the balancing code from coming in and moving
1984          * extents around in the middle of the commit
1985          */
1986         mutex_lock(&root->fs_info->reloc_mutex);
1987
1988         /*
1989          * We needn't worry about the delayed items because we will
1990          * deal with them in create_pending_snapshot(), which is the
1991          * core function of the snapshot creation.
1992          */
1993         ret = create_pending_snapshots(trans, root->fs_info);
1994         if (ret) {
1995                 mutex_unlock(&root->fs_info->reloc_mutex);
1996                 goto scrub_continue;
1997         }
1998
1999         /*
2000          * We insert the dir indexes of the snapshots and update the inode
2001          * of the snapshots' parents after the snapshot creation, so there
2002          * are some delayed items which are not dealt with. Now deal with
2003          * them.
2004          *
2005          * We needn't worry that this operation will corrupt the snapshots,
2006          * because all the tree which are snapshoted will be forced to COW
2007          * the nodes and leaves.
2008          */
2009         ret = btrfs_run_delayed_items(trans, root);
2010         if (ret) {
2011                 mutex_unlock(&root->fs_info->reloc_mutex);
2012                 goto scrub_continue;
2013         }
2014
2015         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
2016         if (ret) {
2017                 mutex_unlock(&root->fs_info->reloc_mutex);
2018                 goto scrub_continue;
2019         }
2020
2021         /* Reocrd old roots for later qgroup accounting */
2022         ret = btrfs_qgroup_prepare_account_extents(trans, root->fs_info);
2023         if (ret) {
2024                 mutex_unlock(&root->fs_info->reloc_mutex);
2025                 goto scrub_continue;
2026         }
2027
2028         /*
2029          * make sure none of the code above managed to slip in a
2030          * delayed item
2031          */
2032         btrfs_assert_delayed_root_empty(root);
2033
2034         WARN_ON(cur_trans != trans->transaction);
2035
2036         /* btrfs_commit_tree_roots is responsible for getting the
2037          * various roots consistent with each other.  Every pointer
2038          * in the tree of tree roots has to point to the most up to date
2039          * root for every subvolume and other tree.  So, we have to keep
2040          * the tree logging code from jumping in and changing any
2041          * of the trees.
2042          *
2043          * At this point in the commit, there can't be any tree-log
2044          * writers, but a little lower down we drop the trans mutex
2045          * and let new people in.  By holding the tree_log_mutex
2046          * from now until after the super is written, we avoid races
2047          * with the tree-log code.
2048          */
2049         mutex_lock(&root->fs_info->tree_log_mutex);
2050
2051         ret = commit_fs_roots(trans, root);
2052         if (ret) {
2053                 mutex_unlock(&root->fs_info->tree_log_mutex);
2054                 mutex_unlock(&root->fs_info->reloc_mutex);
2055                 goto scrub_continue;
2056         }
2057
2058         /*
2059          * Since the transaction is done, we can apply the pending changes
2060          * before the next transaction.
2061          */
2062         btrfs_apply_pending_changes(root->fs_info);
2063
2064         /* commit_fs_roots gets rid of all the tree log roots, it is now
2065          * safe to free the root of tree log roots
2066          */
2067         btrfs_free_log_root_tree(trans, root->fs_info);
2068
2069         /*
2070          * Since fs roots are all committed, we can get a quite accurate
2071          * new_roots. So let's do quota accounting.
2072          */
2073         ret = btrfs_qgroup_account_extents(trans, root->fs_info);
2074         if (ret < 0) {
2075                 mutex_unlock(&root->fs_info->tree_log_mutex);
2076                 mutex_unlock(&root->fs_info->reloc_mutex);
2077                 goto scrub_continue;
2078         }
2079
2080         ret = commit_cowonly_roots(trans, root);
2081         if (ret) {
2082                 mutex_unlock(&root->fs_info->tree_log_mutex);
2083                 mutex_unlock(&root->fs_info->reloc_mutex);
2084                 goto scrub_continue;
2085         }
2086
2087         /*
2088          * The tasks which save the space cache and inode cache may also
2089          * update ->aborted, check it.
2090          */
2091         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
2092                 ret = cur_trans->aborted;
2093                 mutex_unlock(&root->fs_info->tree_log_mutex);
2094                 mutex_unlock(&root->fs_info->reloc_mutex);
2095                 goto scrub_continue;
2096         }
2097
2098         btrfs_prepare_extent_commit(trans, root);
2099
2100         cur_trans = root->fs_info->running_transaction;
2101
2102         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
2103                             root->fs_info->tree_root->node);
2104         list_add_tail(&root->fs_info->tree_root->dirty_list,
2105                       &cur_trans->switch_commits);
2106
2107         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
2108                             root->fs_info->chunk_root->node);
2109         list_add_tail(&root->fs_info->chunk_root->dirty_list,
2110                       &cur_trans->switch_commits);
2111
2112         switch_commit_roots(cur_trans, root->fs_info);
2113
2114         assert_qgroups_uptodate(trans);
2115         ASSERT(list_empty(&cur_trans->dirty_bgs));
2116         ASSERT(list_empty(&cur_trans->io_bgs));
2117         update_super_roots(root);
2118
2119         btrfs_set_super_log_root(root->fs_info->super_copy, 0);
2120         btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
2121         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
2122                sizeof(*root->fs_info->super_copy));
2123
2124         btrfs_update_commit_device_size(root->fs_info);
2125         btrfs_update_commit_device_bytes_used(root, cur_trans);
2126
2127         clear_bit(BTRFS_INODE_BTREE_LOG1_ERR, &btree_ino->runtime_flags);
2128         clear_bit(BTRFS_INODE_BTREE_LOG2_ERR, &btree_ino->runtime_flags);
2129
2130         btrfs_trans_release_chunk_metadata(trans);
2131
2132         spin_lock(&root->fs_info->trans_lock);
2133         cur_trans->state = TRANS_STATE_UNBLOCKED;
2134         root->fs_info->running_transaction = NULL;
2135         spin_unlock(&root->fs_info->trans_lock);
2136         mutex_unlock(&root->fs_info->reloc_mutex);
2137
2138         wake_up(&root->fs_info->transaction_wait);
2139
2140         ret = btrfs_write_and_wait_transaction(trans, root);
2141         if (ret) {
2142                 btrfs_error(root->fs_info, ret,
2143                             "Error while writing out transaction");
2144                 mutex_unlock(&root->fs_info->tree_log_mutex);
2145                 goto scrub_continue;
2146         }
2147
2148         ret = write_ctree_super(trans, root, 0);
2149         if (ret) {
2150                 mutex_unlock(&root->fs_info->tree_log_mutex);
2151                 goto scrub_continue;
2152         }
2153
2154         /*
2155          * the super is written, we can safely allow the tree-loggers
2156          * to go about their business
2157          */
2158         mutex_unlock(&root->fs_info->tree_log_mutex);
2159
2160         btrfs_finish_extent_commit(trans, root);
2161
2162         if (cur_trans->have_free_bgs)
2163                 btrfs_clear_space_info_full(root->fs_info);
2164
2165         root->fs_info->last_trans_committed = cur_trans->transid;
2166         /*
2167          * We needn't acquire the lock here because there is no other task
2168          * which can change it.
2169          */
2170         cur_trans->state = TRANS_STATE_COMPLETED;
2171         wake_up(&cur_trans->commit_wait);
2172
2173         spin_lock(&root->fs_info->trans_lock);
2174         list_del_init(&cur_trans->list);
2175         spin_unlock(&root->fs_info->trans_lock);
2176
2177         btrfs_put_transaction(cur_trans);
2178         btrfs_put_transaction(cur_trans);
2179
2180         if (trans->type & __TRANS_FREEZABLE)
2181                 sb_end_intwrite(root->fs_info->sb);
2182
2183         trace_btrfs_transaction_commit(root);
2184
2185         btrfs_scrub_continue(root);
2186
2187         if (current->journal_info == trans)
2188                 current->journal_info = NULL;
2189
2190         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2191
2192         if (current != root->fs_info->transaction_kthread &&
2193             current != root->fs_info->cleaner_kthread)
2194                 btrfs_run_delayed_iputs(root);
2195
2196         return ret;
2197
2198 scrub_continue:
2199         btrfs_scrub_continue(root);
2200 cleanup_transaction:
2201         btrfs_trans_release_metadata(trans, root);
2202         btrfs_trans_release_chunk_metadata(trans);
2203         trans->block_rsv = NULL;
2204         if (trans->qgroup_reserved) {
2205                 btrfs_qgroup_free(root, trans->qgroup_reserved);
2206                 trans->qgroup_reserved = 0;
2207         }
2208         btrfs_warn(root->fs_info, "Skipping commit of aborted transaction.");
2209         if (current->journal_info == trans)
2210                 current->journal_info = NULL;
2211         cleanup_transaction(trans, root, ret);
2212
2213         return ret;
2214 }
2215
2216 /*
2217  * return < 0 if error
2218  * 0 if there are no more dead_roots at the time of call
2219  * 1 there are more to be processed, call me again
2220  *
2221  * The return value indicates there are certainly more snapshots to delete, but
2222  * if there comes a new one during processing, it may return 0. We don't mind,
2223  * because btrfs_commit_super will poke cleaner thread and it will process it a
2224  * few seconds later.
2225  */
2226 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2227 {
2228         int ret;
2229         struct btrfs_fs_info *fs_info = root->fs_info;
2230
2231         spin_lock(&fs_info->trans_lock);
2232         if (list_empty(&fs_info->dead_roots)) {
2233                 spin_unlock(&fs_info->trans_lock);
2234                 return 0;
2235         }
2236         root = list_first_entry(&fs_info->dead_roots,
2237                         struct btrfs_root, root_list);
2238         list_del_init(&root->root_list);
2239         spin_unlock(&fs_info->trans_lock);
2240
2241         pr_debug("BTRFS: cleaner removing %llu\n", root->objectid);
2242
2243         btrfs_kill_all_delayed_nodes(root);
2244
2245         if (btrfs_header_backref_rev(root->node) <
2246                         BTRFS_MIXED_BACKREF_REV)
2247                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2248         else
2249                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2250
2251         return (ret < 0) ? 0 : 1;
2252 }
2253
2254 void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2255 {
2256         unsigned long prev;
2257         unsigned long bit;
2258
2259         prev = xchg(&fs_info->pending_changes, 0);
2260         if (!prev)
2261                 return;
2262
2263         bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2264         if (prev & bit)
2265                 btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2266         prev &= ~bit;
2267
2268         bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2269         if (prev & bit)
2270                 btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2271         prev &= ~bit;
2272
2273         bit = 1 << BTRFS_PENDING_COMMIT;
2274         if (prev & bit)
2275                 btrfs_debug(fs_info, "pending commit done");
2276         prev &= ~bit;
2277
2278         if (prev)
2279                 btrfs_warn(fs_info,
2280                         "unknown pending changes left 0x%lx, ignoring", prev);
2281 }