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Btrfs: add qgroup inheritance
[~shefty/rdma-dev.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 "ctree.h"
26 #include "disk-io.h"
27 #include "transaction.h"
28 #include "locking.h"
29 #include "tree-log.h"
30 #include "inode-map.h"
31 #include "volumes.h"
32
33 #define BTRFS_ROOT_TRANS_TAG 0
34
35 void put_transaction(struct btrfs_transaction *transaction)
36 {
37         WARN_ON(atomic_read(&transaction->use_count) == 0);
38         if (atomic_dec_and_test(&transaction->use_count)) {
39                 BUG_ON(!list_empty(&transaction->list));
40                 WARN_ON(transaction->delayed_refs.root.rb_node);
41                 memset(transaction, 0, sizeof(*transaction));
42                 kmem_cache_free(btrfs_transaction_cachep, transaction);
43         }
44 }
45
46 static noinline void switch_commit_root(struct btrfs_root *root)
47 {
48         free_extent_buffer(root->commit_root);
49         root->commit_root = btrfs_root_node(root);
50 }
51
52 /*
53  * either allocate a new transaction or hop into the existing one
54  */
55 static noinline int join_transaction(struct btrfs_root *root, int nofail)
56 {
57         struct btrfs_transaction *cur_trans;
58         struct btrfs_fs_info *fs_info = root->fs_info;
59
60         spin_lock(&fs_info->trans_lock);
61 loop:
62         /* The file system has been taken offline. No new transactions. */
63         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
64                 spin_unlock(&fs_info->trans_lock);
65                 return -EROFS;
66         }
67
68         if (fs_info->trans_no_join) {
69                 if (!nofail) {
70                         spin_unlock(&fs_info->trans_lock);
71                         return -EBUSY;
72                 }
73         }
74
75         cur_trans = fs_info->running_transaction;
76         if (cur_trans) {
77                 if (cur_trans->aborted) {
78                         spin_unlock(&fs_info->trans_lock);
79                         return cur_trans->aborted;
80                 }
81                 atomic_inc(&cur_trans->use_count);
82                 atomic_inc(&cur_trans->num_writers);
83                 cur_trans->num_joined++;
84                 spin_unlock(&fs_info->trans_lock);
85                 return 0;
86         }
87         spin_unlock(&fs_info->trans_lock);
88
89         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
90         if (!cur_trans)
91                 return -ENOMEM;
92
93         spin_lock(&fs_info->trans_lock);
94         if (fs_info->running_transaction) {
95                 /*
96                  * someone started a transaction after we unlocked.  Make sure
97                  * to redo the trans_no_join checks above
98                  */
99                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
100                 cur_trans = fs_info->running_transaction;
101                 goto loop;
102         } else if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
103                 spin_unlock(&root->fs_info->trans_lock);
104                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
105                 return -EROFS;
106         }
107
108         atomic_set(&cur_trans->num_writers, 1);
109         cur_trans->num_joined = 0;
110         init_waitqueue_head(&cur_trans->writer_wait);
111         init_waitqueue_head(&cur_trans->commit_wait);
112         cur_trans->in_commit = 0;
113         cur_trans->blocked = 0;
114         /*
115          * One for this trans handle, one so it will live on until we
116          * commit the transaction.
117          */
118         atomic_set(&cur_trans->use_count, 2);
119         cur_trans->commit_done = 0;
120         cur_trans->start_time = get_seconds();
121
122         cur_trans->delayed_refs.root = RB_ROOT;
123         cur_trans->delayed_refs.num_entries = 0;
124         cur_trans->delayed_refs.num_heads_ready = 0;
125         cur_trans->delayed_refs.num_heads = 0;
126         cur_trans->delayed_refs.flushing = 0;
127         cur_trans->delayed_refs.run_delayed_start = 0;
128
129         /*
130          * although the tree mod log is per file system and not per transaction,
131          * the log must never go across transaction boundaries.
132          */
133         smp_mb();
134         if (!list_empty(&fs_info->tree_mod_seq_list)) {
135                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
136                         "creating a fresh transaction\n");
137                 WARN_ON(1);
138         }
139         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
140                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
141                         "creating a fresh transaction\n");
142                 WARN_ON(1);
143         }
144         atomic_set(&fs_info->tree_mod_seq, 0);
145
146         spin_lock_init(&cur_trans->commit_lock);
147         spin_lock_init(&cur_trans->delayed_refs.lock);
148
149         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
150         list_add_tail(&cur_trans->list, &fs_info->trans_list);
151         extent_io_tree_init(&cur_trans->dirty_pages,
152                              fs_info->btree_inode->i_mapping);
153         fs_info->generation++;
154         cur_trans->transid = fs_info->generation;
155         fs_info->running_transaction = cur_trans;
156         cur_trans->aborted = 0;
157         spin_unlock(&fs_info->trans_lock);
158
159         return 0;
160 }
161
162 /*
163  * this does all the record keeping required to make sure that a reference
164  * counted root is properly recorded in a given transaction.  This is required
165  * to make sure the old root from before we joined the transaction is deleted
166  * when the transaction commits
167  */
168 static int record_root_in_trans(struct btrfs_trans_handle *trans,
169                                struct btrfs_root *root)
170 {
171         if (root->ref_cows && root->last_trans < trans->transid) {
172                 WARN_ON(root == root->fs_info->extent_root);
173                 WARN_ON(root->commit_root != root->node);
174
175                 /*
176                  * see below for in_trans_setup usage rules
177                  * we have the reloc mutex held now, so there
178                  * is only one writer in this function
179                  */
180                 root->in_trans_setup = 1;
181
182                 /* make sure readers find in_trans_setup before
183                  * they find our root->last_trans update
184                  */
185                 smp_wmb();
186
187                 spin_lock(&root->fs_info->fs_roots_radix_lock);
188                 if (root->last_trans == trans->transid) {
189                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
190                         return 0;
191                 }
192                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
193                            (unsigned long)root->root_key.objectid,
194                            BTRFS_ROOT_TRANS_TAG);
195                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
196                 root->last_trans = trans->transid;
197
198                 /* this is pretty tricky.  We don't want to
199                  * take the relocation lock in btrfs_record_root_in_trans
200                  * unless we're really doing the first setup for this root in
201                  * this transaction.
202                  *
203                  * Normally we'd use root->last_trans as a flag to decide
204                  * if we want to take the expensive mutex.
205                  *
206                  * But, we have to set root->last_trans before we
207                  * init the relocation root, otherwise, we trip over warnings
208                  * in ctree.c.  The solution used here is to flag ourselves
209                  * with root->in_trans_setup.  When this is 1, we're still
210                  * fixing up the reloc trees and everyone must wait.
211                  *
212                  * When this is zero, they can trust root->last_trans and fly
213                  * through btrfs_record_root_in_trans without having to take the
214                  * lock.  smp_wmb() makes sure that all the writes above are
215                  * done before we pop in the zero below
216                  */
217                 btrfs_init_reloc_root(trans, root);
218                 smp_wmb();
219                 root->in_trans_setup = 0;
220         }
221         return 0;
222 }
223
224
225 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
226                                struct btrfs_root *root)
227 {
228         if (!root->ref_cows)
229                 return 0;
230
231         /*
232          * see record_root_in_trans for comments about in_trans_setup usage
233          * and barriers
234          */
235         smp_rmb();
236         if (root->last_trans == trans->transid &&
237             !root->in_trans_setup)
238                 return 0;
239
240         mutex_lock(&root->fs_info->reloc_mutex);
241         record_root_in_trans(trans, root);
242         mutex_unlock(&root->fs_info->reloc_mutex);
243
244         return 0;
245 }
246
247 /* wait for commit against the current transaction to become unblocked
248  * when this is done, it is safe to start a new transaction, but the current
249  * transaction might not be fully on disk.
250  */
251 static void wait_current_trans(struct btrfs_root *root)
252 {
253         struct btrfs_transaction *cur_trans;
254
255         spin_lock(&root->fs_info->trans_lock);
256         cur_trans = root->fs_info->running_transaction;
257         if (cur_trans && cur_trans->blocked) {
258                 atomic_inc(&cur_trans->use_count);
259                 spin_unlock(&root->fs_info->trans_lock);
260
261                 wait_event(root->fs_info->transaction_wait,
262                            !cur_trans->blocked);
263                 put_transaction(cur_trans);
264         } else {
265                 spin_unlock(&root->fs_info->trans_lock);
266         }
267 }
268
269 enum btrfs_trans_type {
270         TRANS_START,
271         TRANS_JOIN,
272         TRANS_USERSPACE,
273         TRANS_JOIN_NOLOCK,
274 };
275
276 static int may_wait_transaction(struct btrfs_root *root, int type)
277 {
278         if (root->fs_info->log_root_recovering)
279                 return 0;
280
281         if (type == TRANS_USERSPACE)
282                 return 1;
283
284         if (type == TRANS_START &&
285             !atomic_read(&root->fs_info->open_ioctl_trans))
286                 return 1;
287
288         return 0;
289 }
290
291 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
292                                                     u64 num_items, int type)
293 {
294         struct btrfs_trans_handle *h;
295         struct btrfs_transaction *cur_trans;
296         u64 num_bytes = 0;
297         int ret;
298         u64 qgroup_reserved = 0;
299
300         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
301                 return ERR_PTR(-EROFS);
302
303         if (current->journal_info) {
304                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
305                 h = current->journal_info;
306                 h->use_count++;
307                 h->orig_rsv = h->block_rsv;
308                 h->block_rsv = NULL;
309                 goto got_it;
310         }
311
312         /*
313          * Do the reservation before we join the transaction so we can do all
314          * the appropriate flushing if need be.
315          */
316         if (num_items > 0 && root != root->fs_info->chunk_root) {
317                 if (root->fs_info->quota_enabled &&
318                     is_fstree(root->root_key.objectid)) {
319                         qgroup_reserved = num_items * root->leafsize;
320                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
321                         if (ret)
322                                 return ERR_PTR(ret);
323                 }
324
325                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
326                 ret = btrfs_block_rsv_add(root,
327                                           &root->fs_info->trans_block_rsv,
328                                           num_bytes);
329                 if (ret)
330                         return ERR_PTR(ret);
331         }
332 again:
333         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
334         if (!h)
335                 return ERR_PTR(-ENOMEM);
336
337         if (may_wait_transaction(root, type))
338                 wait_current_trans(root);
339
340         do {
341                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
342                 if (ret == -EBUSY)
343                         wait_current_trans(root);
344         } while (ret == -EBUSY);
345
346         if (ret < 0) {
347                 kmem_cache_free(btrfs_trans_handle_cachep, h);
348                 return ERR_PTR(ret);
349         }
350
351         cur_trans = root->fs_info->running_transaction;
352
353         h->transid = cur_trans->transid;
354         h->transaction = cur_trans;
355         h->blocks_used = 0;
356         h->bytes_reserved = 0;
357         h->root = root;
358         h->delayed_ref_updates = 0;
359         h->use_count = 1;
360         h->block_rsv = NULL;
361         h->orig_rsv = NULL;
362         h->aborted = 0;
363         h->qgroup_reserved = qgroup_reserved;
364         h->delayed_ref_elem.seq = 0;
365         INIT_LIST_HEAD(&h->qgroup_ref_list);
366
367         smp_mb();
368         if (cur_trans->blocked && may_wait_transaction(root, type)) {
369                 btrfs_commit_transaction(h, root);
370                 goto again;
371         }
372
373         if (num_bytes) {
374                 trace_btrfs_space_reservation(root->fs_info, "transaction",
375                                               h->transid, num_bytes, 1);
376                 h->block_rsv = &root->fs_info->trans_block_rsv;
377                 h->bytes_reserved = num_bytes;
378         }
379
380 got_it:
381         btrfs_record_root_in_trans(h, root);
382
383         if (!current->journal_info && type != TRANS_USERSPACE)
384                 current->journal_info = h;
385         return h;
386 }
387
388 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
389                                                    int num_items)
390 {
391         return start_transaction(root, num_items, TRANS_START);
392 }
393 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
394 {
395         return start_transaction(root, 0, TRANS_JOIN);
396 }
397
398 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
399 {
400         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
401 }
402
403 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
404 {
405         return start_transaction(root, 0, TRANS_USERSPACE);
406 }
407
408 /* wait for a transaction commit to be fully complete */
409 static noinline void wait_for_commit(struct btrfs_root *root,
410                                     struct btrfs_transaction *commit)
411 {
412         wait_event(commit->commit_wait, commit->commit_done);
413 }
414
415 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
416 {
417         struct btrfs_transaction *cur_trans = NULL, *t;
418         int ret;
419
420         ret = 0;
421         if (transid) {
422                 if (transid <= root->fs_info->last_trans_committed)
423                         goto out;
424
425                 /* find specified transaction */
426                 spin_lock(&root->fs_info->trans_lock);
427                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
428                         if (t->transid == transid) {
429                                 cur_trans = t;
430                                 atomic_inc(&cur_trans->use_count);
431                                 break;
432                         }
433                         if (t->transid > transid)
434                                 break;
435                 }
436                 spin_unlock(&root->fs_info->trans_lock);
437                 ret = -EINVAL;
438                 if (!cur_trans)
439                         goto out;  /* bad transid */
440         } else {
441                 /* find newest transaction that is committing | committed */
442                 spin_lock(&root->fs_info->trans_lock);
443                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
444                                             list) {
445                         if (t->in_commit) {
446                                 if (t->commit_done)
447                                         break;
448                                 cur_trans = t;
449                                 atomic_inc(&cur_trans->use_count);
450                                 break;
451                         }
452                 }
453                 spin_unlock(&root->fs_info->trans_lock);
454                 if (!cur_trans)
455                         goto out;  /* nothing committing|committed */
456         }
457
458         wait_for_commit(root, cur_trans);
459
460         put_transaction(cur_trans);
461         ret = 0;
462 out:
463         return ret;
464 }
465
466 void btrfs_throttle(struct btrfs_root *root)
467 {
468         if (!atomic_read(&root->fs_info->open_ioctl_trans))
469                 wait_current_trans(root);
470 }
471
472 static int should_end_transaction(struct btrfs_trans_handle *trans,
473                                   struct btrfs_root *root)
474 {
475         int ret;
476
477         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
478         return ret ? 1 : 0;
479 }
480
481 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
482                                  struct btrfs_root *root)
483 {
484         struct btrfs_transaction *cur_trans = trans->transaction;
485         struct btrfs_block_rsv *rsv = trans->block_rsv;
486         int updates;
487         int err;
488
489         smp_mb();
490         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
491                 return 1;
492
493         /*
494          * We need to do this in case we're deleting csums so the global block
495          * rsv get's used instead of the csum block rsv.
496          */
497         trans->block_rsv = NULL;
498
499         updates = trans->delayed_ref_updates;
500         trans->delayed_ref_updates = 0;
501         if (updates) {
502                 err = btrfs_run_delayed_refs(trans, root, updates);
503                 if (err) /* Error code will also eval true */
504                         return err;
505         }
506
507         trans->block_rsv = rsv;
508
509         return should_end_transaction(trans, root);
510 }
511
512 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
513                           struct btrfs_root *root, int throttle, int lock)
514 {
515         struct btrfs_transaction *cur_trans = trans->transaction;
516         struct btrfs_fs_info *info = root->fs_info;
517         int count = 0;
518         int err = 0;
519
520         if (--trans->use_count) {
521                 trans->block_rsv = trans->orig_rsv;
522                 return 0;
523         }
524
525         /*
526          * do the qgroup accounting as early as possible
527          */
528         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
529
530         btrfs_trans_release_metadata(trans, root);
531         trans->block_rsv = NULL;
532         /*
533          * the same root has to be passed to start_transaction and
534          * end_transaction. Subvolume quota depends on this.
535          */
536         WARN_ON(trans->root != root);
537
538         if (trans->qgroup_reserved) {
539                 btrfs_qgroup_free(root, trans->qgroup_reserved);
540                 trans->qgroup_reserved = 0;
541         }
542
543         while (count < 2) {
544                 unsigned long cur = trans->delayed_ref_updates;
545                 trans->delayed_ref_updates = 0;
546                 if (cur &&
547                     trans->transaction->delayed_refs.num_heads_ready > 64) {
548                         trans->delayed_ref_updates = 0;
549                         btrfs_run_delayed_refs(trans, root, cur);
550                 } else {
551                         break;
552                 }
553                 count++;
554         }
555
556         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
557             should_end_transaction(trans, root)) {
558                 trans->transaction->blocked = 1;
559                 smp_wmb();
560         }
561
562         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
563                 if (throttle) {
564                         /*
565                          * We may race with somebody else here so end up having
566                          * to call end_transaction on ourselves again, so inc
567                          * our use_count.
568                          */
569                         trans->use_count++;
570                         return btrfs_commit_transaction(trans, root);
571                 } else {
572                         wake_up_process(info->transaction_kthread);
573                 }
574         }
575
576         WARN_ON(cur_trans != info->running_transaction);
577         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
578         atomic_dec(&cur_trans->num_writers);
579
580         smp_mb();
581         if (waitqueue_active(&cur_trans->writer_wait))
582                 wake_up(&cur_trans->writer_wait);
583         put_transaction(cur_trans);
584
585         if (current->journal_info == trans)
586                 current->journal_info = NULL;
587
588         if (throttle)
589                 btrfs_run_delayed_iputs(root);
590
591         if (trans->aborted ||
592             root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
593                 err = -EIO;
594         }
595         assert_qgroups_uptodate(trans);
596
597         memset(trans, 0, sizeof(*trans));
598         kmem_cache_free(btrfs_trans_handle_cachep, trans);
599         return err;
600 }
601
602 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
603                           struct btrfs_root *root)
604 {
605         int ret;
606
607         ret = __btrfs_end_transaction(trans, root, 0, 1);
608         if (ret)
609                 return ret;
610         return 0;
611 }
612
613 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
614                                    struct btrfs_root *root)
615 {
616         int ret;
617
618         ret = __btrfs_end_transaction(trans, root, 1, 1);
619         if (ret)
620                 return ret;
621         return 0;
622 }
623
624 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
625                                  struct btrfs_root *root)
626 {
627         int ret;
628
629         ret = __btrfs_end_transaction(trans, root, 0, 0);
630         if (ret)
631                 return ret;
632         return 0;
633 }
634
635 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
636                                 struct btrfs_root *root)
637 {
638         return __btrfs_end_transaction(trans, root, 1, 1);
639 }
640
641 /*
642  * when btree blocks are allocated, they have some corresponding bits set for
643  * them in one of two extent_io trees.  This is used to make sure all of
644  * those extents are sent to disk but does not wait on them
645  */
646 int btrfs_write_marked_extents(struct btrfs_root *root,
647                                struct extent_io_tree *dirty_pages, int mark)
648 {
649         int err = 0;
650         int werr = 0;
651         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
652         u64 start = 0;
653         u64 end;
654
655         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
656                                       mark)) {
657                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
658                                    GFP_NOFS);
659                 err = filemap_fdatawrite_range(mapping, start, end);
660                 if (err)
661                         werr = err;
662                 cond_resched();
663                 start = end + 1;
664         }
665         if (err)
666                 werr = err;
667         return werr;
668 }
669
670 /*
671  * when btree blocks are allocated, they have some corresponding bits set for
672  * them in one of two extent_io trees.  This is used to make sure all of
673  * those extents are on disk for transaction or log commit.  We wait
674  * on all the pages and clear them from the dirty pages state tree
675  */
676 int btrfs_wait_marked_extents(struct btrfs_root *root,
677                               struct extent_io_tree *dirty_pages, int mark)
678 {
679         int err = 0;
680         int werr = 0;
681         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
682         u64 start = 0;
683         u64 end;
684
685         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
686                                       EXTENT_NEED_WAIT)) {
687                 clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
688                 err = filemap_fdatawait_range(mapping, start, end);
689                 if (err)
690                         werr = err;
691                 cond_resched();
692                 start = end + 1;
693         }
694         if (err)
695                 werr = err;
696         return werr;
697 }
698
699 /*
700  * when btree blocks are allocated, they have some corresponding bits set for
701  * them in one of two extent_io trees.  This is used to make sure all of
702  * those extents are on disk for transaction or log commit
703  */
704 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
705                                 struct extent_io_tree *dirty_pages, int mark)
706 {
707         int ret;
708         int ret2;
709
710         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
711         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
712
713         if (ret)
714                 return ret;
715         if (ret2)
716                 return ret2;
717         return 0;
718 }
719
720 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
721                                      struct btrfs_root *root)
722 {
723         if (!trans || !trans->transaction) {
724                 struct inode *btree_inode;
725                 btree_inode = root->fs_info->btree_inode;
726                 return filemap_write_and_wait(btree_inode->i_mapping);
727         }
728         return btrfs_write_and_wait_marked_extents(root,
729                                            &trans->transaction->dirty_pages,
730                                            EXTENT_DIRTY);
731 }
732
733 /*
734  * this is used to update the root pointer in the tree of tree roots.
735  *
736  * But, in the case of the extent allocation tree, updating the root
737  * pointer may allocate blocks which may change the root of the extent
738  * allocation tree.
739  *
740  * So, this loops and repeats and makes sure the cowonly root didn't
741  * change while the root pointer was being updated in the metadata.
742  */
743 static int update_cowonly_root(struct btrfs_trans_handle *trans,
744                                struct btrfs_root *root)
745 {
746         int ret;
747         u64 old_root_bytenr;
748         u64 old_root_used;
749         struct btrfs_root *tree_root = root->fs_info->tree_root;
750
751         old_root_used = btrfs_root_used(&root->root_item);
752         btrfs_write_dirty_block_groups(trans, root);
753
754         while (1) {
755                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
756                 if (old_root_bytenr == root->node->start &&
757                     old_root_used == btrfs_root_used(&root->root_item))
758                         break;
759
760                 btrfs_set_root_node(&root->root_item, root->node);
761                 ret = btrfs_update_root(trans, tree_root,
762                                         &root->root_key,
763                                         &root->root_item);
764                 if (ret)
765                         return ret;
766
767                 old_root_used = btrfs_root_used(&root->root_item);
768                 ret = btrfs_write_dirty_block_groups(trans, root);
769                 if (ret)
770                         return ret;
771         }
772
773         if (root != root->fs_info->extent_root)
774                 switch_commit_root(root);
775
776         return 0;
777 }
778
779 /*
780  * update all the cowonly tree roots on disk
781  *
782  * The error handling in this function may not be obvious. Any of the
783  * failures will cause the file system to go offline. We still need
784  * to clean up the delayed refs.
785  */
786 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
787                                          struct btrfs_root *root)
788 {
789         struct btrfs_fs_info *fs_info = root->fs_info;
790         struct list_head *next;
791         struct extent_buffer *eb;
792         int ret;
793
794         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
795         if (ret)
796                 return ret;
797
798         eb = btrfs_lock_root_node(fs_info->tree_root);
799         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
800                               0, &eb);
801         btrfs_tree_unlock(eb);
802         free_extent_buffer(eb);
803
804         if (ret)
805                 return ret;
806
807         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
808         if (ret)
809                 return ret;
810
811         ret = btrfs_run_dev_stats(trans, root->fs_info);
812         BUG_ON(ret);
813
814         ret = btrfs_run_qgroups(trans, root->fs_info);
815         BUG_ON(ret);
816
817         /* run_qgroups might have added some more refs */
818         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
819         BUG_ON(ret);
820
821         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
822                 next = fs_info->dirty_cowonly_roots.next;
823                 list_del_init(next);
824                 root = list_entry(next, struct btrfs_root, dirty_list);
825
826                 ret = update_cowonly_root(trans, root);
827                 if (ret)
828                         return ret;
829         }
830
831         down_write(&fs_info->extent_commit_sem);
832         switch_commit_root(fs_info->extent_root);
833         up_write(&fs_info->extent_commit_sem);
834
835         return 0;
836 }
837
838 /*
839  * dead roots are old snapshots that need to be deleted.  This allocates
840  * a dirty root struct and adds it into the list of dead roots that need to
841  * be deleted
842  */
843 int btrfs_add_dead_root(struct btrfs_root *root)
844 {
845         spin_lock(&root->fs_info->trans_lock);
846         list_add(&root->root_list, &root->fs_info->dead_roots);
847         spin_unlock(&root->fs_info->trans_lock);
848         return 0;
849 }
850
851 /*
852  * update all the cowonly tree roots on disk
853  */
854 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
855                                     struct btrfs_root *root)
856 {
857         struct btrfs_root *gang[8];
858         struct btrfs_fs_info *fs_info = root->fs_info;
859         int i;
860         int ret;
861         int err = 0;
862
863         spin_lock(&fs_info->fs_roots_radix_lock);
864         while (1) {
865                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
866                                                  (void **)gang, 0,
867                                                  ARRAY_SIZE(gang),
868                                                  BTRFS_ROOT_TRANS_TAG);
869                 if (ret == 0)
870                         break;
871                 for (i = 0; i < ret; i++) {
872                         root = gang[i];
873                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
874                                         (unsigned long)root->root_key.objectid,
875                                         BTRFS_ROOT_TRANS_TAG);
876                         spin_unlock(&fs_info->fs_roots_radix_lock);
877
878                         btrfs_free_log(trans, root);
879                         btrfs_update_reloc_root(trans, root);
880                         btrfs_orphan_commit_root(trans, root);
881
882                         btrfs_save_ino_cache(root, trans);
883
884                         /* see comments in should_cow_block() */
885                         root->force_cow = 0;
886                         smp_wmb();
887
888                         if (root->commit_root != root->node) {
889                                 mutex_lock(&root->fs_commit_mutex);
890                                 switch_commit_root(root);
891                                 btrfs_unpin_free_ino(root);
892                                 mutex_unlock(&root->fs_commit_mutex);
893
894                                 btrfs_set_root_node(&root->root_item,
895                                                     root->node);
896                         }
897
898                         err = btrfs_update_root(trans, fs_info->tree_root,
899                                                 &root->root_key,
900                                                 &root->root_item);
901                         spin_lock(&fs_info->fs_roots_radix_lock);
902                         if (err)
903                                 break;
904                 }
905         }
906         spin_unlock(&fs_info->fs_roots_radix_lock);
907         return err;
908 }
909
910 /*
911  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
912  * otherwise every leaf in the btree is read and defragged.
913  */
914 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
915 {
916         struct btrfs_fs_info *info = root->fs_info;
917         struct btrfs_trans_handle *trans;
918         int ret;
919         unsigned long nr;
920
921         if (xchg(&root->defrag_running, 1))
922                 return 0;
923
924         while (1) {
925                 trans = btrfs_start_transaction(root, 0);
926                 if (IS_ERR(trans))
927                         return PTR_ERR(trans);
928
929                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
930
931                 nr = trans->blocks_used;
932                 btrfs_end_transaction(trans, root);
933                 btrfs_btree_balance_dirty(info->tree_root, nr);
934                 cond_resched();
935
936                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
937                         break;
938         }
939         root->defrag_running = 0;
940         return ret;
941 }
942
943 /*
944  * new snapshots need to be created at a very specific time in the
945  * transaction commit.  This does the actual creation
946  */
947 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
948                                    struct btrfs_fs_info *fs_info,
949                                    struct btrfs_pending_snapshot *pending)
950 {
951         struct btrfs_key key;
952         struct btrfs_root_item *new_root_item;
953         struct btrfs_root *tree_root = fs_info->tree_root;
954         struct btrfs_root *root = pending->root;
955         struct btrfs_root *parent_root;
956         struct btrfs_block_rsv *rsv;
957         struct inode *parent_inode;
958         struct dentry *parent;
959         struct dentry *dentry;
960         struct extent_buffer *tmp;
961         struct extent_buffer *old;
962         int ret;
963         u64 to_reserve = 0;
964         u64 index = 0;
965         u64 objectid;
966         u64 root_flags;
967
968         rsv = trans->block_rsv;
969
970         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
971         if (!new_root_item) {
972                 ret = pending->error = -ENOMEM;
973                 goto fail;
974         }
975
976         ret = btrfs_find_free_objectid(tree_root, &objectid);
977         if (ret) {
978                 pending->error = ret;
979                 goto fail;
980         }
981
982         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
983
984         if (to_reserve > 0) {
985                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
986                                                   to_reserve);
987                 if (ret) {
988                         pending->error = ret;
989                         goto fail;
990                 }
991         }
992
993         ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
994                                    objectid, pending->inherit);
995         kfree(pending->inherit);
996         if (ret) {
997                 pending->error = ret;
998                 goto fail;
999         }
1000
1001         key.objectid = objectid;
1002         key.offset = (u64)-1;
1003         key.type = BTRFS_ROOT_ITEM_KEY;
1004
1005         trans->block_rsv = &pending->block_rsv;
1006
1007         dentry = pending->dentry;
1008         parent = dget_parent(dentry);
1009         parent_inode = parent->d_inode;
1010         parent_root = BTRFS_I(parent_inode)->root;
1011         record_root_in_trans(trans, parent_root);
1012
1013         /*
1014          * insert the directory item
1015          */
1016         ret = btrfs_set_inode_index(parent_inode, &index);
1017         BUG_ON(ret); /* -ENOMEM */
1018         ret = btrfs_insert_dir_item(trans, parent_root,
1019                                 dentry->d_name.name, dentry->d_name.len,
1020                                 parent_inode, &key,
1021                                 BTRFS_FT_DIR, index);
1022         if (ret == -EEXIST) {
1023                 pending->error = -EEXIST;
1024                 dput(parent);
1025                 goto fail;
1026         } else if (ret) {
1027                 goto abort_trans_dput;
1028         }
1029
1030         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1031                                          dentry->d_name.len * 2);
1032         ret = btrfs_update_inode(trans, parent_root, parent_inode);
1033         if (ret)
1034                 goto abort_trans_dput;
1035
1036         /*
1037          * pull in the delayed directory update
1038          * and the delayed inode item
1039          * otherwise we corrupt the FS during
1040          * snapshot
1041          */
1042         ret = btrfs_run_delayed_items(trans, root);
1043         if (ret) { /* Transaction aborted */
1044                 dput(parent);
1045                 goto fail;
1046         }
1047
1048         record_root_in_trans(trans, root);
1049         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1050         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1051         btrfs_check_and_init_root_item(new_root_item);
1052
1053         root_flags = btrfs_root_flags(new_root_item);
1054         if (pending->readonly)
1055                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1056         else
1057                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1058         btrfs_set_root_flags(new_root_item, root_flags);
1059
1060         old = btrfs_lock_root_node(root);
1061         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1062         if (ret) {
1063                 btrfs_tree_unlock(old);
1064                 free_extent_buffer(old);
1065                 goto abort_trans_dput;
1066         }
1067
1068         btrfs_set_lock_blocking(old);
1069
1070         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1071         /* clean up in any case */
1072         btrfs_tree_unlock(old);
1073         free_extent_buffer(old);
1074         if (ret)
1075                 goto abort_trans_dput;
1076
1077         /* see comments in should_cow_block() */
1078         root->force_cow = 1;
1079         smp_wmb();
1080
1081         btrfs_set_root_node(new_root_item, tmp);
1082         /* record when the snapshot was created in key.offset */
1083         key.offset = trans->transid;
1084         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1085         btrfs_tree_unlock(tmp);
1086         free_extent_buffer(tmp);
1087         if (ret)
1088                 goto abort_trans_dput;
1089
1090         /*
1091          * insert root back/forward references
1092          */
1093         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1094                                  parent_root->root_key.objectid,
1095                                  btrfs_ino(parent_inode), index,
1096                                  dentry->d_name.name, dentry->d_name.len);
1097         dput(parent);
1098         if (ret)
1099                 goto fail;
1100
1101         key.offset = (u64)-1;
1102         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1103         if (IS_ERR(pending->snap)) {
1104                 ret = PTR_ERR(pending->snap);
1105                 goto abort_trans;
1106         }
1107
1108         ret = btrfs_reloc_post_snapshot(trans, pending);
1109         if (ret)
1110                 goto abort_trans;
1111         ret = 0;
1112 fail:
1113         kfree(new_root_item);
1114         trans->block_rsv = rsv;
1115         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1116         return ret;
1117
1118 abort_trans_dput:
1119         dput(parent);
1120 abort_trans:
1121         btrfs_abort_transaction(trans, root, ret);
1122         goto fail;
1123 }
1124
1125 /*
1126  * create all the snapshots we've scheduled for creation
1127  */
1128 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1129                                              struct btrfs_fs_info *fs_info)
1130 {
1131         struct btrfs_pending_snapshot *pending;
1132         struct list_head *head = &trans->transaction->pending_snapshots;
1133
1134         list_for_each_entry(pending, head, list)
1135                 create_pending_snapshot(trans, fs_info, pending);
1136         return 0;
1137 }
1138
1139 static void update_super_roots(struct btrfs_root *root)
1140 {
1141         struct btrfs_root_item *root_item;
1142         struct btrfs_super_block *super;
1143
1144         super = root->fs_info->super_copy;
1145
1146         root_item = &root->fs_info->chunk_root->root_item;
1147         super->chunk_root = root_item->bytenr;
1148         super->chunk_root_generation = root_item->generation;
1149         super->chunk_root_level = root_item->level;
1150
1151         root_item = &root->fs_info->tree_root->root_item;
1152         super->root = root_item->bytenr;
1153         super->generation = root_item->generation;
1154         super->root_level = root_item->level;
1155         if (btrfs_test_opt(root, SPACE_CACHE))
1156                 super->cache_generation = root_item->generation;
1157 }
1158
1159 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1160 {
1161         int ret = 0;
1162         spin_lock(&info->trans_lock);
1163         if (info->running_transaction)
1164                 ret = info->running_transaction->in_commit;
1165         spin_unlock(&info->trans_lock);
1166         return ret;
1167 }
1168
1169 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1170 {
1171         int ret = 0;
1172         spin_lock(&info->trans_lock);
1173         if (info->running_transaction)
1174                 ret = info->running_transaction->blocked;
1175         spin_unlock(&info->trans_lock);
1176         return ret;
1177 }
1178
1179 /*
1180  * wait for the current transaction commit to start and block subsequent
1181  * transaction joins
1182  */
1183 static void wait_current_trans_commit_start(struct btrfs_root *root,
1184                                             struct btrfs_transaction *trans)
1185 {
1186         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1187 }
1188
1189 /*
1190  * wait for the current transaction to start and then become unblocked.
1191  * caller holds ref.
1192  */
1193 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1194                                          struct btrfs_transaction *trans)
1195 {
1196         wait_event(root->fs_info->transaction_wait,
1197                    trans->commit_done || (trans->in_commit && !trans->blocked));
1198 }
1199
1200 /*
1201  * commit transactions asynchronously. once btrfs_commit_transaction_async
1202  * returns, any subsequent transaction will not be allowed to join.
1203  */
1204 struct btrfs_async_commit {
1205         struct btrfs_trans_handle *newtrans;
1206         struct btrfs_root *root;
1207         struct delayed_work work;
1208 };
1209
1210 static void do_async_commit(struct work_struct *work)
1211 {
1212         struct btrfs_async_commit *ac =
1213                 container_of(work, struct btrfs_async_commit, work.work);
1214
1215         btrfs_commit_transaction(ac->newtrans, ac->root);
1216         kfree(ac);
1217 }
1218
1219 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1220                                    struct btrfs_root *root,
1221                                    int wait_for_unblock)
1222 {
1223         struct btrfs_async_commit *ac;
1224         struct btrfs_transaction *cur_trans;
1225
1226         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1227         if (!ac)
1228                 return -ENOMEM;
1229
1230         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1231         ac->root = root;
1232         ac->newtrans = btrfs_join_transaction(root);
1233         if (IS_ERR(ac->newtrans)) {
1234                 int err = PTR_ERR(ac->newtrans);
1235                 kfree(ac);
1236                 return err;
1237         }
1238
1239         /* take transaction reference */
1240         cur_trans = trans->transaction;
1241         atomic_inc(&cur_trans->use_count);
1242
1243         btrfs_end_transaction(trans, root);
1244         schedule_delayed_work(&ac->work, 0);
1245
1246         /* wait for transaction to start and unblock */
1247         if (wait_for_unblock)
1248                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1249         else
1250                 wait_current_trans_commit_start(root, cur_trans);
1251
1252         if (current->journal_info == trans)
1253                 current->journal_info = NULL;
1254
1255         put_transaction(cur_trans);
1256         return 0;
1257 }
1258
1259
1260 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1261                                 struct btrfs_root *root, int err)
1262 {
1263         struct btrfs_transaction *cur_trans = trans->transaction;
1264
1265         WARN_ON(trans->use_count > 1);
1266
1267         btrfs_abort_transaction(trans, root, err);
1268
1269         spin_lock(&root->fs_info->trans_lock);
1270         list_del_init(&cur_trans->list);
1271         if (cur_trans == root->fs_info->running_transaction) {
1272                 root->fs_info->running_transaction = NULL;
1273                 root->fs_info->trans_no_join = 0;
1274         }
1275         spin_unlock(&root->fs_info->trans_lock);
1276
1277         btrfs_cleanup_one_transaction(trans->transaction, root);
1278
1279         put_transaction(cur_trans);
1280         put_transaction(cur_trans);
1281
1282         trace_btrfs_transaction_commit(root);
1283
1284         btrfs_scrub_continue(root);
1285
1286         if (current->journal_info == trans)
1287                 current->journal_info = NULL;
1288
1289         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1290 }
1291
1292 /*
1293  * btrfs_transaction state sequence:
1294  *    in_commit = 0, blocked = 0  (initial)
1295  *    in_commit = 1, blocked = 1
1296  *    blocked = 0
1297  *    commit_done = 1
1298  */
1299 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1300                              struct btrfs_root *root)
1301 {
1302         unsigned long joined = 0;
1303         struct btrfs_transaction *cur_trans = trans->transaction;
1304         struct btrfs_transaction *prev_trans = NULL;
1305         DEFINE_WAIT(wait);
1306         int ret = -EIO;
1307         int should_grow = 0;
1308         unsigned long now = get_seconds();
1309         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1310
1311         btrfs_run_ordered_operations(root, 0);
1312
1313         btrfs_trans_release_metadata(trans, root);
1314         trans->block_rsv = NULL;
1315
1316         if (cur_trans->aborted)
1317                 goto cleanup_transaction;
1318
1319         /* make a pass through all the delayed refs we have so far
1320          * any runnings procs may add more while we are here
1321          */
1322         ret = btrfs_run_delayed_refs(trans, root, 0);
1323         if (ret)
1324                 goto cleanup_transaction;
1325
1326         cur_trans = trans->transaction;
1327
1328         /*
1329          * set the flushing flag so procs in this transaction have to
1330          * start sending their work down.
1331          */
1332         cur_trans->delayed_refs.flushing = 1;
1333
1334         ret = btrfs_run_delayed_refs(trans, root, 0);
1335         if (ret)
1336                 goto cleanup_transaction;
1337
1338         spin_lock(&cur_trans->commit_lock);
1339         if (cur_trans->in_commit) {
1340                 spin_unlock(&cur_trans->commit_lock);
1341                 atomic_inc(&cur_trans->use_count);
1342                 ret = btrfs_end_transaction(trans, root);
1343
1344                 wait_for_commit(root, cur_trans);
1345
1346                 put_transaction(cur_trans);
1347
1348                 return ret;
1349         }
1350
1351         trans->transaction->in_commit = 1;
1352         trans->transaction->blocked = 1;
1353         spin_unlock(&cur_trans->commit_lock);
1354         wake_up(&root->fs_info->transaction_blocked_wait);
1355
1356         spin_lock(&root->fs_info->trans_lock);
1357         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1358                 prev_trans = list_entry(cur_trans->list.prev,
1359                                         struct btrfs_transaction, list);
1360                 if (!prev_trans->commit_done) {
1361                         atomic_inc(&prev_trans->use_count);
1362                         spin_unlock(&root->fs_info->trans_lock);
1363
1364                         wait_for_commit(root, prev_trans);
1365
1366                         put_transaction(prev_trans);
1367                 } else {
1368                         spin_unlock(&root->fs_info->trans_lock);
1369                 }
1370         } else {
1371                 spin_unlock(&root->fs_info->trans_lock);
1372         }
1373
1374         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1375                 should_grow = 1;
1376
1377         do {
1378                 int snap_pending = 0;
1379
1380                 joined = cur_trans->num_joined;
1381                 if (!list_empty(&trans->transaction->pending_snapshots))
1382                         snap_pending = 1;
1383
1384                 WARN_ON(cur_trans != trans->transaction);
1385
1386                 if (flush_on_commit || snap_pending) {
1387                         btrfs_start_delalloc_inodes(root, 1);
1388                         btrfs_wait_ordered_extents(root, 0, 1);
1389                 }
1390
1391                 ret = btrfs_run_delayed_items(trans, root);
1392                 if (ret)
1393                         goto cleanup_transaction;
1394
1395                 /*
1396                  * running the delayed items may have added new refs. account
1397                  * them now so that they hinder processing of more delayed refs
1398                  * as little as possible.
1399                  */
1400                 btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1401
1402                 /*
1403                  * rename don't use btrfs_join_transaction, so, once we
1404                  * set the transaction to blocked above, we aren't going
1405                  * to get any new ordered operations.  We can safely run
1406                  * it here and no for sure that nothing new will be added
1407                  * to the list
1408                  */
1409                 btrfs_run_ordered_operations(root, 1);
1410
1411                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1412                                 TASK_UNINTERRUPTIBLE);
1413
1414                 if (atomic_read(&cur_trans->num_writers) > 1)
1415                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1416                 else if (should_grow)
1417                         schedule_timeout(1);
1418
1419                 finish_wait(&cur_trans->writer_wait, &wait);
1420         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1421                  (should_grow && cur_trans->num_joined != joined));
1422
1423         /*
1424          * Ok now we need to make sure to block out any other joins while we
1425          * commit the transaction.  We could have started a join before setting
1426          * no_join so make sure to wait for num_writers to == 1 again.
1427          */
1428         spin_lock(&root->fs_info->trans_lock);
1429         root->fs_info->trans_no_join = 1;
1430         spin_unlock(&root->fs_info->trans_lock);
1431         wait_event(cur_trans->writer_wait,
1432                    atomic_read(&cur_trans->num_writers) == 1);
1433
1434         /*
1435          * the reloc mutex makes sure that we stop
1436          * the balancing code from coming in and moving
1437          * extents around in the middle of the commit
1438          */
1439         mutex_lock(&root->fs_info->reloc_mutex);
1440
1441         ret = btrfs_run_delayed_items(trans, root);
1442         if (ret) {
1443                 mutex_unlock(&root->fs_info->reloc_mutex);
1444                 goto cleanup_transaction;
1445         }
1446
1447         ret = create_pending_snapshots(trans, root->fs_info);
1448         if (ret) {
1449                 mutex_unlock(&root->fs_info->reloc_mutex);
1450                 goto cleanup_transaction;
1451         }
1452
1453         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1454         if (ret) {
1455                 mutex_unlock(&root->fs_info->reloc_mutex);
1456                 goto cleanup_transaction;
1457         }
1458
1459         /*
1460          * make sure none of the code above managed to slip in a
1461          * delayed item
1462          */
1463         btrfs_assert_delayed_root_empty(root);
1464
1465         WARN_ON(cur_trans != trans->transaction);
1466
1467         btrfs_scrub_pause(root);
1468         /* btrfs_commit_tree_roots is responsible for getting the
1469          * various roots consistent with each other.  Every pointer
1470          * in the tree of tree roots has to point to the most up to date
1471          * root for every subvolume and other tree.  So, we have to keep
1472          * the tree logging code from jumping in and changing any
1473          * of the trees.
1474          *
1475          * At this point in the commit, there can't be any tree-log
1476          * writers, but a little lower down we drop the trans mutex
1477          * and let new people in.  By holding the tree_log_mutex
1478          * from now until after the super is written, we avoid races
1479          * with the tree-log code.
1480          */
1481         mutex_lock(&root->fs_info->tree_log_mutex);
1482
1483         ret = commit_fs_roots(trans, root);
1484         if (ret) {
1485                 mutex_unlock(&root->fs_info->tree_log_mutex);
1486                 mutex_unlock(&root->fs_info->reloc_mutex);
1487                 goto cleanup_transaction;
1488         }
1489
1490         /* commit_fs_roots gets rid of all the tree log roots, it is now
1491          * safe to free the root of tree log roots
1492          */
1493         btrfs_free_log_root_tree(trans, root->fs_info);
1494
1495         ret = commit_cowonly_roots(trans, root);
1496         if (ret) {
1497                 mutex_unlock(&root->fs_info->tree_log_mutex);
1498                 mutex_unlock(&root->fs_info->reloc_mutex);
1499                 goto cleanup_transaction;
1500         }
1501
1502         btrfs_prepare_extent_commit(trans, root);
1503
1504         cur_trans = root->fs_info->running_transaction;
1505
1506         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1507                             root->fs_info->tree_root->node);
1508         switch_commit_root(root->fs_info->tree_root);
1509
1510         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1511                             root->fs_info->chunk_root->node);
1512         switch_commit_root(root->fs_info->chunk_root);
1513
1514         assert_qgroups_uptodate(trans);
1515         update_super_roots(root);
1516
1517         if (!root->fs_info->log_root_recovering) {
1518                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1519                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1520         }
1521
1522         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1523                sizeof(*root->fs_info->super_copy));
1524
1525         trans->transaction->blocked = 0;
1526         spin_lock(&root->fs_info->trans_lock);
1527         root->fs_info->running_transaction = NULL;
1528         root->fs_info->trans_no_join = 0;
1529         spin_unlock(&root->fs_info->trans_lock);
1530         mutex_unlock(&root->fs_info->reloc_mutex);
1531
1532         wake_up(&root->fs_info->transaction_wait);
1533
1534         ret = btrfs_write_and_wait_transaction(trans, root);
1535         if (ret) {
1536                 btrfs_error(root->fs_info, ret,
1537                             "Error while writing out transaction.");
1538                 mutex_unlock(&root->fs_info->tree_log_mutex);
1539                 goto cleanup_transaction;
1540         }
1541
1542         ret = write_ctree_super(trans, root, 0);
1543         if (ret) {
1544                 mutex_unlock(&root->fs_info->tree_log_mutex);
1545                 goto cleanup_transaction;
1546         }
1547
1548         /*
1549          * the super is written, we can safely allow the tree-loggers
1550          * to go about their business
1551          */
1552         mutex_unlock(&root->fs_info->tree_log_mutex);
1553
1554         btrfs_finish_extent_commit(trans, root);
1555
1556         cur_trans->commit_done = 1;
1557
1558         root->fs_info->last_trans_committed = cur_trans->transid;
1559
1560         wake_up(&cur_trans->commit_wait);
1561
1562         spin_lock(&root->fs_info->trans_lock);
1563         list_del_init(&cur_trans->list);
1564         spin_unlock(&root->fs_info->trans_lock);
1565
1566         put_transaction(cur_trans);
1567         put_transaction(cur_trans);
1568
1569         trace_btrfs_transaction_commit(root);
1570
1571         btrfs_scrub_continue(root);
1572
1573         if (current->journal_info == trans)
1574                 current->journal_info = NULL;
1575
1576         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1577
1578         if (current != root->fs_info->transaction_kthread)
1579                 btrfs_run_delayed_iputs(root);
1580
1581         return ret;
1582
1583 cleanup_transaction:
1584         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1585 //      WARN_ON(1);
1586         if (current->journal_info == trans)
1587                 current->journal_info = NULL;
1588         cleanup_transaction(trans, root, ret);
1589
1590         return ret;
1591 }
1592
1593 /*
1594  * interface function to delete all the snapshots we have scheduled for deletion
1595  */
1596 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1597 {
1598         LIST_HEAD(list);
1599         struct btrfs_fs_info *fs_info = root->fs_info;
1600
1601         spin_lock(&fs_info->trans_lock);
1602         list_splice_init(&fs_info->dead_roots, &list);
1603         spin_unlock(&fs_info->trans_lock);
1604
1605         while (!list_empty(&list)) {
1606                 int ret;
1607
1608                 root = list_entry(list.next, struct btrfs_root, root_list);
1609                 list_del(&root->root_list);
1610
1611                 btrfs_kill_all_delayed_nodes(root);
1612
1613                 if (btrfs_header_backref_rev(root->node) <
1614                     BTRFS_MIXED_BACKREF_REV)
1615                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1616                 else
1617                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1618                 BUG_ON(ret < 0);
1619         }
1620         return 0;
1621 }