Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable
[linux-2.6.git] / fs / btrfs / transaction.c
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/fs.h>
20 #include <linux/slab.h>
21 #include <linux/sched.h>
22 #include <linux/writeback.h>
23 #include <linux/pagemap.h>
24 #include <linux/blkdev.h>
25 #include "ctree.h"
26 #include "disk-io.h"
27 #include "transaction.h"
28 #include "locking.h"
29 #include "tree-log.h"
30
31 #define BTRFS_ROOT_TRANS_TAG 0
32
33 static noinline void put_transaction(struct btrfs_transaction *transaction)
34 {
35         WARN_ON(transaction->use_count == 0);
36         transaction->use_count--;
37         if (transaction->use_count == 0) {
38                 list_del_init(&transaction->list);
39                 memset(transaction, 0, sizeof(*transaction));
40                 kmem_cache_free(btrfs_transaction_cachep, transaction);
41         }
42 }
43
44 static noinline void switch_commit_root(struct btrfs_root *root)
45 {
46         free_extent_buffer(root->commit_root);
47         root->commit_root = btrfs_root_node(root);
48 }
49
50 /*
51  * either allocate a new transaction or hop into the existing one
52  */
53 static noinline int join_transaction(struct btrfs_root *root)
54 {
55         struct btrfs_transaction *cur_trans;
56         cur_trans = root->fs_info->running_transaction;
57         if (!cur_trans) {
58                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
59                                              GFP_NOFS);
60                 BUG_ON(!cur_trans);
61                 root->fs_info->generation++;
62                 cur_trans->num_writers = 1;
63                 cur_trans->num_joined = 0;
64                 cur_trans->transid = root->fs_info->generation;
65                 init_waitqueue_head(&cur_trans->writer_wait);
66                 init_waitqueue_head(&cur_trans->commit_wait);
67                 cur_trans->in_commit = 0;
68                 cur_trans->blocked = 0;
69                 cur_trans->use_count = 1;
70                 cur_trans->commit_done = 0;
71                 cur_trans->start_time = get_seconds();
72
73                 cur_trans->delayed_refs.root = RB_ROOT;
74                 cur_trans->delayed_refs.num_entries = 0;
75                 cur_trans->delayed_refs.num_heads_ready = 0;
76                 cur_trans->delayed_refs.num_heads = 0;
77                 cur_trans->delayed_refs.flushing = 0;
78                 cur_trans->delayed_refs.run_delayed_start = 0;
79                 spin_lock_init(&cur_trans->delayed_refs.lock);
80
81                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
82                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
83                 extent_io_tree_init(&cur_trans->dirty_pages,
84                                      root->fs_info->btree_inode->i_mapping,
85                                      GFP_NOFS);
86                 spin_lock(&root->fs_info->new_trans_lock);
87                 root->fs_info->running_transaction = cur_trans;
88                 spin_unlock(&root->fs_info->new_trans_lock);
89         } else {
90                 cur_trans->num_writers++;
91                 cur_trans->num_joined++;
92         }
93
94         return 0;
95 }
96
97 /*
98  * this does all the record keeping required to make sure that a reference
99  * counted root is properly recorded in a given transaction.  This is required
100  * to make sure the old root from before we joined the transaction is deleted
101  * when the transaction commits
102  */
103 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
104                                          struct btrfs_root *root)
105 {
106         if (root->ref_cows && root->last_trans < trans->transid) {
107                 WARN_ON(root == root->fs_info->extent_root);
108                 WARN_ON(root->commit_root != root->node);
109
110                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
111                            (unsigned long)root->root_key.objectid,
112                            BTRFS_ROOT_TRANS_TAG);
113                 root->last_trans = trans->transid;
114                 btrfs_init_reloc_root(trans, root);
115         }
116         return 0;
117 }
118
119 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
120                                struct btrfs_root *root)
121 {
122         if (!root->ref_cows)
123                 return 0;
124
125         mutex_lock(&root->fs_info->trans_mutex);
126         if (root->last_trans == trans->transid) {
127                 mutex_unlock(&root->fs_info->trans_mutex);
128                 return 0;
129         }
130
131         record_root_in_trans(trans, root);
132         mutex_unlock(&root->fs_info->trans_mutex);
133         return 0;
134 }
135
136 /* wait for commit against the current transaction to become unblocked
137  * when this is done, it is safe to start a new transaction, but the current
138  * transaction might not be fully on disk.
139  */
140 static void wait_current_trans(struct btrfs_root *root)
141 {
142         struct btrfs_transaction *cur_trans;
143
144         cur_trans = root->fs_info->running_transaction;
145         if (cur_trans && cur_trans->blocked) {
146                 DEFINE_WAIT(wait);
147                 cur_trans->use_count++;
148                 while (1) {
149                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
150                                         TASK_UNINTERRUPTIBLE);
151                         if (!cur_trans->blocked)
152                                 break;
153                         mutex_unlock(&root->fs_info->trans_mutex);
154                         schedule();
155                         mutex_lock(&root->fs_info->trans_mutex);
156                 }
157                 finish_wait(&root->fs_info->transaction_wait, &wait);
158                 put_transaction(cur_trans);
159         }
160 }
161
162 enum btrfs_trans_type {
163         TRANS_START,
164         TRANS_JOIN,
165         TRANS_USERSPACE,
166 };
167
168 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
169                                              int num_blocks, int type)
170 {
171         struct btrfs_trans_handle *h =
172                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
173         int ret;
174
175         mutex_lock(&root->fs_info->trans_mutex);
176         if (!root->fs_info->log_root_recovering &&
177             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
178              type == TRANS_USERSPACE))
179                 wait_current_trans(root);
180         ret = join_transaction(root);
181         BUG_ON(ret);
182
183         h->transid = root->fs_info->running_transaction->transid;
184         h->transaction = root->fs_info->running_transaction;
185         h->blocks_reserved = num_blocks;
186         h->blocks_used = 0;
187         h->block_group = 0;
188         h->alloc_exclude_nr = 0;
189         h->alloc_exclude_start = 0;
190         h->delayed_ref_updates = 0;
191
192         if (!current->journal_info && type != TRANS_USERSPACE)
193                 current->journal_info = h;
194
195         root->fs_info->running_transaction->use_count++;
196         record_root_in_trans(h, root);
197         mutex_unlock(&root->fs_info->trans_mutex);
198         return h;
199 }
200
201 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
202                                                    int num_blocks)
203 {
204         return start_transaction(root, num_blocks, TRANS_START);
205 }
206 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
207                                                    int num_blocks)
208 {
209         return start_transaction(root, num_blocks, TRANS_JOIN);
210 }
211
212 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
213                                                          int num_blocks)
214 {
215         return start_transaction(r, num_blocks, TRANS_USERSPACE);
216 }
217
218 /* wait for a transaction commit to be fully complete */
219 static noinline int wait_for_commit(struct btrfs_root *root,
220                                     struct btrfs_transaction *commit)
221 {
222         DEFINE_WAIT(wait);
223         mutex_lock(&root->fs_info->trans_mutex);
224         while (!commit->commit_done) {
225                 prepare_to_wait(&commit->commit_wait, &wait,
226                                 TASK_UNINTERRUPTIBLE);
227                 if (commit->commit_done)
228                         break;
229                 mutex_unlock(&root->fs_info->trans_mutex);
230                 schedule();
231                 mutex_lock(&root->fs_info->trans_mutex);
232         }
233         mutex_unlock(&root->fs_info->trans_mutex);
234         finish_wait(&commit->commit_wait, &wait);
235         return 0;
236 }
237
238 #if 0
239 /*
240  * rate limit against the drop_snapshot code.  This helps to slow down new
241  * operations if the drop_snapshot code isn't able to keep up.
242  */
243 static void throttle_on_drops(struct btrfs_root *root)
244 {
245         struct btrfs_fs_info *info = root->fs_info;
246         int harder_count = 0;
247
248 harder:
249         if (atomic_read(&info->throttles)) {
250                 DEFINE_WAIT(wait);
251                 int thr;
252                 thr = atomic_read(&info->throttle_gen);
253
254                 do {
255                         prepare_to_wait(&info->transaction_throttle,
256                                         &wait, TASK_UNINTERRUPTIBLE);
257                         if (!atomic_read(&info->throttles)) {
258                                 finish_wait(&info->transaction_throttle, &wait);
259                                 break;
260                         }
261                         schedule();
262                         finish_wait(&info->transaction_throttle, &wait);
263                 } while (thr == atomic_read(&info->throttle_gen));
264                 harder_count++;
265
266                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
267                     harder_count < 2)
268                         goto harder;
269
270                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
271                     harder_count < 10)
272                         goto harder;
273
274                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
275                     harder_count < 20)
276                         goto harder;
277         }
278 }
279 #endif
280
281 void btrfs_throttle(struct btrfs_root *root)
282 {
283         mutex_lock(&root->fs_info->trans_mutex);
284         if (!root->fs_info->open_ioctl_trans)
285                 wait_current_trans(root);
286         mutex_unlock(&root->fs_info->trans_mutex);
287 }
288
289 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
290                           struct btrfs_root *root, int throttle)
291 {
292         struct btrfs_transaction *cur_trans;
293         struct btrfs_fs_info *info = root->fs_info;
294         int count = 0;
295
296         while (count < 4) {
297                 unsigned long cur = trans->delayed_ref_updates;
298                 trans->delayed_ref_updates = 0;
299                 if (cur &&
300                     trans->transaction->delayed_refs.num_heads_ready > 64) {
301                         trans->delayed_ref_updates = 0;
302
303                         /*
304                          * do a full flush if the transaction is trying
305                          * to close
306                          */
307                         if (trans->transaction->delayed_refs.flushing)
308                                 cur = 0;
309                         btrfs_run_delayed_refs(trans, root, cur);
310                 } else {
311                         break;
312                 }
313                 count++;
314         }
315
316         mutex_lock(&info->trans_mutex);
317         cur_trans = info->running_transaction;
318         WARN_ON(cur_trans != trans->transaction);
319         WARN_ON(cur_trans->num_writers < 1);
320         cur_trans->num_writers--;
321
322         if (waitqueue_active(&cur_trans->writer_wait))
323                 wake_up(&cur_trans->writer_wait);
324         put_transaction(cur_trans);
325         mutex_unlock(&info->trans_mutex);
326
327         if (current->journal_info == trans)
328                 current->journal_info = NULL;
329         memset(trans, 0, sizeof(*trans));
330         kmem_cache_free(btrfs_trans_handle_cachep, trans);
331
332         if (throttle)
333                 btrfs_run_delayed_iputs(root);
334
335         return 0;
336 }
337
338 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
339                           struct btrfs_root *root)
340 {
341         return __btrfs_end_transaction(trans, root, 0);
342 }
343
344 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
345                                    struct btrfs_root *root)
346 {
347         return __btrfs_end_transaction(trans, root, 1);
348 }
349
350 /*
351  * when btree blocks are allocated, they have some corresponding bits set for
352  * them in one of two extent_io trees.  This is used to make sure all of
353  * those extents are sent to disk but does not wait on them
354  */
355 int btrfs_write_marked_extents(struct btrfs_root *root,
356                                struct extent_io_tree *dirty_pages, int mark)
357 {
358         int ret;
359         int err = 0;
360         int werr = 0;
361         struct page *page;
362         struct inode *btree_inode = root->fs_info->btree_inode;
363         u64 start = 0;
364         u64 end;
365         unsigned long index;
366
367         while (1) {
368                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
369                                             mark);
370                 if (ret)
371                         break;
372                 while (start <= end) {
373                         cond_resched();
374
375                         index = start >> PAGE_CACHE_SHIFT;
376                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
377                         page = find_get_page(btree_inode->i_mapping, index);
378                         if (!page)
379                                 continue;
380
381                         btree_lock_page_hook(page);
382                         if (!page->mapping) {
383                                 unlock_page(page);
384                                 page_cache_release(page);
385                                 continue;
386                         }
387
388                         if (PageWriteback(page)) {
389                                 if (PageDirty(page))
390                                         wait_on_page_writeback(page);
391                                 else {
392                                         unlock_page(page);
393                                         page_cache_release(page);
394                                         continue;
395                                 }
396                         }
397                         err = write_one_page(page, 0);
398                         if (err)
399                                 werr = err;
400                         page_cache_release(page);
401                 }
402         }
403         if (err)
404                 werr = err;
405         return werr;
406 }
407
408 /*
409  * when btree blocks are allocated, they have some corresponding bits set for
410  * them in one of two extent_io trees.  This is used to make sure all of
411  * those extents are on disk for transaction or log commit.  We wait
412  * on all the pages and clear them from the dirty pages state tree
413  */
414 int btrfs_wait_marked_extents(struct btrfs_root *root,
415                               struct extent_io_tree *dirty_pages, int mark)
416 {
417         int ret;
418         int err = 0;
419         int werr = 0;
420         struct page *page;
421         struct inode *btree_inode = root->fs_info->btree_inode;
422         u64 start = 0;
423         u64 end;
424         unsigned long index;
425
426         while (1) {
427                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
428                                             mark);
429                 if (ret)
430                         break;
431
432                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
433                 while (start <= end) {
434                         index = start >> PAGE_CACHE_SHIFT;
435                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
436                         page = find_get_page(btree_inode->i_mapping, index);
437                         if (!page)
438                                 continue;
439                         if (PageDirty(page)) {
440                                 btree_lock_page_hook(page);
441                                 wait_on_page_writeback(page);
442                                 err = write_one_page(page, 0);
443                                 if (err)
444                                         werr = err;
445                         }
446                         wait_on_page_writeback(page);
447                         page_cache_release(page);
448                         cond_resched();
449                 }
450         }
451         if (err)
452                 werr = err;
453         return werr;
454 }
455
456 /*
457  * when btree blocks are allocated, they have some corresponding bits set for
458  * them in one of two extent_io trees.  This is used to make sure all of
459  * those extents are on disk for transaction or log commit
460  */
461 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
462                                 struct extent_io_tree *dirty_pages, int mark)
463 {
464         int ret;
465         int ret2;
466
467         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
468         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
469         return ret || ret2;
470 }
471
472 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
473                                      struct btrfs_root *root)
474 {
475         if (!trans || !trans->transaction) {
476                 struct inode *btree_inode;
477                 btree_inode = root->fs_info->btree_inode;
478                 return filemap_write_and_wait(btree_inode->i_mapping);
479         }
480         return btrfs_write_and_wait_marked_extents(root,
481                                            &trans->transaction->dirty_pages,
482                                            EXTENT_DIRTY);
483 }
484
485 /*
486  * this is used to update the root pointer in the tree of tree roots.
487  *
488  * But, in the case of the extent allocation tree, updating the root
489  * pointer may allocate blocks which may change the root of the extent
490  * allocation tree.
491  *
492  * So, this loops and repeats and makes sure the cowonly root didn't
493  * change while the root pointer was being updated in the metadata.
494  */
495 static int update_cowonly_root(struct btrfs_trans_handle *trans,
496                                struct btrfs_root *root)
497 {
498         int ret;
499         u64 old_root_bytenr;
500         u64 old_root_used;
501         struct btrfs_root *tree_root = root->fs_info->tree_root;
502
503         old_root_used = btrfs_root_used(&root->root_item);
504         btrfs_write_dirty_block_groups(trans, root);
505
506         while (1) {
507                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
508                 if (old_root_bytenr == root->node->start &&
509                     old_root_used == btrfs_root_used(&root->root_item))
510                         break;
511
512                 btrfs_set_root_node(&root->root_item, root->node);
513                 ret = btrfs_update_root(trans, tree_root,
514                                         &root->root_key,
515                                         &root->root_item);
516                 BUG_ON(ret);
517
518                 old_root_used = btrfs_root_used(&root->root_item);
519                 ret = btrfs_write_dirty_block_groups(trans, root);
520                 BUG_ON(ret);
521         }
522
523         if (root != root->fs_info->extent_root)
524                 switch_commit_root(root);
525
526         return 0;
527 }
528
529 /*
530  * update all the cowonly tree roots on disk
531  */
532 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
533                                          struct btrfs_root *root)
534 {
535         struct btrfs_fs_info *fs_info = root->fs_info;
536         struct list_head *next;
537         struct extent_buffer *eb;
538         int ret;
539
540         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
541         BUG_ON(ret);
542
543         eb = btrfs_lock_root_node(fs_info->tree_root);
544         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
545         btrfs_tree_unlock(eb);
546         free_extent_buffer(eb);
547
548         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
549         BUG_ON(ret);
550
551         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
552                 next = fs_info->dirty_cowonly_roots.next;
553                 list_del_init(next);
554                 root = list_entry(next, struct btrfs_root, dirty_list);
555
556                 update_cowonly_root(trans, root);
557         }
558
559         down_write(&fs_info->extent_commit_sem);
560         switch_commit_root(fs_info->extent_root);
561         up_write(&fs_info->extent_commit_sem);
562
563         return 0;
564 }
565
566 /*
567  * dead roots are old snapshots that need to be deleted.  This allocates
568  * a dirty root struct and adds it into the list of dead roots that need to
569  * be deleted
570  */
571 int btrfs_add_dead_root(struct btrfs_root *root)
572 {
573         mutex_lock(&root->fs_info->trans_mutex);
574         list_add(&root->root_list, &root->fs_info->dead_roots);
575         mutex_unlock(&root->fs_info->trans_mutex);
576         return 0;
577 }
578
579 /*
580  * update all the cowonly tree roots on disk
581  */
582 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
583                                     struct btrfs_root *root)
584 {
585         struct btrfs_root *gang[8];
586         struct btrfs_fs_info *fs_info = root->fs_info;
587         int i;
588         int ret;
589         int err = 0;
590
591         while (1) {
592                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
593                                                  (void **)gang, 0,
594                                                  ARRAY_SIZE(gang),
595                                                  BTRFS_ROOT_TRANS_TAG);
596                 if (ret == 0)
597                         break;
598                 for (i = 0; i < ret; i++) {
599                         root = gang[i];
600                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
601                                         (unsigned long)root->root_key.objectid,
602                                         BTRFS_ROOT_TRANS_TAG);
603
604                         btrfs_free_log(trans, root);
605                         btrfs_update_reloc_root(trans, root);
606
607                         if (root->commit_root != root->node) {
608                                 switch_commit_root(root);
609                                 btrfs_set_root_node(&root->root_item,
610                                                     root->node);
611                         }
612
613                         err = btrfs_update_root(trans, fs_info->tree_root,
614                                                 &root->root_key,
615                                                 &root->root_item);
616                         if (err)
617                                 break;
618                 }
619         }
620         return err;
621 }
622
623 /*
624  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
625  * otherwise every leaf in the btree is read and defragged.
626  */
627 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
628 {
629         struct btrfs_fs_info *info = root->fs_info;
630         int ret;
631         struct btrfs_trans_handle *trans;
632         unsigned long nr;
633
634         smp_mb();
635         if (root->defrag_running)
636                 return 0;
637         trans = btrfs_start_transaction(root, 1);
638         while (1) {
639                 root->defrag_running = 1;
640                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
641                 nr = trans->blocks_used;
642                 btrfs_end_transaction(trans, root);
643                 btrfs_btree_balance_dirty(info->tree_root, nr);
644                 cond_resched();
645
646                 trans = btrfs_start_transaction(root, 1);
647                 if (root->fs_info->closing || ret != -EAGAIN)
648                         break;
649         }
650         root->defrag_running = 0;
651         smp_mb();
652         btrfs_end_transaction(trans, root);
653         return 0;
654 }
655
656 #if 0
657 /*
658  * when dropping snapshots, we generate a ton of delayed refs, and it makes
659  * sense not to join the transaction while it is trying to flush the current
660  * queue of delayed refs out.
661  *
662  * This is used by the drop snapshot code only
663  */
664 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
665 {
666         DEFINE_WAIT(wait);
667
668         mutex_lock(&info->trans_mutex);
669         while (info->running_transaction &&
670                info->running_transaction->delayed_refs.flushing) {
671                 prepare_to_wait(&info->transaction_wait, &wait,
672                                 TASK_UNINTERRUPTIBLE);
673                 mutex_unlock(&info->trans_mutex);
674
675                 schedule();
676
677                 mutex_lock(&info->trans_mutex);
678                 finish_wait(&info->transaction_wait, &wait);
679         }
680         mutex_unlock(&info->trans_mutex);
681         return 0;
682 }
683
684 /*
685  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
686  * all of them
687  */
688 int btrfs_drop_dead_root(struct btrfs_root *root)
689 {
690         struct btrfs_trans_handle *trans;
691         struct btrfs_root *tree_root = root->fs_info->tree_root;
692         unsigned long nr;
693         int ret;
694
695         while (1) {
696                 /*
697                  * we don't want to jump in and create a bunch of
698                  * delayed refs if the transaction is starting to close
699                  */
700                 wait_transaction_pre_flush(tree_root->fs_info);
701                 trans = btrfs_start_transaction(tree_root, 1);
702
703                 /*
704                  * we've joined a transaction, make sure it isn't
705                  * closing right now
706                  */
707                 if (trans->transaction->delayed_refs.flushing) {
708                         btrfs_end_transaction(trans, tree_root);
709                         continue;
710                 }
711
712                 ret = btrfs_drop_snapshot(trans, root);
713                 if (ret != -EAGAIN)
714                         break;
715
716                 ret = btrfs_update_root(trans, tree_root,
717                                         &root->root_key,
718                                         &root->root_item);
719                 if (ret)
720                         break;
721
722                 nr = trans->blocks_used;
723                 ret = btrfs_end_transaction(trans, tree_root);
724                 BUG_ON(ret);
725
726                 btrfs_btree_balance_dirty(tree_root, nr);
727                 cond_resched();
728         }
729         BUG_ON(ret);
730
731         ret = btrfs_del_root(trans, tree_root, &root->root_key);
732         BUG_ON(ret);
733
734         nr = trans->blocks_used;
735         ret = btrfs_end_transaction(trans, tree_root);
736         BUG_ON(ret);
737
738         free_extent_buffer(root->node);
739         free_extent_buffer(root->commit_root);
740         kfree(root);
741
742         btrfs_btree_balance_dirty(tree_root, nr);
743         return ret;
744 }
745 #endif
746
747 /*
748  * new snapshots need to be created at a very specific time in the
749  * transaction commit.  This does the actual creation
750  */
751 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
752                                    struct btrfs_fs_info *fs_info,
753                                    struct btrfs_pending_snapshot *pending)
754 {
755         struct btrfs_key key;
756         struct btrfs_root_item *new_root_item;
757         struct btrfs_root *tree_root = fs_info->tree_root;
758         struct btrfs_root *root = pending->root;
759         struct btrfs_root *parent_root;
760         struct inode *parent_inode;
761         struct extent_buffer *tmp;
762         struct extent_buffer *old;
763         int ret;
764         u64 objectid;
765         int namelen;
766         u64 index = 0;
767
768         parent_inode = pending->dentry->d_parent->d_inode;
769         parent_root = BTRFS_I(parent_inode)->root;
770
771         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
772         if (!new_root_item) {
773                 ret = -ENOMEM;
774                 goto fail;
775         }
776         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
777         if (ret)
778                 goto fail;
779
780         key.objectid = objectid;
781         /* record when the snapshot was created in key.offset */
782         key.offset = trans->transid;
783         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
784
785         memcpy(&pending->root_key, &key, sizeof(key));
786         pending->root_key.offset = (u64)-1;
787
788         record_root_in_trans(trans, parent_root);
789         /*
790          * insert the directory item
791          */
792         namelen = strlen(pending->name);
793         ret = btrfs_set_inode_index(parent_inode, &index);
794         BUG_ON(ret);
795         ret = btrfs_insert_dir_item(trans, parent_root,
796                             pending->name, namelen,
797                             parent_inode->i_ino,
798                             &pending->root_key, BTRFS_FT_DIR, index);
799         BUG_ON(ret);
800
801         btrfs_i_size_write(parent_inode, parent_inode->i_size + namelen * 2);
802         ret = btrfs_update_inode(trans, parent_root, parent_inode);
803         BUG_ON(ret);
804
805         record_root_in_trans(trans, root);
806         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
807         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
808
809         old = btrfs_lock_root_node(root);
810         btrfs_cow_block(trans, root, old, NULL, 0, &old);
811         btrfs_set_lock_blocking(old);
812
813         btrfs_copy_root(trans, root, old, &tmp, objectid);
814         btrfs_tree_unlock(old);
815         free_extent_buffer(old);
816
817         btrfs_set_root_node(new_root_item, tmp);
818         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
819                                 new_root_item);
820         BUG_ON(ret);
821         btrfs_tree_unlock(tmp);
822         free_extent_buffer(tmp);
823
824         ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
825                                  pending->root_key.objectid,
826                                  parent_root->root_key.objectid,
827                                  parent_inode->i_ino, index, pending->name,
828                                  namelen);
829         BUG_ON(ret);
830
831 fail:
832         kfree(new_root_item);
833         return ret;
834 }
835
836 /*
837  * create all the snapshots we've scheduled for creation
838  */
839 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
840                                              struct btrfs_fs_info *fs_info)
841 {
842         struct btrfs_pending_snapshot *pending;
843         struct list_head *head = &trans->transaction->pending_snapshots;
844         int ret;
845
846         list_for_each_entry(pending, head, list) {
847                 ret = create_pending_snapshot(trans, fs_info, pending);
848                 BUG_ON(ret);
849         }
850         return 0;
851 }
852
853 static void update_super_roots(struct btrfs_root *root)
854 {
855         struct btrfs_root_item *root_item;
856         struct btrfs_super_block *super;
857
858         super = &root->fs_info->super_copy;
859
860         root_item = &root->fs_info->chunk_root->root_item;
861         super->chunk_root = root_item->bytenr;
862         super->chunk_root_generation = root_item->generation;
863         super->chunk_root_level = root_item->level;
864
865         root_item = &root->fs_info->tree_root->root_item;
866         super->root = root_item->bytenr;
867         super->generation = root_item->generation;
868         super->root_level = root_item->level;
869 }
870
871 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
872 {
873         int ret = 0;
874         spin_lock(&info->new_trans_lock);
875         if (info->running_transaction)
876                 ret = info->running_transaction->in_commit;
877         spin_unlock(&info->new_trans_lock);
878         return ret;
879 }
880
881 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
882                              struct btrfs_root *root)
883 {
884         unsigned long joined = 0;
885         unsigned long timeout = 1;
886         struct btrfs_transaction *cur_trans;
887         struct btrfs_transaction *prev_trans = NULL;
888         DEFINE_WAIT(wait);
889         int ret;
890         int should_grow = 0;
891         unsigned long now = get_seconds();
892         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
893
894         btrfs_run_ordered_operations(root, 0);
895
896         /* make a pass through all the delayed refs we have so far
897          * any runnings procs may add more while we are here
898          */
899         ret = btrfs_run_delayed_refs(trans, root, 0);
900         BUG_ON(ret);
901
902         cur_trans = trans->transaction;
903         /*
904          * set the flushing flag so procs in this transaction have to
905          * start sending their work down.
906          */
907         cur_trans->delayed_refs.flushing = 1;
908
909         ret = btrfs_run_delayed_refs(trans, root, 0);
910         BUG_ON(ret);
911
912         mutex_lock(&root->fs_info->trans_mutex);
913         if (cur_trans->in_commit) {
914                 cur_trans->use_count++;
915                 mutex_unlock(&root->fs_info->trans_mutex);
916                 btrfs_end_transaction(trans, root);
917
918                 ret = wait_for_commit(root, cur_trans);
919                 BUG_ON(ret);
920
921                 mutex_lock(&root->fs_info->trans_mutex);
922                 put_transaction(cur_trans);
923                 mutex_unlock(&root->fs_info->trans_mutex);
924
925                 return 0;
926         }
927
928         trans->transaction->in_commit = 1;
929         trans->transaction->blocked = 1;
930         if (cur_trans->list.prev != &root->fs_info->trans_list) {
931                 prev_trans = list_entry(cur_trans->list.prev,
932                                         struct btrfs_transaction, list);
933                 if (!prev_trans->commit_done) {
934                         prev_trans->use_count++;
935                         mutex_unlock(&root->fs_info->trans_mutex);
936
937                         wait_for_commit(root, prev_trans);
938
939                         mutex_lock(&root->fs_info->trans_mutex);
940                         put_transaction(prev_trans);
941                 }
942         }
943
944         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
945                 should_grow = 1;
946
947         do {
948                 int snap_pending = 0;
949                 joined = cur_trans->num_joined;
950                 if (!list_empty(&trans->transaction->pending_snapshots))
951                         snap_pending = 1;
952
953                 WARN_ON(cur_trans != trans->transaction);
954                 prepare_to_wait(&cur_trans->writer_wait, &wait,
955                                 TASK_UNINTERRUPTIBLE);
956
957                 if (cur_trans->num_writers > 1)
958                         timeout = MAX_SCHEDULE_TIMEOUT;
959                 else if (should_grow)
960                         timeout = 1;
961
962                 mutex_unlock(&root->fs_info->trans_mutex);
963
964                 if (flush_on_commit || snap_pending) {
965                         btrfs_start_delalloc_inodes(root, 1);
966                         ret = btrfs_wait_ordered_extents(root, 0, 1);
967                         BUG_ON(ret);
968                 }
969
970                 /*
971                  * rename don't use btrfs_join_transaction, so, once we
972                  * set the transaction to blocked above, we aren't going
973                  * to get any new ordered operations.  We can safely run
974                  * it here and no for sure that nothing new will be added
975                  * to the list
976                  */
977                 btrfs_run_ordered_operations(root, 1);
978
979                 smp_mb();
980                 if (cur_trans->num_writers > 1 || should_grow)
981                         schedule_timeout(timeout);
982
983                 mutex_lock(&root->fs_info->trans_mutex);
984                 finish_wait(&cur_trans->writer_wait, &wait);
985         } while (cur_trans->num_writers > 1 ||
986                  (should_grow && cur_trans->num_joined != joined));
987
988         ret = create_pending_snapshots(trans, root->fs_info);
989         BUG_ON(ret);
990
991         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
992         BUG_ON(ret);
993
994         WARN_ON(cur_trans != trans->transaction);
995
996         /* btrfs_commit_tree_roots is responsible for getting the
997          * various roots consistent with each other.  Every pointer
998          * in the tree of tree roots has to point to the most up to date
999          * root for every subvolume and other tree.  So, we have to keep
1000          * the tree logging code from jumping in and changing any
1001          * of the trees.
1002          *
1003          * At this point in the commit, there can't be any tree-log
1004          * writers, but a little lower down we drop the trans mutex
1005          * and let new people in.  By holding the tree_log_mutex
1006          * from now until after the super is written, we avoid races
1007          * with the tree-log code.
1008          */
1009         mutex_lock(&root->fs_info->tree_log_mutex);
1010
1011         ret = commit_fs_roots(trans, root);
1012         BUG_ON(ret);
1013
1014         /* commit_fs_roots gets rid of all the tree log roots, it is now
1015          * safe to free the root of tree log roots
1016          */
1017         btrfs_free_log_root_tree(trans, root->fs_info);
1018
1019         ret = commit_cowonly_roots(trans, root);
1020         BUG_ON(ret);
1021
1022         btrfs_prepare_extent_commit(trans, root);
1023
1024         cur_trans = root->fs_info->running_transaction;
1025         spin_lock(&root->fs_info->new_trans_lock);
1026         root->fs_info->running_transaction = NULL;
1027         spin_unlock(&root->fs_info->new_trans_lock);
1028
1029         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1030                             root->fs_info->tree_root->node);
1031         switch_commit_root(root->fs_info->tree_root);
1032
1033         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1034                             root->fs_info->chunk_root->node);
1035         switch_commit_root(root->fs_info->chunk_root);
1036
1037         update_super_roots(root);
1038
1039         if (!root->fs_info->log_root_recovering) {
1040                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1041                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1042         }
1043
1044         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1045                sizeof(root->fs_info->super_copy));
1046
1047         trans->transaction->blocked = 0;
1048
1049         wake_up(&root->fs_info->transaction_wait);
1050
1051         mutex_unlock(&root->fs_info->trans_mutex);
1052         ret = btrfs_write_and_wait_transaction(trans, root);
1053         BUG_ON(ret);
1054         write_ctree_super(trans, root, 0);
1055
1056         /*
1057          * the super is written, we can safely allow the tree-loggers
1058          * to go about their business
1059          */
1060         mutex_unlock(&root->fs_info->tree_log_mutex);
1061
1062         btrfs_finish_extent_commit(trans, root);
1063
1064         mutex_lock(&root->fs_info->trans_mutex);
1065
1066         cur_trans->commit_done = 1;
1067
1068         root->fs_info->last_trans_committed = cur_trans->transid;
1069
1070         wake_up(&cur_trans->commit_wait);
1071
1072         put_transaction(cur_trans);
1073         put_transaction(cur_trans);
1074
1075         mutex_unlock(&root->fs_info->trans_mutex);
1076
1077         if (current->journal_info == trans)
1078                 current->journal_info = NULL;
1079
1080         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1081
1082         if (current != root->fs_info->transaction_kthread)
1083                 btrfs_run_delayed_iputs(root);
1084
1085         return ret;
1086 }
1087
1088 /*
1089  * interface function to delete all the snapshots we have scheduled for deletion
1090  */
1091 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1092 {
1093         LIST_HEAD(list);
1094         struct btrfs_fs_info *fs_info = root->fs_info;
1095
1096         mutex_lock(&fs_info->trans_mutex);
1097         list_splice_init(&fs_info->dead_roots, &list);
1098         mutex_unlock(&fs_info->trans_mutex);
1099
1100         while (!list_empty(&list)) {
1101                 root = list_entry(list.next, struct btrfs_root, root_list);
1102                 list_del(&root->root_list);
1103
1104                 if (btrfs_header_backref_rev(root->node) <
1105                     BTRFS_MIXED_BACKREF_REV)
1106                         btrfs_drop_snapshot(root, 0);
1107                 else
1108                         btrfs_drop_snapshot(root, 1);
1109         }
1110         return 0;
1111 }