Btrfs: extent_map and data=ordered fixes for space balancing
[linux-2.6] / 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/sched.h>
21 #include <linux/writeback.h>
22 #include <linux/pagemap.h>
23 #include "ctree.h"
24 #include "disk-io.h"
25 #include "transaction.h"
26 #include "locking.h"
27 #include "ref-cache.h"
28 #include "tree-log.h"
29
30 static int total_trans = 0;
31 extern struct kmem_cache *btrfs_trans_handle_cachep;
32 extern struct kmem_cache *btrfs_transaction_cachep;
33
34 #define BTRFS_ROOT_TRANS_TAG 0
35
36 static noinline void put_transaction(struct btrfs_transaction *transaction)
37 {
38         WARN_ON(transaction->use_count == 0);
39         transaction->use_count--;
40         if (transaction->use_count == 0) {
41                 WARN_ON(total_trans == 0);
42                 total_trans--;
43                 list_del_init(&transaction->list);
44                 memset(transaction, 0, sizeof(*transaction));
45                 kmem_cache_free(btrfs_transaction_cachep, transaction);
46         }
47 }
48
49 static noinline int join_transaction(struct btrfs_root *root)
50 {
51         struct btrfs_transaction *cur_trans;
52         cur_trans = root->fs_info->running_transaction;
53         if (!cur_trans) {
54                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
55                                              GFP_NOFS);
56                 total_trans++;
57                 BUG_ON(!cur_trans);
58                 root->fs_info->generation++;
59                 root->fs_info->last_alloc = 0;
60                 root->fs_info->last_data_alloc = 0;
61                 root->fs_info->last_log_alloc = 0;
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                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
73                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
74                 extent_io_tree_init(&cur_trans->dirty_pages,
75                                      root->fs_info->btree_inode->i_mapping,
76                                      GFP_NOFS);
77                 spin_lock(&root->fs_info->new_trans_lock);
78                 root->fs_info->running_transaction = cur_trans;
79                 spin_unlock(&root->fs_info->new_trans_lock);
80         } else {
81                 cur_trans->num_writers++;
82                 cur_trans->num_joined++;
83         }
84
85         return 0;
86 }
87
88 noinline int btrfs_record_root_in_trans(struct btrfs_root *root)
89 {
90         struct btrfs_dirty_root *dirty;
91         u64 running_trans_id = root->fs_info->running_transaction->transid;
92         if (root->ref_cows && root->last_trans < running_trans_id) {
93                 WARN_ON(root == root->fs_info->extent_root);
94                 if (root->root_item.refs != 0) {
95                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
96                                    (unsigned long)root->root_key.objectid,
97                                    BTRFS_ROOT_TRANS_TAG);
98
99                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
100                         BUG_ON(!dirty);
101                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
102                         BUG_ON(!dirty->root);
103                         dirty->latest_root = root;
104                         INIT_LIST_HEAD(&dirty->list);
105
106                         root->commit_root = btrfs_root_node(root);
107
108                         memcpy(dirty->root, root, sizeof(*root));
109                         spin_lock_init(&dirty->root->node_lock);
110                         spin_lock_init(&dirty->root->list_lock);
111                         mutex_init(&dirty->root->objectid_mutex);
112                         mutex_init(&dirty->root->log_mutex);
113                         INIT_LIST_HEAD(&dirty->root->dead_list);
114                         dirty->root->node = root->commit_root;
115                         dirty->root->commit_root = NULL;
116
117                         spin_lock(&root->list_lock);
118                         list_add(&dirty->root->dead_list, &root->dead_list);
119                         spin_unlock(&root->list_lock);
120
121                         root->dirty_root = dirty;
122                 } else {
123                         WARN_ON(1);
124                 }
125                 root->last_trans = running_trans_id;
126         }
127         return 0;
128 }
129
130 static void wait_current_trans(struct btrfs_root *root)
131 {
132         struct btrfs_transaction *cur_trans;
133
134         cur_trans = root->fs_info->running_transaction;
135         if (cur_trans && cur_trans->blocked) {
136                 DEFINE_WAIT(wait);
137                 cur_trans->use_count++;
138                 while(1) {
139                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
140                                         TASK_UNINTERRUPTIBLE);
141                         if (cur_trans->blocked) {
142                                 mutex_unlock(&root->fs_info->trans_mutex);
143                                 schedule();
144                                 mutex_lock(&root->fs_info->trans_mutex);
145                                 finish_wait(&root->fs_info->transaction_wait,
146                                             &wait);
147                         } else {
148                                 finish_wait(&root->fs_info->transaction_wait,
149                                             &wait);
150                                 break;
151                         }
152                 }
153                 put_transaction(cur_trans);
154         }
155 }
156
157 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
158                                              int num_blocks, int wait)
159 {
160         struct btrfs_trans_handle *h =
161                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
162         int ret;
163
164         mutex_lock(&root->fs_info->trans_mutex);
165         if (!root->fs_info->log_root_recovering &&
166             ((wait == 1 && !root->fs_info->open_ioctl_trans) || wait == 2))
167                 wait_current_trans(root);
168         ret = join_transaction(root);
169         BUG_ON(ret);
170
171         btrfs_record_root_in_trans(root);
172         h->transid = root->fs_info->running_transaction->transid;
173         h->transaction = root->fs_info->running_transaction;
174         h->blocks_reserved = num_blocks;
175         h->blocks_used = 0;
176         h->block_group = NULL;
177         h->alloc_exclude_nr = 0;
178         h->alloc_exclude_start = 0;
179         root->fs_info->running_transaction->use_count++;
180         mutex_unlock(&root->fs_info->trans_mutex);
181         return h;
182 }
183
184 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
185                                                    int num_blocks)
186 {
187         return start_transaction(root, num_blocks, 1);
188 }
189 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
190                                                    int num_blocks)
191 {
192         return start_transaction(root, num_blocks, 0);
193 }
194
195 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
196                                                          int num_blocks)
197 {
198         return start_transaction(r, num_blocks, 2);
199 }
200
201
202 static noinline int wait_for_commit(struct btrfs_root *root,
203                                     struct btrfs_transaction *commit)
204 {
205         DEFINE_WAIT(wait);
206         mutex_lock(&root->fs_info->trans_mutex);
207         while(!commit->commit_done) {
208                 prepare_to_wait(&commit->commit_wait, &wait,
209                                 TASK_UNINTERRUPTIBLE);
210                 if (commit->commit_done)
211                         break;
212                 mutex_unlock(&root->fs_info->trans_mutex);
213                 schedule();
214                 mutex_lock(&root->fs_info->trans_mutex);
215         }
216         mutex_unlock(&root->fs_info->trans_mutex);
217         finish_wait(&commit->commit_wait, &wait);
218         return 0;
219 }
220
221 static void throttle_on_drops(struct btrfs_root *root)
222 {
223         struct btrfs_fs_info *info = root->fs_info;
224         int harder_count = 0;
225
226 harder:
227         if (atomic_read(&info->throttles)) {
228                 DEFINE_WAIT(wait);
229                 int thr;
230                 thr = atomic_read(&info->throttle_gen);
231
232                 do {
233                         prepare_to_wait(&info->transaction_throttle,
234                                         &wait, TASK_UNINTERRUPTIBLE);
235                         if (!atomic_read(&info->throttles)) {
236                                 finish_wait(&info->transaction_throttle, &wait);
237                                 break;
238                         }
239                         schedule();
240                         finish_wait(&info->transaction_throttle, &wait);
241                 } while (thr == atomic_read(&info->throttle_gen));
242                 harder_count++;
243
244                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
245                     harder_count < 2)
246                         goto harder;
247
248                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
249                     harder_count < 10)
250                         goto harder;
251
252                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
253                     harder_count < 20)
254                         goto harder;
255         }
256 }
257
258 void btrfs_throttle(struct btrfs_root *root)
259 {
260         mutex_lock(&root->fs_info->trans_mutex);
261         if (!root->fs_info->open_ioctl_trans)
262                 wait_current_trans(root);
263         mutex_unlock(&root->fs_info->trans_mutex);
264
265         throttle_on_drops(root);
266 }
267
268 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
269                           struct btrfs_root *root, int throttle)
270 {
271         struct btrfs_transaction *cur_trans;
272         struct btrfs_fs_info *info = root->fs_info;
273
274         mutex_lock(&info->trans_mutex);
275         cur_trans = info->running_transaction;
276         WARN_ON(cur_trans != trans->transaction);
277         WARN_ON(cur_trans->num_writers < 1);
278         cur_trans->num_writers--;
279
280         if (waitqueue_active(&cur_trans->writer_wait))
281                 wake_up(&cur_trans->writer_wait);
282         put_transaction(cur_trans);
283         mutex_unlock(&info->trans_mutex);
284         memset(trans, 0, sizeof(*trans));
285         kmem_cache_free(btrfs_trans_handle_cachep, trans);
286
287         if (throttle)
288                 throttle_on_drops(root);
289
290         return 0;
291 }
292
293 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
294                           struct btrfs_root *root)
295 {
296         return __btrfs_end_transaction(trans, root, 0);
297 }
298
299 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
300                                    struct btrfs_root *root)
301 {
302         return __btrfs_end_transaction(trans, root, 1);
303 }
304
305
306 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
307                                         struct extent_io_tree *dirty_pages)
308 {
309         int ret;
310         int err = 0;
311         int werr = 0;
312         struct page *page;
313         struct inode *btree_inode = root->fs_info->btree_inode;
314         u64 start = 0;
315         u64 end;
316         unsigned long index;
317
318         while(1) {
319                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
320                                             EXTENT_DIRTY);
321                 if (ret)
322                         break;
323                 while(start <= end) {
324                         cond_resched();
325
326                         index = start >> PAGE_CACHE_SHIFT;
327                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
328                         page = find_get_page(btree_inode->i_mapping, index);
329                         if (!page)
330                                 continue;
331
332                         btree_lock_page_hook(page);
333                         if (!page->mapping) {
334                                 unlock_page(page);
335                                 page_cache_release(page);
336                                 continue;
337                         }
338
339                         if (PageWriteback(page)) {
340                                 if (PageDirty(page))
341                                         wait_on_page_writeback(page);
342                                 else {
343                                         unlock_page(page);
344                                         page_cache_release(page);
345                                         continue;
346                                 }
347                         }
348                         err = write_one_page(page, 0);
349                         if (err)
350                                 werr = err;
351                         page_cache_release(page);
352                 }
353         }
354         while(1) {
355                 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
356                                             EXTENT_DIRTY);
357                 if (ret)
358                         break;
359
360                 clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
361                 while(start <= end) {
362                         index = start >> PAGE_CACHE_SHIFT;
363                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
364                         page = find_get_page(btree_inode->i_mapping, index);
365                         if (!page)
366                                 continue;
367                         if (PageDirty(page)) {
368                                 btree_lock_page_hook(page);
369                                 wait_on_page_writeback(page);
370                                 err = write_one_page(page, 0);
371                                 if (err)
372                                         werr = err;
373                         }
374                         wait_on_page_writeback(page);
375                         page_cache_release(page);
376                         cond_resched();
377                 }
378         }
379         if (err)
380                 werr = err;
381         return werr;
382 }
383
384 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
385                                      struct btrfs_root *root)
386 {
387         if (!trans || !trans->transaction) {
388                 struct inode *btree_inode;
389                 btree_inode = root->fs_info->btree_inode;
390                 return filemap_write_and_wait(btree_inode->i_mapping);
391         }
392         return btrfs_write_and_wait_marked_extents(root,
393                                            &trans->transaction->dirty_pages);
394 }
395
396 static int update_cowonly_root(struct btrfs_trans_handle *trans,
397                                struct btrfs_root *root)
398 {
399         int ret;
400         u64 old_root_bytenr;
401         struct btrfs_root *tree_root = root->fs_info->tree_root;
402
403         btrfs_write_dirty_block_groups(trans, root);
404         while(1) {
405                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
406                 if (old_root_bytenr == root->node->start)
407                         break;
408                 btrfs_set_root_bytenr(&root->root_item,
409                                        root->node->start);
410                 btrfs_set_root_level(&root->root_item,
411                                      btrfs_header_level(root->node));
412                 ret = btrfs_update_root(trans, tree_root,
413                                         &root->root_key,
414                                         &root->root_item);
415                 BUG_ON(ret);
416                 btrfs_write_dirty_block_groups(trans, root);
417         }
418         return 0;
419 }
420
421 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
422                             struct btrfs_root *root)
423 {
424         struct btrfs_fs_info *fs_info = root->fs_info;
425         struct list_head *next;
426
427         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
428                 next = fs_info->dirty_cowonly_roots.next;
429                 list_del_init(next);
430                 root = list_entry(next, struct btrfs_root, dirty_list);
431                 update_cowonly_root(trans, root);
432         }
433         return 0;
434 }
435
436 int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest)
437 {
438         struct btrfs_dirty_root *dirty;
439
440         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
441         if (!dirty)
442                 return -ENOMEM;
443         dirty->root = root;
444         dirty->latest_root = latest;
445
446         mutex_lock(&root->fs_info->trans_mutex);
447         list_add(&dirty->list, &latest->fs_info->dead_roots);
448         mutex_unlock(&root->fs_info->trans_mutex);
449         return 0;
450 }
451
452 static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
453                                     struct radix_tree_root *radix,
454                                     struct list_head *list)
455 {
456         struct btrfs_dirty_root *dirty;
457         struct btrfs_root *gang[8];
458         struct btrfs_root *root;
459         int i;
460         int ret;
461         int err = 0;
462         u32 refs;
463
464         while(1) {
465                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
466                                                  ARRAY_SIZE(gang),
467                                                  BTRFS_ROOT_TRANS_TAG);
468                 if (ret == 0)
469                         break;
470                 for (i = 0; i < ret; i++) {
471                         root = gang[i];
472                         radix_tree_tag_clear(radix,
473                                      (unsigned long)root->root_key.objectid,
474                                      BTRFS_ROOT_TRANS_TAG);
475
476                         BUG_ON(!root->ref_tree);
477                         dirty = root->dirty_root;
478
479                         btrfs_free_log(trans, root);
480
481                         if (root->commit_root == root->node) {
482                                 WARN_ON(root->node->start !=
483                                         btrfs_root_bytenr(&root->root_item));
484
485                                 free_extent_buffer(root->commit_root);
486                                 root->commit_root = NULL;
487                                 root->dirty_root = NULL;
488
489                                 spin_lock(&root->list_lock);
490                                 list_del_init(&dirty->root->dead_list);
491                                 spin_unlock(&root->list_lock);
492
493                                 kfree(dirty->root);
494                                 kfree(dirty);
495
496                                 /* make sure to update the root on disk
497                                  * so we get any updates to the block used
498                                  * counts
499                                  */
500                                 err = btrfs_update_root(trans,
501                                                 root->fs_info->tree_root,
502                                                 &root->root_key,
503                                                 &root->root_item);
504                                 continue;
505                         }
506
507                         memset(&root->root_item.drop_progress, 0,
508                                sizeof(struct btrfs_disk_key));
509                         root->root_item.drop_level = 0;
510                         root->commit_root = NULL;
511                         root->dirty_root = NULL;
512                         root->root_key.offset = root->fs_info->generation;
513                         btrfs_set_root_bytenr(&root->root_item,
514                                               root->node->start);
515                         btrfs_set_root_level(&root->root_item,
516                                              btrfs_header_level(root->node));
517                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
518                                                 &root->root_key,
519                                                 &root->root_item);
520                         if (err)
521                                 break;
522
523                         refs = btrfs_root_refs(&dirty->root->root_item);
524                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
525                         err = btrfs_update_root(trans, root->fs_info->tree_root,
526                                                 &dirty->root->root_key,
527                                                 &dirty->root->root_item);
528
529                         BUG_ON(err);
530                         if (refs == 1) {
531                                 list_add(&dirty->list, list);
532                         } else {
533                                 WARN_ON(1);
534                                 free_extent_buffer(dirty->root->node);
535                                 kfree(dirty->root);
536                                 kfree(dirty);
537                         }
538                 }
539         }
540         return err;
541 }
542
543 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
544 {
545         struct btrfs_fs_info *info = root->fs_info;
546         int ret;
547         struct btrfs_trans_handle *trans;
548         unsigned long nr;
549
550         smp_mb();
551         if (root->defrag_running)
552                 return 0;
553         trans = btrfs_start_transaction(root, 1);
554         while (1) {
555                 root->defrag_running = 1;
556                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
557                 nr = trans->blocks_used;
558                 btrfs_end_transaction(trans, root);
559                 btrfs_btree_balance_dirty(info->tree_root, nr);
560                 cond_resched();
561
562                 trans = btrfs_start_transaction(root, 1);
563                 if (root->fs_info->closing || ret != -EAGAIN)
564                         break;
565         }
566         root->defrag_running = 0;
567         smp_mb();
568         btrfs_end_transaction(trans, root);
569         return 0;
570 }
571
572 static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
573                                      struct list_head *list)
574 {
575         struct btrfs_dirty_root *dirty;
576         struct btrfs_trans_handle *trans;
577         unsigned long nr;
578         u64 num_bytes;
579         u64 bytes_used;
580         u64 max_useless;
581         int ret = 0;
582         int err;
583
584         while(!list_empty(list)) {
585                 struct btrfs_root *root;
586
587                 dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
588                 list_del_init(&dirty->list);
589
590                 num_bytes = btrfs_root_used(&dirty->root->root_item);
591                 root = dirty->latest_root;
592                 atomic_inc(&root->fs_info->throttles);
593
594                 while(1) {
595                         trans = btrfs_start_transaction(tree_root, 1);
596                         mutex_lock(&root->fs_info->drop_mutex);
597                         ret = btrfs_drop_snapshot(trans, dirty->root);
598                         if (ret != -EAGAIN) {
599                                 break;
600                         }
601                         mutex_unlock(&root->fs_info->drop_mutex);
602
603                         err = btrfs_update_root(trans,
604                                         tree_root,
605                                         &dirty->root->root_key,
606                                         &dirty->root->root_item);
607                         if (err)
608                                 ret = err;
609                         nr = trans->blocks_used;
610                         ret = btrfs_end_transaction(trans, tree_root);
611                         BUG_ON(ret);
612
613                         btrfs_btree_balance_dirty(tree_root, nr);
614                         cond_resched();
615                 }
616                 BUG_ON(ret);
617                 atomic_dec(&root->fs_info->throttles);
618                 wake_up(&root->fs_info->transaction_throttle);
619
620                 mutex_lock(&root->fs_info->alloc_mutex);
621                 num_bytes -= btrfs_root_used(&dirty->root->root_item);
622                 bytes_used = btrfs_root_used(&root->root_item);
623                 if (num_bytes) {
624                         btrfs_record_root_in_trans(root);
625                         btrfs_set_root_used(&root->root_item,
626                                             bytes_used - num_bytes);
627                 }
628                 mutex_unlock(&root->fs_info->alloc_mutex);
629
630                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
631                 if (ret) {
632                         BUG();
633                         break;
634                 }
635                 mutex_unlock(&root->fs_info->drop_mutex);
636
637                 spin_lock(&root->list_lock);
638                 list_del_init(&dirty->root->dead_list);
639                 if (!list_empty(&root->dead_list)) {
640                         struct btrfs_root *oldest;
641                         oldest = list_entry(root->dead_list.prev,
642                                             struct btrfs_root, dead_list);
643                         max_useless = oldest->root_key.offset - 1;
644                 } else {
645                         max_useless = root->root_key.offset - 1;
646                 }
647                 spin_unlock(&root->list_lock);
648
649                 nr = trans->blocks_used;
650                 ret = btrfs_end_transaction(trans, tree_root);
651                 BUG_ON(ret);
652
653                 ret = btrfs_remove_leaf_refs(root, max_useless, 0);
654                 BUG_ON(ret);
655
656                 free_extent_buffer(dirty->root->node);
657                 kfree(dirty->root);
658                 kfree(dirty);
659
660                 btrfs_btree_balance_dirty(tree_root, nr);
661                 cond_resched();
662         }
663         return ret;
664 }
665
666 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
667                                    struct btrfs_fs_info *fs_info,
668                                    struct btrfs_pending_snapshot *pending)
669 {
670         struct btrfs_key key;
671         struct btrfs_root_item *new_root_item;
672         struct btrfs_root *tree_root = fs_info->tree_root;
673         struct btrfs_root *root = pending->root;
674         struct extent_buffer *tmp;
675         struct extent_buffer *old;
676         int ret;
677         int namelen;
678         u64 objectid;
679
680         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
681         if (!new_root_item) {
682                 ret = -ENOMEM;
683                 goto fail;
684         }
685         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
686         if (ret)
687                 goto fail;
688
689         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
690
691         key.objectid = objectid;
692         key.offset = trans->transid;
693         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
694
695         old = btrfs_lock_root_node(root);
696         btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
697
698         btrfs_copy_root(trans, root, old, &tmp, objectid);
699         btrfs_tree_unlock(old);
700         free_extent_buffer(old);
701
702         btrfs_set_root_bytenr(new_root_item, tmp->start);
703         btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
704         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
705                                 new_root_item);
706         btrfs_tree_unlock(tmp);
707         free_extent_buffer(tmp);
708         if (ret)
709                 goto fail;
710
711         /*
712          * insert the directory item
713          */
714         key.offset = (u64)-1;
715         namelen = strlen(pending->name);
716         ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
717                                     pending->name, namelen,
718                                     root->fs_info->sb->s_root->d_inode->i_ino,
719                                     &key, BTRFS_FT_DIR, 0);
720
721         if (ret)
722                 goto fail;
723
724         ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
725                              pending->name, strlen(pending->name), objectid,
726                              root->fs_info->sb->s_root->d_inode->i_ino, 0);
727
728         /* Invalidate existing dcache entry for new snapshot. */
729         btrfs_invalidate_dcache_root(root, pending->name, namelen);
730
731 fail:
732         kfree(new_root_item);
733         return ret;
734 }
735
736 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
737                                              struct btrfs_fs_info *fs_info)
738 {
739         struct btrfs_pending_snapshot *pending;
740         struct list_head *head = &trans->transaction->pending_snapshots;
741         int ret;
742
743         while(!list_empty(head)) {
744                 pending = list_entry(head->next,
745                                      struct btrfs_pending_snapshot, list);
746                 ret = create_pending_snapshot(trans, fs_info, pending);
747                 BUG_ON(ret);
748                 list_del(&pending->list);
749                 kfree(pending->name);
750                 kfree(pending);
751         }
752         return 0;
753 }
754
755 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
756                              struct btrfs_root *root)
757 {
758         unsigned long joined = 0;
759         unsigned long timeout = 1;
760         struct btrfs_transaction *cur_trans;
761         struct btrfs_transaction *prev_trans = NULL;
762         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
763         struct list_head dirty_fs_roots;
764         struct extent_io_tree *pinned_copy;
765         DEFINE_WAIT(wait);
766         int ret;
767
768         INIT_LIST_HEAD(&dirty_fs_roots);
769         mutex_lock(&root->fs_info->trans_mutex);
770         if (trans->transaction->in_commit) {
771                 cur_trans = trans->transaction;
772                 trans->transaction->use_count++;
773                 mutex_unlock(&root->fs_info->trans_mutex);
774                 btrfs_end_transaction(trans, root);
775
776                 ret = wait_for_commit(root, cur_trans);
777                 BUG_ON(ret);
778
779                 mutex_lock(&root->fs_info->trans_mutex);
780                 put_transaction(cur_trans);
781                 mutex_unlock(&root->fs_info->trans_mutex);
782
783                 return 0;
784         }
785
786         pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
787         if (!pinned_copy)
788                 return -ENOMEM;
789
790         extent_io_tree_init(pinned_copy,
791                              root->fs_info->btree_inode->i_mapping, GFP_NOFS);
792
793         trans->transaction->in_commit = 1;
794         trans->transaction->blocked = 1;
795         cur_trans = trans->transaction;
796         if (cur_trans->list.prev != &root->fs_info->trans_list) {
797                 prev_trans = list_entry(cur_trans->list.prev,
798                                         struct btrfs_transaction, list);
799                 if (!prev_trans->commit_done) {
800                         prev_trans->use_count++;
801                         mutex_unlock(&root->fs_info->trans_mutex);
802
803                         wait_for_commit(root, prev_trans);
804
805                         mutex_lock(&root->fs_info->trans_mutex);
806                         put_transaction(prev_trans);
807                 }
808         }
809
810         do {
811                 int snap_pending = 0;
812                 joined = cur_trans->num_joined;
813                 if (!list_empty(&trans->transaction->pending_snapshots))
814                         snap_pending = 1;
815
816                 WARN_ON(cur_trans != trans->transaction);
817                 prepare_to_wait(&cur_trans->writer_wait, &wait,
818                                 TASK_UNINTERRUPTIBLE);
819
820                 if (cur_trans->num_writers > 1)
821                         timeout = MAX_SCHEDULE_TIMEOUT;
822                 else
823                         timeout = 1;
824
825                 mutex_unlock(&root->fs_info->trans_mutex);
826
827                 if (snap_pending) {
828                         ret = btrfs_wait_ordered_extents(root, 1);
829                         BUG_ON(ret);
830                 }
831
832                 schedule_timeout(timeout);
833
834                 mutex_lock(&root->fs_info->trans_mutex);
835                 finish_wait(&cur_trans->writer_wait, &wait);
836         } while (cur_trans->num_writers > 1 ||
837                  (cur_trans->num_joined != joined));
838
839         ret = create_pending_snapshots(trans, root->fs_info);
840         BUG_ON(ret);
841
842         WARN_ON(cur_trans != trans->transaction);
843
844         /* btrfs_commit_tree_roots is responsible for getting the
845          * various roots consistent with each other.  Every pointer
846          * in the tree of tree roots has to point to the most up to date
847          * root for every subvolume and other tree.  So, we have to keep
848          * the tree logging code from jumping in and changing any
849          * of the trees.
850          *
851          * At this point in the commit, there can't be any tree-log
852          * writers, but a little lower down we drop the trans mutex
853          * and let new people in.  By holding the tree_log_mutex
854          * from now until after the super is written, we avoid races
855          * with the tree-log code.
856          */
857         mutex_lock(&root->fs_info->tree_log_mutex);
858
859         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
860                               &dirty_fs_roots);
861         BUG_ON(ret);
862
863         /* add_dirty_roots gets rid of all the tree log roots, it is now
864          * safe to free the root of tree log roots
865          */
866         btrfs_free_log_root_tree(trans, root->fs_info);
867
868         ret = btrfs_commit_tree_roots(trans, root);
869         BUG_ON(ret);
870
871         cur_trans = root->fs_info->running_transaction;
872         spin_lock(&root->fs_info->new_trans_lock);
873         root->fs_info->running_transaction = NULL;
874         spin_unlock(&root->fs_info->new_trans_lock);
875         btrfs_set_super_generation(&root->fs_info->super_copy,
876                                    cur_trans->transid);
877         btrfs_set_super_root(&root->fs_info->super_copy,
878                              root->fs_info->tree_root->node->start);
879         btrfs_set_super_root_level(&root->fs_info->super_copy,
880                            btrfs_header_level(root->fs_info->tree_root->node));
881
882         btrfs_set_super_chunk_root(&root->fs_info->super_copy,
883                                    chunk_root->node->start);
884         btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
885                                          btrfs_header_level(chunk_root->node));
886
887         if (!root->fs_info->log_root_recovering) {
888                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
889                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
890         }
891
892         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
893                sizeof(root->fs_info->super_copy));
894
895         btrfs_copy_pinned(root, pinned_copy);
896
897         trans->transaction->blocked = 0;
898         wake_up(&root->fs_info->transaction_throttle);
899         wake_up(&root->fs_info->transaction_wait);
900
901         mutex_unlock(&root->fs_info->trans_mutex);
902         ret = btrfs_write_and_wait_transaction(trans, root);
903         BUG_ON(ret);
904         write_ctree_super(trans, root);
905
906         /*
907          * the super is written, we can safely allow the tree-loggers
908          * to go about their business
909          */
910         mutex_unlock(&root->fs_info->tree_log_mutex);
911
912         btrfs_finish_extent_commit(trans, root, pinned_copy);
913         mutex_lock(&root->fs_info->trans_mutex);
914
915         kfree(pinned_copy);
916
917         cur_trans->commit_done = 1;
918         root->fs_info->last_trans_committed = cur_trans->transid;
919         wake_up(&cur_trans->commit_wait);
920         put_transaction(cur_trans);
921         put_transaction(cur_trans);
922
923         list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
924         if (root->fs_info->closing)
925                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
926
927         mutex_unlock(&root->fs_info->trans_mutex);
928         kmem_cache_free(btrfs_trans_handle_cachep, trans);
929
930         if (root->fs_info->closing) {
931                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
932         }
933         return ret;
934 }
935
936 int btrfs_clean_old_snapshots(struct btrfs_root *root)
937 {
938         struct list_head dirty_roots;
939         INIT_LIST_HEAD(&dirty_roots);
940 again:
941         mutex_lock(&root->fs_info->trans_mutex);
942         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
943         mutex_unlock(&root->fs_info->trans_mutex);
944
945         if (!list_empty(&dirty_roots)) {
946                 drop_dirty_roots(root, &dirty_roots);
947                 goto again;
948         }
949         return 0;
950 }