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 <linux/blkdev.h>
24 #include "ctree.h"
25 #include "disk-io.h"
26 #include "transaction.h"
27 #include "locking.h"
28 #include "ref-cache.h"
29 #include "tree-log.h"
30
31 #define BTRFS_ROOT_TRANS_TAG 0
32
put_transaction(struct btrfs_transaction * transaction)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 /*
45 * either allocate a new transaction or hop into the existing one
46 */
join_transaction(struct btrfs_root * root)47 static noinline int join_transaction(struct btrfs_root *root)
48 {
49 struct btrfs_transaction *cur_trans;
50 cur_trans = root->fs_info->running_transaction;
51 if (!cur_trans) {
52 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
53 GFP_NOFS);
54 BUG_ON(!cur_trans);
55 root->fs_info->generation++;
56 root->fs_info->last_alloc = 0;
57 root->fs_info->last_data_alloc = 0;
58 cur_trans->num_writers = 1;
59 cur_trans->num_joined = 0;
60 cur_trans->transid = root->fs_info->generation;
61 init_waitqueue_head(&cur_trans->writer_wait);
62 init_waitqueue_head(&cur_trans->commit_wait);
63 cur_trans->in_commit = 0;
64 cur_trans->blocked = 0;
65 cur_trans->use_count = 1;
66 cur_trans->commit_done = 0;
67 cur_trans->start_time = get_seconds();
68 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
69 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
70 extent_io_tree_init(&cur_trans->dirty_pages,
71 root->fs_info->btree_inode->i_mapping,
72 GFP_NOFS);
73 spin_lock(&root->fs_info->new_trans_lock);
74 root->fs_info->running_transaction = cur_trans;
75 spin_unlock(&root->fs_info->new_trans_lock);
76 } else {
77 cur_trans->num_writers++;
78 cur_trans->num_joined++;
79 }
80
81 return 0;
82 }
83
84 /*
85 * this does all the record keeping required to make sure that a reference
86 * counted root is properly recorded in a given transaction. This is required
87 * to make sure the old root from before we joined the transaction is deleted
88 * when the transaction commits
89 */
btrfs_record_root_in_trans(struct btrfs_root * root)90 noinline int btrfs_record_root_in_trans(struct btrfs_root *root)
91 {
92 struct btrfs_dirty_root *dirty;
93 u64 running_trans_id = root->fs_info->running_transaction->transid;
94 if (root->ref_cows && root->last_trans < running_trans_id) {
95 WARN_ON(root == root->fs_info->extent_root);
96 if (root->root_item.refs != 0) {
97 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
98 (unsigned long)root->root_key.objectid,
99 BTRFS_ROOT_TRANS_TAG);
100
101 dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
102 BUG_ON(!dirty);
103 dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
104 BUG_ON(!dirty->root);
105 dirty->latest_root = root;
106 INIT_LIST_HEAD(&dirty->list);
107
108 root->commit_root = btrfs_root_node(root);
109
110 memcpy(dirty->root, root, sizeof(*root));
111 spin_lock_init(&dirty->root->node_lock);
112 spin_lock_init(&dirty->root->list_lock);
113 mutex_init(&dirty->root->objectid_mutex);
114 mutex_init(&dirty->root->log_mutex);
115 INIT_LIST_HEAD(&dirty->root->dead_list);
116 dirty->root->node = root->commit_root;
117 dirty->root->commit_root = NULL;
118
119 spin_lock(&root->list_lock);
120 list_add(&dirty->root->dead_list, &root->dead_list);
121 spin_unlock(&root->list_lock);
122
123 root->dirty_root = dirty;
124 } else {
125 WARN_ON(1);
126 }
127 root->last_trans = running_trans_id;
128 }
129 return 0;
130 }
131
132 /* wait for commit against the current transaction to become unblocked
133 * when this is done, it is safe to start a new transaction, but the current
134 * transaction might not be fully on disk.
135 */
wait_current_trans(struct btrfs_root * root)136 static void wait_current_trans(struct btrfs_root *root)
137 {
138 struct btrfs_transaction *cur_trans;
139
140 cur_trans = root->fs_info->running_transaction;
141 if (cur_trans && cur_trans->blocked) {
142 DEFINE_WAIT(wait);
143 cur_trans->use_count++;
144 while (1) {
145 prepare_to_wait(&root->fs_info->transaction_wait, &wait,
146 TASK_UNINTERRUPTIBLE);
147 if (cur_trans->blocked) {
148 mutex_unlock(&root->fs_info->trans_mutex);
149 schedule();
150 mutex_lock(&root->fs_info->trans_mutex);
151 finish_wait(&root->fs_info->transaction_wait,
152 &wait);
153 } else {
154 finish_wait(&root->fs_info->transaction_wait,
155 &wait);
156 break;
157 }
158 }
159 put_transaction(cur_trans);
160 }
161 }
162
start_transaction(struct btrfs_root * root,int num_blocks,int wait)163 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
164 int num_blocks, int wait)
165 {
166 struct btrfs_trans_handle *h =
167 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
168 int ret;
169
170 mutex_lock(&root->fs_info->trans_mutex);
171 if (!root->fs_info->log_root_recovering &&
172 ((wait == 1 && !root->fs_info->open_ioctl_trans) || wait == 2))
173 wait_current_trans(root);
174 ret = join_transaction(root);
175 BUG_ON(ret);
176
177 btrfs_record_root_in_trans(root);
178 h->transid = root->fs_info->running_transaction->transid;
179 h->transaction = root->fs_info->running_transaction;
180 h->blocks_reserved = num_blocks;
181 h->blocks_used = 0;
182 h->block_group = 0;
183 h->alloc_exclude_nr = 0;
184 h->alloc_exclude_start = 0;
185 root->fs_info->running_transaction->use_count++;
186 mutex_unlock(&root->fs_info->trans_mutex);
187 return h;
188 }
189
btrfs_start_transaction(struct btrfs_root * root,int num_blocks)190 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
191 int num_blocks)
192 {
193 return start_transaction(root, num_blocks, 1);
194 }
btrfs_join_transaction(struct btrfs_root * root,int num_blocks)195 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
196 int num_blocks)
197 {
198 return start_transaction(root, num_blocks, 0);
199 }
200
btrfs_start_ioctl_transaction(struct btrfs_root * r,int num_blocks)201 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
202 int num_blocks)
203 {
204 return start_transaction(r, num_blocks, 2);
205 }
206
207 /* wait for a transaction commit to be fully complete */
wait_for_commit(struct btrfs_root * root,struct btrfs_transaction * commit)208 static noinline int wait_for_commit(struct btrfs_root *root,
209 struct btrfs_transaction *commit)
210 {
211 DEFINE_WAIT(wait);
212 mutex_lock(&root->fs_info->trans_mutex);
213 while (!commit->commit_done) {
214 prepare_to_wait(&commit->commit_wait, &wait,
215 TASK_UNINTERRUPTIBLE);
216 if (commit->commit_done)
217 break;
218 mutex_unlock(&root->fs_info->trans_mutex);
219 schedule();
220 mutex_lock(&root->fs_info->trans_mutex);
221 }
222 mutex_unlock(&root->fs_info->trans_mutex);
223 finish_wait(&commit->commit_wait, &wait);
224 return 0;
225 }
226
227 /*
228 * rate limit against the drop_snapshot code. This helps to slow down new
229 * operations if the drop_snapshot code isn't able to keep up.
230 */
throttle_on_drops(struct btrfs_root * root)231 static void throttle_on_drops(struct btrfs_root *root)
232 {
233 struct btrfs_fs_info *info = root->fs_info;
234 int harder_count = 0;
235
236 harder:
237 if (atomic_read(&info->throttles)) {
238 DEFINE_WAIT(wait);
239 int thr;
240 thr = atomic_read(&info->throttle_gen);
241
242 do {
243 prepare_to_wait(&info->transaction_throttle,
244 &wait, TASK_UNINTERRUPTIBLE);
245 if (!atomic_read(&info->throttles)) {
246 finish_wait(&info->transaction_throttle, &wait);
247 break;
248 }
249 schedule();
250 finish_wait(&info->transaction_throttle, &wait);
251 } while (thr == atomic_read(&info->throttle_gen));
252 harder_count++;
253
254 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
255 harder_count < 2)
256 goto harder;
257
258 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
259 harder_count < 10)
260 goto harder;
261
262 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
263 harder_count < 20)
264 goto harder;
265 }
266 }
267
btrfs_throttle(struct btrfs_root * root)268 void btrfs_throttle(struct btrfs_root *root)
269 {
270 mutex_lock(&root->fs_info->trans_mutex);
271 if (!root->fs_info->open_ioctl_trans)
272 wait_current_trans(root);
273 mutex_unlock(&root->fs_info->trans_mutex);
274
275 throttle_on_drops(root);
276 }
277
__btrfs_end_transaction(struct btrfs_trans_handle * trans,struct btrfs_root * root,int throttle)278 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
279 struct btrfs_root *root, int throttle)
280 {
281 struct btrfs_transaction *cur_trans;
282 struct btrfs_fs_info *info = root->fs_info;
283
284 mutex_lock(&info->trans_mutex);
285 cur_trans = info->running_transaction;
286 WARN_ON(cur_trans != trans->transaction);
287 WARN_ON(cur_trans->num_writers < 1);
288 cur_trans->num_writers--;
289
290 if (waitqueue_active(&cur_trans->writer_wait))
291 wake_up(&cur_trans->writer_wait);
292 put_transaction(cur_trans);
293 mutex_unlock(&info->trans_mutex);
294 memset(trans, 0, sizeof(*trans));
295 kmem_cache_free(btrfs_trans_handle_cachep, trans);
296
297 if (throttle)
298 throttle_on_drops(root);
299
300 return 0;
301 }
302
btrfs_end_transaction(struct btrfs_trans_handle * trans,struct btrfs_root * root)303 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
304 struct btrfs_root *root)
305 {
306 return __btrfs_end_transaction(trans, root, 0);
307 }
308
btrfs_end_transaction_throttle(struct btrfs_trans_handle * trans,struct btrfs_root * root)309 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
310 struct btrfs_root *root)
311 {
312 return __btrfs_end_transaction(trans, root, 1);
313 }
314
315 /*
316 * when btree blocks are allocated, they have some corresponding bits set for
317 * them in one of two extent_io trees. This is used to make sure all of
318 * those extents are on disk for transaction or log commit
319 */
btrfs_write_and_wait_marked_extents(struct btrfs_root * root,struct extent_io_tree * dirty_pages)320 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
321 struct extent_io_tree *dirty_pages)
322 {
323 int ret;
324 int err = 0;
325 int werr = 0;
326 struct page *page;
327 struct inode *btree_inode = root->fs_info->btree_inode;
328 u64 start = 0;
329 u64 end;
330 unsigned long index;
331
332 while (1) {
333 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
334 EXTENT_DIRTY);
335 if (ret)
336 break;
337 while (start <= end) {
338 cond_resched();
339
340 index = start >> PAGE_CACHE_SHIFT;
341 start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
342 page = find_get_page(btree_inode->i_mapping, index);
343 if (!page)
344 continue;
345
346 btree_lock_page_hook(page);
347 if (!page->mapping) {
348 unlock_page(page);
349 page_cache_release(page);
350 continue;
351 }
352
353 if (PageWriteback(page)) {
354 if (PageDirty(page))
355 wait_on_page_writeback(page);
356 else {
357 unlock_page(page);
358 page_cache_release(page);
359 continue;
360 }
361 }
362 err = write_one_page(page, 0);
363 if (err)
364 werr = err;
365 page_cache_release(page);
366 }
367 }
368 while (1) {
369 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
370 EXTENT_DIRTY);
371 if (ret)
372 break;
373
374 clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
375 while (start <= end) {
376 index = start >> PAGE_CACHE_SHIFT;
377 start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
378 page = find_get_page(btree_inode->i_mapping, index);
379 if (!page)
380 continue;
381 if (PageDirty(page)) {
382 btree_lock_page_hook(page);
383 wait_on_page_writeback(page);
384 err = write_one_page(page, 0);
385 if (err)
386 werr = err;
387 }
388 wait_on_page_writeback(page);
389 page_cache_release(page);
390 cond_resched();
391 }
392 }
393 if (err)
394 werr = err;
395 return werr;
396 }
397
btrfs_write_and_wait_transaction(struct btrfs_trans_handle * trans,struct btrfs_root * root)398 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
399 struct btrfs_root *root)
400 {
401 if (!trans || !trans->transaction) {
402 struct inode *btree_inode;
403 btree_inode = root->fs_info->btree_inode;
404 return filemap_write_and_wait(btree_inode->i_mapping);
405 }
406 return btrfs_write_and_wait_marked_extents(root,
407 &trans->transaction->dirty_pages);
408 }
409
410 /*
411 * this is used to update the root pointer in the tree of tree roots.
412 *
413 * But, in the case of the extent allocation tree, updating the root
414 * pointer may allocate blocks which may change the root of the extent
415 * allocation tree.
416 *
417 * So, this loops and repeats and makes sure the cowonly root didn't
418 * change while the root pointer was being updated in the metadata.
419 */
update_cowonly_root(struct btrfs_trans_handle * trans,struct btrfs_root * root)420 static int update_cowonly_root(struct btrfs_trans_handle *trans,
421 struct btrfs_root *root)
422 {
423 int ret;
424 u64 old_root_bytenr;
425 struct btrfs_root *tree_root = root->fs_info->tree_root;
426
427 btrfs_extent_post_op(trans, root);
428 btrfs_write_dirty_block_groups(trans, root);
429 btrfs_extent_post_op(trans, root);
430
431 while (1) {
432 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
433 if (old_root_bytenr == root->node->start)
434 break;
435 btrfs_set_root_bytenr(&root->root_item,
436 root->node->start);
437 btrfs_set_root_level(&root->root_item,
438 btrfs_header_level(root->node));
439 btrfs_set_root_generation(&root->root_item, trans->transid);
440
441 btrfs_extent_post_op(trans, root);
442
443 ret = btrfs_update_root(trans, tree_root,
444 &root->root_key,
445 &root->root_item);
446 BUG_ON(ret);
447 btrfs_write_dirty_block_groups(trans, root);
448 btrfs_extent_post_op(trans, root);
449 }
450 return 0;
451 }
452
453 /*
454 * update all the cowonly tree roots on disk
455 */
btrfs_commit_tree_roots(struct btrfs_trans_handle * trans,struct btrfs_root * root)456 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
457 struct btrfs_root *root)
458 {
459 struct btrfs_fs_info *fs_info = root->fs_info;
460 struct list_head *next;
461 struct extent_buffer *eb;
462
463 btrfs_extent_post_op(trans, fs_info->tree_root);
464
465 eb = btrfs_lock_root_node(fs_info->tree_root);
466 btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, 0);
467 btrfs_tree_unlock(eb);
468 free_extent_buffer(eb);
469
470 btrfs_extent_post_op(trans, fs_info->tree_root);
471
472 while (!list_empty(&fs_info->dirty_cowonly_roots)) {
473 next = fs_info->dirty_cowonly_roots.next;
474 list_del_init(next);
475 root = list_entry(next, struct btrfs_root, dirty_list);
476
477 update_cowonly_root(trans, root);
478 }
479 return 0;
480 }
481
482 /*
483 * dead roots are old snapshots that need to be deleted. This allocates
484 * a dirty root struct and adds it into the list of dead roots that need to
485 * be deleted
486 */
btrfs_add_dead_root(struct btrfs_root * root,struct btrfs_root * latest)487 int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest)
488 {
489 struct btrfs_dirty_root *dirty;
490
491 dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
492 if (!dirty)
493 return -ENOMEM;
494 dirty->root = root;
495 dirty->latest_root = latest;
496
497 mutex_lock(&root->fs_info->trans_mutex);
498 list_add(&dirty->list, &latest->fs_info->dead_roots);
499 mutex_unlock(&root->fs_info->trans_mutex);
500 return 0;
501 }
502
503 /*
504 * at transaction commit time we need to schedule the old roots for
505 * deletion via btrfs_drop_snapshot. This runs through all the
506 * reference counted roots that were modified in the current
507 * transaction and puts them into the drop list
508 */
add_dirty_roots(struct btrfs_trans_handle * trans,struct radix_tree_root * radix,struct list_head * list)509 static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
510 struct radix_tree_root *radix,
511 struct list_head *list)
512 {
513 struct btrfs_dirty_root *dirty;
514 struct btrfs_root *gang[8];
515 struct btrfs_root *root;
516 int i;
517 int ret;
518 int err = 0;
519 u32 refs;
520
521 while (1) {
522 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
523 ARRAY_SIZE(gang),
524 BTRFS_ROOT_TRANS_TAG);
525 if (ret == 0)
526 break;
527 for (i = 0; i < ret; i++) {
528 root = gang[i];
529 radix_tree_tag_clear(radix,
530 (unsigned long)root->root_key.objectid,
531 BTRFS_ROOT_TRANS_TAG);
532
533 BUG_ON(!root->ref_tree);
534 dirty = root->dirty_root;
535
536 btrfs_free_log(trans, root);
537 btrfs_free_reloc_root(trans, root);
538
539 if (root->commit_root == root->node) {
540 WARN_ON(root->node->start !=
541 btrfs_root_bytenr(&root->root_item));
542
543 free_extent_buffer(root->commit_root);
544 root->commit_root = NULL;
545 root->dirty_root = NULL;
546
547 spin_lock(&root->list_lock);
548 list_del_init(&dirty->root->dead_list);
549 spin_unlock(&root->list_lock);
550
551 kfree(dirty->root);
552 kfree(dirty);
553
554 /* make sure to update the root on disk
555 * so we get any updates to the block used
556 * counts
557 */
558 err = btrfs_update_root(trans,
559 root->fs_info->tree_root,
560 &root->root_key,
561 &root->root_item);
562 continue;
563 }
564
565 memset(&root->root_item.drop_progress, 0,
566 sizeof(struct btrfs_disk_key));
567 root->root_item.drop_level = 0;
568 root->commit_root = NULL;
569 root->dirty_root = NULL;
570 root->root_key.offset = root->fs_info->generation;
571 btrfs_set_root_bytenr(&root->root_item,
572 root->node->start);
573 btrfs_set_root_level(&root->root_item,
574 btrfs_header_level(root->node));
575 btrfs_set_root_generation(&root->root_item,
576 root->root_key.offset);
577
578 err = btrfs_insert_root(trans, root->fs_info->tree_root,
579 &root->root_key,
580 &root->root_item);
581 if (err)
582 break;
583
584 refs = btrfs_root_refs(&dirty->root->root_item);
585 btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
586 err = btrfs_update_root(trans, root->fs_info->tree_root,
587 &dirty->root->root_key,
588 &dirty->root->root_item);
589
590 BUG_ON(err);
591 if (refs == 1) {
592 list_add(&dirty->list, list);
593 } else {
594 WARN_ON(1);
595 free_extent_buffer(dirty->root->node);
596 kfree(dirty->root);
597 kfree(dirty);
598 }
599 }
600 }
601 return err;
602 }
603
604 /*
605 * defrag a given btree. If cacheonly == 1, this won't read from the disk,
606 * otherwise every leaf in the btree is read and defragged.
607 */
btrfs_defrag_root(struct btrfs_root * root,int cacheonly)608 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
609 {
610 struct btrfs_fs_info *info = root->fs_info;
611 int ret;
612 struct btrfs_trans_handle *trans;
613 unsigned long nr;
614
615 smp_mb();
616 if (root->defrag_running)
617 return 0;
618 trans = btrfs_start_transaction(root, 1);
619 while (1) {
620 root->defrag_running = 1;
621 ret = btrfs_defrag_leaves(trans, root, cacheonly);
622 nr = trans->blocks_used;
623 btrfs_end_transaction(trans, root);
624 btrfs_btree_balance_dirty(info->tree_root, nr);
625 cond_resched();
626
627 trans = btrfs_start_transaction(root, 1);
628 if (root->fs_info->closing || ret != -EAGAIN)
629 break;
630 }
631 root->defrag_running = 0;
632 smp_mb();
633 btrfs_end_transaction(trans, root);
634 return 0;
635 }
636
637 /*
638 * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
639 * all of them
640 */
drop_dirty_roots(struct btrfs_root * tree_root,struct list_head * list)641 static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
642 struct list_head *list)
643 {
644 struct btrfs_dirty_root *dirty;
645 struct btrfs_trans_handle *trans;
646 unsigned long nr;
647 u64 num_bytes;
648 u64 bytes_used;
649 u64 max_useless;
650 int ret = 0;
651 int err;
652
653 while (!list_empty(list)) {
654 struct btrfs_root *root;
655
656 dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
657 list_del_init(&dirty->list);
658
659 num_bytes = btrfs_root_used(&dirty->root->root_item);
660 root = dirty->latest_root;
661 atomic_inc(&root->fs_info->throttles);
662
663 while (1) {
664 trans = btrfs_start_transaction(tree_root, 1);
665 mutex_lock(&root->fs_info->drop_mutex);
666 ret = btrfs_drop_snapshot(trans, dirty->root);
667 if (ret != -EAGAIN)
668 break;
669 mutex_unlock(&root->fs_info->drop_mutex);
670
671 err = btrfs_update_root(trans,
672 tree_root,
673 &dirty->root->root_key,
674 &dirty->root->root_item);
675 if (err)
676 ret = err;
677 nr = trans->blocks_used;
678 ret = btrfs_end_transaction(trans, tree_root);
679 BUG_ON(ret);
680
681 btrfs_btree_balance_dirty(tree_root, nr);
682 cond_resched();
683 }
684 BUG_ON(ret);
685 atomic_dec(&root->fs_info->throttles);
686 wake_up(&root->fs_info->transaction_throttle);
687
688 num_bytes -= btrfs_root_used(&dirty->root->root_item);
689 bytes_used = btrfs_root_used(&root->root_item);
690 if (num_bytes) {
691 mutex_lock(&root->fs_info->trans_mutex);
692 btrfs_record_root_in_trans(root);
693 mutex_unlock(&root->fs_info->trans_mutex);
694 btrfs_set_root_used(&root->root_item,
695 bytes_used - num_bytes);
696 }
697
698 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
699 if (ret) {
700 BUG();
701 break;
702 }
703 mutex_unlock(&root->fs_info->drop_mutex);
704
705 spin_lock(&root->list_lock);
706 list_del_init(&dirty->root->dead_list);
707 if (!list_empty(&root->dead_list)) {
708 struct btrfs_root *oldest;
709 oldest = list_entry(root->dead_list.prev,
710 struct btrfs_root, dead_list);
711 max_useless = oldest->root_key.offset - 1;
712 } else {
713 max_useless = root->root_key.offset - 1;
714 }
715 spin_unlock(&root->list_lock);
716
717 nr = trans->blocks_used;
718 ret = btrfs_end_transaction(trans, tree_root);
719 BUG_ON(ret);
720
721 ret = btrfs_remove_leaf_refs(root, max_useless, 0);
722 BUG_ON(ret);
723
724 free_extent_buffer(dirty->root->node);
725 kfree(dirty->root);
726 kfree(dirty);
727
728 btrfs_btree_balance_dirty(tree_root, nr);
729 cond_resched();
730 }
731 return ret;
732 }
733
734 /*
735 * new snapshots need to be created at a very specific time in the
736 * transaction commit. This does the actual creation
737 */
create_pending_snapshot(struct btrfs_trans_handle * trans,struct btrfs_fs_info * fs_info,struct btrfs_pending_snapshot * pending)738 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
739 struct btrfs_fs_info *fs_info,
740 struct btrfs_pending_snapshot *pending)
741 {
742 struct btrfs_key key;
743 struct btrfs_root_item *new_root_item;
744 struct btrfs_root *tree_root = fs_info->tree_root;
745 struct btrfs_root *root = pending->root;
746 struct extent_buffer *tmp;
747 struct extent_buffer *old;
748 int ret;
749 u64 objectid;
750
751 new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
752 if (!new_root_item) {
753 ret = -ENOMEM;
754 goto fail;
755 }
756 ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
757 if (ret)
758 goto fail;
759
760 btrfs_record_root_in_trans(root);
761 btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
762 memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
763
764 key.objectid = objectid;
765 key.offset = trans->transid;
766 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
767
768 old = btrfs_lock_root_node(root);
769 btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
770
771 btrfs_copy_root(trans, root, old, &tmp, objectid);
772 btrfs_tree_unlock(old);
773 free_extent_buffer(old);
774
775 btrfs_set_root_bytenr(new_root_item, tmp->start);
776 btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
777 btrfs_set_root_generation(new_root_item, trans->transid);
778 ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
779 new_root_item);
780 btrfs_tree_unlock(tmp);
781 free_extent_buffer(tmp);
782 if (ret)
783 goto fail;
784
785 key.offset = (u64)-1;
786 memcpy(&pending->root_key, &key, sizeof(key));
787 fail:
788 kfree(new_root_item);
789 return ret;
790 }
791
finish_pending_snapshot(struct btrfs_fs_info * fs_info,struct btrfs_pending_snapshot * pending)792 static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info,
793 struct btrfs_pending_snapshot *pending)
794 {
795 int ret;
796 int namelen;
797 u64 index = 0;
798 struct btrfs_trans_handle *trans;
799 struct inode *parent_inode;
800 struct inode *inode;
801 struct btrfs_root *parent_root;
802
803 parent_inode = pending->dentry->d_parent->d_inode;
804 parent_root = BTRFS_I(parent_inode)->root;
805 trans = btrfs_join_transaction(parent_root, 1);
806
807 /*
808 * insert the directory item
809 */
810 namelen = strlen(pending->name);
811 ret = btrfs_set_inode_index(parent_inode, &index);
812 ret = btrfs_insert_dir_item(trans, parent_root,
813 pending->name, namelen,
814 parent_inode->i_ino,
815 &pending->root_key, BTRFS_FT_DIR, index);
816
817 if (ret)
818 goto fail;
819
820 btrfs_i_size_write(parent_inode, parent_inode->i_size + namelen * 2);
821 ret = btrfs_update_inode(trans, parent_root, parent_inode);
822 BUG_ON(ret);
823
824 /* add the backref first */
825 ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
826 pending->root_key.objectid,
827 BTRFS_ROOT_BACKREF_KEY,
828 parent_root->root_key.objectid,
829 parent_inode->i_ino, index, pending->name,
830 namelen);
831
832 BUG_ON(ret);
833
834 /* now add the forward ref */
835 ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
836 parent_root->root_key.objectid,
837 BTRFS_ROOT_REF_KEY,
838 pending->root_key.objectid,
839 parent_inode->i_ino, index, pending->name,
840 namelen);
841
842 inode = btrfs_lookup_dentry(parent_inode, pending->dentry);
843 d_instantiate(pending->dentry, inode);
844 fail:
845 btrfs_end_transaction(trans, fs_info->fs_root);
846 return ret;
847 }
848
849 /*
850 * create all the snapshots we've scheduled for creation
851 */
create_pending_snapshots(struct btrfs_trans_handle * trans,struct btrfs_fs_info * fs_info)852 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
853 struct btrfs_fs_info *fs_info)
854 {
855 struct btrfs_pending_snapshot *pending;
856 struct list_head *head = &trans->transaction->pending_snapshots;
857 int ret;
858
859 list_for_each_entry(pending, head, list) {
860 ret = create_pending_snapshot(trans, fs_info, pending);
861 BUG_ON(ret);
862 }
863 return 0;
864 }
865
finish_pending_snapshots(struct btrfs_trans_handle * trans,struct btrfs_fs_info * fs_info)866 static noinline int finish_pending_snapshots(struct btrfs_trans_handle *trans,
867 struct btrfs_fs_info *fs_info)
868 {
869 struct btrfs_pending_snapshot *pending;
870 struct list_head *head = &trans->transaction->pending_snapshots;
871 int ret;
872
873 while (!list_empty(head)) {
874 pending = list_entry(head->next,
875 struct btrfs_pending_snapshot, list);
876 ret = finish_pending_snapshot(fs_info, pending);
877 BUG_ON(ret);
878 list_del(&pending->list);
879 kfree(pending->name);
880 kfree(pending);
881 }
882 return 0;
883 }
884
btrfs_commit_transaction(struct btrfs_trans_handle * trans,struct btrfs_root * root)885 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
886 struct btrfs_root *root)
887 {
888 unsigned long joined = 0;
889 unsigned long timeout = 1;
890 struct btrfs_transaction *cur_trans;
891 struct btrfs_transaction *prev_trans = NULL;
892 struct btrfs_root *chunk_root = root->fs_info->chunk_root;
893 struct list_head dirty_fs_roots;
894 struct extent_io_tree *pinned_copy;
895 DEFINE_WAIT(wait);
896 int ret;
897
898 INIT_LIST_HEAD(&dirty_fs_roots);
899 mutex_lock(&root->fs_info->trans_mutex);
900 if (trans->transaction->in_commit) {
901 cur_trans = trans->transaction;
902 trans->transaction->use_count++;
903 mutex_unlock(&root->fs_info->trans_mutex);
904 btrfs_end_transaction(trans, root);
905
906 ret = wait_for_commit(root, cur_trans);
907 BUG_ON(ret);
908
909 mutex_lock(&root->fs_info->trans_mutex);
910 put_transaction(cur_trans);
911 mutex_unlock(&root->fs_info->trans_mutex);
912
913 return 0;
914 }
915
916 pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
917 if (!pinned_copy)
918 return -ENOMEM;
919
920 extent_io_tree_init(pinned_copy,
921 root->fs_info->btree_inode->i_mapping, GFP_NOFS);
922
923 trans->transaction->in_commit = 1;
924 trans->transaction->blocked = 1;
925 cur_trans = trans->transaction;
926 if (cur_trans->list.prev != &root->fs_info->trans_list) {
927 prev_trans = list_entry(cur_trans->list.prev,
928 struct btrfs_transaction, list);
929 if (!prev_trans->commit_done) {
930 prev_trans->use_count++;
931 mutex_unlock(&root->fs_info->trans_mutex);
932
933 wait_for_commit(root, prev_trans);
934
935 mutex_lock(&root->fs_info->trans_mutex);
936 put_transaction(prev_trans);
937 }
938 }
939
940 do {
941 int snap_pending = 0;
942 joined = cur_trans->num_joined;
943 if (!list_empty(&trans->transaction->pending_snapshots))
944 snap_pending = 1;
945
946 WARN_ON(cur_trans != trans->transaction);
947 prepare_to_wait(&cur_trans->writer_wait, &wait,
948 TASK_UNINTERRUPTIBLE);
949
950 if (cur_trans->num_writers > 1)
951 timeout = MAX_SCHEDULE_TIMEOUT;
952 else
953 timeout = 1;
954
955 mutex_unlock(&root->fs_info->trans_mutex);
956
957 if (snap_pending) {
958 ret = btrfs_wait_ordered_extents(root, 1);
959 BUG_ON(ret);
960 }
961
962 schedule_timeout(timeout);
963
964 mutex_lock(&root->fs_info->trans_mutex);
965 finish_wait(&cur_trans->writer_wait, &wait);
966 } while (cur_trans->num_writers > 1 ||
967 (cur_trans->num_joined != joined));
968
969 ret = create_pending_snapshots(trans, root->fs_info);
970 BUG_ON(ret);
971
972 WARN_ON(cur_trans != trans->transaction);
973
974 /* btrfs_commit_tree_roots is responsible for getting the
975 * various roots consistent with each other. Every pointer
976 * in the tree of tree roots has to point to the most up to date
977 * root for every subvolume and other tree. So, we have to keep
978 * the tree logging code from jumping in and changing any
979 * of the trees.
980 *
981 * At this point in the commit, there can't be any tree-log
982 * writers, but a little lower down we drop the trans mutex
983 * and let new people in. By holding the tree_log_mutex
984 * from now until after the super is written, we avoid races
985 * with the tree-log code.
986 */
987 mutex_lock(&root->fs_info->tree_log_mutex);
988 /*
989 * keep tree reloc code from adding new reloc trees
990 */
991 mutex_lock(&root->fs_info->tree_reloc_mutex);
992
993
994 ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
995 &dirty_fs_roots);
996 BUG_ON(ret);
997
998 /* add_dirty_roots gets rid of all the tree log roots, it is now
999 * safe to free the root of tree log roots
1000 */
1001 btrfs_free_log_root_tree(trans, root->fs_info);
1002
1003 ret = btrfs_commit_tree_roots(trans, root);
1004 BUG_ON(ret);
1005
1006 cur_trans = root->fs_info->running_transaction;
1007 spin_lock(&root->fs_info->new_trans_lock);
1008 root->fs_info->running_transaction = NULL;
1009 spin_unlock(&root->fs_info->new_trans_lock);
1010 btrfs_set_super_generation(&root->fs_info->super_copy,
1011 cur_trans->transid);
1012 btrfs_set_super_root(&root->fs_info->super_copy,
1013 root->fs_info->tree_root->node->start);
1014 btrfs_set_super_root_level(&root->fs_info->super_copy,
1015 btrfs_header_level(root->fs_info->tree_root->node));
1016
1017 btrfs_set_super_chunk_root(&root->fs_info->super_copy,
1018 chunk_root->node->start);
1019 btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
1020 btrfs_header_level(chunk_root->node));
1021 btrfs_set_super_chunk_root_generation(&root->fs_info->super_copy,
1022 btrfs_header_generation(chunk_root->node));
1023
1024 if (!root->fs_info->log_root_recovering) {
1025 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1026 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1027 }
1028
1029 memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1030 sizeof(root->fs_info->super_copy));
1031
1032 btrfs_copy_pinned(root, pinned_copy);
1033
1034 trans->transaction->blocked = 0;
1035 wake_up(&root->fs_info->transaction_throttle);
1036 wake_up(&root->fs_info->transaction_wait);
1037
1038 mutex_unlock(&root->fs_info->trans_mutex);
1039 ret = btrfs_write_and_wait_transaction(trans, root);
1040 BUG_ON(ret);
1041 write_ctree_super(trans, root, 0);
1042
1043 /*
1044 * the super is written, we can safely allow the tree-loggers
1045 * to go about their business
1046 */
1047 mutex_unlock(&root->fs_info->tree_log_mutex);
1048
1049 btrfs_finish_extent_commit(trans, root, pinned_copy);
1050 kfree(pinned_copy);
1051
1052 btrfs_drop_dead_reloc_roots(root);
1053 mutex_unlock(&root->fs_info->tree_reloc_mutex);
1054
1055 /* do the directory inserts of any pending snapshot creations */
1056 finish_pending_snapshots(trans, root->fs_info);
1057
1058 mutex_lock(&root->fs_info->trans_mutex);
1059
1060 cur_trans->commit_done = 1;
1061 root->fs_info->last_trans_committed = cur_trans->transid;
1062 wake_up(&cur_trans->commit_wait);
1063
1064 put_transaction(cur_trans);
1065 put_transaction(cur_trans);
1066
1067 list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
1068 if (root->fs_info->closing)
1069 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
1070
1071 mutex_unlock(&root->fs_info->trans_mutex);
1072
1073 kmem_cache_free(btrfs_trans_handle_cachep, trans);
1074
1075 if (root->fs_info->closing)
1076 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
1077 return ret;
1078 }
1079
1080 /*
1081 * interface function to delete all the snapshots we have scheduled for deletion
1082 */
btrfs_clean_old_snapshots(struct btrfs_root * root)1083 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1084 {
1085 struct list_head dirty_roots;
1086 INIT_LIST_HEAD(&dirty_roots);
1087 again:
1088 mutex_lock(&root->fs_info->trans_mutex);
1089 list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
1090 mutex_unlock(&root->fs_info->trans_mutex);
1091
1092 if (!list_empty(&dirty_roots)) {
1093 drop_dirty_roots(root, &dirty_roots);
1094 goto again;
1095 }
1096 return 0;
1097 }
1098