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TOMOYO Linux Cross Reference
Linux/fs/btrfs/transaction.c

Version: ~ [ linux-5.1-rc1 ] ~ [ linux-5.0.3 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.30 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.107 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.164 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.176 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.136 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.63 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /*
  2  * Copyright (C) 2007 Oracle.  All rights reserved.
  3  *
  4  * This program is free software; you can redistribute it and/or
  5  * modify it under the terms of the GNU General Public
  6  * License v2 as published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 11  * General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public
 14  * License along with this program; if not, write to the
 15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 16  * Boston, MA 021110-1307, USA.
 17  */
 18 
 19 #include <linux/fs.h>
 20 #include <linux/slab.h>
 21 #include <linux/sched.h>
 22 #include <linux/writeback.h>
 23 #include <linux/pagemap.h>
 24 #include <linux/blkdev.h>
 25 #include <linux/uuid.h>
 26 #include "ctree.h"
 27 #include "disk-io.h"
 28 #include "transaction.h"
 29 #include "locking.h"
 30 #include "tree-log.h"
 31 #include "inode-map.h"
 32 #include "volumes.h"
 33 #include "dev-replace.h"
 34 #include "qgroup.h"
 35 
 36 #define BTRFS_ROOT_TRANS_TAG 0
 37 
 38 static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
 39         [TRANS_STATE_RUNNING]           = 0U,
 40         [TRANS_STATE_BLOCKED]           = (__TRANS_USERSPACE |
 41                                            __TRANS_START),
 42         [TRANS_STATE_COMMIT_START]      = (__TRANS_USERSPACE |
 43                                            __TRANS_START |
 44                                            __TRANS_ATTACH),
 45         [TRANS_STATE_COMMIT_DOING]      = (__TRANS_USERSPACE |
 46                                            __TRANS_START |
 47                                            __TRANS_ATTACH |
 48                                            __TRANS_JOIN),
 49         [TRANS_STATE_UNBLOCKED]         = (__TRANS_USERSPACE |
 50                                            __TRANS_START |
 51                                            __TRANS_ATTACH |
 52                                            __TRANS_JOIN |
 53                                            __TRANS_JOIN_NOLOCK),
 54         [TRANS_STATE_COMPLETED]         = (__TRANS_USERSPACE |
 55                                            __TRANS_START |
 56                                            __TRANS_ATTACH |
 57                                            __TRANS_JOIN |
 58                                            __TRANS_JOIN_NOLOCK),
 59 };
 60 
 61 void btrfs_put_transaction(struct btrfs_transaction *transaction)
 62 {
 63         WARN_ON(refcount_read(&transaction->use_count) == 0);
 64         if (refcount_dec_and_test(&transaction->use_count)) {
 65                 BUG_ON(!list_empty(&transaction->list));
 66                 WARN_ON(!RB_EMPTY_ROOT(&transaction->delayed_refs.href_root));
 67                 if (transaction->delayed_refs.pending_csums)
 68                         btrfs_err(transaction->fs_info,
 69                                   "pending csums is %llu",
 70                                   transaction->delayed_refs.pending_csums);
 71                 while (!list_empty(&transaction->pending_chunks)) {
 72                         struct extent_map *em;
 73 
 74                         em = list_first_entry(&transaction->pending_chunks,
 75                                               struct extent_map, list);
 76                         list_del_init(&em->list);
 77                         free_extent_map(em);
 78                 }
 79                 /*
 80                  * If any block groups are found in ->deleted_bgs then it's
 81                  * because the transaction was aborted and a commit did not
 82                  * happen (things failed before writing the new superblock
 83                  * and calling btrfs_finish_extent_commit()), so we can not
 84                  * discard the physical locations of the block groups.
 85                  */
 86                 while (!list_empty(&transaction->deleted_bgs)) {
 87                         struct btrfs_block_group_cache *cache;
 88 
 89                         cache = list_first_entry(&transaction->deleted_bgs,
 90                                                  struct btrfs_block_group_cache,
 91                                                  bg_list);
 92                         list_del_init(&cache->bg_list);
 93                         btrfs_put_block_group_trimming(cache);
 94                         btrfs_put_block_group(cache);
 95                 }
 96                 kfree(transaction);
 97         }
 98 }
 99 
100 static void clear_btree_io_tree(struct extent_io_tree *tree)
101 {
102         spin_lock(&tree->lock);
103         /*
104          * Do a single barrier for the waitqueue_active check here, the state
105          * of the waitqueue should not change once clear_btree_io_tree is
106          * called.
107          */
108         smp_mb();
109         while (!RB_EMPTY_ROOT(&tree->state)) {
110                 struct rb_node *node;
111                 struct extent_state *state;
112 
113                 node = rb_first(&tree->state);
114                 state = rb_entry(node, struct extent_state, rb_node);
115                 rb_erase(&state->rb_node, &tree->state);
116                 RB_CLEAR_NODE(&state->rb_node);
117                 /*
118                  * btree io trees aren't supposed to have tasks waiting for
119                  * changes in the flags of extent states ever.
120                  */
121                 ASSERT(!waitqueue_active(&state->wq));
122                 free_extent_state(state);
123 
124                 cond_resched_lock(&tree->lock);
125         }
126         spin_unlock(&tree->lock);
127 }
128 
129 static noinline void switch_commit_roots(struct btrfs_transaction *trans,
130                                          struct btrfs_fs_info *fs_info)
131 {
132         struct btrfs_root *root, *tmp;
133 
134         down_write(&fs_info->commit_root_sem);
135         list_for_each_entry_safe(root, tmp, &trans->switch_commits,
136                                  dirty_list) {
137                 list_del_init(&root->dirty_list);
138                 free_extent_buffer(root->commit_root);
139                 root->commit_root = btrfs_root_node(root);
140                 if (is_fstree(root->objectid))
141                         btrfs_unpin_free_ino(root);
142                 clear_btree_io_tree(&root->dirty_log_pages);
143         }
144 
145         /* We can free old roots now. */
146         spin_lock(&trans->dropped_roots_lock);
147         while (!list_empty(&trans->dropped_roots)) {
148                 root = list_first_entry(&trans->dropped_roots,
149                                         struct btrfs_root, root_list);
150                 list_del_init(&root->root_list);
151                 spin_unlock(&trans->dropped_roots_lock);
152                 btrfs_drop_and_free_fs_root(fs_info, root);
153                 spin_lock(&trans->dropped_roots_lock);
154         }
155         spin_unlock(&trans->dropped_roots_lock);
156         up_write(&fs_info->commit_root_sem);
157 }
158 
159 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
160                                          unsigned int type)
161 {
162         if (type & TRANS_EXTWRITERS)
163                 atomic_inc(&trans->num_extwriters);
164 }
165 
166 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
167                                          unsigned int type)
168 {
169         if (type & TRANS_EXTWRITERS)
170                 atomic_dec(&trans->num_extwriters);
171 }
172 
173 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
174                                           unsigned int type)
175 {
176         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
177 }
178 
179 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
180 {
181         return atomic_read(&trans->num_extwriters);
182 }
183 
184 /*
185  * either allocate a new transaction or hop into the existing one
186  */
187 static noinline int join_transaction(struct btrfs_fs_info *fs_info,
188                                      unsigned int type)
189 {
190         struct btrfs_transaction *cur_trans;
191 
192         spin_lock(&fs_info->trans_lock);
193 loop:
194         /* The file system has been taken offline. No new transactions. */
195         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
196                 spin_unlock(&fs_info->trans_lock);
197                 return -EROFS;
198         }
199 
200         cur_trans = fs_info->running_transaction;
201         if (cur_trans) {
202                 if (cur_trans->aborted) {
203                         spin_unlock(&fs_info->trans_lock);
204                         return cur_trans->aborted;
205                 }
206                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
207                         spin_unlock(&fs_info->trans_lock);
208                         return -EBUSY;
209                 }
210                 refcount_inc(&cur_trans->use_count);
211                 atomic_inc(&cur_trans->num_writers);
212                 extwriter_counter_inc(cur_trans, type);
213                 spin_unlock(&fs_info->trans_lock);
214                 return 0;
215         }
216         spin_unlock(&fs_info->trans_lock);
217 
218         /*
219          * If we are ATTACH, we just want to catch the current transaction,
220          * and commit it. If there is no transaction, just return ENOENT.
221          */
222         if (type == TRANS_ATTACH)
223                 return -ENOENT;
224 
225         /*
226          * JOIN_NOLOCK only happens during the transaction commit, so
227          * it is impossible that ->running_transaction is NULL
228          */
229         BUG_ON(type == TRANS_JOIN_NOLOCK);
230 
231         cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
232         if (!cur_trans)
233                 return -ENOMEM;
234 
235         spin_lock(&fs_info->trans_lock);
236         if (fs_info->running_transaction) {
237                 /*
238                  * someone started a transaction after we unlocked.  Make sure
239                  * to redo the checks above
240                  */
241                 kfree(cur_trans);
242                 goto loop;
243         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
244                 spin_unlock(&fs_info->trans_lock);
245                 kfree(cur_trans);
246                 return -EROFS;
247         }
248 
249         cur_trans->fs_info = fs_info;
250         atomic_set(&cur_trans->num_writers, 1);
251         extwriter_counter_init(cur_trans, type);
252         init_waitqueue_head(&cur_trans->writer_wait);
253         init_waitqueue_head(&cur_trans->commit_wait);
254         init_waitqueue_head(&cur_trans->pending_wait);
255         cur_trans->state = TRANS_STATE_RUNNING;
256         /*
257          * One for this trans handle, one so it will live on until we
258          * commit the transaction.
259          */
260         refcount_set(&cur_trans->use_count, 2);
261         atomic_set(&cur_trans->pending_ordered, 0);
262         cur_trans->flags = 0;
263         cur_trans->start_time = get_seconds();
264 
265         memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
266 
267         cur_trans->delayed_refs.href_root = RB_ROOT;
268         cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
269         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
270 
271         /*
272          * although the tree mod log is per file system and not per transaction,
273          * the log must never go across transaction boundaries.
274          */
275         smp_mb();
276         if (!list_empty(&fs_info->tree_mod_seq_list))
277                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
278         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
279                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
280         atomic64_set(&fs_info->tree_mod_seq, 0);
281 
282         spin_lock_init(&cur_trans->delayed_refs.lock);
283 
284         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
285         INIT_LIST_HEAD(&cur_trans->pending_chunks);
286         INIT_LIST_HEAD(&cur_trans->switch_commits);
287         INIT_LIST_HEAD(&cur_trans->dirty_bgs);
288         INIT_LIST_HEAD(&cur_trans->io_bgs);
289         INIT_LIST_HEAD(&cur_trans->dropped_roots);
290         mutex_init(&cur_trans->cache_write_mutex);
291         cur_trans->num_dirty_bgs = 0;
292         spin_lock_init(&cur_trans->dirty_bgs_lock);
293         INIT_LIST_HEAD(&cur_trans->deleted_bgs);
294         spin_lock_init(&cur_trans->dropped_roots_lock);
295         list_add_tail(&cur_trans->list, &fs_info->trans_list);
296         extent_io_tree_init(&cur_trans->dirty_pages,
297                              fs_info->btree_inode);
298         fs_info->generation++;
299         cur_trans->transid = fs_info->generation;
300         fs_info->running_transaction = cur_trans;
301         cur_trans->aborted = 0;
302         spin_unlock(&fs_info->trans_lock);
303 
304         return 0;
305 }
306 
307 /*
308  * this does all the record keeping required to make sure that a reference
309  * counted root is properly recorded in a given transaction.  This is required
310  * to make sure the old root from before we joined the transaction is deleted
311  * when the transaction commits
312  */
313 static int record_root_in_trans(struct btrfs_trans_handle *trans,
314                                struct btrfs_root *root,
315                                int force)
316 {
317         struct btrfs_fs_info *fs_info = root->fs_info;
318 
319         if ((test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
320             root->last_trans < trans->transid) || force) {
321                 WARN_ON(root == fs_info->extent_root);
322                 WARN_ON(!force && root->commit_root != root->node);
323 
324                 /*
325                  * see below for IN_TRANS_SETUP usage rules
326                  * we have the reloc mutex held now, so there
327                  * is only one writer in this function
328                  */
329                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
330 
331                 /* make sure readers find IN_TRANS_SETUP before
332                  * they find our root->last_trans update
333                  */
334                 smp_wmb();
335 
336                 spin_lock(&fs_info->fs_roots_radix_lock);
337                 if (root->last_trans == trans->transid && !force) {
338                         spin_unlock(&fs_info->fs_roots_radix_lock);
339                         return 0;
340                 }
341                 radix_tree_tag_set(&fs_info->fs_roots_radix,
342                                    (unsigned long)root->root_key.objectid,
343                                    BTRFS_ROOT_TRANS_TAG);
344                 spin_unlock(&fs_info->fs_roots_radix_lock);
345                 root->last_trans = trans->transid;
346 
347                 /* this is pretty tricky.  We don't want to
348                  * take the relocation lock in btrfs_record_root_in_trans
349                  * unless we're really doing the first setup for this root in
350                  * this transaction.
351                  *
352                  * Normally we'd use root->last_trans as a flag to decide
353                  * if we want to take the expensive mutex.
354                  *
355                  * But, we have to set root->last_trans before we
356                  * init the relocation root, otherwise, we trip over warnings
357                  * in ctree.c.  The solution used here is to flag ourselves
358                  * with root IN_TRANS_SETUP.  When this is 1, we're still
359                  * fixing up the reloc trees and everyone must wait.
360                  *
361                  * When this is zero, they can trust root->last_trans and fly
362                  * through btrfs_record_root_in_trans without having to take the
363                  * lock.  smp_wmb() makes sure that all the writes above are
364                  * done before we pop in the zero below
365                  */
366                 btrfs_init_reloc_root(trans, root);
367                 smp_mb__before_atomic();
368                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
369         }
370         return 0;
371 }
372 
373 
374 void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
375                             struct btrfs_root *root)
376 {
377         struct btrfs_fs_info *fs_info = root->fs_info;
378         struct btrfs_transaction *cur_trans = trans->transaction;
379 
380         /* Add ourselves to the transaction dropped list */
381         spin_lock(&cur_trans->dropped_roots_lock);
382         list_add_tail(&root->root_list, &cur_trans->dropped_roots);
383         spin_unlock(&cur_trans->dropped_roots_lock);
384 
385         /* Make sure we don't try to update the root at commit time */
386         spin_lock(&fs_info->fs_roots_radix_lock);
387         radix_tree_tag_clear(&fs_info->fs_roots_radix,
388                              (unsigned long)root->root_key.objectid,
389                              BTRFS_ROOT_TRANS_TAG);
390         spin_unlock(&fs_info->fs_roots_radix_lock);
391 }
392 
393 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
394                                struct btrfs_root *root)
395 {
396         struct btrfs_fs_info *fs_info = root->fs_info;
397 
398         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
399                 return 0;
400 
401         /*
402          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
403          * and barriers
404          */
405         smp_rmb();
406         if (root->last_trans == trans->transid &&
407             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
408                 return 0;
409 
410         mutex_lock(&fs_info->reloc_mutex);
411         record_root_in_trans(trans, root, 0);
412         mutex_unlock(&fs_info->reloc_mutex);
413 
414         return 0;
415 }
416 
417 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
418 {
419         return (trans->state >= TRANS_STATE_BLOCKED &&
420                 trans->state < TRANS_STATE_UNBLOCKED &&
421                 !trans->aborted);
422 }
423 
424 /* wait for commit against the current transaction to become unblocked
425  * when this is done, it is safe to start a new transaction, but the current
426  * transaction might not be fully on disk.
427  */
428 static void wait_current_trans(struct btrfs_fs_info *fs_info)
429 {
430         struct btrfs_transaction *cur_trans;
431 
432         spin_lock(&fs_info->trans_lock);
433         cur_trans = fs_info->running_transaction;
434         if (cur_trans && is_transaction_blocked(cur_trans)) {
435                 refcount_inc(&cur_trans->use_count);
436                 spin_unlock(&fs_info->trans_lock);
437 
438                 wait_event(fs_info->transaction_wait,
439                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
440                            cur_trans->aborted);
441                 btrfs_put_transaction(cur_trans);
442         } else {
443                 spin_unlock(&fs_info->trans_lock);
444         }
445 }
446 
447 static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
448 {
449         if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
450                 return 0;
451 
452         if (type == TRANS_USERSPACE)
453                 return 1;
454 
455         if (type == TRANS_START &&
456             !atomic_read(&fs_info->open_ioctl_trans))
457                 return 1;
458 
459         return 0;
460 }
461 
462 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
463 {
464         struct btrfs_fs_info *fs_info = root->fs_info;
465 
466         if (!fs_info->reloc_ctl ||
467             !test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
468             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
469             root->reloc_root)
470                 return false;
471 
472         return true;
473 }
474 
475 static struct btrfs_trans_handle *
476 start_transaction(struct btrfs_root *root, unsigned int num_items,
477                   unsigned int type, enum btrfs_reserve_flush_enum flush,
478                   bool enforce_qgroups)
479 {
480         struct btrfs_fs_info *fs_info = root->fs_info;
481 
482         struct btrfs_trans_handle *h;
483         struct btrfs_transaction *cur_trans;
484         u64 num_bytes = 0;
485         u64 qgroup_reserved = 0;
486         bool reloc_reserved = false;
487         int ret;
488 
489         /* Send isn't supposed to start transactions. */
490         ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
491 
492         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
493                 return ERR_PTR(-EROFS);
494 
495         if (current->journal_info) {
496                 WARN_ON(type & TRANS_EXTWRITERS);
497                 h = current->journal_info;
498                 refcount_inc(&h->use_count);
499                 WARN_ON(refcount_read(&h->use_count) > 2);
500                 h->orig_rsv = h->block_rsv;
501                 h->block_rsv = NULL;
502                 goto got_it;
503         }
504 
505         /*
506          * Do the reservation before we join the transaction so we can do all
507          * the appropriate flushing if need be.
508          */
509         if (num_items && root != fs_info->chunk_root) {
510                 qgroup_reserved = num_items * fs_info->nodesize;
511                 ret = btrfs_qgroup_reserve_meta(root, qgroup_reserved,
512                                                 enforce_qgroups);
513                 if (ret)
514                         return ERR_PTR(ret);
515 
516                 num_bytes = btrfs_calc_trans_metadata_size(fs_info, num_items);
517                 /*
518                  * Do the reservation for the relocation root creation
519                  */
520                 if (need_reserve_reloc_root(root)) {
521                         num_bytes += fs_info->nodesize;
522                         reloc_reserved = true;
523                 }
524 
525                 ret = btrfs_block_rsv_add(root, &fs_info->trans_block_rsv,
526                                           num_bytes, flush);
527                 if (ret)
528                         goto reserve_fail;
529         }
530 again:
531         h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
532         if (!h) {
533                 ret = -ENOMEM;
534                 goto alloc_fail;
535         }
536 
537         /*
538          * If we are JOIN_NOLOCK we're already committing a transaction and
539          * waiting on this guy, so we don't need to do the sb_start_intwrite
540          * because we're already holding a ref.  We need this because we could
541          * have raced in and did an fsync() on a file which can kick a commit
542          * and then we deadlock with somebody doing a freeze.
543          *
544          * If we are ATTACH, it means we just want to catch the current
545          * transaction and commit it, so we needn't do sb_start_intwrite(). 
546          */
547         if (type & __TRANS_FREEZABLE)
548                 sb_start_intwrite(fs_info->sb);
549 
550         if (may_wait_transaction(fs_info, type))
551                 wait_current_trans(fs_info);
552 
553         do {
554                 ret = join_transaction(fs_info, type);
555                 if (ret == -EBUSY) {
556                         wait_current_trans(fs_info);
557                         if (unlikely(type == TRANS_ATTACH))
558                                 ret = -ENOENT;
559                 }
560         } while (ret == -EBUSY);
561 
562         if (ret < 0)
563                 goto join_fail;
564 
565         cur_trans = fs_info->running_transaction;
566 
567         h->transid = cur_trans->transid;
568         h->transaction = cur_trans;
569         h->root = root;
570         refcount_set(&h->use_count, 1);
571         h->fs_info = root->fs_info;
572 
573         h->type = type;
574         h->can_flush_pending_bgs = true;
575         INIT_LIST_HEAD(&h->new_bgs);
576 
577         smp_mb();
578         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
579             may_wait_transaction(fs_info, type)) {
580                 current->journal_info = h;
581                 btrfs_commit_transaction(h);
582                 goto again;
583         }
584 
585         if (num_bytes) {
586                 trace_btrfs_space_reservation(fs_info, "transaction",
587                                               h->transid, num_bytes, 1);
588                 h->block_rsv = &fs_info->trans_block_rsv;
589                 h->bytes_reserved = num_bytes;
590                 h->reloc_reserved = reloc_reserved;
591         }
592 
593 got_it:
594         btrfs_record_root_in_trans(h, root);
595 
596         if (!current->journal_info && type != TRANS_USERSPACE)
597                 current->journal_info = h;
598         return h;
599 
600 join_fail:
601         if (type & __TRANS_FREEZABLE)
602                 sb_end_intwrite(fs_info->sb);
603         kmem_cache_free(btrfs_trans_handle_cachep, h);
604 alloc_fail:
605         if (num_bytes)
606                 btrfs_block_rsv_release(fs_info, &fs_info->trans_block_rsv,
607                                         num_bytes);
608 reserve_fail:
609         btrfs_qgroup_free_meta(root, qgroup_reserved);
610         return ERR_PTR(ret);
611 }
612 
613 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
614                                                    unsigned int num_items)
615 {
616         return start_transaction(root, num_items, TRANS_START,
617                                  BTRFS_RESERVE_FLUSH_ALL, true);
618 }
619 
620 struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
621                                         struct btrfs_root *root,
622                                         unsigned int num_items,
623                                         int min_factor)
624 {
625         struct btrfs_fs_info *fs_info = root->fs_info;
626         struct btrfs_trans_handle *trans;
627         u64 num_bytes;
628         int ret;
629 
630         /*
631          * We have two callers: unlink and block group removal.  The
632          * former should succeed even if we will temporarily exceed
633          * quota and the latter operates on the extent root so
634          * qgroup enforcement is ignored anyway.
635          */
636         trans = start_transaction(root, num_items, TRANS_START,
637                                   BTRFS_RESERVE_FLUSH_ALL, false);
638         if (!IS_ERR(trans) || PTR_ERR(trans) != -ENOSPC)
639                 return trans;
640 
641         trans = btrfs_start_transaction(root, 0);
642         if (IS_ERR(trans))
643                 return trans;
644 
645         num_bytes = btrfs_calc_trans_metadata_size(fs_info, num_items);
646         ret = btrfs_cond_migrate_bytes(fs_info, &fs_info->trans_block_rsv,
647                                        num_bytes, min_factor);
648         if (ret) {
649                 btrfs_end_transaction(trans);
650                 return ERR_PTR(ret);
651         }
652 
653         trans->block_rsv = &fs_info->trans_block_rsv;
654         trans->bytes_reserved = num_bytes;
655         trace_btrfs_space_reservation(fs_info, "transaction",
656                                       trans->transid, num_bytes, 1);
657 
658         return trans;
659 }
660 
661 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
662                                         struct btrfs_root *root,
663                                         unsigned int num_items)
664 {
665         return start_transaction(root, num_items, TRANS_START,
666                                  BTRFS_RESERVE_FLUSH_LIMIT, true);
667 }
668 
669 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
670 {
671         return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,
672                                  true);
673 }
674 
675 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
676 {
677         return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
678                                  BTRFS_RESERVE_NO_FLUSH, true);
679 }
680 
681 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
682 {
683         return start_transaction(root, 0, TRANS_USERSPACE,
684                                  BTRFS_RESERVE_NO_FLUSH, true);
685 }
686 
687 /*
688  * btrfs_attach_transaction() - catch the running transaction
689  *
690  * It is used when we want to commit the current the transaction, but
691  * don't want to start a new one.
692  *
693  * Note: If this function return -ENOENT, it just means there is no
694  * running transaction. But it is possible that the inactive transaction
695  * is still in the memory, not fully on disk. If you hope there is no
696  * inactive transaction in the fs when -ENOENT is returned, you should
697  * invoke
698  *     btrfs_attach_transaction_barrier()
699  */
700 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
701 {
702         return start_transaction(root, 0, TRANS_ATTACH,
703                                  BTRFS_RESERVE_NO_FLUSH, true);
704 }
705 
706 /*
707  * btrfs_attach_transaction_barrier() - catch the running transaction
708  *
709  * It is similar to the above function, the differentia is this one
710  * will wait for all the inactive transactions until they fully
711  * complete.
712  */
713 struct btrfs_trans_handle *
714 btrfs_attach_transaction_barrier(struct btrfs_root *root)
715 {
716         struct btrfs_trans_handle *trans;
717 
718         trans = start_transaction(root, 0, TRANS_ATTACH,
719                                   BTRFS_RESERVE_NO_FLUSH, true);
720         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
721                 btrfs_wait_for_commit(root->fs_info, 0);
722 
723         return trans;
724 }
725 
726 /* wait for a transaction commit to be fully complete */
727 static noinline void wait_for_commit(struct btrfs_transaction *commit)
728 {
729         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
730 }
731 
732 int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
733 {
734         struct btrfs_transaction *cur_trans = NULL, *t;
735         int ret = 0;
736 
737         if (transid) {
738                 if (transid <= fs_info->last_trans_committed)
739                         goto out;
740 
741                 /* find specified transaction */
742                 spin_lock(&fs_info->trans_lock);
743                 list_for_each_entry(t, &fs_info->trans_list, list) {
744                         if (t->transid == transid) {
745                                 cur_trans = t;
746                                 refcount_inc(&cur_trans->use_count);
747                                 ret = 0;
748                                 break;
749                         }
750                         if (t->transid > transid) {
751                                 ret = 0;
752                                 break;
753                         }
754                 }
755                 spin_unlock(&fs_info->trans_lock);
756 
757                 /*
758                  * The specified transaction doesn't exist, or we
759                  * raced with btrfs_commit_transaction
760                  */
761                 if (!cur_trans) {
762                         if (transid > fs_info->last_trans_committed)
763                                 ret = -EINVAL;
764                         goto out;
765                 }
766         } else {
767                 /* find newest transaction that is committing | committed */
768                 spin_lock(&fs_info->trans_lock);
769                 list_for_each_entry_reverse(t, &fs_info->trans_list,
770                                             list) {
771                         if (t->state >= TRANS_STATE_COMMIT_START) {
772                                 if (t->state == TRANS_STATE_COMPLETED)
773                                         break;
774                                 cur_trans = t;
775                                 refcount_inc(&cur_trans->use_count);
776                                 break;
777                         }
778                 }
779                 spin_unlock(&fs_info->trans_lock);
780                 if (!cur_trans)
781                         goto out;  /* nothing committing|committed */
782         }
783 
784         wait_for_commit(cur_trans);
785         btrfs_put_transaction(cur_trans);
786 out:
787         return ret;
788 }
789 
790 void btrfs_throttle(struct btrfs_fs_info *fs_info)
791 {
792         if (!atomic_read(&fs_info->open_ioctl_trans))
793                 wait_current_trans(fs_info);
794 }
795 
796 static int should_end_transaction(struct btrfs_trans_handle *trans)
797 {
798         struct btrfs_fs_info *fs_info = trans->fs_info;
799 
800         if (btrfs_check_space_for_delayed_refs(trans, fs_info))
801                 return 1;
802 
803         return !!btrfs_block_rsv_check(&fs_info->global_block_rsv, 5);
804 }
805 
806 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
807 {
808         struct btrfs_transaction *cur_trans = trans->transaction;
809         struct btrfs_fs_info *fs_info = trans->fs_info;
810         int updates;
811         int err;
812 
813         smp_mb();
814         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
815             cur_trans->delayed_refs.flushing)
816                 return 1;
817 
818         updates = trans->delayed_ref_updates;
819         trans->delayed_ref_updates = 0;
820         if (updates) {
821                 err = btrfs_run_delayed_refs(trans, fs_info, updates * 2);
822                 if (err) /* Error code will also eval true */
823                         return err;
824         }
825 
826         return should_end_transaction(trans);
827 }
828 
829 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
830                                    int throttle)
831 {
832         struct btrfs_fs_info *info = trans->fs_info;
833         struct btrfs_transaction *cur_trans = trans->transaction;
834         u64 transid = trans->transid;
835         unsigned long cur = trans->delayed_ref_updates;
836         int lock = (trans->type != TRANS_JOIN_NOLOCK);
837         int err = 0;
838         int must_run_delayed_refs = 0;
839 
840         if (refcount_read(&trans->use_count) > 1) {
841                 refcount_dec(&trans->use_count);
842                 trans->block_rsv = trans->orig_rsv;
843                 return 0;
844         }
845 
846         btrfs_trans_release_metadata(trans, info);
847         trans->block_rsv = NULL;
848 
849         if (!list_empty(&trans->new_bgs))
850                 btrfs_create_pending_block_groups(trans, info);
851 
852         trans->delayed_ref_updates = 0;
853         if (!trans->sync) {
854                 must_run_delayed_refs =
855                         btrfs_should_throttle_delayed_refs(trans, info);
856                 cur = max_t(unsigned long, cur, 32);
857 
858                 /*
859                  * don't make the caller wait if they are from a NOLOCK
860                  * or ATTACH transaction, it will deadlock with commit
861                  */
862                 if (must_run_delayed_refs == 1 &&
863                     (trans->type & (__TRANS_JOIN_NOLOCK | __TRANS_ATTACH)))
864                         must_run_delayed_refs = 2;
865         }
866 
867         btrfs_trans_release_metadata(trans, info);
868         trans->block_rsv = NULL;
869 
870         if (!list_empty(&trans->new_bgs))
871                 btrfs_create_pending_block_groups(trans, info);
872 
873         btrfs_trans_release_chunk_metadata(trans);
874 
875         if (lock && !atomic_read(&info->open_ioctl_trans) &&
876             should_end_transaction(trans) &&
877             READ_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
878                 spin_lock(&info->trans_lock);
879                 if (cur_trans->state == TRANS_STATE_RUNNING)
880                         cur_trans->state = TRANS_STATE_BLOCKED;
881                 spin_unlock(&info->trans_lock);
882         }
883 
884         if (lock && READ_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
885                 if (throttle)
886                         return btrfs_commit_transaction(trans);
887                 else
888                         wake_up_process(info->transaction_kthread);
889         }
890 
891         if (trans->type & __TRANS_FREEZABLE)
892                 sb_end_intwrite(info->sb);
893 
894         WARN_ON(cur_trans != info->running_transaction);
895         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
896         atomic_dec(&cur_trans->num_writers);
897         extwriter_counter_dec(cur_trans, trans->type);
898 
899         /*
900          * Make sure counter is updated before we wake up waiters.
901          */
902         smp_mb();
903         if (waitqueue_active(&cur_trans->writer_wait))
904                 wake_up(&cur_trans->writer_wait);
905         btrfs_put_transaction(cur_trans);
906 
907         if (current->journal_info == trans)
908                 current->journal_info = NULL;
909 
910         if (throttle)
911                 btrfs_run_delayed_iputs(info);
912 
913         if (trans->aborted ||
914             test_bit(BTRFS_FS_STATE_ERROR, &info->fs_state)) {
915                 wake_up_process(info->transaction_kthread);
916                 err = -EIO;
917         }
918 
919         kmem_cache_free(btrfs_trans_handle_cachep, trans);
920         if (must_run_delayed_refs) {
921                 btrfs_async_run_delayed_refs(info, cur, transid,
922                                              must_run_delayed_refs == 1);
923         }
924         return err;
925 }
926 
927 int btrfs_end_transaction(struct btrfs_trans_handle *trans)
928 {
929         return __btrfs_end_transaction(trans, 0);
930 }
931 
932 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
933 {
934         return __btrfs_end_transaction(trans, 1);
935 }
936 
937 /*
938  * when btree blocks are allocated, they have some corresponding bits set for
939  * them in one of two extent_io trees.  This is used to make sure all of
940  * those extents are sent to disk but does not wait on them
941  */
942 int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
943                                struct extent_io_tree *dirty_pages, int mark)
944 {
945         int err = 0;
946         int werr = 0;
947         struct address_space *mapping = fs_info->btree_inode->i_mapping;
948         struct extent_state *cached_state = NULL;
949         u64 start = 0;
950         u64 end;
951 
952         atomic_inc(&BTRFS_I(fs_info->btree_inode)->sync_writers);
953         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
954                                       mark, &cached_state)) {
955                 bool wait_writeback = false;
956 
957                 err = convert_extent_bit(dirty_pages, start, end,
958                                          EXTENT_NEED_WAIT,
959                                          mark, &cached_state);
960                 /*
961                  * convert_extent_bit can return -ENOMEM, which is most of the
962                  * time a temporary error. So when it happens, ignore the error
963                  * and wait for writeback of this range to finish - because we
964                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
965                  * to __btrfs_wait_marked_extents() would not know that
966                  * writeback for this range started and therefore wouldn't
967                  * wait for it to finish - we don't want to commit a
968                  * superblock that points to btree nodes/leafs for which
969                  * writeback hasn't finished yet (and without errors).
970                  * We cleanup any entries left in the io tree when committing
971                  * the transaction (through clear_btree_io_tree()).
972                  */
973                 if (err == -ENOMEM) {
974                         err = 0;
975                         wait_writeback = true;
976                 }
977                 if (!err)
978                         err = filemap_fdatawrite_range(mapping, start, end);
979                 if (err)
980                         werr = err;
981                 else if (wait_writeback)
982                         werr = filemap_fdatawait_range(mapping, start, end);
983                 free_extent_state(cached_state);
984                 cached_state = NULL;
985                 cond_resched();
986                 start = end + 1;
987         }
988         atomic_dec(&BTRFS_I(fs_info->btree_inode)->sync_writers);
989         return werr;
990 }
991 
992 /*
993  * when btree blocks are allocated, they have some corresponding bits set for
994  * them in one of two extent_io trees.  This is used to make sure all of
995  * those extents are on disk for transaction or log commit.  We wait
996  * on all the pages and clear them from the dirty pages state tree
997  */
998 static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
999                                        struct extent_io_tree *dirty_pages)
1000 {
1001         int err = 0;
1002         int werr = 0;
1003         struct address_space *mapping = fs_info->btree_inode->i_mapping;
1004         struct extent_state *cached_state = NULL;
1005         u64 start = 0;
1006         u64 end;
1007 
1008         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
1009                                       EXTENT_NEED_WAIT, &cached_state)) {
1010                 /*
1011                  * Ignore -ENOMEM errors returned by clear_extent_bit().
1012                  * When committing the transaction, we'll remove any entries
1013                  * left in the io tree. For a log commit, we don't remove them
1014                  * after committing the log because the tree can be accessed
1015                  * concurrently - we do it only at transaction commit time when
1016                  * it's safe to do it (through clear_btree_io_tree()).
1017                  */
1018                 err = clear_extent_bit(dirty_pages, start, end,
1019                                        EXTENT_NEED_WAIT, 0, 0, &cached_state);
1020                 if (err == -ENOMEM)
1021                         err = 0;
1022                 if (!err)
1023                         err = filemap_fdatawait_range(mapping, start, end);
1024                 if (err)
1025                         werr = err;
1026                 free_extent_state(cached_state);
1027                 cached_state = NULL;
1028                 cond_resched();
1029                 start = end + 1;
1030         }
1031         if (err)
1032                 werr = err;
1033         return werr;
1034 }
1035 
1036 int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1037                        struct extent_io_tree *dirty_pages)
1038 {
1039         bool errors = false;
1040         int err;
1041 
1042         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1043         if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1044                 errors = true;
1045 
1046         if (errors && !err)
1047                 err = -EIO;
1048         return err;
1049 }
1050 
1051 int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1052 {
1053         struct btrfs_fs_info *fs_info = log_root->fs_info;
1054         struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1055         bool errors = false;
1056         int err;
1057 
1058         ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
1059 
1060         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1061         if ((mark & EXTENT_DIRTY) &&
1062             test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1063                 errors = true;
1064 
1065         if ((mark & EXTENT_NEW) &&
1066             test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1067                 errors = true;
1068 
1069         if (errors && !err)
1070                 err = -EIO;
1071         return err;
1072 }
1073 
1074 /*
1075  * when btree blocks are allocated, they have some corresponding bits set for
1076  * them in one of two extent_io trees.  This is used to make sure all of
1077  * those extents are on disk for transaction or log commit
1078  */
1079 static int btrfs_write_and_wait_marked_extents(struct btrfs_fs_info *fs_info,
1080                                 struct extent_io_tree *dirty_pages, int mark)
1081 {
1082         int ret;
1083         int ret2;
1084         struct blk_plug plug;
1085 
1086         blk_start_plug(&plug);
1087         ret = btrfs_write_marked_extents(fs_info, dirty_pages, mark);
1088         blk_finish_plug(&plug);
1089         ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1090 
1091         if (ret)
1092                 return ret;
1093         if (ret2)
1094                 return ret2;
1095         return 0;
1096 }
1097 
1098 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
1099                                             struct btrfs_fs_info *fs_info)
1100 {
1101         int ret;
1102 
1103         ret = btrfs_write_and_wait_marked_extents(fs_info,
1104                                            &trans->transaction->dirty_pages,
1105                                            EXTENT_DIRTY);
1106         clear_btree_io_tree(&trans->transaction->dirty_pages);
1107 
1108         return ret;
1109 }
1110 
1111 /*
1112  * this is used to update the root pointer in the tree of tree roots.
1113  *
1114  * But, in the case of the extent allocation tree, updating the root
1115  * pointer may allocate blocks which may change the root of the extent
1116  * allocation tree.
1117  *
1118  * So, this loops and repeats and makes sure the cowonly root didn't
1119  * change while the root pointer was being updated in the metadata.
1120  */
1121 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1122                                struct btrfs_root *root)
1123 {
1124         int ret;
1125         u64 old_root_bytenr;
1126         u64 old_root_used;
1127         struct btrfs_fs_info *fs_info = root->fs_info;
1128         struct btrfs_root *tree_root = fs_info->tree_root;
1129 
1130         old_root_used = btrfs_root_used(&root->root_item);
1131 
1132         while (1) {
1133                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1134                 if (old_root_bytenr == root->node->start &&
1135                     old_root_used == btrfs_root_used(&root->root_item))
1136                         break;
1137 
1138                 btrfs_set_root_node(&root->root_item, root->node);
1139                 ret = btrfs_update_root(trans, tree_root,
1140                                         &root->root_key,
1141                                         &root->root_item);
1142                 if (ret)
1143                         return ret;
1144 
1145                 old_root_used = btrfs_root_used(&root->root_item);
1146         }
1147 
1148         return 0;
1149 }
1150 
1151 /*
1152  * update all the cowonly tree roots on disk
1153  *
1154  * The error handling in this function may not be obvious. Any of the
1155  * failures will cause the file system to go offline. We still need
1156  * to clean up the delayed refs.
1157  */
1158 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
1159                                          struct btrfs_fs_info *fs_info)
1160 {
1161         struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1162         struct list_head *io_bgs = &trans->transaction->io_bgs;
1163         struct list_head *next;
1164         struct extent_buffer *eb;
1165         int ret;
1166 
1167         eb = btrfs_lock_root_node(fs_info->tree_root);
1168         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1169                               0, &eb);
1170         btrfs_tree_unlock(eb);
1171         free_extent_buffer(eb);
1172 
1173         if (ret)
1174                 return ret;
1175 
1176         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1177         if (ret)
1178                 return ret;
1179 
1180         ret = btrfs_run_dev_stats(trans, fs_info);
1181         if (ret)
1182                 return ret;
1183         ret = btrfs_run_dev_replace(trans, fs_info);
1184         if (ret)
1185                 return ret;
1186         ret = btrfs_run_qgroups(trans, fs_info);
1187         if (ret)
1188                 return ret;
1189 
1190         ret = btrfs_setup_space_cache(trans, fs_info);
1191         if (ret)
1192                 return ret;
1193 
1194         /* run_qgroups might have added some more refs */
1195         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1196         if (ret)
1197                 return ret;
1198 again:
1199         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1200                 struct btrfs_root *root;
1201                 next = fs_info->dirty_cowonly_roots.next;
1202                 list_del_init(next);
1203                 root = list_entry(next, struct btrfs_root, dirty_list);
1204                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1205 
1206                 if (root != fs_info->extent_root)
1207                         list_add_tail(&root->dirty_list,
1208                                       &trans->transaction->switch_commits);
1209                 ret = update_cowonly_root(trans, root);
1210                 if (ret)
1211                         return ret;
1212                 ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1213                 if (ret)
1214                         return ret;
1215         }
1216 
1217         while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1218                 ret = btrfs_write_dirty_block_groups(trans, fs_info);
1219                 if (ret)
1220                         return ret;
1221                 ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1222                 if (ret)
1223                         return ret;
1224         }
1225 
1226         if (!list_empty(&fs_info->dirty_cowonly_roots))
1227                 goto again;
1228 
1229         list_add_tail(&fs_info->extent_root->dirty_list,
1230                       &trans->transaction->switch_commits);
1231         btrfs_after_dev_replace_commit(fs_info);
1232 
1233         return 0;
1234 }
1235 
1236 /*
1237  * dead roots are old snapshots that need to be deleted.  This allocates
1238  * a dirty root struct and adds it into the list of dead roots that need to
1239  * be deleted
1240  */
1241 void btrfs_add_dead_root(struct btrfs_root *root)
1242 {
1243         struct btrfs_fs_info *fs_info = root->fs_info;
1244 
1245         spin_lock(&fs_info->trans_lock);
1246         if (list_empty(&root->root_list))
1247                 list_add_tail(&root->root_list, &fs_info->dead_roots);
1248         spin_unlock(&fs_info->trans_lock);
1249 }
1250 
1251 /*
1252  * update all the cowonly tree roots on disk
1253  */
1254 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
1255                                     struct btrfs_fs_info *fs_info)
1256 {
1257         struct btrfs_root *gang[8];
1258         int i;
1259         int ret;
1260         int err = 0;
1261 
1262         spin_lock(&fs_info->fs_roots_radix_lock);
1263         while (1) {
1264                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1265                                                  (void **)gang, 0,
1266                                                  ARRAY_SIZE(gang),
1267                                                  BTRFS_ROOT_TRANS_TAG);
1268                 if (ret == 0)
1269                         break;
1270                 for (i = 0; i < ret; i++) {
1271                         struct btrfs_root *root = gang[i];
1272                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1273                                         (unsigned long)root->root_key.objectid,
1274                                         BTRFS_ROOT_TRANS_TAG);
1275                         spin_unlock(&fs_info->fs_roots_radix_lock);
1276 
1277                         btrfs_free_log(trans, root);
1278                         btrfs_update_reloc_root(trans, root);
1279                         btrfs_orphan_commit_root(trans, root);
1280 
1281                         btrfs_save_ino_cache(root, trans);
1282 
1283                         /* see comments in should_cow_block() */
1284                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1285                         smp_mb__after_atomic();
1286 
1287                         if (root->commit_root != root->node) {
1288                                 list_add_tail(&root->dirty_list,
1289                                         &trans->transaction->switch_commits);
1290                                 btrfs_set_root_node(&root->root_item,
1291                                                     root->node);
1292                         }
1293 
1294                         err = btrfs_update_root(trans, fs_info->tree_root,
1295                                                 &root->root_key,
1296                                                 &root->root_item);
1297                         spin_lock(&fs_info->fs_roots_radix_lock);
1298                         if (err)
1299                                 break;
1300                         btrfs_qgroup_free_meta_all(root);
1301                 }
1302         }
1303         spin_unlock(&fs_info->fs_roots_radix_lock);
1304         return err;
1305 }
1306 
1307 /*
1308  * defrag a given btree.
1309  * Every leaf in the btree is read and defragged.
1310  */
1311 int btrfs_defrag_root(struct btrfs_root *root)
1312 {
1313         struct btrfs_fs_info *info = root->fs_info;
1314         struct btrfs_trans_handle *trans;
1315         int ret;
1316 
1317         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1318                 return 0;
1319 
1320         while (1) {
1321                 trans = btrfs_start_transaction(root, 0);
1322                 if (IS_ERR(trans))
1323                         return PTR_ERR(trans);
1324 
1325                 ret = btrfs_defrag_leaves(trans, root);
1326 
1327                 btrfs_end_transaction(trans);
1328                 btrfs_btree_balance_dirty(info);
1329                 cond_resched();
1330 
1331                 if (btrfs_fs_closing(info) || ret != -EAGAIN)
1332                         break;
1333 
1334                 if (btrfs_defrag_cancelled(info)) {
1335                         btrfs_debug(info, "defrag_root cancelled");
1336                         ret = -EAGAIN;
1337                         break;
1338                 }
1339         }
1340         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1341         return ret;
1342 }
1343 
1344 /*
1345  * Do all special snapshot related qgroup dirty hack.
1346  *
1347  * Will do all needed qgroup inherit and dirty hack like switch commit
1348  * roots inside one transaction and write all btree into disk, to make
1349  * qgroup works.
1350  */
1351 static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1352                                    struct btrfs_root *src,
1353                                    struct btrfs_root *parent,
1354                                    struct btrfs_qgroup_inherit *inherit,
1355                                    u64 dst_objectid)
1356 {
1357         struct btrfs_fs_info *fs_info = src->fs_info;
1358         int ret;
1359 
1360         /*
1361          * Save some performance in the case that qgroups are not
1362          * enabled. If this check races with the ioctl, rescan will
1363          * kick in anyway.
1364          */
1365         if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
1366                 return 0;
1367 
1368         /*
1369          * Ensure dirty @src will be commited.  Or, after comming
1370          * commit_fs_roots() and switch_commit_roots(), any dirty but not
1371          * recorded root will never be updated again, causing an outdated root
1372          * item.
1373          */
1374         record_root_in_trans(trans, src, 1);
1375 
1376         /*
1377          * We are going to commit transaction, see btrfs_commit_transaction()
1378          * comment for reason locking tree_log_mutex
1379          */
1380         mutex_lock(&fs_info->tree_log_mutex);
1381 
1382         ret = commit_fs_roots(trans, fs_info);
1383         if (ret)
1384                 goto out;
1385         ret = btrfs_qgroup_account_extents(trans, fs_info);
1386         if (ret < 0)
1387                 goto out;
1388 
1389         /* Now qgroup are all updated, we can inherit it to new qgroups */
1390         ret = btrfs_qgroup_inherit(trans, fs_info,
1391                                    src->root_key.objectid, dst_objectid,
1392                                    inherit);
1393         if (ret < 0)
1394                 goto out;
1395 
1396         /*
1397          * Now we do a simplified commit transaction, which will:
1398          * 1) commit all subvolume and extent tree
1399          *    To ensure all subvolume and extent tree have a valid
1400          *    commit_root to accounting later insert_dir_item()
1401          * 2) write all btree blocks onto disk
1402          *    This is to make sure later btree modification will be cowed
1403          *    Or commit_root can be populated and cause wrong qgroup numbers
1404          * In this simplified commit, we don't really care about other trees
1405          * like chunk and root tree, as they won't affect qgroup.
1406          * And we don't write super to avoid half committed status.
1407          */
1408         ret = commit_cowonly_roots(trans, fs_info);
1409         if (ret)
1410                 goto out;
1411         switch_commit_roots(trans->transaction, fs_info);
1412         ret = btrfs_write_and_wait_transaction(trans, fs_info);
1413         if (ret)
1414                 btrfs_handle_fs_error(fs_info, ret,
1415                         "Error while writing out transaction for qgroup");
1416 
1417 out:
1418         mutex_unlock(&fs_info->tree_log_mutex);
1419 
1420         /*
1421          * Force parent root to be updated, as we recorded it before so its
1422          * last_trans == cur_transid.
1423          * Or it won't be committed again onto disk after later
1424          * insert_dir_item()
1425          */
1426         if (!ret)
1427                 record_root_in_trans(trans, parent, 1);
1428         return ret;
1429 }
1430 
1431 /*
1432  * new snapshots need to be created at a very specific time in the
1433  * transaction commit.  This does the actual creation.
1434  *
1435  * Note:
1436  * If the error which may affect the commitment of the current transaction
1437  * happens, we should return the error number. If the error which just affect
1438  * the creation of the pending snapshots, just return 0.
1439  */
1440 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1441                                    struct btrfs_fs_info *fs_info,
1442                                    struct btrfs_pending_snapshot *pending)
1443 {
1444         struct btrfs_key key;
1445         struct btrfs_root_item *new_root_item;
1446         struct btrfs_root *tree_root = fs_info->tree_root;
1447         struct btrfs_root *root = pending->root;
1448         struct btrfs_root *parent_root;
1449         struct btrfs_block_rsv *rsv;
1450         struct inode *parent_inode;
1451         struct btrfs_path *path;
1452         struct btrfs_dir_item *dir_item;
1453         struct dentry *dentry;
1454         struct extent_buffer *tmp;
1455         struct extent_buffer *old;
1456         struct timespec cur_time;
1457         int ret = 0;
1458         u64 to_reserve = 0;
1459         u64 index = 0;
1460         u64 objectid;
1461         u64 root_flags;
1462         uuid_le new_uuid;
1463 
1464         ASSERT(pending->path);
1465         path = pending->path;
1466 
1467         ASSERT(pending->root_item);
1468         new_root_item = pending->root_item;
1469 
1470         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1471         if (pending->error)
1472                 goto no_free_objectid;
1473 
1474         /*
1475          * Make qgroup to skip current new snapshot's qgroupid, as it is
1476          * accounted by later btrfs_qgroup_inherit().
1477          */
1478         btrfs_set_skip_qgroup(trans, objectid);
1479 
1480         btrfs_reloc_pre_snapshot(pending, &to_reserve);
1481 
1482         if (to_reserve > 0) {
1483                 pending->error = btrfs_block_rsv_add(root,
1484                                                      &pending->block_rsv,
1485                                                      to_reserve,
1486                                                      BTRFS_RESERVE_NO_FLUSH);
1487                 if (pending->error)
1488                         goto clear_skip_qgroup;
1489         }
1490 
1491         key.objectid = objectid;
1492         key.offset = (u64)-1;
1493         key.type = BTRFS_ROOT_ITEM_KEY;
1494 
1495         rsv = trans->block_rsv;
1496         trans->block_rsv = &pending->block_rsv;
1497         trans->bytes_reserved = trans->block_rsv->reserved;
1498         trace_btrfs_space_reservation(fs_info, "transaction",
1499                                       trans->transid,
1500                                       trans->bytes_reserved, 1);
1501         dentry = pending->dentry;
1502         parent_inode = pending->dir;
1503         parent_root = BTRFS_I(parent_inode)->root;
1504         record_root_in_trans(trans, parent_root, 0);
1505 
1506         cur_time = current_time(parent_inode);
1507 
1508         /*
1509          * insert the directory item
1510          */
1511         ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);
1512         BUG_ON(ret); /* -ENOMEM */
1513 
1514         /* check if there is a file/dir which has the same name. */
1515         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1516                                          btrfs_ino(BTRFS_I(parent_inode)),
1517                                          dentry->d_name.name,
1518                                          dentry->d_name.len, 0);
1519         if (dir_item != NULL && !IS_ERR(dir_item)) {
1520                 pending->error = -EEXIST;
1521                 goto dir_item_existed;
1522         } else if (IS_ERR(dir_item)) {
1523                 ret = PTR_ERR(dir_item);
1524                 btrfs_abort_transaction(trans, ret);
1525                 goto fail;
1526         }
1527         btrfs_release_path(path);
1528 
1529         /*
1530          * pull in the delayed directory update
1531          * and the delayed inode item
1532          * otherwise we corrupt the FS during
1533          * snapshot
1534          */
1535         ret = btrfs_run_delayed_items(trans, fs_info);
1536         if (ret) {      /* Transaction aborted */
1537                 btrfs_abort_transaction(trans, ret);
1538                 goto fail;
1539         }
1540 
1541         record_root_in_trans(trans, root, 0);
1542         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1543         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1544         btrfs_check_and_init_root_item(new_root_item);
1545 
1546         root_flags = btrfs_root_flags(new_root_item);
1547         if (pending->readonly)
1548                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1549         else
1550                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1551         btrfs_set_root_flags(new_root_item, root_flags);
1552 
1553         btrfs_set_root_generation_v2(new_root_item,
1554                         trans->transid);
1555         uuid_le_gen(&new_uuid);
1556         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1557         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1558                         BTRFS_UUID_SIZE);
1559         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1560                 memset(new_root_item->received_uuid, 0,
1561                        sizeof(new_root_item->received_uuid));
1562                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1563                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1564                 btrfs_set_root_stransid(new_root_item, 0);
1565                 btrfs_set_root_rtransid(new_root_item, 0);
1566         }
1567         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1568         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1569         btrfs_set_root_otransid(new_root_item, trans->transid);
1570 
1571         old = btrfs_lock_root_node(root);
1572         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1573         if (ret) {
1574                 btrfs_tree_unlock(old);
1575                 free_extent_buffer(old);
1576                 btrfs_abort_transaction(trans, ret);
1577                 goto fail;
1578         }
1579 
1580         btrfs_set_lock_blocking(old);
1581 
1582         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1583         /* clean up in any case */
1584         btrfs_tree_unlock(old);
1585         free_extent_buffer(old);
1586         if (ret) {
1587                 btrfs_abort_transaction(trans, ret);
1588                 goto fail;
1589         }
1590         /* see comments in should_cow_block() */
1591         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1592         smp_wmb();
1593 
1594         btrfs_set_root_node(new_root_item, tmp);
1595         /* record when the snapshot was created in key.offset */
1596         key.offset = trans->transid;
1597         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1598         btrfs_tree_unlock(tmp);
1599         free_extent_buffer(tmp);
1600         if (ret) {
1601                 btrfs_abort_transaction(trans, ret);
1602                 goto fail;
1603         }
1604 
1605         /*
1606          * insert root back/forward references
1607          */
1608         ret = btrfs_add_root_ref(trans, fs_info, objectid,
1609                                  parent_root->root_key.objectid,
1610                                  btrfs_ino(BTRFS_I(parent_inode)), index,
1611                                  dentry->d_name.name, dentry->d_name.len);
1612         if (ret) {
1613                 btrfs_abort_transaction(trans, ret);
1614                 goto fail;
1615         }
1616 
1617         key.offset = (u64)-1;
1618         pending->snap = btrfs_read_fs_root_no_name(fs_info, &key);
1619         if (IS_ERR(pending->snap)) {
1620                 ret = PTR_ERR(pending->snap);
1621                 btrfs_abort_transaction(trans, ret);
1622                 goto fail;
1623         }
1624 
1625         ret = btrfs_reloc_post_snapshot(trans, pending);
1626         if (ret) {
1627                 btrfs_abort_transaction(trans, ret);
1628                 goto fail;
1629         }
1630 
1631         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1632         if (ret) {
1633                 btrfs_abort_transaction(trans, ret);
1634                 goto fail;
1635         }
1636 
1637         /*
1638          * Do special qgroup accounting for snapshot, as we do some qgroup
1639          * snapshot hack to do fast snapshot.
1640          * To co-operate with that hack, we do hack again.
1641          * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1642          */
1643         ret = qgroup_account_snapshot(trans, root, parent_root,
1644                                       pending->inherit, objectid);
1645         if (ret < 0)
1646                 goto fail;
1647 
1648         ret = btrfs_insert_dir_item(trans, parent_root,
1649                                     dentry->d_name.name, dentry->d_name.len,
1650                                     BTRFS_I(parent_inode), &key,
1651                                     BTRFS_FT_DIR, index);
1652         /* We have check then name at the beginning, so it is impossible. */
1653         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1654         if (ret) {
1655                 btrfs_abort_transaction(trans, ret);
1656                 goto fail;
1657         }
1658 
1659         btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +
1660                                          dentry->d_name.len * 2);
1661         parent_inode->i_mtime = parent_inode->i_ctime =
1662                 current_time(parent_inode);
1663         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1664         if (ret) {
1665                 btrfs_abort_transaction(trans, ret);
1666                 goto fail;
1667         }
1668         ret = btrfs_uuid_tree_add(trans, fs_info, new_uuid.b,
1669                                   BTRFS_UUID_KEY_SUBVOL, objectid);
1670         if (ret) {
1671                 btrfs_abort_transaction(trans, ret);
1672                 goto fail;
1673         }
1674         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1675                 ret = btrfs_uuid_tree_add(trans, fs_info,
1676                                           new_root_item->received_uuid,
1677                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1678                                           objectid);
1679                 if (ret && ret != -EEXIST) {
1680                         btrfs_abort_transaction(trans, ret);
1681                         goto fail;
1682                 }
1683         }
1684 
1685         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1686         if (ret) {
1687                 btrfs_abort_transaction(trans, ret);
1688                 goto fail;
1689         }
1690 
1691 fail:
1692         pending->error = ret;
1693 dir_item_existed:
1694         trans->block_rsv = rsv;
1695         trans->bytes_reserved = 0;
1696 clear_skip_qgroup:
1697         btrfs_clear_skip_qgroup(trans);
1698 no_free_objectid:
1699         kfree(new_root_item);
1700         pending->root_item = NULL;
1701         btrfs_free_path(path);
1702         pending->path = NULL;
1703 
1704         return ret;
1705 }
1706 
1707 /*
1708  * create all the snapshots we've scheduled for creation
1709  */
1710 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1711                                              struct btrfs_fs_info *fs_info)
1712 {
1713         struct btrfs_pending_snapshot *pending, *next;
1714         struct list_head *head = &trans->transaction->pending_snapshots;
1715         int ret = 0;
1716 
1717         list_for_each_entry_safe(pending, next, head, list) {
1718                 list_del(&pending->list);
1719                 ret = create_pending_snapshot(trans, fs_info, pending);
1720                 if (ret)
1721                         break;
1722         }
1723         return ret;
1724 }
1725 
1726 static void update_super_roots(struct btrfs_fs_info *fs_info)
1727 {
1728         struct btrfs_root_item *root_item;
1729         struct btrfs_super_block *super;
1730 
1731         super = fs_info->super_copy;
1732 
1733         root_item = &fs_info->chunk_root->root_item;
1734         super->chunk_root = root_item->bytenr;
1735         super->chunk_root_generation = root_item->generation;
1736         super->chunk_root_level = root_item->level;
1737 
1738         root_item = &fs_info->tree_root->root_item;
1739         super->root = root_item->bytenr;
1740         super->generation = root_item->generation;
1741         super->root_level = root_item->level;
1742         if (btrfs_test_opt(fs_info, SPACE_CACHE))
1743                 super->cache_generation = root_item->generation;
1744         if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1745                 super->uuid_tree_generation = root_item->generation;
1746 }
1747 
1748 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1749 {
1750         struct btrfs_transaction *trans;
1751         int ret = 0;
1752 
1753         spin_lock(&info->trans_lock);
1754         trans = info->running_transaction;
1755         if (trans)
1756                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1757         spin_unlock(&info->trans_lock);
1758         return ret;
1759 }
1760 
1761 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1762 {
1763         struct btrfs_transaction *trans;
1764         int ret = 0;
1765 
1766         spin_lock(&info->trans_lock);
1767         trans = info->running_transaction;
1768         if (trans)
1769                 ret = is_transaction_blocked(trans);
1770         spin_unlock(&info->trans_lock);
1771         return ret;
1772 }
1773 
1774 /*
1775  * wait for the current transaction commit to start and block subsequent
1776  * transaction joins
1777  */
1778 static void wait_current_trans_commit_start(struct btrfs_fs_info *fs_info,
1779                                             struct btrfs_transaction *trans)
1780 {
1781         wait_event(fs_info->transaction_blocked_wait,
1782                    trans->state >= TRANS_STATE_COMMIT_START || trans->aborted);
1783 }
1784 
1785 /*
1786  * wait for the current transaction to start and then become unblocked.
1787  * caller holds ref.
1788  */
1789 static void wait_current_trans_commit_start_and_unblock(
1790                                         struct btrfs_fs_info *fs_info,
1791                                         struct btrfs_transaction *trans)
1792 {
1793         wait_event(fs_info->transaction_wait,
1794                    trans->state >= TRANS_STATE_UNBLOCKED || trans->aborted);
1795 }
1796 
1797 /*
1798  * commit transactions asynchronously. once btrfs_commit_transaction_async
1799  * returns, any subsequent transaction will not be allowed to join.
1800  */
1801 struct btrfs_async_commit {
1802         struct btrfs_trans_handle *newtrans;
1803         struct work_struct work;
1804 };
1805 
1806 static void do_async_commit(struct work_struct *work)
1807 {
1808         struct btrfs_async_commit *ac =
1809                 container_of(work, struct btrfs_async_commit, work);
1810 
1811         /*
1812          * We've got freeze protection passed with the transaction.
1813          * Tell lockdep about it.
1814          */
1815         if (ac->newtrans->type & __TRANS_FREEZABLE)
1816                 __sb_writers_acquired(ac->newtrans->fs_info->sb, SB_FREEZE_FS);
1817 
1818         current->journal_info = ac->newtrans;
1819 
1820         btrfs_commit_transaction(ac->newtrans);
1821         kfree(ac);
1822 }
1823 
1824 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1825                                    int wait_for_unblock)
1826 {
1827         struct btrfs_fs_info *fs_info = trans->fs_info;
1828         struct btrfs_async_commit *ac;
1829         struct btrfs_transaction *cur_trans;
1830 
1831         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1832         if (!ac)
1833                 return -ENOMEM;
1834 
1835         INIT_WORK(&ac->work, do_async_commit);
1836         ac->newtrans = btrfs_join_transaction(trans->root);
1837         if (IS_ERR(ac->newtrans)) {
1838                 int err = PTR_ERR(ac->newtrans);
1839                 kfree(ac);
1840                 return err;
1841         }
1842 
1843         /* take transaction reference */
1844         cur_trans = trans->transaction;
1845         refcount_inc(&cur_trans->use_count);
1846 
1847         btrfs_end_transaction(trans);
1848 
1849         /*
1850          * Tell lockdep we've released the freeze rwsem, since the
1851          * async commit thread will be the one to unlock it.
1852          */
1853         if (ac->newtrans->type & __TRANS_FREEZABLE)
1854                 __sb_writers_release(fs_info->sb, SB_FREEZE_FS);
1855 
1856         schedule_work(&ac->work);
1857 
1858         /* wait for transaction to start and unblock */
1859         if (wait_for_unblock)
1860                 wait_current_trans_commit_start_and_unblock(fs_info, cur_trans);
1861         else
1862                 wait_current_trans_commit_start(fs_info, cur_trans);
1863 
1864         if (current->journal_info == trans)
1865                 current->journal_info = NULL;
1866 
1867         btrfs_put_transaction(cur_trans);
1868         return 0;
1869 }
1870 
1871 
1872 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1873                                 struct btrfs_root *root, int err)
1874 {
1875         struct btrfs_fs_info *fs_info = root->fs_info;
1876         struct btrfs_transaction *cur_trans = trans->transaction;
1877         DEFINE_WAIT(wait);
1878 
1879         WARN_ON(refcount_read(&trans->use_count) > 1);
1880 
1881         btrfs_abort_transaction(trans, err);
1882 
1883         spin_lock(&fs_info->trans_lock);
1884 
1885         /*
1886          * If the transaction is removed from the list, it means this
1887          * transaction has been committed successfully, so it is impossible
1888          * to call the cleanup function.
1889          */
1890         BUG_ON(list_empty(&cur_trans->list));
1891 
1892         list_del_init(&cur_trans->list);
1893         if (cur_trans == fs_info->running_transaction) {
1894                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1895                 spin_unlock(&fs_info->trans_lock);
1896                 wait_event(cur_trans->writer_wait,
1897                            atomic_read(&cur_trans->num_writers) == 1);
1898 
1899                 spin_lock(&fs_info->trans_lock);
1900         }
1901         spin_unlock(&fs_info->trans_lock);
1902 
1903         btrfs_cleanup_one_transaction(trans->transaction, fs_info);
1904 
1905         spin_lock(&fs_info->trans_lock);
1906         if (cur_trans == fs_info->running_transaction)
1907                 fs_info->running_transaction = NULL;
1908         spin_unlock(&fs_info->trans_lock);
1909 
1910         if (trans->type & __TRANS_FREEZABLE)
1911                 sb_end_intwrite(fs_info->sb);
1912         btrfs_put_transaction(cur_trans);
1913         btrfs_put_transaction(cur_trans);
1914 
1915         trace_btrfs_transaction_commit(root);
1916 
1917         if (current->journal_info == trans)
1918                 current->journal_info = NULL;
1919         btrfs_scrub_cancel(fs_info);
1920 
1921         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1922 }
1923 
1924 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1925 {
1926         /*
1927          * We use writeback_inodes_sb here because if we used
1928          * btrfs_start_delalloc_roots we would deadlock with fs freeze.
1929          * Currently are holding the fs freeze lock, if we do an async flush
1930          * we'll do btrfs_join_transaction() and deadlock because we need to
1931          * wait for the fs freeze lock.  Using the direct flushing we benefit
1932          * from already being in a transaction and our join_transaction doesn't
1933          * have to re-take the fs freeze lock.
1934          */
1935         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1936                 writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
1937         return 0;
1938 }
1939 
1940 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1941 {
1942         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1943                 btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1944 }
1945 
1946 static inline void
1947 btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans)
1948 {
1949         wait_event(cur_trans->pending_wait,
1950                    atomic_read(&cur_trans->pending_ordered) == 0);
1951 }
1952 
1953 int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
1954 {
1955         struct btrfs_fs_info *fs_info = trans->fs_info;
1956         struct btrfs_transaction *cur_trans = trans->transaction;
1957         struct btrfs_transaction *prev_trans = NULL;
1958         int ret;
1959 
1960         /* Stop the commit early if ->aborted is set */
1961         if (unlikely(READ_ONCE(cur_trans->aborted))) {
1962                 ret = cur_trans->aborted;
1963                 btrfs_end_transaction(trans);
1964                 return ret;
1965         }
1966 
1967         /* make a pass through all the delayed refs we have so far
1968          * any runnings procs may add more while we are here
1969          */
1970         ret = btrfs_run_delayed_refs(trans, fs_info, 0);
1971         if (ret) {
1972                 btrfs_end_transaction(trans);
1973                 return ret;
1974         }
1975 
1976         btrfs_trans_release_metadata(trans, fs_info);
1977         trans->block_rsv = NULL;
1978 
1979         cur_trans = trans->transaction;
1980 
1981         /*
1982          * set the flushing flag so procs in this transaction have to
1983          * start sending their work down.
1984          */
1985         cur_trans->delayed_refs.flushing = 1;
1986         smp_wmb();
1987 
1988         if (!list_empty(&trans->new_bgs))
1989                 btrfs_create_pending_block_groups(trans, fs_info);
1990 
1991         ret = btrfs_run_delayed_refs(trans, fs_info, 0);
1992         if (ret) {
1993                 btrfs_end_transaction(trans);
1994                 return ret;
1995         }
1996 
1997         if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
1998                 int run_it = 0;
1999 
2000                 /* this mutex is also taken before trying to set
2001                  * block groups readonly.  We need to make sure
2002                  * that nobody has set a block group readonly
2003                  * after a extents from that block group have been
2004                  * allocated for cache files.  btrfs_set_block_group_ro
2005                  * will wait for the transaction to commit if it
2006                  * finds BTRFS_TRANS_DIRTY_BG_RUN set.
2007                  *
2008                  * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
2009                  * only one process starts all the block group IO.  It wouldn't
2010                  * hurt to have more than one go through, but there's no
2011                  * real advantage to it either.
2012                  */
2013                 mutex_lock(&fs_info->ro_block_group_mutex);
2014                 if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
2015                                       &cur_trans->flags))
2016                         run_it = 1;
2017                 mutex_unlock(&fs_info->ro_block_group_mutex);
2018 
2019                 if (run_it)
2020                         ret = btrfs_start_dirty_block_groups(trans, fs_info);
2021         }
2022         if (ret) {
2023                 btrfs_end_transaction(trans);
2024                 return ret;
2025         }
2026 
2027         spin_lock(&fs_info->trans_lock);
2028         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
2029                 spin_unlock(&fs_info->trans_lock);
2030                 refcount_inc(&cur_trans->use_count);
2031                 ret = btrfs_end_transaction(trans);
2032 
2033                 wait_for_commit(cur_trans);
2034 
2035                 if (unlikely(cur_trans->aborted))
2036                         ret = cur_trans->aborted;
2037 
2038                 btrfs_put_transaction(cur_trans);
2039 
2040                 return ret;
2041         }
2042 
2043         cur_trans->state = TRANS_STATE_COMMIT_START;
2044         wake_up(&fs_info->transaction_blocked_wait);
2045 
2046         if (cur_trans->list.prev != &fs_info->trans_list) {
2047                 prev_trans = list_entry(cur_trans->list.prev,
2048                                         struct btrfs_transaction, list);
2049                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
2050                         refcount_inc(&prev_trans->use_count);
2051                         spin_unlock(&fs_info->trans_lock);
2052 
2053                         wait_for_commit(prev_trans);
2054                         ret = prev_trans->aborted;
2055 
2056                         btrfs_put_transaction(prev_trans);
2057                         if (ret)
2058                                 goto cleanup_transaction;
2059                 } else {
2060                         spin_unlock(&fs_info->trans_lock);
2061                 }
2062         } else {
2063                 spin_unlock(&fs_info->trans_lock);
2064         }
2065 
2066         extwriter_counter_dec(cur_trans, trans->type);
2067 
2068         ret = btrfs_start_delalloc_flush(fs_info);
2069         if (ret)
2070                 goto cleanup_transaction;
2071 
2072         ret = btrfs_run_delayed_items(trans, fs_info);
2073         if (ret)
2074                 goto cleanup_transaction;
2075 
2076         wait_event(cur_trans->writer_wait,
2077                    extwriter_counter_read(cur_trans) == 0);
2078 
2079         /* some pending stuffs might be added after the previous flush. */
2080         ret = btrfs_run_delayed_items(trans, fs_info);
2081         if (ret)
2082                 goto cleanup_transaction;
2083 
2084         btrfs_wait_delalloc_flush(fs_info);
2085 
2086         btrfs_wait_pending_ordered(cur_trans);
2087 
2088         btrfs_scrub_pause(fs_info);
2089         /*
2090          * Ok now we need to make sure to block out any other joins while we
2091          * commit the transaction.  We could have started a join before setting
2092          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2093          */
2094         spin_lock(&fs_info->trans_lock);
2095         cur_trans->state = TRANS_STATE_COMMIT_DOING;
2096         spin_unlock(&fs_info->trans_lock);
2097         wait_event(cur_trans->writer_wait,
2098                    atomic_read(&cur_trans->num_writers) == 1);
2099 
2100         /* ->aborted might be set after the previous check, so check it */
2101         if (unlikely(READ_ONCE(cur_trans->aborted))) {
2102                 ret = cur_trans->aborted;
2103                 goto scrub_continue;
2104         }
2105         /*
2106          * the reloc mutex makes sure that we stop
2107          * the balancing code from coming in and moving
2108          * extents around in the middle of the commit
2109          */
2110         mutex_lock(&fs_info->reloc_mutex);
2111 
2112         /*
2113          * We needn't worry about the delayed items because we will
2114          * deal with them in create_pending_snapshot(), which is the
2115          * core function of the snapshot creation.
2116          */
2117         ret = create_pending_snapshots(trans, fs_info);
2118         if (ret) {
2119                 mutex_unlock(&fs_info->reloc_mutex);
2120                 goto scrub_continue;
2121         }
2122 
2123         /*
2124          * We insert the dir indexes of the snapshots and update the inode
2125          * of the snapshots' parents after the snapshot creation, so there
2126          * are some delayed items which are not dealt with. Now deal with
2127          * them.
2128          *
2129          * We needn't worry that this operation will corrupt the snapshots,
2130          * because all the tree which are snapshoted will be forced to COW
2131          * the nodes and leaves.
2132          */
2133         ret = btrfs_run_delayed_items(trans, fs_info);
2134         if (ret) {
2135                 mutex_unlock(&fs_info->reloc_mutex);
2136                 goto scrub_continue;
2137         }
2138 
2139         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
2140         if (ret) {
2141                 mutex_unlock(&fs_info->reloc_mutex);
2142                 goto scrub_continue;
2143         }
2144 
2145         /*
2146          * make sure none of the code above managed to slip in a
2147          * delayed item
2148          */
2149         btrfs_assert_delayed_root_empty(fs_info);
2150 
2151         WARN_ON(cur_trans != trans->transaction);
2152 
2153         /* btrfs_commit_tree_roots is responsible for getting the
2154          * various roots consistent with each other.  Every pointer
2155          * in the tree of tree roots has to point to the most up to date
2156          * root for every subvolume and other tree.  So, we have to keep
2157          * the tree logging code from jumping in and changing any
2158          * of the trees.
2159          *
2160          * At this point in the commit, there can't be any tree-log
2161          * writers, but a little lower down we drop the trans mutex
2162          * and let new people in.  By holding the tree_log_mutex
2163          * from now until after the super is written, we avoid races
2164          * with the tree-log code.
2165          */
2166         mutex_lock(&fs_info->tree_log_mutex);
2167 
2168         ret = commit_fs_roots(trans, fs_info);
2169         if (ret) {
2170                 mutex_unlock(&fs_info->tree_log_mutex);
2171                 mutex_unlock(&fs_info->reloc_mutex);
2172                 goto scrub_continue;
2173         }
2174 
2175         /*
2176          * Since the transaction is done, we can apply the pending changes
2177          * before the next transaction.
2178          */
2179         btrfs_apply_pending_changes(fs_info);
2180 
2181         /* commit_fs_roots gets rid of all the tree log roots, it is now
2182          * safe to free the root of tree log roots
2183          */
2184         btrfs_free_log_root_tree(trans, fs_info);
2185 
2186         /*
2187          * commit_fs_roots() can call btrfs_save_ino_cache(), which generates
2188          * new delayed refs. Must handle them or qgroup can be wrong.
2189          */
2190         ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
2191         if (ret) {
2192                 mutex_unlock(&fs_info->tree_log_mutex);
2193                 mutex_unlock(&fs_info->reloc_mutex);
2194                 goto scrub_continue;
2195         }
2196 
2197         /*
2198          * Since fs roots are all committed, we can get a quite accurate
2199          * new_roots. So let's do quota accounting.
2200          */
2201         ret = btrfs_qgroup_account_extents(trans, fs_info);
2202         if (ret < 0) {
2203                 mutex_unlock(&fs_info->tree_log_mutex);
2204                 mutex_unlock(&fs_info->reloc_mutex);
2205                 goto scrub_continue;
2206         }
2207 
2208         ret = commit_cowonly_roots(trans, fs_info);
2209         if (ret) {
2210                 mutex_unlock(&fs_info->tree_log_mutex);
2211                 mutex_unlock(&fs_info->reloc_mutex);
2212                 goto scrub_continue;
2213         }
2214 
2215         /*
2216          * The tasks which save the space cache and inode cache may also
2217          * update ->aborted, check it.
2218          */
2219         if (unlikely(READ_ONCE(cur_trans->aborted))) {
2220                 ret = cur_trans->aborted;
2221                 mutex_unlock(&fs_info->tree_log_mutex);
2222                 mutex_unlock(&fs_info->reloc_mutex);
2223                 goto scrub_continue;
2224         }
2225 
2226         btrfs_prepare_extent_commit(fs_info);
2227 
2228         cur_trans = fs_info->running_transaction;
2229 
2230         btrfs_set_root_node(&fs_info->tree_root->root_item,
2231                             fs_info->tree_root->node);
2232         list_add_tail(&fs_info->tree_root->dirty_list,
2233                       &cur_trans->switch_commits);
2234 
2235         btrfs_set_root_node(&fs_info->chunk_root->root_item,
2236                             fs_info->chunk_root->node);
2237         list_add_tail(&fs_info->chunk_root->dirty_list,
2238                       &cur_trans->switch_commits);
2239 
2240         switch_commit_roots(cur_trans, fs_info);
2241 
2242         ASSERT(list_empty(&cur_trans->dirty_bgs));
2243         ASSERT(list_empty(&cur_trans->io_bgs));
2244         update_super_roots(fs_info);
2245 
2246         btrfs_set_super_log_root(fs_info->super_copy, 0);
2247         btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2248         memcpy(fs_info->super_for_commit, fs_info->super_copy,
2249                sizeof(*fs_info->super_copy));
2250 
2251         btrfs_update_commit_device_size(fs_info);
2252         btrfs_update_commit_device_bytes_used(fs_info, cur_trans);
2253 
2254         clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2255         clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2256 
2257         btrfs_trans_release_chunk_metadata(trans);
2258 
2259         spin_lock(&fs_info->trans_lock);
2260         cur_trans->state = TRANS_STATE_UNBLOCKED;
2261         fs_info->running_transaction = NULL;
2262         spin_unlock(&fs_info->trans_lock);
2263         mutex_unlock(&fs_info->reloc_mutex);
2264 
2265         wake_up(&fs_info->transaction_wait);
2266 
2267         ret = btrfs_write_and_wait_transaction(trans, fs_info);
2268         if (ret) {
2269                 btrfs_handle_fs_error(fs_info, ret,
2270                                       "Error while writing out transaction");
2271                 mutex_unlock(&fs_info->tree_log_mutex);
2272                 goto scrub_continue;
2273         }
2274 
2275         ret = write_all_supers(fs_info, 0);
2276         /*
2277          * the super is written, we can safely allow the tree-loggers
2278          * to go about their business
2279          */
2280         mutex_unlock(&fs_info->tree_log_mutex);
2281         if (ret)
2282                 goto scrub_continue;
2283 
2284         btrfs_finish_extent_commit(trans, fs_info);
2285 
2286         if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2287                 btrfs_clear_space_info_full(fs_info);
2288 
2289         fs_info->last_trans_committed = cur_trans->transid;
2290         /*
2291          * We needn't acquire the lock here because there is no other task
2292          * which can change it.
2293          */
2294         cur_trans->state = TRANS_STATE_COMPLETED;
2295         wake_up(&cur_trans->commit_wait);
2296 
2297         spin_lock(&fs_info->trans_lock);
2298         list_del_init(&cur_trans->list);
2299         spin_unlock(&fs_info->trans_lock);
2300 
2301         btrfs_put_transaction(cur_trans);
2302         btrfs_put_transaction(cur_trans);
2303 
2304         if (trans->type & __TRANS_FREEZABLE)
2305                 sb_end_intwrite(fs_info->sb);
2306 
2307         trace_btrfs_transaction_commit(trans->root);
2308 
2309         btrfs_scrub_continue(fs_info);
2310 
2311         if (current->journal_info == trans)
2312                 current->journal_info = NULL;
2313 
2314         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2315 
2316         /*
2317          * If fs has been frozen, we can not handle delayed iputs, otherwise
2318          * it'll result in deadlock about SB_FREEZE_FS.
2319          */
2320         if (current != fs_info->transaction_kthread &&
2321             current != fs_info->cleaner_kthread &&
2322             !test_bit(BTRFS_FS_FROZEN, &fs_info->flags))
2323                 btrfs_run_delayed_iputs(fs_info);
2324 
2325         return ret;
2326 
2327 scrub_continue:
2328         btrfs_scrub_continue(fs_info);
2329 cleanup_transaction:
2330         btrfs_trans_release_metadata(trans, fs_info);
2331         btrfs_trans_release_chunk_metadata(trans);
2332         trans->block_rsv = NULL;
2333         btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2334         if (current->journal_info == trans)
2335                 current->journal_info = NULL;
2336         cleanup_transaction(trans, trans->root, ret);
2337 
2338         return ret;
2339 }
2340 
2341 /*
2342  * return < 0 if error
2343  * 0 if there are no more dead_roots at the time of call
2344  * 1 there are more to be processed, call me again
2345  *
2346  * The return value indicates there are certainly more snapshots to delete, but
2347  * if there comes a new one during processing, it may return 0. We don't mind,
2348  * because btrfs_commit_super will poke cleaner thread and it will process it a
2349  * few seconds later.
2350  */
2351 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2352 {
2353         int ret;
2354         struct btrfs_fs_info *fs_info = root->fs_info;
2355 
2356         spin_lock(&fs_info->trans_lock);
2357         if (list_empty(&fs_info->dead_roots)) {
2358                 spin_unlock(&fs_info->trans_lock);
2359                 return 0;
2360         }
2361         root = list_first_entry(&fs_info->dead_roots,
2362                         struct btrfs_root, root_list);
2363         list_del_init(&root->root_list);
2364         spin_unlock(&fs_info->trans_lock);
2365 
2366         btrfs_debug(fs_info, "cleaner removing %llu", root->objectid);
2367 
2368         btrfs_kill_all_delayed_nodes(root);
2369 
2370         if (btrfs_header_backref_rev(root->node) <
2371                         BTRFS_MIXED_BACKREF_REV)
2372                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2373         else
2374                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2375 
2376         return (ret < 0) ? 0 : 1;
2377 }
2378 
2379 void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2380 {
2381         unsigned long prev;
2382         unsigned long bit;
2383 
2384         prev = xchg(&fs_info->pending_changes, 0);
2385         if (!prev)
2386                 return;
2387 
2388         bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2389         if (prev & bit)
2390                 btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2391         prev &= ~bit;
2392 
2393         bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2394         if (prev & bit)
2395                 btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2396         prev &= ~bit;
2397 
2398         bit = 1 << BTRFS_PENDING_COMMIT;
2399         if (prev & bit)
2400                 btrfs_debug(fs_info, "pending commit done");
2401         prev &= ~bit;
2402 
2403         if (prev)
2404                 btrfs_warn(fs_info,
2405                         "unknown pending changes left 0x%lx, ignoring", prev);
2406 }
2407 

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