diff options
| -rw-r--r-- | fs/btrfs/transaction.c | 76 |
1 files changed, 42 insertions, 34 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 1c3a1189c0bd..eb1c916d4884 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -162,6 +162,12 @@ static noinline void switch_commit_roots(struct btrfs_trans_handle *trans) struct btrfs_root *root, *tmp; struct btrfs_caching_control *caching_ctl, *next; + /* + * At this point no one can be using this transaction to modify any tree + * and no one can start another transaction to modify any tree either. + */ + ASSERT(cur_trans->state == TRANS_STATE_COMMIT_DOING); + down_write(&fs_info->commit_root_sem); list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits, dirty_list) { @@ -1236,6 +1242,12 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans) struct extent_buffer *eb; int ret; + /* + * At this point no one can be using this transaction to modify any tree + * and no one can start another transaction to modify any tree either. + */ + ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING); + eb = btrfs_lock_root_node(fs_info->tree_root); ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, BTRFS_NESTING_COW); @@ -1327,7 +1339,8 @@ void btrfs_add_dead_root(struct btrfs_root *root) } /* - * update all the cowonly tree roots on disk + * Update each subvolume root and its relocation root, if it exists, in the tree + * of tree roots. Also free log roots if they exist. */ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans) { @@ -1336,6 +1349,12 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans) int i; int ret; + /* + * At this point no one can be using this transaction to modify any tree + * and no one can start another transaction to modify any tree either. + */ + ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING); + spin_lock(&fs_info->fs_roots_radix_lock); while (1) { ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix, @@ -1348,6 +1367,14 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans) struct btrfs_root *root = gang[i]; int ret2; + /* + * At this point we can neither have tasks logging inodes + * from a root nor trying to commit a log tree. + */ + ASSERT(atomic_read(&root->log_writers) == 0); + ASSERT(atomic_read(&root->log_commit[0]) == 0); + ASSERT(atomic_read(&root->log_commit[1]) == 0); + radix_tree_tag_clear(&fs_info->fs_roots_radix, (unsigned long)root->root_key.objectid, BTRFS_ROOT_TRANS_TAG); @@ -1472,12 +1499,6 @@ static int qgroup_account_snapshot(struct btrfs_trans_handle *trans, return ret; } - /* - * We are going to commit transaction, see btrfs_commit_transaction() - * comment for reason locking tree_log_mutex - */ - mutex_lock(&fs_info->tree_log_mutex); - ret = commit_fs_roots(trans); if (ret) goto out; @@ -1513,8 +1534,6 @@ static int qgroup_account_snapshot(struct btrfs_trans_handle *trans, "Error while writing out transaction for qgroup"); out: - mutex_unlock(&fs_info->tree_log_mutex); - /* * Force parent root to be updated, as we recorded it before so its * last_trans == cur_transid. @@ -2246,24 +2265,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) WARN_ON(cur_trans != trans->transaction); - /* btrfs_commit_tree_roots is responsible for getting the - * various roots consistent with each other. Every pointer - * in the tree of tree roots has to point to the most up to date - * root for every subvolume and other tree. So, we have to keep - * the tree logging code from jumping in and changing any - * of the trees. - * - * At this point in the commit, there can't be any tree-log - * writers, but a little lower down we drop the trans mutex - * and let new people in. By holding the tree_log_mutex - * from now until after the super is written, we avoid races - * with the tree-log code. - */ - mutex_lock(&fs_info->tree_log_mutex); - ret = commit_fs_roots(trans); if (ret) - goto unlock_tree_log; + goto unlock_reloc; /* * Since the transaction is done, we can apply the pending changes @@ -2282,11 +2286,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) */ ret = btrfs_qgroup_account_extents(trans); if (ret < 0) - goto unlock_tree_log; + goto unlock_reloc; ret = commit_cowonly_roots(trans); if (ret) - goto unlock_tree_log; + goto unlock_reloc; /* * The tasks which save the space cache and inode cache may also @@ -2294,7 +2298,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) */ if (TRANS_ABORTED(cur_trans)) { ret = cur_trans->aborted; - goto unlock_tree_log; + goto unlock_reloc; } cur_trans = fs_info->running_transaction; @@ -2327,6 +2331,16 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) btrfs_trans_release_chunk_metadata(trans); + /* + * Before changing the transaction state to TRANS_STATE_UNBLOCKED and + * setting fs_info->running_transaction to NULL, lock tree_log_mutex to + * make sure that before we commit our superblock, no other task can + * start a new transaction and commit a log tree before we commit our + * superblock. Anyone trying to commit a log tree locks this mutex before + * writing its superblock. + */ + mutex_lock(&fs_info->tree_log_mutex); + spin_lock(&fs_info->trans_lock); cur_trans->state = TRANS_STATE_UNBLOCKED; fs_info->running_transaction = NULL; @@ -2339,10 +2353,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) if (ret) { btrfs_handle_fs_error(fs_info, ret, "Error while writing out transaction"); - /* - * reloc_mutex has been unlocked, tree_log_mutex is still held - * but we can't jump to unlock_tree_log causing double unlock - */ mutex_unlock(&fs_info->tree_log_mutex); goto scrub_continue; } @@ -2404,8 +2414,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) return ret; -unlock_tree_log: - mutex_unlock(&fs_info->tree_log_mutex); unlock_reloc: mutex_unlock(&fs_info->reloc_mutex); scrub_continue: |