diff options
| -rw-r--r-- | fs/btrfs/ctree.h | 2 | ||||
| -rw-r--r-- | fs/btrfs/tree-log.c | 56 |
2 files changed, 40 insertions, 18 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index a0c588e5fc89..331554fd6fd1 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1038,7 +1038,7 @@ enum { BTRFS_ROOT_DEAD_RELOC_TREE, /* Mark dead root stored on device whose cleanup needs to be resumed */ BTRFS_ROOT_DEAD_TREE, - /* The root has a log tree. Used only for subvolume roots. */ + /* The root has a log tree. Used for subvolume roots and the tree root. */ BTRFS_ROOT_HAS_LOG_TREE, /* Qgroup flushing is in progress */ BTRFS_ROOT_QGROUP_FLUSHING, diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 582911a36ee0..254c2ee43aae 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -138,8 +138,25 @@ static int start_log_trans(struct btrfs_trans_handle *trans, struct btrfs_log_ctx *ctx) { struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_root *tree_root = fs_info->tree_root; int ret = 0; + /* + * First check if the log root tree was already created. If not, create + * it before locking the root's log_mutex, just to keep lockdep happy. + */ + if (!test_bit(BTRFS_ROOT_HAS_LOG_TREE, &tree_root->state)) { + mutex_lock(&tree_root->log_mutex); + if (!fs_info->log_root_tree) { + ret = btrfs_init_log_root_tree(trans, fs_info); + if (!ret) + set_bit(BTRFS_ROOT_HAS_LOG_TREE, &tree_root->state); + } + mutex_unlock(&tree_root->log_mutex); + if (ret) + return ret; + } + mutex_lock(&root->log_mutex); if (root->log_root) { @@ -155,13 +172,6 @@ static int start_log_trans(struct btrfs_trans_handle *trans, set_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state); } } else { - mutex_lock(&fs_info->tree_log_mutex); - if (!fs_info->log_root_tree) - ret = btrfs_init_log_root_tree(trans, fs_info); - mutex_unlock(&fs_info->tree_log_mutex); - if (ret) - goto out; - ret = btrfs_add_log_tree(trans, root); if (ret) goto out; @@ -3021,6 +3031,8 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, int log_transid = 0; struct btrfs_log_ctx root_log_ctx; struct blk_plug plug; + u64 log_root_start; + u64 log_root_level; mutex_lock(&root->log_mutex); log_transid = ctx->log_transid; @@ -3198,22 +3210,31 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, goto out_wake_log_root; } - btrfs_set_super_log_root(fs_info->super_for_commit, - log_root_tree->node->start); - btrfs_set_super_log_root_level(fs_info->super_for_commit, - btrfs_header_level(log_root_tree->node)); - + log_root_start = log_root_tree->node->start; + log_root_level = btrfs_header_level(log_root_tree->node); log_root_tree->log_transid++; mutex_unlock(&log_root_tree->log_mutex); /* - * Nobody else is going to jump in and write the ctree - * super here because the log_commit atomic below is protecting - * us. We must be called with a transaction handle pinning - * the running transaction open, so a full commit can't hop - * in and cause problems either. + * Here we are guaranteed that nobody is going to write the superblock + * for the current transaction before us and that neither we do write + * our superblock before the previous transaction finishes its commit + * and writes its superblock, because: + * + * 1) We are holding a handle on the current transaction, so no body + * can commit it until we release the handle; + * + * 2) Before writing our superblock we acquire the tree_log_mutex, so + * if the previous transaction is still committing, and hasn't yet + * written its superblock, we wait for it to do it, because a + * transaction commit acquires the tree_log_mutex when the commit + * begins and releases it only after writing its superblock. */ + mutex_lock(&fs_info->tree_log_mutex); + btrfs_set_super_log_root(fs_info->super_for_commit, log_root_start); + btrfs_set_super_log_root_level(fs_info->super_for_commit, log_root_level); ret = write_all_supers(fs_info, 1); + mutex_unlock(&fs_info->tree_log_mutex); if (ret) { btrfs_set_log_full_commit(trans); btrfs_abort_transaction(trans, ret); @@ -3298,6 +3319,7 @@ int btrfs_free_log_root_tree(struct btrfs_trans_handle *trans, if (fs_info->log_root_tree) { free_log_tree(trans, fs_info->log_root_tree); fs_info->log_root_tree = NULL; + clear_bit(BTRFS_ROOT_HAS_LOG_TREE, &fs_info->tree_root->state); } return 0; } |