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) {
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;
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;
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);
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;
}