diff options
Diffstat (limited to 'fs/btrfs/locking.c')
| -rw-r--r-- | fs/btrfs/locking.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 9063072b399b..0eab3cb274a1 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -286,6 +286,31 @@ struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root) } /* + * Loop around taking references on and locking the root node of the tree in + * nowait mode until we end up with a lock on the root node or returning to + * avoid blocking. + * + * Return: root extent buffer with read lock held or -EAGAIN. + */ +struct extent_buffer *btrfs_try_read_lock_root_node(struct btrfs_root *root) +{ + struct extent_buffer *eb; + + while (1) { + eb = btrfs_root_node(root); + if (!btrfs_try_tree_read_lock(eb)) { + free_extent_buffer(eb); + return ERR_PTR(-EAGAIN); + } + if (eb == root->node) + break; + btrfs_tree_read_unlock(eb); + free_extent_buffer(eb); + } + return eb; +} + +/* * DREW locks * ========== * |