Commit 160f4089 authored Jul 28, 2014 by Filipe Manana Committed by Chris Mason Sep 17, 2014

Btrfs: avoid unnecessary switch of path locks to blocking mode

If we need to cow a node, increase the write lock level and retry the
tree search, there's no point of changing the node locks in our path
to blocking mode, as we only waste time and unnecessarily wake up other
tasks waiting on the spinning locks (just to block them again shortly
after) because we release our path before repeating the tree search.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

parent 24cdc847

fs/btrfs/ctree.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -2792,8 +2792,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
		if (!should_cow_block(trans, root, b))
		goto cow_done;

		btrfs_set_path_blocking(p);

		/*
		* must have write locks on this node and the
		* parent
		@@ -2807,6 +2805,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
		goto again;
		}

		btrfs_set_path_blocking(p);
		err = btrfs_cow_block(trans, root, b,
		p->nodes[level + 1],
		p->slots[level + 1], &b);