From a83342aa0c8f0ca90057d3837ae8d198186e5153 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Mon, 16 Feb 2015 19:36:47 +0100 Subject: btrfs: add comments to barriers before waitqueue_active Reduce number of undocumented barriers out there. Signed-off-by: David Sterba --- fs/btrfs/locking.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/btrfs/locking.c') diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index d7e6baf1b205..03f8630dbaf2 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -280,6 +280,9 @@ void btrfs_tree_unlock(struct extent_buffer *eb) if (blockers) { WARN_ON(atomic_read(&eb->spinning_writers)); atomic_dec(&eb->blocking_writers); + /* + * Make sure counter is updated before we wake up waiters. + */ smp_mb(); if (waitqueue_active(&eb->write_lock_wq)) wake_up(&eb->write_lock_wq); -- cgit v1.2.3