From: Liu Bo <bo.li.liu@oracle.com>
Date: Thu, 27 Dec 2012 09:01:22 +0000 (+0000)
Subject: Btrfs: save us a read_lock
X-Git-Tag: v3.9-rc1~4^2~30^2~62
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=39f9d028c9906cc7b625df84442205f6bcc84477;p=cascardo%2Flinux.git

Btrfs: save us a read_lock

This does not change the logic of code, but can save us a read_lock.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
---

diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 2a1762c66041..e95df435d897 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -113,11 +113,10 @@ again:
 		read_unlock(&eb->lock);
 		return;
 	}
-	read_unlock(&eb->lock);
-	wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
-	read_lock(&eb->lock);
 	if (atomic_read(&eb->blocking_writers)) {
 		read_unlock(&eb->lock);
+		wait_event(eb->write_lock_wq,
+			   atomic_read(&eb->blocking_writers) == 0);
 		goto again;
 	}
 	atomic_inc(&eb->read_locks);