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 2a1762c..e95df43 100644 (file)
--- 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);