[PATCH v2] locks: skip posix unlock when there are no posix locks

[David Teigland <teigland@redhat.com>]

When i_flock contains only flocks, the posix unlock is
unnecessary, but called anyway.  On gfs2, ocfs2, and
possibly others with f_op->lock, the posix unlock can
be costly, so only do it if posix locks exist.

Signed-off-by: David Teigland <teigland@redhat.com>
---
 fs/locks.c |   17 ++++++++++++++++-
 1 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 703f545..d47f497 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1982,15 +1982,30 @@ out:
 void locks_remove_posix(struct file *filp, fl_owner_t owner)
 {
 	struct file_lock lock;
+	struct file_lock **before;
+	struct inode *inode;
 
 	/*
 	 * If there are no locks held on this file, we don't need to call
 	 * posix_lock_file().  Another process could be setting a lock on this
 	 * file at the same time, but we wouldn't remove that lock anyway.
 	 */
-	if (!filp->f_path.dentry->d_inode->i_flock)
+	inode = filp->f_path.dentry->d_inode;
+
+	if (!inode->i_flock)
 		return;
 
+	lock_flocks();
+	for_each_lock(inode, before) {
+		struct file_lock *fl = *before;
+		if (IS_POSIX(fl))
+			goto do_unlock;
+	}
+	unlock_flocks();
+	return;
+
+do_unlock:
+	unlock_flocks();
 	lock.fl_type = F_UNLCK;
 	lock.fl_flags = FL_POSIX | FL_CLOSE;
 	lock.fl_start = 0;
-- 
1.7.6