ceph: pass parent inode info to ceph_encode_dentry_release if we have it

If we have a parent inode reference already, then we don't need to
go back up the directory tree to find one.

Link: http://tracker.ceph.com/issues/18148
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/caps.c

@@ -3924,9 +3924,10 @@ int ceph_encode_inode_release(void **p, struct inode *inode,
 }
 
 int ceph_encode_dentry_release(void **p, struct dentry *dentry,
+			       struct inode *dir,
 			       int mds, int drop, int unless)
 {
-	struct dentry *parent;
+	struct dentry *parent = NULL;
 	struct ceph_mds_request_release *rel = *p;
 	struct ceph_dentry_info *di = ceph_dentry(dentry);
 	int force = 0;
@@ -3941,11 +3942,13 @@ int ceph_encode_dentry_release(void **p, struct dentry *dentry,
 	spin_lock(&dentry->d_lock);
 	if (di->lease_session && di->lease_session->s_mds == mds)
 		force = 1;
-	parent = dget(dentry->d_parent);
+	if (!dir) {
+		parent = dget(dentry->d_parent);
+		dir = d_inode(parent);
+	}
 	spin_unlock(&dentry->d_lock);
 
-	ret = ceph_encode_inode_release(p, d_inode(parent), mds, drop,
-					unless, force);
+	ret = ceph_encode_inode_release(p, dir, mds, drop, unless, force);
 	dput(parent);
 
 	spin_lock(&dentry->d_lock);