ceph: no need to get parent inode in ceph_open

parent inode is needed in creating new inode case.  For ceph_open,
the target inode already exists.
Signed-off-by: NJianpeng Ma <jianpeng.ma@intel.com>
Signed-off-by: NYan, Zheng <zyan@redhat.com>

fs/ceph/file.c

@@ -136,7 +136,6 @@ int ceph_open(struct inode *inode, struct file *file)
 	struct ceph_mds_client *mdsc = fsc->mdsc;
 	struct ceph_mds_request *req;
 	struct ceph_file_info *cf = file->private_data;
-	struct inode *parent_inode = NULL;
 	int err;
 	int flags, fmode, wanted;
 
@@ -210,10 +209,7 @@ int ceph_open(struct inode *inode, struct file *file)
 	ihold(inode);
 
 	req->r_num_caps = 1;
-	if (flags & O_CREAT)
-		parent_inode = ceph_get_dentry_parent_inode(file->f_path.dentry);
-	err = ceph_mdsc_do_request(mdsc, parent_inode, req);
-	iput(parent_inode);
+	err = ceph_mdsc_do_request(mdsc, NULL, req);
 	if (!err)
 		err = ceph_init_file(inode, file, req->r_fmode);
 	ceph_mdsc_put_request(req);