ceph: Don't forget the 'up_read(&osdc->map_sem)' if met error.

commit 494ddd11 upstream.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/ceph/ioctl.c

@@ -196,8 +196,10 @@ static long ceph_ioctl_get_dataloc(struct file *file, void __user *arg)
 	r = ceph_calc_file_object_mapping(&ci->i_layout, dl.file_offset, len,
 					  &dl.object_no, &dl.object_offset,
 					  &olen);
-	if (r < 0)
+	if (r < 0) {
+		up_read(&osdc->map_sem);
 		return -EIO;
+	}
 	dl.file_offset -= dl.object_offset;
 	dl.object_size = ceph_file_layout_object_size(ci->i_layout);
 	dl.block_size = ceph_file_layout_su(ci->i_layout);