ceph: request xattrs if xattr_version is zero

Following sequence of events can happen.
  - Client releases an inode, queues cap release message.
  - A 'lookup' reply brings the same inode back, but the reply
    doesn't contain xattrs because MDS didn't receive the cap release
    message and thought client already has up-to-data xattrs.

The fix is force sending a getattr request to MDS if xattrs_version
is 0. The getattr mask is set to CEPH_STAT_CAP_XATTR, so MDS knows client
does not have xattr.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/ioctl.c b/fs/ceph/ioctl.c
index a822a6e..d7dc812 100644
--- a/fs/ceph/ioctl.c
+++ b/fs/ceph/ioctl.c
@@ -19,7 +19,7 @@
 	struct ceph_ioctl_layout l;
 	int err;
 
-	err = ceph_do_getattr(file_inode(file), CEPH_STAT_CAP_LAYOUT);
+	err = ceph_do_getattr(file_inode(file), CEPH_STAT_CAP_LAYOUT, false);
 	if (!err) {
 		l.stripe_unit = ceph_file_layout_su(ci->i_layout);
 		l.stripe_count = ceph_file_layout_stripe_count(ci->i_layout);
@@ -74,7 +74,7 @@
 		return -EFAULT;
 
 	/* validate changed params against current layout */
-	err = ceph_do_getattr(file_inode(file), CEPH_STAT_CAP_LAYOUT);
+	err = ceph_do_getattr(file_inode(file), CEPH_STAT_CAP_LAYOUT, false);
 	if (err)
 		return err;