locks: break delegations on any attribute modification

NFSv4 uses leases to guarantee that clients can cache metadata as well
as data.

Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 27ba21b..94b5f5d 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -427,7 +427,7 @@
 			goto out_nfserr;
 		fh_lock(fhp);
 
-		host_err = notify_change(dentry, iap);
+		host_err = notify_change(dentry, iap, NULL);
 		err = nfserrno(host_err);
 		fh_unlock(fhp);
 	}
@@ -988,7 +988,11 @@
 	ia.ia_valid = ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
-	notify_change(dentry, &ia);
+	/*
+	 * Note we call this on write, so notify_change will not
+	 * encounter any conflicting delegations:
+	 */
+	notify_change(dentry, &ia, NULL);
 	mutex_unlock(&dentry->d_inode->i_mutex);
 }