nfs4: client: do not send empty SETATTR after OPEN_CREATE

OPEN_CREATE with EXCLUSIVE4_1 sends initial file permission.
Ignoring  fact, that server have indicated that file mod is set, client
will send yet another SETATTR request, but, as mode is already set,
new SETATTR will be empty. This is not a problem, nevertheless
an extra roundtrip and slow open on high latency networks.

This change is aims to skip extra setattr after open  if there are
no attributes to be set.

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4proc.c

@@ -74,6 +74,17 @@
 #define NFS4_POLL_RETRY_MIN	(HZ/10)
 #define NFS4_POLL_RETRY_MAX	(15*HZ)
 
+/* file attributes which can be mapped to nfs attributes */
+#define NFS4_VALID_ATTRS (ATTR_MODE \
+	| ATTR_UID \
+	| ATTR_GID \
+	| ATTR_SIZE \
+	| ATTR_ATIME \
+	| ATTR_MTIME \
+	| ATTR_CTIME \
+	| ATTR_ATIME_SET \
+	| ATTR_MTIME_SET)
+
 struct nfs4_opendata;
 static int _nfs4_proc_open(struct nfs4_opendata *data);
 static int _nfs4_recover_proc_open(struct nfs4_opendata *data);
@@ -2558,15 +2569,20 @@ static int _nfs4_do_open(struct inode *dir,
 	if ((opendata->o_arg.open_flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL) &&
 	    (opendata->o_arg.createmode != NFS4_CREATE_GUARDED)) {
 		nfs4_exclusive_attrset(opendata, sattr, &label);
-
+		/*
-		nfs_fattr_init(opendata->o_res.f_attr);
+		 * send create attributes which was not set by open
-		status = nfs4_do_setattr(state->inode, cred,
+		 * with an extra setattr.
-				opendata->o_res.f_attr, sattr,
+		 */
-				state, label, olabel);
+		if (sattr->ia_valid & NFS4_VALID_ATTRS) {
-		if (status == 0) {
+			nfs_fattr_init(opendata->o_res.f_attr);
-			nfs_setattr_update_inode(state->inode, sattr,
+			status = nfs4_do_setattr(state->inode, cred,
-					opendata->o_res.f_attr);
+					opendata->o_res.f_attr, sattr,
-			nfs_setsecurity(state->inode, opendata->o_res.f_attr, olabel);
+					state, label, olabel);
+			if (status == 0) {
+				nfs_setattr_update_inode(state->inode, sattr,
+						opendata->o_res.f_attr);
+				nfs_setsecurity(state->inode, opendata->o_res.f_attr, olabel);
+			}
 		}
 	}
 	if (opened && opendata->file_created)