nfs: fix open(O_RDONLY|O_TRUNC) in NFS4.0

nfs4_proc_setattr removes ATTR_OPEN from sattr->ia_valid, but later
nfs4_do_setattr checks for it

Signed-off-by: Nadav Shemer <nadav@tonian.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -2940,10 +2940,10 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 
 	/* Deal with open(O_TRUNC) */
 	if (sattr->ia_valid & ATTR_OPEN)
-		sattr->ia_valid &= ~(ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
+		sattr->ia_valid &= ~(ATTR_MTIME|ATTR_CTIME);
 
 	/* Optimization: if the end result is no change, don't RPC */
-	if ((sattr->ia_valid & ~(ATTR_FILE)) == 0)
+	if ((sattr->ia_valid & ~(ATTR_FILE|ATTR_OPEN)) == 0)
 		return 0;
 
 	/* Search for an existing open(O_WRITE) file */