NFSv3: Ensure that do_proc_get_root() reports errors correctly

commit 08660043 upstream.

If the rpc call to NFS3PROC_FSINFO fails, then we need to report that
error so that the mount fails. Otherwise we can end up with a
superblock with completely unusable values for block sizes, maxfilesize,
etc.
Reported-by: Yuanming Chen <hikvision_linux@163.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/nfs/nfs3proc.c

@@ -68,7 +68,7 @@ do_proc_get_root(struct rpc_clnt *client, struct nfs_fh *fhandle,
 	nfs_fattr_init(info->fattr);
 	status = rpc_call_sync(client, &msg, 0);
 	dprintk("%s: reply fsinfo: %d\n", __func__, status);
-	if (!(info->fattr->valid & NFS_ATTR_FATTR)) {
+	if (status == 0 && !(info->fattr->valid & NFS_ATTR_FATTR)) {
 		msg.rpc_proc = &nfs3_procedures[NFS3PROC_GETATTR];
 		msg.rpc_resp = info->fattr;
 		status = rpc_call_sync(client, &msg, 0);