NFS: Don't accept more reads/writes if the open context recovery failed

If the state recovery failed, we want to ensure that the application
doesn't try to use the same file descriptor for more reads or writes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pagelist.c

@@ -104,6 +104,8 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
 	struct nfs_page		*req;
 	struct nfs_lock_context *l_ctx;
 
+	if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
+		return ERR_PTR(-EBADF);
 	/* try to allocate the request struct */
 	req = nfs_page_alloc();
 	if (req == NULL)