Merge tag 'nfs-for-5.0-3' of git://git.linux-nfs.org/projects/anna/linux-nfs

Pull NFS client fixes from Anna Schumaker:
 "This addresses two bugs, one in the error code handling of
  nfs_page_async_flush() and one to fix a potential NULL pointer
  dereference in nfs_parse_devname().

  Stable bugfix:
   - Fix up return value on fatal errors in nfs_page_async_flush()

  Other bugfix:
   - Fix NULL pointer dereference of dev_name"

* tag 'nfs-for-5.0-3' of git://git.linux-nfs.org/projects/anna/linux-nfs:
  NFS: Fix up return value on fatal errors in nfs_page_async_flush()
  nfs: Fix NULL pointer dereference of dev_name

fs/nfs/super.c

@@ -1895,6 +1895,11 @@ static int nfs_parse_devname(const char *dev_name,
 	size_t len;
 	char *end;
 
+	if (unlikely(!dev_name || !*dev_name)) {
+		dfprintk(MOUNT, "NFS: device name not specified\n");
+		return -EINVAL;
+	}
+
 	/* Is the host name protected with square brakcets? */
 	if (*dev_name == '[') {
 		end = strchr(++dev_name, ']');

fs/nfs/write.c

@@ -621,11 +621,12 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 	nfs_set_page_writeback(page);
 	WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 
-	ret = 0;
+	ret = req->wb_context->error;
 	/* If there is a fatal error that covers this write, just exit */
-	if (nfs_error_is_fatal_on_server(req->wb_context->error))
+	if (nfs_error_is_fatal_on_server(ret))
 		goto out_launder;
 
+	ret = 0;
 	if (!nfs_pageio_add_request(pgio, req)) {
 		ret = pgio->pg_error;
 		/*
@@ -635,9 +636,9 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 			nfs_context_set_write_error(req->wb_context, ret);
 			if (nfs_error_is_fatal_on_server(ret))
 				goto out_launder;
-		}
+		} else
+			ret = -EAGAIN;
 		nfs_redirty_request(req);
-		ret = -EAGAIN;
 	} else
 		nfs_add_stats(page_file_mapping(page)->host,
 				NFSIOS_WRITEPAGES, 1);