filemap: minor cleanup for filemap_write_and_wait_range

Restructure the logic in filemap_write_and_wait_range to simplify the code
and make it more consistent with file_write_and_wait_range. No functional
change intended.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Miaohe Lin <[e-mail]>
Reviewed-by: Muchun Song <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

mm/filemap.c

···
 int filemap_write_and_wait_range(struct address_space *mapping,
 				 loff_t lstart, loff_t lend)
 {
-	int err = 0;
+	int err = 0, err2;
 
 	if (mapping_needs_writeback(mapping)) {
 		err = __filemap_fdatawrite_range(mapping, lstart, lend,
···
 		 * But the -EIO is special case, it may indicate the worst
 		 * thing (e.g. bug) happened, so we avoid waiting for it.
 		 */
-		if (err != -EIO) {
-			int err2 = filemap_fdatawait_range(mapping,
-						lstart, lend);
-			if (!err)
-				err = err2;
-		} else {
-			/* Clear any previously stored errors */
-			filemap_check_errors(mapping);
-		}
-	} else {
-		err = filemap_check_errors(mapping);
+		if (err != -EIO)
+			__filemap_fdatawait_range(mapping, lstart, lend);
 	}
+	err2 = filemap_check_errors(mapping);
+	if (!err)
+		err = err2;
 	return err;
 }
 EXPORT_SYMBOL(filemap_write_and_wait_range);