ext4: use generic_writepages instead of __writepage/write_cache_pages

Code cleanup. Instead of writing an internal static function, use the
available generic_writepages().

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/inode.c

@@ -2694,15 +2694,6 @@ out:
 	return err;
 }
 
-static int __writepage(struct page *page, struct writeback_control *wbc,
-		       void *data)
-{
-	struct address_space *mapping = data;
-	int ret = ext4_writepage(page, wbc);
-	mapping_set_error(mapping, ret);
-	return ret;
-}
-
 static int ext4_writepages(struct address_space *mapping,
 			   struct writeback_control *wbc)
 {
@@ -2740,11 +2731,7 @@ static int ext4_writepages(struct address_space *mapping,
 		goto out_writepages;
 
 	if (ext4_should_journal_data(inode)) {
-		struct blk_plug plug;
-
-		blk_start_plug(&plug);
-		ret = write_cache_pages(mapping, wbc, __writepage, mapping);
-		blk_finish_plug(&plug);
+		ret = generic_writepages(mapping, wbc);
 		goto out_writepages;
 	}