f2fs: submit node page write bios when really required

If many threads calls fsync with data writes, we don't need to flush every
bios having node page writes.
The f2fs_wait_on_page_writeback will flush its bios when the page is really
needed.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/node.c

@@ -1236,7 +1236,7 @@ int sync_node_pages(struct f2fs_sb_info *sbi, nid_t ino,
 	pgoff_t index, end;
 	struct pagevec pvec;
 	int step = ino ? 2 : 0;
-	int nwritten = 0, wrote = 0;
+	int nwritten = 0;
 
 	pagevec_init(&pvec, 0);
 
@@ -1326,8 +1326,6 @@ continue_unlock:
 
 			if (NODE_MAPPING(sbi)->a_ops->writepage(page, wbc))
 				unlock_page(page);
-			else
-				wrote++;
 
 			if (--wbc->nr_to_write == 0)
 				break;
@@ -1345,14 +1343,6 @@ continue_unlock:
 		step++;
 		goto next_step;
 	}
-
-	if (wrote) {
-		if (ino)
-			f2fs_submit_merged_bio_cond(sbi, NULL, NULL,
-							ino, NODE, WRITE);
-		else
-			f2fs_submit_merged_bio(sbi, NODE, WRITE);
-	}
 	return nwritten;
 }