Revert: "f2fs: check last page index in cached bio to decide submission"

There is one case that we can leave bio in f2fs, result in hanging
page writeback waiter.

Thread A				Thread B
- f2fs_write_cache_pages
 - f2fs_submit_page_write
 page #0 cached in bio #0 of cold log
 - f2fs_submit_page_write
 page #1 cached in bio #1 of warm log
					- f2fs_write_cache_pages
					 - f2fs_submit_page_write
					 bio is full, submit bio #1 contain page #1
 - f2fs_submit_merged_write_cond(, page #1)
 fail to submit bio #0 due to page #1 is not in any cached bios.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index f4b9b81..97b429b 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -276,8 +276,7 @@
 	dec_page_count(sbi, F2FS_DIRTY_META);
 
 	if (wbc->for_reclaim)
-		f2fs_submit_merged_write_cond(sbi, page->mapping->host,
-						0, page->index, META);
+		f2fs_submit_merged_write_cond(sbi, NULL, page, 0, META);
 
 	unlock_page(page);