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/node.c b/fs/f2fs/node.c
index acb819b..b1e3ff8 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1565,8 +1565,7 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
 	up_read(&sbi->node_write);
 
 	if (wbc->for_reclaim) {
-		f2fs_submit_merged_write_cond(sbi, page->mapping->host, 0,
-						page->index, NODE);
+		f2fs_submit_merged_write_cond(sbi, NULL, page, 0, NODE);
 		submitted = NULL;
 	}
 
@@ -1631,13 +1630,13 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 			unsigned int *seq_id)
 {
 	pgoff_t index;
-	pgoff_t last_idx = ULONG_MAX;
 	struct pagevec pvec;
 	int ret = 0;
 	struct page *last_page = NULL;
 	bool marked = false;
 	nid_t ino = inode->i_ino;
 	int nr_pages;
+	int nwritten = 0;
 
 	if (atomic) {
 		last_page = last_fsync_dnode(sbi, ino);
@@ -1715,7 +1714,7 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 				f2fs_put_page(last_page, 0);
 				break;
 			} else if (submitted) {
-				last_idx = page->index;
+				nwritten++;
 			}
 
 			if (page == last_page) {
@@ -1741,8 +1740,8 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 		goto retry;
 	}
 out:
-	if (last_idx != ULONG_MAX)
-		f2fs_submit_merged_write_cond(sbi, NULL, ino, last_idx, NODE);
+	if (nwritten)
+		f2fs_submit_merged_write_cond(sbi, NULL, NULL, ino, NODE);
 	return ret ? -EIO: 0;
 }