f2fs: fix to reorder set_page_dirty and wait_on_page_writeback

This patch reorders flow from

- update page
- set_page_dirty
- wait_on_page_writeback

to

- wait_on_page_writeback
- update page
- set_page_dirty

The reason is:
- set_page_dirty will increase reference of dirty page, the reference
should be cleared before wait_on_page_writeback to keep its consistency.
- some devices need stable page during page writebacking, so we
should not change page's data.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index f13548e59124..eb5991d57e06 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1291,11 +1291,12 @@ static void commit_checkpoint(struct f2fs_sb_info *sbi,
 	struct page *page = f2fs_grab_meta_page(sbi, blk_addr);
 	int err;
 
-	memcpy(page_address(page), src, PAGE_SIZE);
-	set_page_dirty(page);
-
 	f2fs_wait_on_page_writeback(page, META, true);
 	f2fs_bug_on(sbi, PageWriteback(page));
+
+	memcpy(page_address(page), src, PAGE_SIZE);
+
+	set_page_dirty(page);
 	if (unlikely(!clear_page_dirty_for_io(page)))
 		f2fs_bug_on(sbi, 1);