[f2fs-dev][PATCH 3/3] f2fs: avoid to truncate non-updated page partially

[Chao Yu <chao2.yu@samsung.com>]

After we call find_data_page in truncate_partial_data_page, we could not
guarantee this page is updated or not as error may occurred in lower layer.

We'd better check status of the page to avoid this no updated page be
writebacked to device.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
 fs/f2fs/file.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 9c49c59..fc569ca 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -380,13 +380,15 @@ static void truncate_partial_data_page(struct inode *inode, u64 from)
 		return;
 
 	lock_page(page);
-	if (unlikely(page->mapping != inode->i_mapping)) {
-		f2fs_put_page(page, 1);
-		return;
-	}
+	if (unlikely(!PageUptodate(page) ||
+			page->mapping != inode->i_mapping))
+		goto out;
+
 	f2fs_wait_on_page_writeback(page, DATA);
 	zero_user(page, offset, PAGE_CACHE_SIZE - offset);
 	set_page_dirty(page);
+
+out:
 	f2fs_put_page(page, 1);
 }
 
-- 
1.7.9.5