On Sat 06-04-19 15:13:13, ZhangXiaoxu wrote:
> When the buffer write failed, 'end_buffer_write_sync' and
> 'end_buffer_async_write' will clear the uptodate flag. But the
> data in the buffer maybe newer than disk. In some case, this
> will lead data corruption.
>
> For example: ext4 flush metadata to disk failed, it will clear
> the uptodate flag. when a new coming call want the buffer, it will
> read it from the disk(because the buffer no uptodate flag). But
> the journal not checkpoint now, it will read old data from disk.
> If read successfully, ext4 will write the old data to the new
> journal, the data will corruption.
>
> So, don't clear the uptodate flag when write the buffer failed.
>
> Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@xxxxxxxxxx>
Thanks for the patch. But what are the chances that after the write has
failed the read will succeed? Also there were places that were using
buffer_uptodate() to detect IO errors. Did you check all those got
converted to using buffer_write_io_error() instead?
Honza
> ---
> fs/buffer.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index ce35760..9fe1827 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -172,7 +172,6 @@ void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
> } else {
> buffer_io_error(bh, ", lost sync page write");
> mark_buffer_write_io_error(bh);
> - clear_buffer_uptodate(bh);
> }
> unlock_buffer(bh);
> put_bh(bh);
> @@ -325,7 +324,6 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate)
> } else {
> buffer_io_error(bh, ", lost async page write");
> mark_buffer_write_io_error(bh);
> - clear_buffer_uptodate(bh);
> SetPageError(page);
> }
>
> --
> 2.7.4
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
