Re: [PATCH] ext4: fix checking on nr_to_write

Ming Lei
2013-10-14T13:50:54Z

On Mon, Oct 14, 2013 at 8:58 PM, Jan Kara <jack@suse.cz> wrote:
> Umm, I guess I see what are you pointing at. Thanks for catching that.
> mpage_process_page_bufs() always adds a buffer to mpd even if nr_to_write
> is already <= 0. But I would somewhat prefer not to call
> mpage_prepare_extent_to_map() at all when nr_to_write <= 0. So a patch
> like:
> ret = mpage_prepare_extent_to_map(&mpd);
> if (!ret) {
> - if (mpd.map.m_len)
> + if (mpd.map.m_len) {
> ret = mpage_map_and_submit_extent(handle, &mpd,
> &give_up_on_write);
> - else {
> + done = (wbc->nr_to_write <= 0);
> + } else {
>
> Should also fix your problem, am I right?

I am afraid it can't, because we need to stop scanning page cache
if end of file is reached.

nr_to_write will become negative inside mpage_map_and_submit_extent(),
that is why I fix it inside mpage_prepare_extent_to_map().

Thanks,
--
Ming Lei