Re: [PATCH 2/3] writeback: Fix sync livelock due to b_dirty_time processing

[Christoph Hellwig <hch@infradead.org>]

On Wed, Jun 10, 2020 at 05:54:56PM +0200, Jan Kara wrote:
> On Wed 10-06-20 08:06:14, Christoph Hellwig wrote:
> > On Mon, Jun 01, 2020 at 11:18:56AM +0200, Jan Kara wrote:
> > > When we are processing writeback for sync(2), move_expired_inodes()
> > > didn't set any inode expiry value (older_than_this). This can result in
> > > writeback never completing if there's steady stream of inodes added to
> > > b_dirty_time list as writeback rechecks dirty lists after each writeback
> > > round whether there's more work to be done. Fix the problem by using
> > > sync(2) start time is inode expiry value when processing b_dirty_time
> > > list similarly as for ordinarily dirtied inodes. This requires some
> > > refactoring of older_than_this handling which simplifies the code
> > > noticeably as a bonus.
> > 
> > Looks sane, but if you touch all the older_than_this users can we
> > rename it to something more reasonable like oldest or oldest_jif?
> 
> OK, I can certainly rename this. I've just realized that 'oldest' is really
> misleading since we are in fact processing inodes that were dirtied before
> the given time. So maybe name that 'dirtied_before'?

Sounds good to me.