Re: [PATCH 3/4] writeback: Fix sync livelock due to b_dirty_time processing

On Thu, Jun 11, 2020 at 10:11:54AM +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 good,

Reviewed-by: Christoph Hellwig hch@lst.de