Re: [PATCH RFC 04/29] fsverity: add per-sb workqueue for post read processing

Tejun Heo
2025-08-11T17:51:28Z

Hello,

On Mon, Aug 11, 2025 at 01:45:19PM +0200, Christoph Hellwig wrote:
> On Mon, Jul 28, 2025 at 10:30:08PM +0200, Andrey Albershteyn wrote:
> > From: Andrey Albershteyn <aalbersh@redhat.com>
> >
> > For XFS, fsverity's global workqueue is not really suitable due to:
> >
> > 1. High priority workqueues are used within XFS to ensure that data
> > IO completion cannot stall processing of journal IO completions.
> > Hence using a WQ_HIGHPRI workqueue directly in the user data IO
> > path is a potential filesystem livelock/deadlock vector.
>
> Do they? I though the whole point of WQ_HIGHPRI was that they'd
> have separate rescue workers to avoid any global pool effects.

HIGHPRI and MEM_RECLAIM are orthogonal. HIGHPRI makes the workqueue use
worker pools with high priority, so all work items would execute at MIN_NICE
(-20). Hmm... actually, rescuer doesn't set priority according to the
workqueue's, which seems buggy.

Thanks.

--
tejun