linux-kernel - Re: [PATCH v3] dm writecache: reject asynchronous pmem.

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Date:   Tue, 30 Jun 2020 12:14:26 -0400 (EDT)
From:   Mikulas Patocka <mpatocka@...hat.com>
To:     Michal Suchanek <msuchanek@...e.de>
cc:     linux-nvdimm@...ts.01.org,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Jan Kara <jack@...e.cz>, Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        Jakub Staron <jstaron@...gle.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Yuval Shaia <yuval.shaia@...cle.com>,
        Cornelia Huck <cohuck@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] dm writecache: reject asynchronous pmem.



On Tue, 30 Jun 2020, Mikulas Patocka wrote:

> 
> 
> On Tue, 30 Jun 2020, Michal Suchanek wrote:
> 
> > The writecache driver does not handle asynchronous pmem. Reject it when
> > supplied as cache.
> > 
> > Link: https://lore.kernel.org/linux-nvdimm/87lfk5hahc.fsf@linux.ibm.com/
> > Fixes: 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver")
> > 
> > Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> 
> Acked-by: Mikulas Patocka <mpatocka@...hat.com>

BTW, we should also add

Cc: stable@...r.kernel.org	# v5.3+

> > ---
> >  drivers/md/dm-writecache.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
> > index 30505d70f423..5358894bb9fd 100644
> > --- a/drivers/md/dm-writecache.c
> > +++ b/drivers/md/dm-writecache.c
> > @@ -2266,6 +2266,12 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
> >  	}
> >  
> >  	if (WC_MODE_PMEM(wc)) {
> > +		if (!dax_synchronous(wc->ssd_dev->dax_dev)) {
> > +			r = -EOPNOTSUPP;
> > +			ti->error = "Asynchronous persistent memory not supported as pmem cache";
> > +			goto bad;
> > +		}
> > +
> >  		r = persistent_memory_claim(wc);
> >  		if (r) {
> >  			ti->error = "Unable to map persistent memory for cache";
> > -- 
> > 2.26.2
> > 
>