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

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Date:   Tue, 30 Jun 2020 17:49:24 +0200
From:   Michal Suchanek <msuchanek@...e.de>
To:     Mikulas Patocka <mpatocka@...hat.com>
Cc:     Michal Suchanek <msuchanek@...e.de>, 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: [PATCH v3] dm writecache: reject asynchronous pmem.

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>
---
 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