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

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Date:   Tue, 30 Jun 2020 14:35:28 +0200
From:   Michal Suchanek <msuchanek@...e.de>
To:     linux-nvdimm@...ts.01.org
Cc:     Michal Suchanek <msuchanek@...e.de>,
        Mikulas Patocka <mpatocka@...hat.com>,
        "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,
        Pankaj Gupta <pagupta@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Yuval Shaia <yuval.shaia@...cle.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Jakub Staron <jstaron@...gle.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] 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..57b0a972f6fd 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -2277,6 +2277,12 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
 		wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
 
+		if (!dax_synchronous(wc->ssd_dev->dax_dev)) {
+			r = -EOPNOTSUPP;
+			ti->error = "Asynchronous persistent memory not supported as pmem cache";
+			goto bad;
+		}
+
 		bio_list_init(&wc->flush_list);
 		wc->flush_thread = kthread_create(writecache_flush_thread, wc, "dm_writecache_flush");
 		if (IS_ERR(wc->flush_thread)) {
-- 
2.26.2