From: Michal Suchanek <[email protected]>

commit a46624580376a3a0beb218d94cbc7f258696e29f upstream.

DM writecache does not handle asynchronous pmem. Reject it when
supplied as cache.

Link: https://lore.kernel.org/linux-nvdimm/[email protected]/
Fixes: 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver")
Signed-off-by: Michal Suchanek <[email protected]>
Acked-by: Mikulas Patocka <[email protected]>
Cc: [email protected] # 5.3+
Signed-off-by: Mike Snitzer <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/md/dm-writecache.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -2104,6 +2104,12 @@ invalid_optional:
        }
 
        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";


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