On Tue, Jun 30, 2020 at 09:32:01AM -0400, 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....@linux.ibm.com/ > > Fixes: 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver") > > > > Signed-off-by: Michal Suchanek <msucha...@suse.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)) { > > -- > > Hi > > Shouldn't this be in the "if (WC_MODE_PMEM(wc))" block? That should be always the case at this point. > > WC_MODE_PMEM(wc) retrurns true if we are using persistent memory as a > cache device, otherwise we are using generic block device as a cache > device. This is to prevent the situation where we have WC_MODE_PMEM(wc) but cannot guarantee consistency because the async flush is not handled.
Thanks Michal
