pmem: only set QUEUE_FLAG_DAX for fsdax mode

QUEUE_FLAG_DAX is an indication that a given block device supports
filesystem DAX and should not be set for PMEM namespaces which are in "raw"
mode.  These namespaces lack struct page and are prevented from
participating in filesystem DAX as of commit 569d0365 ("dax: require
'struct page' by default for filesystem dax").
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: NMike Snitzer <snitzer@redhat.com>
Fixes: 569d0365 ("dax: require 'struct page' by default for filesystem dax")
Cc: stable@vger.kernel.org
Acked-by: NDan Williams <dan.j.williams@intel.com>
Reviewed-by: NToshi Kani <toshi.kani@hpe.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

drivers/nvdimm/pmem.c

@@ -414,7 +414,8 @@ static int pmem_attach_disk(struct device *dev,
 	blk_queue_logical_block_size(q, pmem_sector_size(ndns));
 	blk_queue_max_hw_sectors(q, UINT_MAX);
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
-	blk_queue_flag_set(QUEUE_FLAG_DAX, q);
+	if (pmem->pfn_flags & PFN_MAP)
+		blk_queue_flag_set(QUEUE_FLAG_DAX, q);
 	q->queuedata = pmem;
 
 	disk = alloc_disk_node(0, nid);