[PATCH v4 11/16] libnvdimm, pmem: fix persistence warning

[Dan Williams]

The pmem driver assumes if platform firmware describes the memory
devices associated with a persistent memory range and
CONFIG_ARCH_HAS_PMEM_API=y that it has all the mechanism necessary to
flush data to a power-fail safe zone. We warn if the firmware does not
describe memory devices, but we also need to warn if the architecture
does not claim pmem support.

Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
 drivers/nvdimm/region_devs.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 3c06a6ea6958..41b4cdf5dea8 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1037,8 +1037,9 @@ int nvdimm_has_flush(struct nd_region *nd_region)
 {
 	int i;
 
-	/* no nvdimm == flushing capability unknown */
-	if (nd_region->ndr_mappings == 0)
+	/* no nvdimm or pmem api == flushing capability unknown */
+	if (nd_region->ndr_mappings == 0
+			|| !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
 		return -ENXIO;
 
 	for (i = 0; i < nd_region->ndr_mappings; i++) {