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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Dan Williams <dan.j.williams@intel.com>,
        Jeff Moyer <jmoyer@redhat.com>, Christoph Hellwig <hch@lst.de>,
        Matthew Wilcox <mawilcox@microsoft.com>,
        Ross Zwisler <ross.zwisler@linux.intel.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 152/293] libnvdimm, pmem: fix persistence
 warning
Thread-Topic: [PATCH AUTOSEL for 4.9 152/293] libnvdimm, pmem: fix persistence
 warning
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Date:   Mon, 9 Apr 2018 00:24:52 +0000
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From: Dan Williams <dan.j.williams@intel.com>

[ Upstream commit c00b396ef782cb2296200d868a0013d8ca1d615e ]

The pmem driver assumes if platform firmware describes the memory
devices associated with a persistent memory range and
CONFIG_ARCH_HAS_PMEM_API=3Dy 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@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 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 f62306246ca4..2ac9c6222914 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -970,8 +970,9 @@ int nvdimm_has_flush(struct nd_region *nd_region)
 {
 	int i;
=20
-	/* no nvdimm =3D=3D flushing capability unknown */
-	if (nd_region->ndr_mappings =3D=3D 0)
+	/* no nvdimm or pmem api =3D=3D flushing capability unknown */
+	if (nd_region->ndr_mappings =3D=3D 0
+			|| !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
 		return -ENXIO;
=20
 	for (i =3D 0; i < nd_region->ndr_mappings; i++) {
--=20
2.15.1