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

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Message-ID: <149875883642.10031.1077982680312378809.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:   Thu, 29 Jun 2017 10:53:56 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-nvdimm@...ts.01.org
Cc:     Jan Kara <jack@...e.cz>, Matthew Wilcox <mawilcox@...rosoft.com>,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Jeff Moyer <jmoyer@...hat.com>, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org,
        Ross Zwisler <ross.zwisler@...ux.intel.com>, hch@....de
Subject: [PATCH v4 11/16] libnvdimm, pmem: fix persistence warning

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@...hat.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Matthew Wilcox <mawilcox@...rosoft.com>
Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Signed-off-by: Dan Williams <dan.j.williams@...el.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 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++) {