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Commit 4d69883e authored by Vaibhav Jain's avatar Vaibhav Jain Committed by Lee Jones
Browse files

UPSTREAM: libnvdimm/region: Fix nvdimm_has_flush() to handle ND_REGION_ASYNC 

In case a platform doesn't provide explicit flush-hints but provides an
explicit flush callback via ND_REGION_ASYNC region flag, then
nvdimm_has_flush() still returns '0' indicating that writes do not
require flushing. This happens on PPC64 with patch at [1] applied, where
'deep_flush' of a region was denied even though an explicit flush
function was provided.

Fix this by adding a condition to nvdimm_has_flush() to test for the
ND_REGION_ASYNC flag on the region and see if a 'region->flush' callback
is assigned.

Bug: 254441685
Link: http://lore.kernel.org/r/161703936121.36.7260632399582101498.stgit@e1fbed493c87

 [1]
Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
Reported-by: default avatarShivaprasad G Bhat <sbhat@linux.ibm.com>
Signed-off-by: default avatarVaibhav Jain <vaibhav@linux.ibm.com>
Link: https://lore.kernel.org/r/20210402092555.208590-1-vaibhav@linux.ibm.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
(cherry picked from commit a2948b17f6b936fc52f86c0f92c46d2f91928b79)
Signed-off-by: default avatarLee Jones <joneslee@google.com>
Change-Id: I220650135909d6a57f46443ea98b9aae5228d008
parent fb9ad704

drivers/nvdimm/region_devs.c

+7 −2
Original line number Diff line number Diff line
@@ -1186,6 +1186,11 @@ int nvdimm_has_flush(struct nd_region *nd_region) 
			|| !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))

		return -ENXIO;



	/* Test if an explicit flush function is defined */

	if (test_bit(ND_REGION_ASYNC, &nd_region->flags) && nd_region->flush)

		return 1;



	/* Test if any flush hints for the region are available */

	for (i = 0; i < nd_region->ndr_mappings; i++) {

		struct nd_mapping *nd_mapping = &nd_region->mapping[i];

		struct nvdimm *nvdimm = nd_mapping->nvdimm;
@@ -1196,8 +1201,8 @@ int nvdimm_has_flush(struct nd_region *nd_region) 
	}



	/*

	 * The platform defines dimm devices without hints, assume

	 * platform persistence mechanism like ADR

	 * The platform defines dimm devices without hints nor explicit flush,

	 * assume platform persistence mechanism like ADR

	 */

	return 0;

}