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authorAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>2019-09-24 17:13:27 +0530
committerDan Williams <dan.j.williams@intel.com>2019-09-24 10:33:19 -0700
commit4c806b897d6075bfa5067e524fb058c57ab64e7b (patch)
tree45a203c9771bbe13a8b4ee06252abc10234f8c2f
parent674f31a352da5e9f621f757b9a89262f486533a0 (diff)
libnvdimm/region: Enable MAP_SYNC for volatile regions
Some environments want to use a host tmpfs/ramdisk to back guest pmem. While the data is not persisted relative to the host it *is* persisted relative to guest crashes / reboots. The guest is free to use dax and MAP_SYNC to keep filesystem metadata consistent with dax accesses without requiring guest fsync(). The guest can also observe that the region is volatile and skip cache flushing as global visibility is enough to "persist" data relative to the host staying alive over guest reset events. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Reviewed-by: Pankaj Gupta <pagupta@redhat.com> Link: https://lore.kernel.org/r/20190924114327.14700-1-aneesh.kumar@linux.ibm.com [djbw: reword the changelog] Signed-off-by: Dan Williams <dan.j.williams@intel.com>
-rw-r--r--drivers/nvdimm/region_devs.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index ab91890f2486..ef423ba1a711 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1168,6 +1168,9 @@ EXPORT_SYMBOL_GPL(nvdimm_has_cache);
bool is_nvdimm_sync(struct nd_region *nd_region)
{
+ if (is_nd_volatile(&nd_region->dev))
+ return true;
+
return is_nd_pmem(&nd_region->dev) &&
!test_bit(ND_REGION_ASYNC, &nd_region->flags);
}