From: Vaibhav Jain <vaibhav@xxxxxxxxxxxxx> commit a2948b17f6b936fc52f86c0f92c46d2f91928b79 upstream. 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. Link: http://lore.kernel.org/r/161703936121.36.7260632399582101498.stgit@e1fbed493c87 [1] Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support") Reported-by: Shivaprasad G Bhat <sbhat@xxxxxxxxxxxxx> Signed-off-by: Vaibhav Jain <vaibhav@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210402092555.208590-1-vaibhav@xxxxxxxxxxxxx Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/nvdimm/region_devs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -1142,6 +1142,11 @@ int nvdimm_has_flush(struct nd_region *n || !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; @@ -1152,8 +1157,8 @@ int nvdimm_has_flush(struct nd_region *n } /* - * 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; }
