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. References: [1] "powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall" https://lore.kernel.org/linux-nvdimm/161703936121.36.7260632399 582101498.stgit@e1fbed493c87 Reported-by: Shivaprasad G Bhat <[email protected]> Signed-off-by: Vaibhav Jain <[email protected]> --- drivers/nvdimm/region_devs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index ef23119db574..e05cc9f8a9fd 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -1239,6 +1239,11 @@ 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; @@ -1249,8 +1254,8 @@ 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; } -- 2.30.2 _______________________________________________ Linux-nvdimm mailing list -- [email protected] To unsubscribe send an email to [email protected]
