Vaibhav Jain <[email protected]> writes:
> 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.
>
May be this should have
Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
Without this we will mark the pmem disk not having FUA support?
> 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
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