Re: [PATCH v4] libnvdimm, btt: BTT updates for UEFI 2.7 format

The UEFI 2.7 specification defines an updated BTT metadata format, bumping the revision to 2.0. Add support for the new format, while retaining compatibility for the old 1.1 format. Cc: Toshi Kani <toshi.kani(a)hpe.com&gt; Cc: Linda Knippers <linda.knippers(a)hpe.com&gt; Cc: Dan Williams <dan.j.williams(a)intel.com&gt; Signed-off-by: Vishal Verma <vishal.l.verma(a)intel.com&gt;

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c index f05d9b0..09e7e76 100644 --- a/drivers/nvdimm/namespace_devs.c +++ b/drivers/nvdimm/namespace_devs.c @@ -1411,6 +1411,58 @@ static ssize_t dpa_extents_show(struct device *dev, } static DEVICE_ATTR_RO(dpa_extents); +static int btt_claim_class(struct device *dev) +{ + struct nd_region *nd_region = to_nd_region(dev->parent); + int i, loop_bitmask = 0; + + for (i = 0; i < nd_region->ndr_mappings; i++) { + struct nd_mapping *nd_mapping = &nd_region->mapping[i]; + struct nvdimm_drvdata *ndd = to_ndd(nd_mapping); + struct nd_namespace_index *nsindex; + + nsindex = to_namespace_index(ndd, ndd->ns_current); + if (nsindex == NULL) + loop_bitmask |= 1; + else { + /* check whether existing labels are v1.1 or v1.2 */ + if (__le16_to_cpu(nsindex->major) == 1 + && __le16_to_cpu(nsindex->minor) == 1) + loop_bitmask |= 2; + else + loop_bitmask |= 4; + } + } + /* + * If nsindex is null loop_bitmask's bit 0 will be set, and if an index + * block is found, a v1.1 label for any mapping will set bit 1, and a + * v1.2 label will set bit 2. + * + * At the end of the loop, only one of the three bits must be set. + * If multiple bits were set, it means the different mappings disagree + * about their labels, and this must be cleaned up first. + * + * If all the label index blocks are found to agree, nsindex of NULL + * implies labels haven't been initialized yet, and when they will, + * they will be of the 1.2 format, so we can assume BTT2.0 + * + * If 1.1 labels are found, we enforce BTT1.1, and if 1.2 labels are + * found, we enforce BTT2.0 + * + * If the loop was never entered, default to BTT1.1 (legacy namespaces) + */ + switch (loop_bitmask) { + case 0: + case 2: + return NVDIMM_CCLASS_BTT; + case 1: + case 4: + return NVDIMM_CCLASS_BTT2; + default: + return -ENXIO; + }