In support of fixing a pfn info-block interpretation problem that requires a backwards incompatible format change introduce a mechanism to indicate a minimum support level to the parsing agent. Hopefully this mechanism never needs to be used, but it otherwise prevents the need to hunt for a state that causes old implementations to bail out.
For now, the method chosen to make implementations prior to this introduction fail is to use new PFN3_MODE_* values. The use of 'mode' ensures that older Linux fails, but agents like the EFI driver that only care about 'data_offset' can continue to ignore the requirement. That is to say 'data_offset' should always be valid, but the interpretation of values that older Linux kernels use to setup the dev_pagemap and perform sector-to-pfn translations is going to change. Cc: Jeff Moyer <[email protected]> Cc: Johannes Thumshirn <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- drivers/nvdimm/pfn.h | 4 +++- drivers/nvdimm/pfn_devs.c | 7 +++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h index dde9853453d3..710cb743fad6 100644 --- a/drivers/nvdimm/pfn.h +++ b/drivers/nvdimm/pfn.h @@ -20,6 +20,7 @@ #define PFN_SIG_LEN 16 #define PFN_SIG "NVDIMM_PFN_INFO\0" #define DAX_SIG "NVDIMM_DAX_INFO\0" +#define PFN_VERSION_SUPPORT 2 struct nd_pfn_sb { u8 signature[PFN_SIG_LEN]; @@ -36,7 +37,8 @@ struct nd_pfn_sb { __le32 end_trunc; /* minor-version-2 record the base alignment of the mapping */ __le32 align; - u8 padding[4000]; + __le16 min_version; + u8 padding[3998]; __le64 checksum; }; diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c index ba74a341da5d..108f9f7ed064 100644 --- a/drivers/nvdimm/pfn_devs.c +++ b/drivers/nvdimm/pfn_devs.c @@ -459,6 +459,12 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig) if (__le16_to_cpu(pfn_sb->version_minor) < 2) pfn_sb->align = 0; + if (__le16_to_cpu(pfn_sb->version_major) != 1) + return -EINVAL; + + if (__le16_to_cpu(pfn_sb->min_version) > PFN_VERSION_SUPPORT) + return -EINVAL; + switch (le32_to_cpu(pfn_sb->mode)) { case PFN_MODE_RAM: case PFN_MODE_PMEM: @@ -771,6 +777,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16); pfn_sb->version_major = cpu_to_le16(1); pfn_sb->version_minor = cpu_to_le16(2); + pfn_sb->min_version = cpu_to_le16(2); pfn_sb->start_pad = cpu_to_le32(start_pad); pfn_sb->end_trunc = cpu_to_le32(end_trunc); pfn_sb->align = cpu_to_le32(nd_pfn->align); _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
