On 5/22/19 11:50 AM, Aneesh Kumar K.V wrote:
This allows us to make changes in a backward incompatible way. I have
kept the PFN_MIN_VERSION in this patch '0' because we are not introducing
any incompatible changes in this patch. We also may want to backport this
to older kernels.
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
---
drivers/nvdimm/pfn.h | 9 ++++++++-
drivers/nvdimm/pfn_devs.c | 4 ++++
drivers/nvdimm/pmem.c | 26 ++++++++++++++++++++++----
3 files changed, 34 insertions(+), 5 deletions(-)
diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h
index dde9853453d3..1b10ae5773b6 100644
--- a/drivers/nvdimm/pfn.h
+++ b/drivers/nvdimm/pfn.h
@@ -20,6 +20,12 @@
#define PFN_SIG_LEN 16
#define PFN_SIG "NVDIMM_PFN_INFO\0"
#define DAX_SIG "NVDIMM_DAX_INFO\0"
+/*
+ * increment this when we are making changes such that older
+ * kernel should fail to initialize that namespace.
+ */
+
+#define PFN_MIN_VERSION 0
struct nd_pfn_sb {
u8 signature[PFN_SIG_LEN];
@@ -36,7 +42,8 @@ struct nd_pfn_sb {
__le32 end_trunc;
/* minor-version-2 record the base alignment of the mapping */
__le32 align;
- u8 padding[4000];
+ __le16 min_verison;
+ u8 padding[3998];
__le64 checksum;
};
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 01f40672507f..3250de70a7b3 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -439,6 +439,9 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb), 0))
return -ENXIO;
+ if (le16_to_cpu(pfn_sb->min_version > PFN_MIN_VERSION))
+ return -EOPNOTSUPP;
+ if (le16_to_cpu(pfn_sb->min_version) > PFN_MIN_VERSION)
+ return -EOPNOTSUPP;
-aneesh
