1:49 a.m.
Yi reported[1] that after commit a3619190d62e ("libnvdimm/pfn: stop
padding pmem namespaces to section alignment"), it was no longer
possible to create a device dax namespace with a 1G alignment. The
reason was that the pmem region was not itself 1G-aligned. The code
happily skips past the first 512M, but fails to account for a now
misaligned end offset (since space was allocated starting at that
misaligned address, and extending for size GBs). Reintroduce
end_trunc, so that the code correctly handles the misaligned end
address. This results in the same behavior as before the introduction
of the offending commit.
[1] https://lists.01.org/pipermail/linux-nvdimm/2019-July/022813.html
Fixes: commit a3619190d62e ("libnvdimm/pfn: stop padding pmem namespaces ...")
Reported-and-tested-by: Yi Zhang <yi.zhang(a)redhat.com>
Signed-off-by: Jeff Moyer <jmoyer(a)redhat.com>
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 3e7b11c..cb98b8f 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -655,6 +655,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
resource_size_t start, size;
struct nd_region *nd_region;
unsigned long npfns, align;
+ u32 end_trunc;
struct nd_pfn_sb *pfn_sb;
phys_addr_t offset;
const char *sig;
@@ -696,6 +697,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
size = resource_size(&nsio->res);
npfns = PHYS_PFN(size - SZ_8K);
align = max(nd_pfn->align, (1UL << SUBSECTION_SHIFT));
+ end_trunc = start + size - ALIGN_DOWN(start + size, align);
if (nd_pfn->mode == PFN_MODE_PMEM) {
/*
* The altmap should be padded out to the block size used
@@ -714,7 +716,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
return -ENXIO;
}
- npfns = PHYS_PFN(size - offset);
+ npfns = PHYS_PFN(size - offset - end_trunc);
pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
pfn_sb->dataoff = cpu_to_le64(offset);
pfn_sb->npfns = cpu_to_le64(npfns);
@@ -723,6 +725,7 @@ 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(3);
+ pfn_sb->end_trunc = cpu_to_le32(end_trunc);
pfn_sb->align = cpu_to_le32(nd_pfn->align);
checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
pfn_sb->checksum = cpu_to_le64(checksum);