The pmem driver does not honor a forced read-only setting for very long:
$ blockdev --setro /dev/pmem0
$ blockdev --getro /dev/pmem0
1
followed by various commands like these:
$ blockdev --rereadpt /dev/pmem0
or
$ mkfs.ext4 /dev/pmem0
results in this in the kernel serial log:
nd_pmem namespace0.0: region0 read-write, marking pmem0 read-write
with the read-only setting lost:
$ blockdev --getro /dev/pmem0
0
That's from bus.c nvdimm_revalidate_disk(), which always applies the
setting from nd_region (which is initially based on the ACPI NFIT
NVDIMM state flags not_armed bit).
In contrast, commit 20bd1d026a ("scsi: sd: Keep disk read-only when
re-reading partition") fixed this issue for SCSI devices to preserve
the previous setting if it was set to read-only.
This patch modifies bus.c to preserve any previous read-only setting.
It also eliminates the kernel serial log print except for cases where
read-write is changed to read-only, so it doesn't print read-only to
read-only non-changes.
Cc: <stable@vger.kernel.org>
Fixes: 5813882094 ("libnvdimm, nfit: handle unarmed dimms, mark namespaces read-only")
Signed-off-by: Robert Elliott <elliott@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
254a4cd50b