linvdimm, pmem: Preserve read-only setting for pmem devices
authorRobert Elliott <elliott@hpe.com>
Thu, 31 May 2018 23:36:36 +0000 (18:36 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 3 Jul 2018 09:23:13 +0000 (11:23 +0200)
commitf216d1e9339dfb2981d2a0e44a15501cfa76f4ad
treeef1b62156576f0296eb2f47eb7c7b3ff2cef7420
parentc6751cb1e828d7aa93cedfcee65534318278713e
linvdimm, pmem: Preserve read-only setting for pmem devices

commit 254a4cd50b9fe2291a12b8902e08e56dcc4e9b10 upstream.

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 20bd1d026aac ("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: 581388209405 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/nvdimm/bus.c