Re: [PATCH 1/2] Create Intel pmem shutdown latch rule

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Tue, 2018-08-07 at 16:26 -0600, Keith Busch wrote:
> This patch provides a udev rule and the program it runs for Intel
> nvdimms. The program the rule executes runs two commands to allow
> applications to manage unsafe shutdowns.
> 
> The first command enables the shutdown latch. Without this, the last
> shutdown status will remain fixed to the status set when the latch was
> last enabled.
> 
> The second command retrieves the unclean shutdown counts and saves it
> in a known location. Only root can access the health's shutdown count,
> so we have to stash it somewhere accessible to non-privileged users. A
> successful execution of the rule will write USC to the run time tmpfs
> location. By default, the location will be set to:
> 
>   /run/ndctl/<dimm-id>/usc
> 
> A distro may change this location using the '--with-tmpfsdir=[DIR]'.
> 
> Reading the file will report the count observed when the dimm was
> added.
> 
> Signed-off-by: Keith Busch <keith.busch@intel.com>
> ---
>  .gitignore                  |   1 +
>  Makefile.am                 |   3 +
>  configure.ac                |  10 ++++
>  contrib/80-intel-pmem.rules |   1 +
>  ndctl.spec.in               |   5 +-
>  ndctl/Makefile.am           |   5 ++
>  ndctl/latch-shutdown.c      | 140 ++++++++++++++++++++++++++++++++++++++++++++
>  7 files changed, 164 insertions(+), 1 deletion(-)
>  create mode 100644 contrib/80-intel-pmem.rules
>  create mode 100644 ndctl/latch-shutdown.c
> 
> diff --git a/.gitignore b/.gitignore
> index 1016b3b..1601738 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -25,6 +25,7 @@ daxctl/lib/libdaxctl.pc
>  *.a
>  ndctl/lib/libndctl.pc
>  ndctl/ndctl
> +ndctl/latch-shutdown
>  rhel/
>  sles/ndctl.spec
>  util/log.lo
> diff --git a/Makefile.am b/Makefile.am
> index e0c463a..9d3913e 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -42,6 +42,9 @@ bashcompletiondir = $(BASH_COMPLETION_DIR)
>  dist_bashcompletion_DATA = contrib/ndctl
>  endif
>  
> +udevrulesdir = $(UDEVDIR)/rules.d
> +dist_udevrules_DATA = contrib/80-intel-pmem.rules
> +
>  noinst_LIBRARIES = libccan.a
>  libccan_a_SOURCES = \
>  	ccan/str/str.h \
> diff --git a/configure.ac b/configure.ac
> index cf44260..15f336b 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -143,7 +143,16 @@ AC_CHECK_FUNCS([ \
>  	secure_getenv\
>  ])
>  
> +AC_ARG_WITH([tmpfsdir],
> +  [AS_HELP_STRING([--with-tmpfsdir=DIR], [Directory for temporary runtime files])],
> +  [tmpfsdir=$withval],
> +  [tmpfsdir="/run"])
> +
> +UDEVDIR="$(pkg-config udev --variable=udevdir)"
> +AC_SUBST([UDEVDIR])
> +
>  my_CFLAGS="\
> +-D DEF_TMPFS_DIR='\"${tmpfsdir}/ndctl\"' \
>  -Wall \
>  -Wchar-subscripts \
>  -Wformat-security \
> @@ -182,6 +191,7 @@ AC_MSG_RESULT([
>  
>          prefix:                 ${prefix}
>          sysconfdir:             ${sysconfdir}
> +        tmpfsdir:               ${tmpfsdir}
>          libdir:                 ${libdir}
>          includedir:             ${includedir}
>  
> diff --git a/contrib/80-intel-pmem.rules b/contrib/80-intel-pmem.rules
> new file mode 100644
> index 0000000..20fcef9
> --- /dev/null
> +++ b/contrib/80-intel-pmem.rules
> @@ -0,0 +1 @@
> +ACTION=="add", KERNEL=="nmem*", RUN+="latch-shutdown $kernel"
> diff --git a/ndctl.spec.in b/ndctl.spec.in
> index e2c879c..25edf7e 100644
> --- a/ndctl.spec.in
> +++ b/ndctl.spec.in
> @@ -90,7 +90,7 @@ control API for these devices.
>  %build
>  echo %{version} > version
>  ./autogen.sh
> -%configure --disable-static --disable-silent-rules
> +%configure --disable-static --disable-silent-rules --with-tmpfsdir=%{_tmpfilesdir}

One more thing - looks like tmpfilesdir expands to:

$ rpm --eval "%{_tmpfilesdir}"
/usr/lib/tmpfiles.d

And using it requires a specific config file as described in the
following places:
https://fedoraproject.org/wiki/Packaging:Tmpfiles.d
http://0pointer.de/public/systemd-man/tmpfiles.d.html

So for this, I think we can simply drop the

	--with-tmpfsdir=%{_tmpfilesdir}

to configure above, and let autoconf use its default. If a distro
wanted to change that location, they still have the option of doing it
be passing something else to configure.

>  make %{?_smp_mflags}
>  
>  %install
> @@ -109,6 +109,7 @@ make check
>  %postun -n DAX_LNAME -p /sbin/ldconfig
>  
>  %define bashcompdir %(pkg-config --variable=completionsdir bash-completion)
> +%define udevdir  %(pkg-config --variable=udevdir udev)
>  
>  %files
>  %defattr(-,root,root)
> @@ -116,6 +117,8 @@ make check
>  %{_bindir}/ndctl
>  %{_mandir}/man1/ndctl*
>  %{bashcompdir}/
> +%{_udevrulesdir}/80-intel-pmem.rules
> +%{udevdir}/latch-shutdown
>  
>  %files -n daxctl
>  %defattr(-,root,root)
> diff --git a/ndctl/Makefile.am b/ndctl/Makefile.am
> index 0f56871..155179b 100644
> --- a/ndctl/Makefile.am
> +++ b/ndctl/Makefile.am
> @@ -41,3 +41,8 @@ ndctl_SOURCES += ../test/libndctl.c \
>  		 ../test/core.c \
>  		 test.c
>  endif
> +
> +latch_shutdowndir = $(UDEVDIR)
> +latch_shutdown_PROGRAMS = latch-shutdown
> +latch_shutdown_SOURCES = latch-shutdown.c
> +latch_shutdown_LDADD = lib/libndctl.la
> diff --git a/ndctl/latch-shutdown.c b/ndctl/latch-shutdown.c
> new file mode 100644
> index 0000000..704fb8f
> --- /dev/null
> +++ b/ndctl/latch-shutdown.c
> @@ -0,0 +1,140 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright(c) 2018 Intel Corporation. All rights reserved. */
> +
> +#include <ctype.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stddef.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/stat.h>
> +#include <sys/types.h>
> +#include <ndctl/libndctl.h>
> +
> +/**
> + * mkdir_p
> + *
> + * Copied from util-linux lib/fileutils.c
> + */
> +static int mkdir_p(const char *path, mode_t mode)
> +{
> +	char *p, *dir;
> +	int rc = 0;
> +
> +	if (!path || !*path)
> +		return -EINVAL;
> +
> +	dir = p = strdup(path);
> +	if (!dir)
> +		return -ENOMEM;
> +
> +	if (*p == '/')
> +		p++;
> +
> +	while (p && *p) {
> +		char *e = strchr(p, '/');
> +		if (e)
> +			*e = '\0';
> +		if (*p) {
> +			rc = mkdir(dir, mode);
> +			if (rc && errno != EEXIST)
> +				break;
> +			rc = 0;
> +		}
> +		if (!e)
> +			break;
> +		*e = '/';
> +		p = e + 1;
> +	}
> +
> +	free(dir);
> +	return rc;
> +}
> +
> +static struct ndctl_dimm *find_dimm(struct ndctl_ctx *ctx, char *devname)
> +{
> +	struct ndctl_bus *bus;
> +	struct ndctl_dimm *dimm;
> +
> +	ndctl_bus_foreach(ctx, bus) {
> +		ndctl_dimm_foreach(bus, dimm) {
> +			if (strcmp(ndctl_dimm_get_devname(dimm), devname) == 0)
> +				return dimm;
> +		}
> +	}
> +	return NULL;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	struct ndctl_ctx *ctx;
> +	struct ndctl_cmd *cmd;
> +	struct ndctl_dimm *dimm = NULL;
> +	char *path, *usc, count[16];
> +	const char *id;
> +	unsigned int shutdown;
> +	int rc, fd;
> +
> +	if (argc < 2)
> +		return EINVAL;
> +
> +	rc = ndctl_new(&ctx);
> +	if (rc)
> +		return ENOMEM;
> +
> +	dimm = find_dimm(ctx, argv[1]);
> +	if (!dimm)
> +		return ENODEV;
> +
> +	cmd = ndctl_dimm_cmd_new_ack_shutdown_count(dimm);
> +	if (!cmd)
> +		return ENOMEM;
> +
> +	rc = ndctl_cmd_submit(cmd);
> +	if (rc)
> +		return rc;
> +	ndctl_cmd_unref(cmd);
> +
> +	id = ndctl_dimm_get_unique_id(dimm);
> +	if (!id)
> +		return ENXIO;
> +
> +	cmd = ndctl_dimm_cmd_new_smart(dimm);
> +	if (!cmd)
> +		return ENOMEM;
> +
> +	rc = ndctl_cmd_submit(cmd);
> +	if (rc)
> +		return rc;
> +
> +	shutdown = ndctl_cmd_smart_get_shutdown_count(cmd);
> +	ndctl_cmd_unref(cmd);
> +
> +	rc = asprintf(&path, DEF_TMPFS_DIR "/%s", id);
> +	if (rc < 0)
> +		return ENOMEM;
> +	ndctl_unref(ctx);
> +
> +	rc = mkdir_p(path, 0755);
> +	if (rc)
> +		return rc;
> +
> +	rc = asprintf(&usc, "%s/usc", path);
> +	if (rc < 0)
> +		return ENOMEM;
> +	free(path);
> +
> +	fd = open(usc, O_WRONLY | O_CREAT, 0644);
> +	if (!fd)
> +		return errno;
> +	free(usc);
> +
> +	rc = snprintf(count, sizeof(count), "%u\n", shutdown);
> +	if (rc < 0)
> +		return rc;
> +
> +	if (write(fd, count, strlen(count)))
> +		return errno;
> +	return 0;
> +}
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