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

[Keith Busch <keith.busch@intel.com>]

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}
 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;
+}
-- 
2.14.4

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