[ndctl PATCHv2 1/2] ndctl: Create ndctl udev rules for dirty shutdown

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

This patch provides an ndctl udev rule and the program it runs. The rule
sends two ndctl commands to allow applications to manage unsafe shutdowns.

The first command acknowledges the shutdown. For nvdimms that support
this, the last shutdown status will remain set to its current status
until it is acknowledged.

The second command retrieves the unclean shutdown count (USC) and saves it
in a known location. Only root can directly 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/nmem<X>/usc

A distro may change this location using the '--with-tmpfilesdir=[DIR]'.

Reading the file will report the count observed when the dimm was
added.

Signed-off-by: Keith Busch <keith.busch@intel.com>
---
v1 -> v2:

  Merged to ndctl/pending

  Used more generic names

  Split the udev program actions, and save USC regardless of the outcome
  of the first action

  Removed rpm spec setting configure's tmpfilesdir

  Use nmem<X> instead of dimm-id for runtime directory name

  Update changelog

 .gitignore             |   1 +
 Makefile.am            |   3 +
 configure.ac           |  10 ++++
 contrib/80-ndctl.rules |   3 +
 ndctl.spec.in          |   3 +
 ndctl/Makefile.am      |   5 ++
 ndctl/ndctl-udev.c     | 147 +++++++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 172 insertions(+)
 create mode 100644 contrib/80-ndctl.rules
 create mode 100644 ndctl/ndctl-udev.c

diff --git a/.gitignore b/.gitignore
index 0baace4..f13a7ef 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,6 +25,7 @@ daxctl/lib/libdaxctl.pc
 *.a
 ndctl/lib/libndctl.pc
 ndctl/ndctl
+ndctl/ndctl-udev
 rhel/
 sles/ndctl.spec
 util/log.lo
diff --git a/Makefile.am b/Makefile.am
index e0c463a..7880eef 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -42,6 +42,9 @@ bashcompletiondir = $(BASH_COMPLETION_DIR)
 dist_bashcompletion_DATA = contrib/ndctl
 endif
 
+udevrulesdir = $(UDEVDIR)/rules.d
+dist_udevrules_DATA = contrib/80-ndctl.rules
+
 noinst_LIBRARIES = libccan.a
 libccan_a_SOURCES = \
 	ccan/str/str.h \
diff --git a/configure.ac b/configure.ac
index e242334..4441a44 100644
--- a/configure.ac
+++ b/configure.ac
@@ -164,8 +164,17 @@ AS_IF([test "x$with_systemd_unit_dir" != "xno"],
 	[AC_SUBST([systemd_unitdir], [$with_systemd_unit_dir])])
 AM_CONDITIONAL([ENABLE_SYSTEMD_UNIT_DIR], [test "x$with_systemd_unit_dir" != "xno"])
 
+AC_ARG_WITH([tmpfilesdir],
+	[AS_HELP_STRING([--with-tmpfilesdir=DIR], [Directory for temporary runtime files])],
+	[tmpfilesdir=$withval],
+	[tmpfilesdir="/run"])
+
+UDEVDIR="$(pkg-config udev --variable=udevdir)"
+AC_SUBST([UDEVDIR])
+
 my_CFLAGS="\
 -D DEF_CONF_FILE='\"${sysconfdir}/ndctl/monitor.conf\"' \
+-D DEF_TMPFS_DIR='\"${tmpfilesdir}/ndctl\"' \
 -Wall \
 -Wchar-subscripts \
 -Wformat-security \
@@ -207,6 +216,7 @@ AC_MSG_RESULT([
         libdir:                 ${libdir}
         includedir:             ${includedir}
 	systemd-unit-dir:	${systemd_unitdir}
+        tmpfilesdir:            ${tmpfilesdir}
 
         compiler:               ${CC}
         cflags:                 ${CFLAGS}
diff --git a/contrib/80-ndctl.rules b/contrib/80-ndctl.rules
new file mode 100644
index 0000000..54788c4
--- /dev/null
+++ b/contrib/80-ndctl.rules
@@ -0,0 +1,3 @@
+# do not edit this file, it will be overwritten on update
+
+ACTION=="add", KERNEL=="nmem*", RUN+="ndctl-udev $kernel"
diff --git a/ndctl.spec.in b/ndctl.spec.in
index 17152c1..062aafb 100644
--- a/ndctl.spec.in
+++ b/ndctl.spec.in
@@ -110,6 +110,7 @@ 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)
@@ -119,6 +120,8 @@ make check
 %{bashcompdir}/
 %{_sysconfdir}/ndctl/monitor.conf
 %{_unitdir}/ndctl-monitor.service
+%{_udevrulesdir}/80-ndctl.rules
+%{udevdir}/ndctl-udev
 
 %files -n daxctl
 %defattr(-,root,root)
diff --git a/ndctl/Makefile.am b/ndctl/Makefile.am
index 0f9bb43..4b44294 100644
--- a/ndctl/Makefile.am
+++ b/ndctl/Makefile.am
@@ -51,3 +51,8 @@ EXTRA_DIST += $(monitor_config_file)
 if ENABLE_SYSTEMD_UNIT_DIR
 systemd_unit_DATA = ndctl-monitor.service
 endif
+
+ndctl_udevdir = $(UDEVDIR)
+ndctl_udev_PROGRAMS = ndctl-udev
+ndctl_udev_SOURCES = ndctl-udev.c
+ndctl_udev_LDADD = lib/libndctl.la
diff --git a/ndctl/ndctl-udev.c b/ndctl/ndctl-udev.c
new file mode 100644
index 0000000..2b4d067
--- /dev/null
+++ b/ndctl/ndctl-udev.c
@@ -0,0 +1,147 @@
+/* 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, const 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;
+}
+
+static void ack_shutdown(struct ndctl_dimm *dimm)
+{
+	struct ndctl_cmd *cmd;
+
+	cmd = ndctl_dimm_cmd_new_ack_shutdown_count(dimm);
+	if (!cmd)
+		return;
+	ndctl_cmd_submit(cmd);
+	ndctl_cmd_unref(cmd);
+}
+
+static void save_unsafe_shutdown_count(struct ndctl_dimm *dimm,
+				       const char *devname)
+{
+	char *path, *usc, count[16];
+	unsigned int shutdown;
+	struct ndctl_cmd *cmd;
+	int fd;
+
+	cmd = ndctl_dimm_cmd_new_smart(dimm);
+	if (!cmd)
+		return;
+
+	if (ndctl_cmd_submit(cmd))
+		goto unref_cmd;
+
+	shutdown = ndctl_cmd_smart_get_shutdown_count(cmd);
+	if (shutdown == UINT_MAX)
+		goto unref_cmd;
+
+	if (asprintf(&path, DEF_TMPFS_DIR "/%s", devname) < 0)
+		goto unref_cmd;
+
+	if (mkdir_p(path, 0755))
+		goto free_path;
+
+	if (asprintf(&usc, "%s/usc", path) < 0)
+		goto free_path;
+
+	fd = open(usc, O_WRONLY | O_CREAT, 0644);
+	if (fd < 0)
+		goto free_usc;
+
+	if (snprintf(count, sizeof(count), "%u\n", shutdown) < 0)
+		goto free_usc;
+
+	if (write(fd, count, strlen(count)) < 0)
+		goto free_usc;
+ free_usc:
+	free(usc);
+ free_path:
+	free(path);
+ unref_cmd:
+	ndctl_cmd_unref(cmd);
+}
+
+int main(int argc, char *argv[])
+{
+	struct ndctl_ctx *ctx;
+	struct ndctl_dimm *dimm = NULL;
+	const char *devname;
+
+	if (argc < 2)
+		return EINVAL;
+
+	devname = argv[1];
+	if (ndctl_new(&ctx))
+		return ENOMEM;
+
+	dimm = find_dimm(ctx, devname);
+	if (!dimm)
+		return ENODEV;
+
+	ack_shutdown(dimm);
+	save_unsafe_shutdown_count(dimm, devname);
+
+	ndctl_unref(ctx);
+	return 0;
+}
-- 
2.14.4

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