From 47e653373073f1564844465eb416cdebb1dc4aa6 Mon Sep 17 00:00:00 2001
From: David Disseldorp <ddiss@samba.org>
Date: Thu, 1 Dec 2016 13:33:22 +0100
Subject: [PATCH 1/2] ctdb: cluster mutex helper using Ceph RADOS
ctdb_mutex_ceph_rados_helper implements the cluster mutex helper API
atop Ceph using the librados rados_lock_exclusive()/rados_unlock()
functionality.
Once configured, split brain avoidance during CTDB recovery will be
handled using locks against an object located in a Ceph RADOS pool.
Signed-off-by: David Disseldorp <ddiss@samba.org>
---
ctdb/tools/ctdb_mutex_ceph_rados_helper.c | 334 ++++++++++++++++++++++++++++++
ctdb/wscript | 19 ++
2 files changed, 353 insertions(+)
create mode 100644 ctdb/tools/ctdb_mutex_ceph_rados_helper.c
new file mode 100644
@@ -0,0 +1,334 @@
+/*
+ CTDB mutex helper using Ceph librados locks
+
+ Copyright (C) David Disseldorp 2016
+
+ Based on ctdb_mutex_fcntl_helper.c, which is:
+ Copyright (C) Martin Schwenke 2015
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "replace.h"
+#include "system/filesys.h"
+#include "system/network.h"
+
+/* protocol.h is just needed for ctdb_sock_addr, which is used in system.h */
+#include "protocol/protocol.h"
+#include "common/system.h"
+#include "lib/util/time.h"
+#include "tevent.h"
+#include "talloc.h"
+#include "rados/librados.h"
+
+#define CTDB_MUTEX_CEPH_LOCK_NAME "ctdb_reclock_mutex"
+#define CTDB_MUTEX_CEPH_LOCK_COOKIE CTDB_MUTEX_CEPH_LOCK_NAME
+#define CTDB_MUTEX_CEPH_LOCK_DESC "CTDB recovery lock"
+
+#define CTDB_MUTEX_STATUS_HOLDING "0"
+#define CTDB_MUTEX_STATUS_CONTENDED "1"
+#define CTDB_MUTEX_STATUS_TIMEOUT "2"
+#define CTDB_MUTEX_STATUS_ERROR "3"
+
+static char *progname = NULL;
+
+static int ctdb_mutex_rados_ctx_create(const char *ceph_cluster_name,
+ const char *ceph_auth_name,
+ const char *pool_name,
+ rados_t *_ceph_cluster,
+ rados_ioctx_t *_ioctx)
+{
+ rados_t ceph_cluster = NULL;
+ rados_ioctx_t ioctx = NULL;
+ int ret;
+
+ ret = rados_create2(&ceph_cluster, ceph_cluster_name, ceph_auth_name, 0);
+ if (ret < 0) {
+ fprintf(stderr, "%s: failed to initialise Ceph cluster %s as %s"
+ " - (%s)\n", progname, ceph_cluster_name, ceph_auth_name,
+ strerror(-ret));
+ return ret;
+ }
+
+ /* path=NULL tells librados to use default locations */
+ ret = rados_conf_read_file(ceph_cluster, NULL);
+ if (ret < 0) {
+ fprintf(stderr, "%s: failed to parse Ceph cluster config"
+ " - (%s)\n", progname, strerror(-ret));
+ rados_shutdown(ceph_cluster);
+ return ret;
+ }
+
+ ret = rados_connect(ceph_cluster);
+ if (ret < 0) {
+ fprintf(stderr, "%s: failed to connect to Ceph cluster %s as %s"
+ " - (%s)\n", progname, ceph_cluster_name, ceph_auth_name,
+ strerror(-ret));
+ rados_shutdown(ceph_cluster);
+ return ret;
+ }
+
+
+ ret = rados_ioctx_create(ceph_cluster, pool_name, &ioctx);
+ if (ret < 0) {
+ fprintf(stderr, "%s: failed to create Ceph ioctx for pool %s"
+ " - (%s)\n", progname, pool_name, strerror(-ret));
+ rados_shutdown(ceph_cluster);
+ return ret;
+ }
+
+ *_ceph_cluster = ceph_cluster;
+ *_ioctx = ioctx;
+
+ return 0;
+}
+
+static void ctdb_mutex_rados_ctx_destroy(rados_t ceph_cluster,
+ rados_ioctx_t ioctx)
+{
+ rados_ioctx_destroy(ioctx);
+ rados_shutdown(ceph_cluster);
+}
+
+static int ctdb_mutex_rados_lock(rados_ioctx_t *ioctx,
+ const char *oid)
+{
+ int ret;
+
+ ret = rados_lock_exclusive(ioctx, oid,
+ CTDB_MUTEX_CEPH_LOCK_NAME,
+ CTDB_MUTEX_CEPH_LOCK_COOKIE,
+ CTDB_MUTEX_CEPH_LOCK_DESC,
+ NULL, /* infinite duration */
+ 0);
+ if ((ret == -EEXIST) || (ret == -EBUSY)) {
+ /* lock contention */
+ return ret;
+ } else if (ret < 0) {
+ /* unexpected failure */
+ fprintf(stderr,
+ "%s: Failed to get lock on RADOS object '%s' - (%s)\n",
+ progname, oid, strerror(-ret));
+ return ret;
+ }
+
+ /* lock obtained */
+ return 0;
+}
+
+static int ctdb_mutex_rados_unlock(rados_ioctx_t *ioctx,
+ const char *oid)
+{
+ int ret;
+
+ ret = rados_unlock(ioctx, oid,
+ CTDB_MUTEX_CEPH_LOCK_NAME,
+ CTDB_MUTEX_CEPH_LOCK_COOKIE);
+ if (ret < 0) {
+ fprintf(stderr,
+ "%s: Failed to drop lock on RADOS object '%s' - (%s)\n",
+ progname, oid, strerror(-ret));
+ return ret;
+ }
+
+ return 0;
+}
+
+struct ctdb_mutex_rados_state {
+ bool holding_mutex;
+ const char *ceph_cluster_name;
+ const char *ceph_auth_name;
+ const char *pool_name;
+ const char *object;
+ int ppid;
+ struct tevent_context *ev;
+ struct tevent_signal *sig_ev;
+ struct tevent_timer *timer_ev;
+ rados_t ceph_cluster;
+ rados_ioctx_t ioctx;
+};
+
+static void ctdb_mutex_rados_sigterm_cb(struct tevent_context *ev,
+ struct tevent_signal *se,
+ int signum,
+ int count,
+ void *siginfo,
+ void *private_data)
+{
+ struct ctdb_mutex_rados_state *cmr_state = private_data;
+ int ret;
+
+ if (!cmr_state->holding_mutex) {
+ fprintf(stderr, "Sigterm callback invoked without mutex!\n");
+ ret = -EINVAL;
+ goto err_ctx_cleanup;
+ }
+
+ ret = ctdb_mutex_rados_unlock(cmr_state->ioctx, cmr_state->object);
+err_ctx_cleanup:
+ ctdb_mutex_rados_ctx_destroy(cmr_state->ceph_cluster,
+ cmr_state->ioctx);
+ talloc_free(cmr_state);
+ exit(ret ? 1 : 0);
+}
+
+static void ctdb_mutex_rados_timer_cb(struct tevent_context *ev,
+ struct tevent_timer *te,
+ struct timeval current_time,
+ void *private_data)
+{
+ struct ctdb_mutex_rados_state *cmr_state = private_data;
+ int ret;
+
+ if (!cmr_state->holding_mutex) {
+ fprintf(stderr, "Timer callback invoked without mutex!\n");
+ ret = -EINVAL;
+ goto err_ctx_cleanup;
+ }
+
+ if ((kill(cmr_state->ppid, 0) == 0) || (errno != ESRCH)) {
+ /* parent still around, keep waiting */
+ cmr_state->timer_ev = tevent_add_timer(cmr_state->ev, cmr_state,
+ timeval_current_ofs(5,0),
+ ctdb_mutex_rados_timer_cb,
+ cmr_state);
+ if (cmr_state->timer_ev == NULL) {
+ fprintf(stderr, "Failed to create timer event\n");
+ /* rely on signal cb */
+ }
+ return;
+ }
+
+ /* parent ended, drop lock and exit */
+ ret = ctdb_mutex_rados_unlock(cmr_state->ioctx, cmr_state->object);
+err_ctx_cleanup:
+ ctdb_mutex_rados_ctx_destroy(cmr_state->ceph_cluster,
+ cmr_state->ioctx);
+ talloc_free(cmr_state);
+ exit(ret ? 1 : 0);
+}
+
+int main(int argc, char *argv[])
+{
+ int ret;
+ struct ctdb_mutex_rados_state *cmr_state;
+
+ progname = argv[0];
+
+ if (argc != 5) {
+ fprintf(stderr, "Usage: %s <Ceph Cluster> <Ceph user> "
+ "<RADOS pool> <RADOS object>\n",
+ progname);
+ ret = -EINVAL;
+ goto err_out;
+ }
+
+ ret = setvbuf(stdout, NULL, _IONBF, 0);
+ if (ret != 0) {
+ fprintf(stderr, "Failed to configure unbuffered stdout I/O\n");
+ }
+
+ cmr_state = talloc_zero(NULL, struct ctdb_mutex_rados_state);
+ if (cmr_state == NULL) {
+ fprintf(stdout, CTDB_MUTEX_STATUS_ERROR);
+ ret = -ENOMEM;
+ goto err_out;
+ }
+
+ cmr_state->ceph_cluster_name = argv[1];
+ cmr_state->ceph_auth_name = argv[2];
+ cmr_state->pool_name = argv[3];
+ cmr_state->object = argv[4];
+
+ cmr_state->ppid = getppid();
+ if (cmr_state->ppid == 1) {
+ /*
+ * The original parent is gone and the process has
+ * been reparented to init. This can happen if the
+ * helper is started just as the parent is killed
+ * during shutdown. The error message doesn't need to
+ * be stellar, since there won't be anything around to
+ * capture and log it...
+ */
+ fprintf(stderr, "%s: PPID == 1\n", progname);
+ ret = -EPIPE;
+ goto err_state_free;
+ }
+
+ cmr_state->ev = tevent_context_init(cmr_state);
+ if (cmr_state->ev == NULL) {
+ fprintf(stderr, "tevent_context_init failed\n");
+ fprintf(stdout, CTDB_MUTEX_STATUS_ERROR);
+ ret = -ENOMEM;
+ goto err_state_free;
+ }
+
+ /* wait for sigterm */
+ cmr_state->sig_ev = tevent_add_signal(cmr_state->ev, cmr_state, SIGTERM, 0,
+ ctdb_mutex_rados_sigterm_cb,
+ cmr_state);
+ if (cmr_state->sig_ev == NULL) {
+ fprintf(stderr, "Failed to create signal event\n");
+ fprintf(stdout, CTDB_MUTEX_STATUS_ERROR);
+ ret = -ENOMEM;
+ goto err_state_free;
+ }
+
+ /* periodically check parent */
+ cmr_state->timer_ev = tevent_add_timer(cmr_state->ev, cmr_state,
+ timeval_current_ofs(5,0),
+ ctdb_mutex_rados_timer_cb,
+ cmr_state);
+ if (cmr_state->timer_ev == NULL) {
+ fprintf(stderr, "Failed to create timer event\n");
+ fprintf(stdout, CTDB_MUTEX_STATUS_ERROR);
+ ret = -ENOMEM;
+ goto err_state_free;
+ }
+
+ ret = ctdb_mutex_rados_ctx_create(cmr_state->ceph_cluster_name,
+ cmr_state->ceph_auth_name,
+ cmr_state->pool_name,
+ &cmr_state->ceph_cluster,
+ &cmr_state->ioctx);
+ if (ret < 0) {
+ fprintf(stdout, CTDB_MUTEX_STATUS_ERROR);
+ goto err_state_free;
+ }
+
+ ret = ctdb_mutex_rados_lock(cmr_state->ioctx, cmr_state->object);
+ if ((ret == -EEXIST) || (ret == -EBUSY)) {
+ fprintf(stdout, CTDB_MUTEX_STATUS_CONTENDED);
+ goto err_ctx_cleanup;
+ } else if (ret < 0) {
+ fprintf(stdout, CTDB_MUTEX_STATUS_ERROR);
+ goto err_ctx_cleanup;
+ }
+
+ cmr_state->holding_mutex = true;
+ fprintf(stdout, CTDB_MUTEX_STATUS_HOLDING);
+
+ /* wait for the signal / timer events to do their work */
+ ret = tevent_loop_wait(cmr_state->ev);
+ if (ret < 0) {
+ goto err_ctx_cleanup;
+ }
+err_ctx_cleanup:
+ ctdb_mutex_rados_ctx_destroy(cmr_state->ceph_cluster,
+ cmr_state->ioctx);
+err_state_free:
+ talloc_free(cmr_state);
+err_out:
+ return ret ? 1 : 0;
+}
@@ -69,6 +69,9 @@ def set_options(opt):
opt.add_option('--enable-pmda',
help=("Turn on PCP pmda support (default=no)"),
action="store_true", dest='ctdb_pmda', default=False)
+ opt.add_option('--enable-ceph-reclock',
+ help=("Enable Ceph CTDB recovery lock helper (default=no)"),
+ action="store_true", dest='ctdb_ceph_reclock', default=False)
opt.add_option('--with-logdir',
help=("Path to log directory"),
@@ -159,6 +162,15 @@ def configure(conf):
conf.env.CTDB_PMDADIR = os.path.join(conf.env.LOCALSTATEDIR,
'lib/pcp/pmdas/ctdb')
+ if Options.options.ctdb_ceph_reclock:
+ if (conf.CHECK_HEADERS('rados/librados.h', False, False, 'rados') and
+ conf.CHECK_LIB('rados', shlib=True)):
+ Logs.info('Building with Ceph librados recovery lock support')
+ conf.define('HAVE_LIBRADOS', 1)
+ else:
+ Logs.error("Missing librados for Ceph recovery lock support")
+ sys.exit(1)
+
have_infiniband = False
if Options.options.ctdb_infiniband:
ib_support = True
@@ -517,6 +529,13 @@ def build(bld):
bld.INSTALL_FILES('${CTDB_PMDADIR}', 'utils/pmda/README',
destname='README')
+ if bld.env.HAVE_LIBRADOS:
+ bld.SAMBA_BINARY('ctdb_mutex_ceph_rados_helper',
+ source='tools/ctdb_mutex_ceph_rados_helper.c',
+ deps='ctdb-system rados',
+ includes='include',
+ install_path='${CTDB_HELPER_BINDIR}')
+
sed_expr1 = 's|/usr/local/var/lib/ctdb|%s|g' % (bld.env.CTDB_VARDIR)
sed_expr2 = 's|/usr/local/etc/ctdb|%s|g' % (bld.env.CTDB_ETCDIR)
sed_expr3 = 's|/usr/local/var/log|%s|g' % (bld.env.CTDB_LOGDIR)
--
2.10.2
From fb53f42d1e02e0f33d1a1304c7d708203d75a14d Mon Sep 17 00:00:00 2001
From: David Disseldorp <ddiss@samba.org>
Date: Thu, 1 Dec 2016 14:22:45 +0100
Subject: [PATCH 2/2] ctdb/doc: man page for Ceph RADOS cluster mutex helper
Signed-off-by: David Disseldorp <ddiss@samba.org>
---
ctdb/doc/Makefile | 3 +-
ctdb/doc/ctdb_mutex_ceph_rados_helper.7.xml | 90 +++++++++++++++++++++++++++++
2 files changed, 92 insertions(+), 1 deletion(-)
create mode 100644 ctdb/doc/ctdb_mutex_ceph_rados_helper.7.xml
@@ -8,7 +8,8 @@ DOCS = ctdb.1 ctdb.1.html \
ctdbd.conf.5 ctdbd.conf.5.html \
ctdb.7 ctdb.7.html \
ctdb-statistics.7 ctdb-statistics.7.html \
- ctdb-tunables.7 ctdb-tunables.7.html
+ ctdb-tunables.7 ctdb-tunables.7.html \
+ ctdb_mutex_ceph_rados_helper.7 ctdb_mutex_ceph_rados_helper.7.html
all: $(DOCS)
new file mode 100644
@@ -0,0 +1,90 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE refentry
+ PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
+<refentry id="ctdb_mutex_ceph_rados_helper.7">
+
+ <refmeta>
+ <refentrytitle>Ceph RADOS Mutex</refentrytitle>
+ <manvolnum>7</manvolnum>
+ <refmiscinfo class="source">ctdb</refmiscinfo>
+ <refmiscinfo class="manual">CTDB - clustered TDB database</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+ <refname>ctdb_mutex_ceph_rados_helper</refname>
+ <refpurpose>Ceph RADOS cluster mutex helper</refpurpose>
+ </refnamediv>
+
+ <refsect1>
+ <title>DESCRIPTION</title>
+ <para>
+ ctdb_mutex_ceph_rados_helper_lock can be used as a recovery lock provider
+ for CTDB. When configured, split brain avoidance during CTDB recovery
+ will be handled using locks against an object located in a Ceph RADOS
+ pool.
+ To enable this functionality, include the following line in your CTDB
+ config file:
+ </para>
+ <screen format="linespecific">
+CTDB_RECOVERY_LOCK="!ctdb_mutex_ceph_rados_helper_lock [Cluster] [User] [Pool] [Object]"
+
+Cluster: Ceph cluster name (e.g. ceph)
+User: Ceph cluster user name (e.g. client.admin)
+Pool: Ceph RADOS pool name
+Object: Ceph RADOS object name
+ </screen>
+ <para>
+ The Ceph cluster <parameter>Cluster</parameter> must be up and running,
+ with a configuration, and keyring file for <parameter>User</parameter>
+ located in a librados default search path (e.g. /etc/ceph/).
+ <parameter>Pool</parameter> must already exist.
+ </para>
+ </refsect1>
+
+ <refsect1>
+ <title>SEE ALSO</title>
+ <para>
+ <citerefentry><refentrytitle>ctdb</refentrytitle>
+ <manvolnum>7</manvolnum></citerefentry>,
+
+ <citerefentry><refentrytitle>ctdbd</refentrytitle>
+ <manvolnum>1</manvolnum></citerefentry>,
+
+ <ulink url="http://ctdb.samba.org/"/>
+ </para>
+ </refsect1>
+
+ <refentryinfo>
+ <author>
+ <contrib>
+ This documentation was written by David Disseldorp
+ </contrib>
+ </author>
+
+ <copyright>
+ <year>2016</year>
+ <holder>David Disseldorp</holder>
+ </copyright>
+ <legalnotice>
+ <para>
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License as
+ published by the Free Software Foundation; either version 3 of
+ the License, or (at your option) any later version.
+ </para>
+ <para>
+ This program is distributed in the hope that it will be
+ useful, but WITHOUT ANY WARRANTY; without even the implied
+ warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ PURPOSE. See the GNU General Public License for more details.
+ </para>
+ <para>
+ You should have received a copy of the GNU General Public
+ License along with this program; if not, see
+ <ulink url="http://www.gnu.org/licenses"/>.
+ </para>
+ </legalnotice>
+ </refentryinfo>
+
+</refentry>
--
2.10.2