Attachment 849178 Details for Bug 1052049 – votequorum: Add persistent expected_votes tracking

[patch] votequorum: Add persistent expected_votes tracking

0001-votequorum-Add-persistent-expected_votes-tracking.patch (text/plain), 7.65 KB, created by Jan Friesse on 2014-01-13 08:29:58 UTC

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Creator: Jan Friesse

Created: 2014-01-13 08:29:58 UTC

Size: 7.65 KB

patch

obsolete

>From ff6a43edb346a5c313f97c39b6db00f4359c8170 Mon Sep 17 00:00:00 2001
>From: Christine Caulfield <ccaulfie@redhat.com>
>Date: Tue, 7 Jan 2014 15:30:11 +0000
>Subject: [PATCH] votequorum: Add persistent expected_votes tracking.
>
>This patch adds the option to store expected_votes to
>persistent storage. This is needed to allow_downscale
>to operate properly.
>
>Signed-off-by: Christine Caulfield <ccaulfie@redhat.com>
>---
> exec/coroparse.c  |   1 +
> exec/votequorum.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
> man/votequorum.5  |  23 ++++++++++-
> 3 files changed, 132 insertions(+), 4 deletions(-)
>
>diff --git a/exec/coroparse.c b/exec/coroparse.c
>index 1ac0cdd..425e5d6 100644
>--- a/exec/coroparse.c
>+++ b/exec/coroparse.c
>@@ -507,6 +507,7 @@ static int main_config_parser_cb(const char *path,
> 			}
> 
> 			if ((strcmp(path, "quorum.two_node") == 0) ||
>+			    (strcmp(path, "quorum.expected_votes_tracking") == 0) ||
> 			    (strcmp(path, "quorum.allow_downscale") == 0) ||
> 			    (strcmp(path, "quorum.wait_for_all") == 0) ||
> 			    (strcmp(path, "quorum.auto_tie_breaker") == 0) ||
>diff --git a/exec/votequorum.c b/exec/votequorum.c
>index b81b253..1b6a4eb 100644
>--- a/exec/votequorum.c
>+++ b/exec/votequorum.c
>@@ -1,5 +1,5 @@
> /*
>- * Copyright (c) 2009-2012 Red Hat, Inc.
>+ * Copyright (c) 2009-2014 Red Hat, Inc.
>  *
>  * All rights reserved.
>  *
>@@ -36,7 +36,10 @@
> #include <config.h>
> 
> #include <sys/types.h>
>+#include <sys/stat.h>
>+#include <fcntl.h>
> #include <stdint.h>
>+#include <unistd.h>
> 
> #include <qb/qbipc_common.h>
> 
>@@ -85,6 +88,10 @@ static uint32_t last_man_standing_window = DEFAULT_LMS_WIN;
> static uint8_t allow_downscale = 0;
> static uint32_t ev_barrier = 0;
> 
>+static uint8_t ev_tracking = 0;
>+static uint32_t ev_tracking_barrier = 0;
>+static int ev_tracking_fd = -1;
>+
> /*
>  * votequorum_exec defines/structs/forward definitions
>  */
>@@ -589,6 +596,47 @@ static void decode_flags(uint32_t flags)
> 	LEAVE();
> }
> 
>+/*
>+ * load/save are copied almost pristine from totemsrp,c
>+ */
>+static int load_ev_tracking_barrier(void)
>+{
>+	int res = 0;
>+	char filename[PATH_MAX];
>+
>+	ENTER();
>+
>+	snprintf(filename, sizeof(filename) - 1, LOCALSTATEDIR "/lib/corosync/ev_tracking");
>+
>+	ev_tracking_fd = open(filename, O_RDWR, 0700);
>+	if (ev_tracking_fd != -1) {
>+		res = read (ev_tracking_fd, &ev_tracking_barrier, sizeof(uint32_t));
>+		if (res == sizeof (uint32_t)) {
>+		        LEAVE();
>+			return 0;
>+		}
>+	}
>+
>+	ev_tracking_barrier = 0;
>+	umask(0);
>+	ev_tracking_fd = open (filename, O_CREAT|O_RDWR, 0700);
>+	if (ev_tracking_fd != -1) {
>+		res = write (ev_tracking_fd, &ev_tracking_barrier, sizeof (uint32_t));
>+		if ((res == -1) || (res != sizeof (uint32_t))) {
>+			log_printf(LOGSYS_LEVEL_WARNING,
>+				   "Unable to write to %s", filename);
>+		}
>+		LEAVE();
>+		return 0;
>+	}
>+	log_printf(LOGSYS_LEVEL_WARNING,
>+		   "Unable to create %s file", filename);
>+
>+	LEAVE();
>+
>+	return -1;
>+}
>+
> static void update_wait_for_all_status(uint8_t wfa_status)
> {
> 	ENTER(); 
>@@ -644,6 +692,32 @@ static void update_qdevice_master_wins(uint8_t allow)
> 	LEAVE();
> }
> 
>+static void update_ev_tracking_barrier(uint32_t ev_t_barrier)
>+{
>+	int res;
>+
>+	ENTER();
>+
>+	ev_tracking_barrier = ev_t_barrier;
>+	icmap_set_uint32("runtime.votequorum.ev_tracking_barrier", ev_tracking_barrier);
>+
>+	if (lseek (ev_tracking_fd, 0, SEEK_SET) != 0) {
>+		log_printf(LOGSYS_LEVEL_WARNING,
>+			   "Unable to update ev_tracking_barrier on disk data!!!");
>+		LEAVE();
>+		return;
>+	}
>+
>+	res = write (ev_tracking_fd, &ev_tracking_barrier, sizeof (uint32_t));
>+	if (res != sizeof (uint32_t)) {
>+		log_printf(LOGSYS_LEVEL_WARNING,
>+			   "Unable to update ev_tracking_barrier on disk data!!!");
>+	}
>+	fdatasync(ev_tracking_fd);
>+
>+	LEAVE();
>+}
>+
> /*
>  * quorum calculation core bits
>  */
>@@ -854,6 +928,11 @@ static void recalculate_quorum(int allow_decrease, int by_current_nodes)
> 		votequorum_exec_send_expectedvotes_notification();
> 	}
> 
>+	if ((ev_tracking) &&
>+	    (us->expected_votes > ev_tracking_barrier)) {
>+		update_ev_tracking_barrier(us->expected_votes);
>+	}
>+
> 	quorum = calculate_quorum(allow_decrease, cluster_members, &total_votes);
> 	are_we_quorate(total_votes);
> 
>@@ -1022,6 +1101,21 @@ static char *votequorum_readconfig(int runtime)
> 		icmap_get_uint8("quorum.auto_tie_breaker", &auto_tie_breaker);
> 		icmap_get_uint8("quorum.last_man_standing", &last_man_standing);
> 		icmap_get_uint32("quorum.last_man_standing_window", &last_man_standing_window);
>+		icmap_get_uint8("quorum.expected_votes_tracking", &ev_tracking);
>+
>+		/* allow_downscale requires ev_tracking */
>+		if (allow_downscale) {
>+		    ev_tracking = 1;
>+		}
>+
>+		if (ev_tracking) {
>+		    if (load_ev_tracking_barrier() < 0) {
>+		        LEAVE();
>+		        return ((char *)"Unable to load ev_tracking file!");
>+		    }
>+		    update_ev_tracking_barrier(ev_tracking_barrier);
>+		}
>+
> 	}
> 
> 	/*
>@@ -1144,6 +1238,11 @@ static char *votequorum_readconfig(int runtime)
> 	/*
> 	 * set this node votes and expected_votes
> 	 */
>+	log_printf(LOGSYS_LEVEL_DEBUG, "ev_tracking=%d, ev_tracking_barrier = %d: expected_votes = %d\n", ev_tracking, ev_tracking_barrier, expected_votes);
>+
>+	if (ev_tracking) {
>+	        expected_votes = ev_tracking_barrier;
>+	}
> 
> 	if (have_nodelist) {
> 		us->votes = node_votes;
>@@ -1666,7 +1765,7 @@ static void message_handler_req_exec_votequorum_nodeinfo (
> 		us->expected_votes = req_exec_quorum_nodeinfo->expected_votes;
> 	}
> 
>-	if (node->flags & NODE_FLAGS_QUORATE) {
>+	if (node->flags & NODE_FLAGS_QUORATE || (ev_tracking)) {
> 		node->expected_votes = req_exec_quorum_nodeinfo->expected_votes;
> 	} else {
> 		node->expected_votes = us->expected_votes;
>@@ -1683,7 +1782,6 @@ static void message_handler_req_exec_votequorum_nodeinfo (
> 	}
> 
> recalculate:
>-
> 	if ((new_node) ||
> 	    (nodeid == us->node_id) ||
> 	    (node->flags & NODE_FLAGS_FIRST) || 
>@@ -1739,6 +1837,9 @@ static void message_handler_req_exec_votequorum_reconfigure (
> 		}
> 		votequorum_exec_send_expectedvotes_notification();
> 		update_ev_barrier(req_exec_quorum_reconfigure->value);
>+		if (ev_tracking) {
>+		    us->expected_votes = max(us->expected_votes, ev_tracking_barrier);
>+		}
> 		recalculate_quorum(1, 0);  /* Allow decrease */
> 		break;
> 
>@@ -1772,6 +1873,11 @@ static int votequorum_exec_exit_fn (void)
> 		ret = votequorum_exec_send_nodeinfo(us->node_id);
> 	}
> 
>+	if ((ev_tracking) && (ev_tracking_fd != -1)) {
>+	    close(ev_tracking_fd);
>+	}
>+
>+
> 	LEAVE();
> 	return ret;
> }
>diff --git a/man/votequorum.5 b/man/votequorum.5
>index 081431f..ebd2852 100644
>--- a/man/votequorum.5
>+++ b/man/votequorum.5
>@@ -1,5 +1,5 @@
> .\"/*
>-.\" * Copyright (c) 2012 Red Hat, Inc.
>+.\" * Copyright (c) 2012-2014 Red Hat, Inc.
> .\" *
> .\" * All rights reserved.
> .\" *
>@@ -317,6 +317,27 @@ quorum {
>     allow_downscale: 1
> }
> .fi
>+allow_downscale implicitly enabled EVT (see below).
>+.PP
>+.B expected_votes_tracking: 1
>+.PP
>+Enables Expected Votes Tracking (EVT) feature (default: 0).
>+.PP
>+Expected Votes Tracking stores the highest-seen value of expected votes on disk and uses
>+that as the minimum value for expected votes in the absence of any higher authority (eg 
>+a current quorate cluster). This is useful for when a group of nodes becomes detached from
>+the main cluster and after a restart could have enough votes to provide quorum, which can 
>+happen after using allow_downscale. 
>+.PP
>+Note that even if the in-memory version of expected_votes is reduced, eg by removing nodes
>+or using corosync-quorumtool, the stored value will still be the highest value seen - it
>+never gets reduced.
>+.PP
>+The value is held in the file /var/lib/corosync/ev_tracking which can be deleted if you 
>+really do need to reduce the expected votes for any reason, like the node has been moved 
>+to a different cluster.
>+.PP
>+.fi
> .PP
> .SH VARIOUS NOTES
> .PP
>-- 
>1.8.2.1
>

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Attachments on bug 1052049: 849178