ocfs2: o2hb: add negotiate timer

From: Junxiao Bi <[email protected]>
Subject: ocfs2: o2hb: add negotiate timer

This series of patches is to fix the issue that when storage down, all nodes will fence self due to write timeout.

With this patch set, all nodes will keep going until storage back online, except if the following issue happens, then all nodes will do as before to fence self.

1. io error got
2. network between nodes down
3. nodes panic

This patch (of 6):

When storage down, all nodes will fence self due to write timeout. The negotiate timer is designed to avoid this, with it node will wait until storage up again.

Negotiate timer working in the following way:

1. The timer expires before write timeout timer, its timeout is half of write timeout now. It is re-queued along with write timeout timer. If expires, it will send NEGO_TIMEOUT message to master node(node with lowest node number). This message does nothing but marks a bit in a bitmap recording which nodes are negotiating timeout on master node.

2. If storage down, nodes will send this message to master node, then when master node finds its bitmap including all online nodes, it sends NEGO_APPROVL message to all nodes one by one, this message will re-queue write timeout timer and negotiate timer. For any node doesn't receive this message or meets some issue when handling this message, it will be fenced. If storage up at any time, o2hb_thread will run and re-queue all the timer, nothing will be affected by these two steps.

Signed-off-by Junxiao Bi <[email protected]>

Reviewed-by Ryan Ding <[email protected]>

Cc Gang He <[email protected]>

Cc rwxybh <[email protected]>

Cc Mark Fasheh <[email protected]>

Cc Joel Becker <[email protected]>

Cc Joseph Qi <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

---

 fs/ocfs2/cluster/heartbeat.c |   52 ++++++++++++++++++++++++++++++---
 1 file changed, 48 insertions(+), 4 deletions(-)

diff -puN fs/ocfs2/cluster/heartbeat.c~ocfs2-o2hb-add-negotiate-timer fs/ocfs2/cluster/heartbeat.c

fs/ocfs2/cluster/heartbeat.c renamed from fs/ocfs2/cluster/heartbeat.c~ocfs2-o2hb-add-negotiate-timer +48 -4

@@ -272,6 +272,10 @@ struct o2hb_region {
 	struct delayed_work	hr_write_timeout_work;
 	unsigned long		hr_last_timeout_start;
 
+	/* negotiate timer, used to negotiate extending hb timeout. */
+	struct delayed_work	hr_nego_timeout_work;
+	unsigned long		hr_nego_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
+
 	/* Used during o2hb_check_slot to hold a copy of the block
 	 * being checked because we temporarily have to zero out the
 	 * crc field. */

@@ -319,7 +323,7 @@ static void o2hb_write_timeout(struct wo
 	o2quo_disk_timeout();
 }
 
-static void o2hb_arm_write_timeout(struct o2hb_region *reg)
+static void o2hb_arm_timeout(struct o2hb_region *reg)
 {
 	/* Arm writeout only after thread reaches steady state */
 	if (atomic_read(&reg->hr_steady_iterations) != 0)

@@ -337,11 +341,50 @@ static void o2hb_arm_write_timeout(struc
 	reg->hr_last_timeout_start = jiffies;
 	schedule_delayed_work(&reg->hr_write_timeout_work,
 			      msecs_to_jiffies(O2HB_MAX_WRITE_TIMEOUT_MS));
+
+	cancel_delayed_work(&reg->hr_nego_timeout_work);
+	/* negotiate timeout must be less than write timeout. */
+	schedule_delayed_work(&reg->hr_nego_timeout_work,
+			      msecs_to_jiffies(O2HB_MAX_WRITE_TIMEOUT_MS)/2);
+	memset(reg->hr_nego_node_bitmap, 0, sizeof(reg->hr_nego_node_bitmap));
 }
 
-static void o2hb_disarm_write_timeout(struct o2hb_region *reg)
+static void o2hb_disarm_timeout(struct o2hb_region *reg)
 {
 	cancel_delayed_work_sync(&reg->hr_write_timeout_work);
+	cancel_delayed_work_sync(&reg->hr_nego_timeout_work);
+}
+
+static void o2hb_nego_timeout(struct work_struct *work)
+{
+	struct o2hb_region *reg =
+		container_of(work, struct o2hb_region,
+			     hr_nego_timeout_work.work);
+	unsigned long live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	int master_node;
+
+	o2hb_fill_node_map(live_node_bitmap, sizeof(live_node_bitmap));
+	/* lowest node as master node to make negotiate decision. */
+	master_node = find_next_bit(live_node_bitmap, O2NM_MAX_NODES, 0);
+
+	if (master_node == o2nm_this_node()) {
+		set_bit(master_node, reg->hr_nego_node_bitmap);
+		if (memcmp(reg->hr_nego_node_bitmap, live_node_bitmap,
+				sizeof(reg->hr_nego_node_bitmap))) {
+			/* check negotiate bitmap every second to do timeout
+			 * approve decision.
+			 */
+			schedule_delayed_work(&reg->hr_nego_timeout_work,
+				msecs_to_jiffies(1000));
+
+			return;
+		}
+
+		/* approve negotiate timeout request. */
+	} else {
+		/* negotiate timeout with master node. */
+	}
+
 }
 
 static inline void o2hb_bio_wait_init(struct o2hb_bio_wait_ctxt *wc)

@@ -1032,7 +1075,7 @@ static int o2hb_do_disk_heartbeat(struct
 	/* Skip disarming the timeout if own slot has stale/bad data */
 	if (own_slot_ok) {
 		o2hb_set_quorum_device(reg);
-		o2hb_arm_write_timeout(reg);
+		o2hb_arm_timeout(reg);
 	}
 
 bail:

@@ -1114,7 +1157,7 @@ static int o2hb_thread(void *data)
 		}
 	}
 
-	o2hb_disarm_write_timeout(reg);
+	o2hb_disarm_timeout(reg);
 
 	/* unclean stop is only used in very bad situation */
 	for(i = 0; !reg->hr_unclean_stop && i < reg->hr_blocks; i++)

@@ -1763,6 +1806,7 @@ static ssize_t o2hb_region_dev_store(str
 	}
 
 	INIT_DELAYED_WORK(&reg->hr_write_timeout_work, o2hb_write_timeout);
+	INIT_DELAYED_WORK(&reg->hr_nego_timeout_work, o2hb_nego_timeout);
 
 	/*
 	 * A node is considered live after it has beat LIVE_THRESHOLD

_

This is v1 version, I sent out V2 patch set before to fix all code style issue.

Quoted 151 lines · akpm at linux-foundation.org

From: Junxiao Bi <[email protected]>
Subject: ocfs2: o2hb: add negotiate timer

This series of patches is to fix the issue that when storage down, all nodes will fence self due to write timeout.

With this patch set, all nodes will keep going until storage back online, except if the following issue happens, then all nodes will do as before to fence self.

1. io error got
2. network between nodes down
3. nodes panic

This patch (of 6):

When storage down, all nodes will fence self due to write timeout. The negotiate timer is designed to avoid this, with it node will wait until storage up again.

Negotiate timer working in the following way:

1. The timer expires before write timeout timer, its timeout is half of write timeout now. It is re-queued along with write timeout timer. If expires, it will send NEGO_TIMEOUT message to master node(node with lowest node number). This message does nothing but marks a bit in a bitmap recording which nodes are negotiating timeout on master node.

2. If storage down, nodes will send this message to master node, then when master node finds its bitmap including all online nodes, it sends NEGO_APPROVL message to all nodes one by one, this message will re-queue write timeout timer and negotiate timer. For any node doesn't receive this message or meets some issue when handling this message, it will be fenced. If storage up at any time, o2hb_thread will run and re-queue all the timer, nothing will be affected by these two steps.

Signed-off-by Junxiao Bi <[email protected]>

Reviewed-by Ryan Ding <[email protected]>

Cc Gang He <[email protected]>

Cc rwxybh <[email protected]>

Cc Mark Fasheh <[email protected]>

Cc Joel Becker <[email protected]>

Cc Joseph Qi <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

---

 fs/ocfs2/cluster/heartbeat.c |   52 ++++++++++++++++++++++++++++++---
 1 file changed, 48 insertions(+), 4 deletions(-)

diff -puN fs/ocfs2/cluster/heartbeat.c~ocfs2-o2hb-add-negotiate-timer fs/ocfs2/cluster/heartbeat.c

fs/ocfs2/cluster/heartbeat.c renamed from fs/ocfs2/cluster/heartbeat.c~ocfs2-o2hb-add-negotiate-timer +48 -4

@@ -272,6 +272,10 @@ struct o2hb_region {
 	struct delayed_work	hr_write_timeout_work;
 	unsigned long		hr_last_timeout_start;
 
+	/* negotiate timer, used to negotiate extending hb timeout. */
+	struct delayed_work	hr_nego_timeout_work;
+	unsigned long		hr_nego_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
+
 	/* Used during o2hb_check_slot to hold a copy of the block
 	 * being checked because we temporarily have to zero out the
 	 * crc field. */

@@ -319,7 +323,7 @@ static void o2hb_write_timeout(struct wo
 	o2quo_disk_timeout();
 }
 
-static void o2hb_arm_write_timeout(struct o2hb_region *reg)
+static void o2hb_arm_timeout(struct o2hb_region *reg)
 {
 	/* Arm writeout only after thread reaches steady state */
 	if (atomic_read(&reg->hr_steady_iterations) != 0)

@@ -337,11 +341,50 @@ static void o2hb_arm_write_timeout(struc
 	reg->hr_last_timeout_start = jiffies;
 	schedule_delayed_work(&reg->hr_write_timeout_work,
 			      msecs_to_jiffies(O2HB_MAX_WRITE_TIMEOUT_MS));
+
+	cancel_delayed_work(&reg->hr_nego_timeout_work);
+	/* negotiate timeout must be less than write timeout. */
+	schedule_delayed_work(&reg->hr_nego_timeout_work,
+			      msecs_to_jiffies(O2HB_MAX_WRITE_TIMEOUT_MS)/2);
+	memset(reg->hr_nego_node_bitmap, 0, sizeof(reg->hr_nego_node_bitmap));
 }
 
-static void o2hb_disarm_write_timeout(struct o2hb_region *reg)
+static void o2hb_disarm_timeout(struct o2hb_region *reg)
 {
 	cancel_delayed_work_sync(&reg->hr_write_timeout_work);
+	cancel_delayed_work_sync(&reg->hr_nego_timeout_work);
+}
+
+static void o2hb_nego_timeout(struct work_struct *work)
+{
+	struct o2hb_region *reg =
+		container_of(work, struct o2hb_region,
+			     hr_nego_timeout_work.work);
+	unsigned long live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	int master_node;
+
+	o2hb_fill_node_map(live_node_bitmap, sizeof(live_node_bitmap));
+	/* lowest node as master node to make negotiate decision. */
+	master_node = find_next_bit(live_node_bitmap, O2NM_MAX_NODES, 0);
+
+	if (master_node == o2nm_this_node()) {
+		set_bit(master_node, reg->hr_nego_node_bitmap);
+		if (memcmp(reg->hr_nego_node_bitmap, live_node_bitmap,
+				sizeof(reg->hr_nego_node_bitmap))) {
+			/* check negotiate bitmap every second to do timeout
+			 * approve decision.
+			 */
+			schedule_delayed_work(&reg->hr_nego_timeout_work,
+				msecs_to_jiffies(1000));
+
+			return;
+		}
+
+		/* approve negotiate timeout request. */
+	} else {
+		/* negotiate timeout with master node. */
+	}
+
 }
 
 static inline void o2hb_bio_wait_init(struct o2hb_bio_wait_ctxt *wc)

@@ -1032,7 +1075,7 @@ static int o2hb_do_disk_heartbeat(struct
 	/* Skip disarming the timeout if own slot has stale/bad data */
 	if (own_slot_ok) {
 		o2hb_set_quorum_device(reg);
-		o2hb_arm_write_timeout(reg);
+		o2hb_arm_timeout(reg);
 	}
 
 bail:

@@ -1114,7 +1157,7 @@ static int o2hb_thread(void *data)
 		}
 	}
 
-	o2hb_disarm_write_timeout(reg);
+	o2hb_disarm_timeout(reg);
 
 	/* unclean stop is only used in very bad situation */
 	for(i = 0; !reg->hr_unclean_stop && i < reg->hr_blocks; i++)

@@ -1763,6 +1806,7 @@ static ssize_t o2hb_region_dev_store(str
 	}
 
 	INIT_DELAYED_WORK(&reg->hr_write_timeout_work, o2hb_write_timeout);
+	INIT_DELAYED_WORK(&reg->hr_nego_timeout_work, o2hb_nego_timeout);
 
 	/*
 	 * A node is considered live after it has beat LIVE_THRESHOLD

Quoted 2 lines

_

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Hi, Junxiao
This patch may have a problem. That is journal of every nodes become abort when storage down, and then when storage up, because journal has become abort, all of operations of metadata will fail. So how to restore environment? panic or reset? how to trigger?

Thanks,
Yiwen Jiang.

Hi Yiwen,

Quoted 5 lines · jiangyiwen

Hi, Junxiao
This patch may have a problem. That is journal of every nodes become abort when storage down, and then when storage up, because journal has become abort, all of operations of metadata will fail. So how to restore environment? panic or reset? how to trigger?

Journal aborted means io error was returned by storage, right? If so, o2hb_thread should also get io error, in this case, nego process will be bypassed, and nodes will be fenced at last, see "[patch 23/25]
ocfs2: o2hb: don't negotiate if last hb fail".

Thanks,
Junxiao.

Quoted 3 lines

Thanks,
Yiwen Jiang.

.

Quoted 18 lines · Junxiao Bi

Hi Yiwen,

Quoted 5 lines · jiangyiwen

Hi, Junxiao
This patch may have a problem. That is journal of every nodes become abort when storage down, and then when storage up, because journal has become abort, all of operations of metadata will fail. So how to restore environment? panic or reset? how to trigger?

Journal aborted means io error was returned by storage, right? If so, o2hb_thread should also get io error, in this case, nego process will be bypassed, and nodes will be fenced at last, see "[patch 23/25]
ocfs2: o2hb: don't negotiate if last hb fail".

Thanks,
Junxiao.

Quoted 2 lines

Thanks,
Yiwen Jiang.

Quoted 2 lines

.

yes, you are right, sorry I don't see this patch before.

But I understand the results of storage down should return IO error rather than getting hang.

Thanks,
Yiwen Jiang.

_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel at oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel

Quoted 19 lines · jiangyiwen

Quoted 18 lines · Junxiao Bi

Hi Yiwen,

Quoted 5 lines · jiangyiwen

Hi, Junxiao
This patch may have a problem. That is journal of every nodes become abort when storage down, and then when storage up, because journal has become abort, all of operations of metadata will fail. So how to restore environment? panic or reset? how to trigger?

Journal aborted means io error was returned by storage, right? If so, o2hb_thread should also get io error, in this case, nego process will be bypassed, and nodes will be fenced at last, see "[patch 23/25]
ocfs2: o2hb: don't negotiate if last hb fail".

Thanks,
Junxiao.

Quoted 2 lines

Thanks,
Yiwen Jiang.

Quoted 6 lines

Quoted 2 lines

.

yes, you are right, sorry I don't see this patch before.

But I understand the results of storage down should return IO error rather than getting hang.

that is upto the driver or storage. If they return I/O error, o2hb i/o's will get i/o errors and will be addressed accordingly. These changes are made for cases where storage is not yet responding due to head failovers/recovery on the storage array.

Quoted 5 lines

Thanks,
Yiwen Jiang.

Quoted 4 lines

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