[patch 0/2] ipvs: avoid overcommit on the standby, take II

[patch 0/2] ipvs: avoid overcommit on the standby, take II

[Simon Horman]

Two related patches from Rumen G. Bogdanovski
to help prevent overcommit on the standby.

After sending the last patchset I discovered scripts/checkpatch.pl and
found that it didn't like quite a few things. I've fixed those problems
and here is the result.

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/

[patch 1/2] ipvs: Bind connections on stanby if the destination exists

[Simon Horman]

[-- Attachment #1: linux-2.6.23.1-ipvs-rb.patch --]
[-- Type: text/plain, Size: 7357 bytes --]

From: Rumen G. Bogdanovski <rumen@voicecho.com>

This patch fixes the problem with node overload on director fail-over.
Given the scenario: 2 nodes each accepting 3 connections at a time and 2
directors, director failover occurs when the nodes are fully loaded (6
connections to the cluster) in this case the new director will assign
another 6 connections to the cluster, If the same real servers exist
there.

The problem turned to be in not binding the inherited connections to
the real servers (destinations) on the backup director. Therefore:
"ipvsadm -l" reports 0 connections:
root@test2:~# ipvsadm -l
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  test2.local:5999 wlc
  -> node473.local:5999           Route   1000   0          0
  -> node484.local:5999           Route   1000   0          0

while "ipvs -lnc" is right
root@test2:~# ipvsadm -lnc
IPVS connection entries
pro expire state       source             virtual            destination
TCP 14:56  ESTABLISHED 192.168.0.10:39164 192.168.0.222:5999
192.168.0.51:5999
TCP 14:59  ESTABLISHED 192.168.0.10:39165 192.168.0.222:5999
192.168.0.52:5999

So the patch I am sending fixes the problem by binding the received
connections to the appropriate service on the backup director, if it
exists, else the connection will be handled the old way. So if the
master and the backup directors are synchronized in terms of real
services there will be no problem with server over-committing since
new connections will not be created on the nonexistent real services
on the backup. However if the service is created later on the backup,
the binding will be performed when the next connection update is
received. With this patch the inherited connections will show as
inactive on the backup:

root@test2:~# ipvsadm -l
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  test2.local:5999 wlc
  -> node473.local:5999           Route   1000   0          1
  -> node484.local:5999           Route   1000   0          1

rumen@test2:~$ cat /proc/net/ip_vs
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP  C0A800DE:176F wlc
  -> C0A80033:176F      Route   1000   0          1
  -> C0A80032:176F      Route   1000   0          1


Regards,
Rumen Bogdanovski

Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Rumen G. Bogdanovski <rumen@voicecho.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

--- 
Thu, 01 Nov 2007 18:26:24 +0900, Horms
* Various whitespace and indentation changes
* Rediffed against net-2.6
* Ran against ./scripts/checkpatch.pl and fixed everything that
  it complained about

Index: net-2.6/include/net/ip_vs.h
===================================================================
--- net-2.6.orig/include/net/ip_vs.h	2007-11-01 17:57:30.000000000 +0900
+++ net-2.6/include/net/ip_vs.h	2007-11-01 18:06:56.000000000 +0900
@@ -901,6 +901,10 @@ extern int ip_vs_use_count_inc(void);
 extern void ip_vs_use_count_dec(void);
 extern int ip_vs_control_init(void);
 extern void ip_vs_control_cleanup(void);
+extern struct ip_vs_dest *
+ip_vs_find_dest(__be32 daddr, __be16 dport,
+		 __be32 vaddr, __be16 vport, __u16 protocol);
+extern struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp);
 
 
 /*
Index: net-2.6/net/ipv4/ipvs/ip_vs_conn.c
===================================================================
--- net-2.6.orig/net/ipv4/ipvs/ip_vs_conn.c	2007-11-01 17:57:30.000000000 +0900
+++ net-2.6/net/ipv4/ipvs/ip_vs_conn.c	2007-11-01 18:06:47.000000000 +0900
@@ -426,6 +426,25 @@ ip_vs_bind_dest(struct ip_vs_conn *cp, s
 
 
 /*
+ * Check if there is a destination for the connection, if so
+ * bind the connection to the destination.
+ */
+struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp)
+{
+	struct ip_vs_dest *dest;
+
+	if ((cp) && (!cp->dest)) {
+		dest = ip_vs_find_dest(cp->daddr, cp->dport,
+				       cp->vaddr, cp->vport, cp->protocol);
+		ip_vs_bind_dest(cp, dest);
+		return dest;
+	} else
+		return NULL;
+}
+EXPORT_SYMBOL(ip_vs_try_bind_dest);
+
+
+/*
  *	Unbind a connection entry with its VS destination
  *	Called by the ip_vs_conn_expire function.
  */
Index: net-2.6/net/ipv4/ipvs/ip_vs_ctl.c
===================================================================
--- net-2.6.orig/net/ipv4/ipvs/ip_vs_ctl.c	2007-11-01 17:57:30.000000000 +0900
+++ net-2.6/net/ipv4/ipvs/ip_vs_ctl.c	2007-11-01 18:06:47.000000000 +0900
@@ -579,6 +579,34 @@ ip_vs_lookup_dest(struct ip_vs_service *
 	return NULL;
 }
 
+/*
+ * Find destination by {daddr,dport,vaddr,protocol}
+ * Cretaed to be used in ip_vs_process_message() in
+ * the backup synchronization daemon. It finds the
+ * destination to be bound to the received connection
+ * on the backup.
+ *
+ * ip_vs_lookup_real_service() looked promissing, but
+ * seems not working as expected.
+ */
+struct ip_vs_dest *ip_vs_find_dest(__be32 daddr, __be16 dport,
+				    __be32 vaddr, __be16 vport,
+				    __u16 protocol)
+{
+	struct ip_vs_dest *dest;
+	struct ip_vs_service *svc;
+
+	svc = ip_vs_service_get(0, protocol, vaddr, vport);
+	if (!svc)
+		return NULL;
+	dest = ip_vs_lookup_dest(svc, daddr, dport);
+	if (dest)
+		atomic_inc(&dest->refcnt);
+	ip_vs_service_put(svc);
+
+	return dest;
+}
+EXPORT_SYMBOL(ip_vs_find_dest);
 
 /*
  *  Lookup dest by {svc,addr,port} in the destination trash.
Index: net-2.6/net/ipv4/ipvs/ip_vs_sync.c
===================================================================
--- net-2.6.orig/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 17:57:30.000000000 +0900
+++ net-2.6/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:06:56.000000000 +0900
@@ -284,6 +284,7 @@ static void ip_vs_process_message(const 
 	struct ip_vs_sync_conn_options *opt;
 	struct ip_vs_conn *cp;
 	struct ip_vs_protocol *pp;
+	struct ip_vs_dest *dest;
 	char *p;
 	int i;
 
@@ -317,20 +318,35 @@ static void ip_vs_process_message(const 
 					       s->caddr, s->cport,
 					       s->vaddr, s->vport);
 		if (!cp) {
+			/*
+			 * Find the appropriate destination for the connection.
+			 * If it is not found the connection will remain unbound
+			 * but still handled.
+			 */
+			dest = ip_vs_find_dest(s->daddr, s->dport,
+					       s->vaddr, s->vport,
+					       s->protocol);
 			cp = ip_vs_conn_new(s->protocol,
 					    s->caddr, s->cport,
 					    s->vaddr, s->vport,
 					    s->daddr, s->dport,
-					    flags, NULL);
+					    flags, dest);
+			if (dest)
+				atomic_dec(&dest->refcnt);
 			if (!cp) {
 				IP_VS_ERR("ip_vs_conn_new failed\n");
 				return;
 			}
 			cp->state = ntohs(s->state);
 		} else if (!cp->dest) {
-			/* it is an entry created by the synchronization */
-			cp->state = ntohs(s->state);
-			cp->flags = flags | IP_VS_CONN_F_HASHED;
+			dest = ip_vs_try_bind_dest(cp);
+			if (!dest) {
+				/* it is an unbound entry created by
+				 * synchronization */
+				cp->state = ntohs(s->state);
+				cp->flags = flags | IP_VS_CONN_F_HASHED;
+			} else
+				atomic_dec(&dest->refcnt);
 		}	/* Note that we don't touch its state and flags
 			   if it is a normal entry. */
 

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/

[patch 2/2] ipvs: Syncrhonise Closing of Connections

[Simon Horman]

[-- Attachment #1: linux-2.6.23.1-ipvs-csync-ag-inc-rb.patch --]
[-- Type: text/plain, Size: 5142 bytes --]

From: Rumen G. Bogdanovski <rumen@voicecho.com>

This patch makes the master daemon to sync the connection when it is about
to close.  This makes the connections on the backup to close or timeout
according their state.  Before the sync was performed only if the
connection is in ESTABLISHED state which always made the connections to
timeout in the hard coded 3 minutes. However the Andy Gospodarek's patch
([IPVS]: use proper timeout instead of fixed value) effectively did nothing
more than increasing this to 15 minutes (Established state timeout).  So
this patch makes use of proper timeout since it syncs the connections on
status changes to FIN_WAIT (2min timeout) and CLOSE (10sec timeout).
However if the backup misses CLOSE hopefully it did not miss FIN_WAIT.
Otherwise we will just have to wait for the ESTABLISHED state timeout. As
it is without this patch.  This way the number of the hanging connections
on the backup is kept to minimum. And very few of them will be left to
timeout with a long timeout.

This is important if we want to make use of the fix for the real server
overcommit on master/backup fail-over.

Regards,
Rumen Bogdanovski

Signed-off-by: Rumen G. Bogdanovski <rumen@voicecho.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

--- 
Thu, 01 Nov 2007 18:25:10 +0900, Horms
* Redifed for net-2.6
* Ran through scripts/checkpatch.pl and fixed up everything
  that it complains about except the use of volatile, as
  its in keeping with other fields in the structure.
  If its wrong, lets fix them all together.

WARNING: Use of volatile is usually wrong: see
Documentation/volatile-considered-harmful.txt
#49: FILE: include/net/ip_vs.h:523:
+	volatile __u16          old_state;      /* old state, to be used for

Index: net-2.6/include/net/ip_vs.h
===================================================================
--- net-2.6.orig/include/net/ip_vs.h	2007-11-01 18:17:55.000000000 +0900
+++ net-2.6/include/net/ip_vs.h	2007-11-01 18:21:02.000000000 +0900
@@ -520,6 +520,10 @@ struct ip_vs_conn {
 	spinlock_t              lock;           /* lock for state transition */
 	volatile __u16          flags;          /* status flags */
 	volatile __u16          state;          /* state info */
+	volatile __u16          old_state;      /* old state, to be used for
+						 * state transition triggerd
+						 * synchronization
+						 */
 
 	/* Control members */
 	struct ip_vs_conn       *control;       /* Master control connection */
Index: net-2.6/net/ipv4/ipvs/ip_vs_core.c
===================================================================
--- net-2.6.orig/net/ipv4/ipvs/ip_vs_core.c	2007-11-01 18:17:55.000000000 +0900
+++ net-2.6/net/ipv4/ipvs/ip_vs_core.c	2007-11-01 18:18:23.000000000 +0900
@@ -979,15 +979,23 @@ ip_vs_in(unsigned int hooknum, struct sk
 		ret = NF_ACCEPT;
 	}
 
-	/* increase its packet counter and check if it is needed
-	   to be synchronized */
+	/* Increase its packet counter and check if it is needed
+	 * to be synchronized
+	 *
+	 * Sync connection if it is about to close to
+	 * encorage the standby servers to update the connections timeout
+	 */
 	atomic_inc(&cp->in_pkts);
 	if ((ip_vs_sync_state & IP_VS_STATE_MASTER) &&
-	    (cp->protocol != IPPROTO_TCP ||
-	     cp->state == IP_VS_TCP_S_ESTABLISHED) &&
-	    (atomic_read(&cp->in_pkts) % sysctl_ip_vs_sync_threshold[1]
-	     == sysctl_ip_vs_sync_threshold[0]))
+	    (((cp->protocol != IPPROTO_TCP ||
+	       cp->state == IP_VS_TCP_S_ESTABLISHED) &&
+	      (atomic_read(&cp->in_pkts) % sysctl_ip_vs_sync_threshold[1]
+	       == sysctl_ip_vs_sync_threshold[0])) ||
+	     ((cp->protocol == IPPROTO_TCP) && (cp->old_state != cp->state) &&
+	      ((cp->state == IP_VS_TCP_S_FIN_WAIT) ||
+	       (cp->state == IP_VS_TCP_S_CLOSE)))))
 		ip_vs_sync_conn(cp);
+	cp->old_state = cp->state;
 
 	ip_vs_conn_put(cp);
 	return ret;
Index: net-2.6/net/ipv4/ipvs/ip_vs_sync.c
===================================================================
--- net-2.6.orig/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:17:55.000000000 +0900
+++ net-2.6/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:20:30.000000000 +0900
@@ -332,7 +332,7 @@ static void ip_vs_process_message(const 
 					    s->daddr, s->dport,
 					    flags, dest);
 			if (dest)
-				atomic_dec(&dest->refcnt);
+				ip_vs_dest_get(dest);
 			if (!cp) {
 				IP_VS_ERR("ip_vs_conn_new failed\n");
 				return;
@@ -343,10 +343,9 @@ static void ip_vs_process_message(const 
 			if (!dest) {
 				/* it is an unbound entry created by
 				 * synchronization */
-				cp->state = ntohs(s->state);
 				cp->flags = flags | IP_VS_CONN_F_HASHED;
 			} else
-				atomic_dec(&dest->refcnt);
+				ip_vs_dest_put(dest);
 		}	/* Note that we don't touch its state and flags
 			   if it is a normal entry. */
 
@@ -358,6 +357,7 @@ static void ip_vs_process_message(const 
 			p += SIMPLE_CONN_SIZE;
 
 		atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
+		cp->state = ntohs(s->state);
 		pp = ip_vs_proto_get(s->protocol);
 		cp->timeout = pp->timeout_table[cp->state];
 		ip_vs_conn_put(cp);

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/

Re: [patch 2/2] ipvs: Syncrhonise Closing of Connections

[Julian Anastasov]

	Hello,

On Thu, 1 Nov 2007, Simon Horman wrote:

> --- net-2.6.orig/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:17:55.000000000 +0900
> +++ net-2.6/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:20:30.000000000 +0900
> @@ -332,7 +332,7 @@ static void ip_vs_process_message(const 
>  					    s->daddr, s->dport,
>  					    flags, dest);
>  			if (dest)

	Is that correct? Sorry, I was flooded with different versions
of this patch and I'm not sure if it is the final one.

> -				atomic_dec(&dest->refcnt);
> +				ip_vs_dest_get(dest);
>  			if (!cp) {
>  				IP_VS_ERR("ip_vs_conn_new failed\n");
>  				return;

Regards

--
Julian Anastasov <ja@ssi.bg>

Re: [patch 2/2] ipvs: Syncrhonise Closing of Connections

[Simon Horman]

On Fri, Nov 02, 2007 at 01:36:07AM +0200, Julian Anastasov wrote:
> 
> 	Hello,
> 
> On Thu, 1 Nov 2007, Simon Horman wrote:
> 
> > --- net-2.6.orig/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:17:55.000000000 +0900
> > +++ net-2.6/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:20:30.000000000 +0900
> > @@ -332,7 +332,7 @@ static void ip_vs_process_message(const 
> >  					    s->daddr, s->dport,
> >  					    flags, dest);
> >  			if (dest)
> 
> 	Is that correct? Sorry, I was flooded with different versions
> of this patch and I'm not sure if it is the final one.
> 
> > -				atomic_dec(&dest->refcnt);
> > +				ip_vs_dest_get(dest);
> >  			if (!cp) {
> >  				IP_VS_ERR("ip_vs_conn_new failed\n");
> >  				return;

The ip_vs_dest_get() call shouldn't be there.
I'll double check the rest of the patch.

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/

Re: [lvs-devel] [patch 2/2] ipvs: Syncrhonise Closing of Connections

[Rumen Bogdanovski]

I should have been very tired to miss this one when I looked at the
patch... 
I looked again in the version I have tested. For some
reason/net/ipv4/ipvs/ip_vs_sync.c is not patched at all, this is what I
have missed.

Rumen

On Fri, 2007-11-02 at 09:53 +0900, Simon Horman wrote:
> On Fri, Nov 02, 2007 at 01:36:07AM +0200, Julian Anastasov wrote:
> > 
> > 	Hello,
> > 
> > On Thu, 1 Nov 2007, Simon Horman wrote:
> > 
> > > --- net-2.6.orig/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:17:55.000000000 +0900
> > > +++ net-2.6/net/ipv4/ipvs/ip_vs_sync.c	2007-11-01 18:20:30.000000000 +0900
> > > @@ -332,7 +332,7 @@ static void ip_vs_process_message(const 
> > >  					    s->daddr, s->dport,
> > >  					    flags, dest);
> > >  			if (dest)
> > 
> > 	Is that correct? Sorry, I was flooded with different versions
> > of this patch and I'm not sure if it is the final one.
> > 
> > > -				atomic_dec(&dest->refcnt);
> > > +				ip_vs_dest_get(dest);
> > >  			if (!cp) {
> > >  				IP_VS_ERR("ip_vs_conn_new failed\n");
> > >  				return;
> 
> The ip_vs_dest_get() call shouldn't be there.
> I'll double check the rest of the patch.
>