Fill in rqstp->rq_daddr in svc_tcp_recvfrom

PATCH In review Olaf Kirch 3 participants 4 messages Jul 12, 2005 – Jul 13, 2005

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Networking NFS client NFS server

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Olaf Kirch

author

2005-07-12 09:05 UTC #0 lore raw

PATCH 1/1 Fill in rqstp->rq_daddr in svc_tcp_recvfrom

Here's a patch we added to SLES in response to a customer bug report:

# Subject: Fill in rqstp->rq_daddr in svc_tcp_recvfrom
#
# This patch fills the daddr member of the rpc struct svc_rqst structure for # TCP-based sockets in the recvfrom proceedure. Currently, the field is

# not set thus leaving it with left over garbage from a previous allocation. 
#
# This makes the behavior consistent between UDP- and TCP-based RPC. 
#
# This patch enables HA software to failover TCP-based RPC services
# such as TCP-based NFS. 
#
# Signed-off-by: [email protected]

net/sunrpc/svcsock.c +2 -1

Index: linux-2.6.12.orig/net/sunrpc/svcsock.c
===================================================================
@@ -455,8 +455,9 @@ svc_recvfrom(struct svc_rqst *rqstp, str
 	struct socket	*sock;
 	int		len, alen;
 
-	rqstp->rq_addrlen = sizeof(rqstp->rq_addr);
 	sock = rqstp->rq_sock->sk_sock;
+	rqstp->rq_daddr = inet_sk((const struct sock *)sock)->rcv_saddr;
+	rqstp->rq_addrlen = sizeof(rqstp->rq_addr);
 
 	msg.msg_name    = &rqstp->rq_addr;
 	msg.msg_namelen = sizeof(rqstp->rq_addr);

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Olaf Kirch   |  --- o --- Nous sommes du soleil we love when we play
[email protected] |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax


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J. Bruce Fields

2005-07-12 16:31 UTC #1 lore raw

Quoted 6 lines · Olaf Kirch

Here's a patch we added to SLES in response to a customer bug report:
# Subject: Fill in rqstp->rq_daddr in svc_tcp_recvfrom
#
# This patch fills the daddr member of the rpc struct svc_rqst structure for # TCP-based sockets in the recvfrom proceedure. Currently, the field is

Quoted 6 lines

# not set thus leaving it with left over garbage from a previous allocation. 
#
# This makes the behavior consistent between UDP- and TCP-based RPC. 
#
# This patch enables HA software to failover TCP-based RPC services
# such as TCP-based NFS.

Could you explain how this patch makes a difference? I can only see the value of rq_daddr used in one place, in svc_sendto:

        if (rqstp->rq_prot == IPPROTO_UDP) {
...
                pki->ipi_spec_dst.s_addr = rqstp->rq_daddr;

                if (sock_sendmsg(sock, &msg, 0) < 0)
                        goto out;
        }

So it doesn't seem to be used at all in the TCP case. Am I confused?

--b.

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Olaf Kirch

author

2005-07-13 05:18 UTC #2 lore raw

Hi Bruce,

Quoted 2 lines

Could you explain how this patch makes a difference? I can only see the value of rq_daddr used in one place, in svc_sendto:

It doesn't make a difference for the existing RPC users, but the customer had some kernel RPC code of their own (I think some HA capable nfsd) that needed this information for migration/failover.

It's not strictly necessary, but it doesn't hurt either - and it makes sense in the way that UDP and TCP now fill in the same set of information.

Olaf

Signature · 12 lines

Olaf Kirch   |  --- o --- Nous sommes du soleil we love when we play
[email protected] |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax


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Christoph Hellwig

2005-07-13 14:36 UTC #3 lore raw

Quoted 8 lines · Olaf Kirch

Hi Bruce,
Quoted 2 lines
Could you explain how this patch makes a difference? I can only see the value of rq_daddr used in one place, in svc_sendto:
It doesn't make a difference for the existing RPC users, but the customer had some kernel RPC code of their own (I think some HA capable nfsd) that needed this information for migration/failover.

So let the customer post the patch, including the code that uses it, as that might actually be useful for others aswell.