Return-Path: Received: from mail-iw0-f174.google.com ([209.85.214.174]:48772 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752136Ab0LQSyk convert rfc822-to-8bit (ORCPT ); Fri, 17 Dec 2010 13:54:40 -0500 Received: by iwn9 with SMTP id 9so1018587iwn.19 for ; Fri, 17 Dec 2010 10:54:39 -0800 (PST) In-Reply-To: <20101217184047.GD11515@fieldses.org> References: <1292610010-19084-1-git-send-email-andros@netapp.com> <1292610010-19084-2-git-send-email-andros@netapp.com> <20101217184047.GD11515@fieldses.org> Date: Fri, 17 Dec 2010 13:54:39 -0500 Message-ID: Subject: Re: [PATCH_V4 1/9] SUNRPC new transport for the NFSv4.1 shared back channel From: "William A. (Andy) Adamson" To: "J. Bruce Fields" Cc: trond.myklebust@netapp.com, bfields@redhat.com, linux-nfs@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Fri, Dec 17, 2010 at 1:40 PM, J. Bruce Fields wrote: > On Fri, Dec 17, 2010 at 01:20:02PM -0500, andros@netapp.com wrote: >> From: Andy Adamson >> >> Create a new transport for the shared back channel.l Move the current sock >> create and destroy routines into the new transport ops. >> >> Reference the back channel transport across message processing (recv/send). >> >> Signed-off-by: Andy Adamson >> --- >> ?include/linux/sunrpc/svcsock.h | ? ?1 + >> ?net/sunrpc/svc.c ? ? ? ? ? ? ? | ? 18 +++--- >> ?net/sunrpc/svcsock.c ? ? ? ? ? | ?122 +++++++++++++++++++++++++++++++++------- >> ?3 files changed, 112 insertions(+), 29 deletions(-) >> >> diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h >> index 1b353a7..3a45a80 100644 >> --- a/include/linux/sunrpc/svcsock.h >> +++ b/include/linux/sunrpc/svcsock.h >> @@ -45,6 +45,7 @@ int ? ? ? ? svc_sock_names(struct svc_serv *serv, char *buf, >> ?int ? ? ? ? ?svc_addsock(struct svc_serv *serv, const int fd, >> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? char *name_return, const size_t len); >> ?void ? ? ? ? svc_init_xprt_sock(void); >> +void ? ? ? ? svc_init_bc_xprt_sock(void); >> ?void ? ? ? ? svc_cleanup_xprt_sock(void); >> ?struct svc_xprt *svc_sock_create(struct svc_serv *serv, int prot); >> ?void ? ? ? ? svc_sock_destroy(struct svc_xprt *); >> diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c >> index 6359c42..3520cb3 100644 >> --- a/net/sunrpc/svc.c >> +++ b/net/sunrpc/svc.c >> @@ -488,10 +488,6 @@ svc_destroy(struct svc_serv *serv) >> ? ? ? if (svc_serv_is_pooled(serv)) >> ? ? ? ? ? ? ? svc_pool_map_put(); >> >> -#if defined(CONFIG_NFS_V4_1) >> - ? ? svc_sock_destroy(serv->bc_xprt); >> -#endif /* CONFIG_NFS_V4_1 */ >> - >> ? ? ? svc_unregister(serv); >> ? ? ? kfree(serv->sv_pools); >> ? ? ? kfree(serv); >> @@ -1264,7 +1260,7 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req, >> ?{ >> ? ? ? struct kvec ? ? *argv = &rqstp->rq_arg.head[0]; >> ? ? ? struct kvec ? ? *resv = &rqstp->rq_res.head[0]; >> - ? ? int ? ? ? ? ? ? error; >> + ? ? int ? ? ? ? ? ? ret; >> >> ? ? ? /* Build the svc_rqst used by the common processing routine */ >> ? ? ? rqstp->rq_xprt = serv->bc_xprt; >> @@ -1292,12 +1288,16 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req, >> ? ? ? svc_getu32(argv); ? ? ? /* XID */ >> ? ? ? svc_getnl(argv); ? ? ? ?/* CALLDIR */ >> >> - ? ? error = svc_process_common(rqstp, argv, resv); >> - ? ? if (error <= 0) >> - ? ? ? ? ? ? return error; >> + ? ? /* Hold a reference to the back channel socket across the call */ >> + ? ? svc_xprt_get(serv->bc_xprt); > > Either we already have a reference, in which case this is unnecessary, > or we don't, in which case this is risky. This is done so that when svc_xprt_put is called due to an svc_drop (svc_xprt_release, svc_xprt_put) it is not freed. It's not risky because AFAICS it's the way the rpc server code is intended to work. Note that svc_recv calls svc_xprt_get, and svc_send calls svc_xprt_put for the same reason. > The nfs client code knows when it wants to create and destroy the > backchannel, so I think all you want is to create the svc_xprt when you > create the backchannel and then put it once when you bring it down. Correct, and without the references in bc_svc_process, svc_drop == freeing. -->Andy > > --b. > >> + ? ? ret = svc_process_common(rqstp, argv, resv); >> + ? ? if (ret <= 0) >> + ? ? ? ? ? ? return ret; >> >> ? ? ? memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf)); >> - ? ? return bc_send(req); >> + ? ? ret = bc_send(req); >> + ? ? svc_xprt_put(serv->bc_xprt); >> + ? ? return ret; >> ?} >> ?EXPORT_SYMBOL(bc_svc_process); >> ?#endif /* CONFIG_NFS_V4_1 */ >> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c >> index 07919e1..5875551 100644 >> --- a/net/sunrpc/svcsock.c >> +++ b/net/sunrpc/svcsock.c >> @@ -66,6 +66,13 @@ static void ? ? ? ? ? ? ? ?svc_sock_free(struct svc_xprt *); >> ?static struct svc_xprt *svc_create_socket(struct svc_serv *, int, >> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? struct net *, struct sockaddr *, >> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? int, int); >> +#if defined(CONFIG_NFS_V4_1) >> +static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *, struct sockaddr *, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int, int); >> +static void svc_bc_sock_free(struct svc_xprt *xprt); >> +#endif /* CONFIG_NFS_V4_1 */ >> + >> ?#ifdef CONFIG_DEBUG_LOCK_ALLOC >> ?static struct lock_class_key svc_key[2]; >> ?static struct lock_class_key svc_slock_key[2]; >> @@ -1184,6 +1191,79 @@ static struct svc_xprt *svc_tcp_create(struct svc_serv *serv, >> ? ? ? return svc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags); >> ?} >> >> +#if defined(CONFIG_NFS_V4_1) >> +static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *, struct sockaddr *, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int, int); >> +static void svc_bc_sock_free(struct svc_xprt *xprt); >> + >> +static struct svc_xprt *svc_bc_tcp_create(struct svc_serv *serv, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *net, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct sockaddr *sa, int salen, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int flags) >> +{ >> + ? ? return svc_bc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags); >> +} >> + >> +static void svc_bc_tcp_sock_detach(struct svc_xprt *xprt) >> +{ >> +} >> + >> +/* These bc ops are never called. The shared fore channel is used instead */ >> +static int svc_bc_tcp_recvfrom(struct svc_rqst *rqstp) >> +{ >> + ? ? return 0; >> +} >> + >> +static int svc_bc_tcp_sendto(struct svc_rqst *rqstp) >> +{ >> + ? ? return 0; >> +} >> + >> +static void svc_bc_tcp_prep_reply_hdr(struct svc_rqst *rqstp) >> +{ >> +} >> + >> +static void svc_bc_release_skb(struct svc_rqst *rqstp) >> +{ >> +} >> + >> +static int svc_bc_tcp_has_wspace(struct svc_xprt *xprt) >> +{ >> + ? ? return 0; >> +} >> + >> +static struct svc_xprt *svc_bc_tcp_accept(struct svc_xprt *xprt) >> +{ >> + ? ? return NULL; >> +} >> + >> +static struct svc_xprt_ops svc_tcp_bc_ops = { >> + ? ? .xpo_create = svc_bc_tcp_create, >> + ? ? .xpo_recvfrom = svc_bc_tcp_recvfrom, >> + ? ? .xpo_sendto = svc_bc_tcp_sendto, >> + ? ? .xpo_release_rqst = svc_bc_release_skb, >> + ? ? .xpo_detach = svc_bc_tcp_sock_detach, >> + ? ? .xpo_free = svc_bc_sock_free, >> + ? ? .xpo_prep_reply_hdr = svc_bc_tcp_prep_reply_hdr, >> + ? ? .xpo_has_wspace = svc_bc_tcp_has_wspace, >> + ? ? .xpo_accept = svc_bc_tcp_accept, >> +}; >> + >> +static struct svc_xprt_class svc_tcp_bc_class = { >> + ? ? .xcl_name = "tcp-bc", >> + ? ? .xcl_owner = THIS_MODULE, >> + ? ? .xcl_ops = &svc_tcp_bc_ops, >> + ? ? .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP, >> +}; >> + >> +void svc_init_bc_xprt_sock(void) >> +{ >> + ? ? svc_reg_xprt_class(&svc_tcp_bc_class); >> +} >> +EXPORT_SYMBOL_GPL(svc_init_bc_xprt_sock); >> +#endif /* CONFIG_NFS_V4_1 */ >> + >> ?static struct svc_xprt_ops svc_tcp_ops = { >> ? ? ? .xpo_create = svc_tcp_create, >> ? ? ? .xpo_recvfrom = svc_tcp_recvfrom, >> @@ -1509,41 +1589,43 @@ static void svc_sock_free(struct svc_xprt *xprt) >> ? ? ? kfree(svsk); >> ?} >> >> +#if defined(CONFIG_NFS_V4_1) >> ?/* >> - * Create a svc_xprt. >> - * >> - * For internal use only (e.g. nfsv4.1 backchannel). >> - * Callers should typically use the xpo_create() method. >> + * Create a back channel svc_xprt which shares the fore channel socket. >> ? */ >> -struct svc_xprt *svc_sock_create(struct svc_serv *serv, int prot) >> +static struct svc_xprt *svc_bc_create_socket(struct svc_serv *serv, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int protocol, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *net, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct sockaddr *sin, int len, >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int flags) >> ?{ >> ? ? ? struct svc_sock *svsk; >> - ? ? struct svc_xprt *xprt = NULL; >> + ? ? struct svc_xprt *xprt; >> + >> + ? ? if (protocol != IPPROTO_TCP) { >> + ? ? ? ? ? ? printk(KERN_WARNING "svc: only and TCP sockets" >> + ? ? ? ? ? ? ? ? ? ? " supported on shared back channel\n"); >> + ? ? ? ? ? ? return ERR_PTR(-EINVAL); >> + ? ? } >> >> - ? ? dprintk("svc: %s\n", __func__); >> ? ? ? svsk = kzalloc(sizeof(*svsk), GFP_KERNEL); >> ? ? ? if (!svsk) >> - ? ? ? ? ? ? goto out; >> + ? ? ? ? ? ? return ERR_PTR(-ENOMEM); >> >> ? ? ? xprt = &svsk->sk_xprt; >> - ? ? if (prot == IPPROTO_TCP) >> - ? ? ? ? ? ? svc_xprt_init(&svc_tcp_class, xprt, serv); >> - ? ? else if (prot == IPPROTO_UDP) >> - ? ? ? ? ? ? svc_xprt_init(&svc_udp_class, xprt, serv); >> - ? ? else >> - ? ? ? ? ? ? BUG(); >> -out: >> - ? ? dprintk("svc: %s return %p\n", __func__, xprt); >> + ? ? svc_xprt_init(&svc_tcp_bc_class, xprt, serv); >> + >> + ? ? serv->bc_xprt = xprt; >> + >> ? ? ? return xprt; >> ?} >> -EXPORT_SYMBOL_GPL(svc_sock_create); >> >> ?/* >> - * Destroy a svc_sock. >> + * Free a back channel svc_sock. >> ? */ >> -void svc_sock_destroy(struct svc_xprt *xprt) >> +static void svc_bc_sock_free(struct svc_xprt *xprt) >> ?{ >> ? ? ? if (xprt) >> ? ? ? ? ? ? ? kfree(container_of(xprt, struct svc_sock, sk_xprt)); >> ?} >> -EXPORT_SYMBOL_GPL(svc_sock_destroy); >> +#endif /* CONFIG_NFS_V4_1 */ >> -- >> 1.6.6 >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at ?http://vger.kernel.org/majordomo-info.html >