From 29ed1407ed81086b778ebf12145b048ac3f7e10e Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 4 Dec 2008 14:20:46 -0500 Subject: [PATCH] NSM: Support IPv6 version of mon_name The "mon_name" argument of the NSMPROC_MON and NSMPROC_UNMON upcalls is a string that contains the hostname or IP address of the remote peer to be notified when this host has rebooted. The sm-notify command uses this identifier to contact the peer when we reboot, so it must be either a well-qualified DNS hostname or a presentation format IP address string. When the "nsm_use_hostnames" sysctl is set to zero, the kernel's NSM provides a presentation format IP address in the "mon_name" argument. Otherwise, the "caller_name" argument from NLM requests is used, which is usually just the DNS hostname of the peer. To support IPv6 addresses for the mon_name argument, we use the nsm_handle's address eye-catcher, which already contains an appropriate presentation format address string. Using the eye-catcher string obviates the need to use a large buffer on the stack to form the presentation address string for the upcall. This patch also addresses a subtle bug. An NSMPROC_MON request and the subsequent NSMPROC_UNMON request for the same peer are required to use the same value for the "mon_name" argument. Otherwise, rpc.statd's NSMPROC_UNMON processing cannot locate the database entry for that peer and remove it. If the setting of nsm_use_hostnames is changed between the time the kernel sends an NSMPROC_MON request and the time it sends the NSMPROC_UNMON request for the same peer, the "mon_name" argument for these two requests may not be the same. This is because the value of "mon_name" is currently chosen at the moment the call is made based on the setting of nsm_use_hostnames To ensure both requests pass identical contents in the "mon_name" argument, we now select which string to use for the argument in the nsm_monitor() function. A pointer to this string is saved in the nsm_handle so it can be used for a subsequent NSMPROC_UNMON upcall. NB: There are other potential problems, such as how nlm_host_rebooted() might behave if nsm_use_hostnames were changed while hosts are still being monitored. This patch does not attempt to address those problems. Signed-off-by: Chuck Lever Signed-off-by: J. Bruce Fields --- fs/lockd/mon.c | 27 ++++++++------------------- include/linux/lockd/lockd.h | 1 + 2 files changed, 9 insertions(+), 19 deletions(-) diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c index 497dfea02e8a..a606fbbf804d 100644 --- a/fs/lockd/mon.c +++ b/fs/lockd/mon.c @@ -18,8 +18,6 @@ #define NLMDBG_FACILITY NLMDBG_MONITOR -#define XDR_ADDRBUF_LEN (20) - static struct rpc_clnt * nsm_create(void); static struct rpc_program nsm_program; @@ -42,7 +40,7 @@ nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res) .prog = NLM_PROGRAM, .vers = 3, .proc = NLMPROC_NSM_NOTIFY, - .mon_name = nsm->sm_name, + .mon_name = nsm->sm_mon_name, }; struct rpc_message msg = { .rpc_argp = &args, @@ -87,6 +85,12 @@ nsm_monitor(struct nlm_host *host) if (nsm->sm_monitored) return 0; + /* + * Choose whether to record the caller_name or IP address of + * this peer in the local rpc.statd's database. + */ + nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf; + status = nsm_mon_unmon(nsm, SM_MON, &res); if (status < 0 || res.status != 0) @@ -167,25 +171,10 @@ static __be32 *xdr_encode_nsm_string(__be32 *p, char *string) /* * "mon_name" specifies the host to be monitored. - * - * Linux uses a text version of the IP address of the remote - * host as the host identifier (the "mon_name" argument). - * - * Linux statd always looks up the canonical hostname first for - * whatever remote hostname it receives, so this works alright. */ static __be32 *xdr_encode_mon_name(__be32 *p, struct nsm_args *argp) { - char buffer[XDR_ADDRBUF_LEN + 1]; - char *name = argp->mon_name; - - if (!nsm_use_hostnames) { - snprintf(buffer, XDR_ADDRBUF_LEN, - "%pI4", &argp->addr); - name = buffer; - } - - return xdr_encode_nsm_string(p, name); + return xdr_encode_nsm_string(p, argp->mon_name); } /* diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h index 54dbb458e73c..d3c7247d23e8 100644 --- a/include/linux/lockd/lockd.h +++ b/include/linux/lockd/lockd.h @@ -79,6 +79,7 @@ struct nlm_host { struct nsm_handle { struct list_head sm_link; atomic_t sm_count; + char *sm_mon_name; char *sm_name; struct sockaddr_storage sm_addr; size_t sm_addrlen; -- 2.30.2