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authorChuck Lever <chuck.lever@oracle.com>2008-12-04 14:20:46 -0500
committerJ. Bruce Fields <bfields@citi.umich.edu>2009-01-06 11:53:51 -0500
commit29ed1407ed81086b778ebf12145b048ac3f7e10e (patch)
tree35523669465a1a37f969054e1c3d7530582701fc
parentf47534f7f0ac7727e05ec4274b764b181df2cf7f (diff)
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 <chuck.lever@oracle.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
-rw-r--r--fs/lockd/mon.c27
-rw-r--r--include/linux/lockd/lockd.h1
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;