On Mon, 15 Mar 2010 13:51:37 -0400
Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
> The mon_name argument of an SM_NOTIFY request is a string that
> identifies the rebooting host.
>
> sm-notify should send the my_name provided by the local lockd at the
> time the remote was monitored, rather than cocking up a mon_name
> argument based on the present return value of gethostname(3). If the
> local system's hostname happened to change after the last reboot, then
> the string returned by gethostname(3) will not be recognized by the
> remote. Thus the remote will never initiate lock recovery for the
> original named host, possibly leaving stale locks.
>
> The existing behavior of using the -v command line option as the
> mon_name argument is preserved, but we now prevent sending an IP
> presentation address, as some non-Linux implementations don't
> recognize addresses as valid mon_names.
>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
>
> utils/statd/sm-notify.c | 41 ++++++++++++++++++++++++++++++++---------
> utils/statd/sm-notify.man | 28 +++++++++++++---------------
> utils/statd/statd.man | 14 ++------------
> 3 files changed, 47 insertions(+), 36 deletions(-)
>
> diff --git a/utils/statd/sm-notify.c b/utils/statd/sm-notify.c
> index 3259a3e..2d14668 100644
> --- a/utils/statd/sm-notify.c
> +++ b/utils/statd/sm-notify.c
> @@ -54,7 +54,7 @@ struct nsm_host {
> uint32_t xid;
> };
>
> -static char nsm_hostname[256];
> +static char nsm_hostname[SM_MAXSTRLEN + 1];
> static int nsm_state;
> static int nsm_family = AF_INET;
> static int opt_debug = 0;
> @@ -412,12 +412,33 @@ usage: fprintf(stderr,
> }
> }
>
> - if (opt_srcaddr) {
> - strncpy(nsm_hostname, opt_srcaddr, sizeof(nsm_hostname)-1);
> - } else
> - if (gethostname(nsm_hostname, sizeof(nsm_hostname)) < 0) {
> - xlog(L_ERROR, "Failed to obtain name of local host: %m");
> - exit(1);
> + if (opt_srcaddr != NULL) {
> + struct addrinfo *ai = NULL;
> + struct addrinfo hint = {
> + .ai_family = AF_UNSPEC,
> + .ai_flags = AI_NUMERICHOST,
> + };
> +
> + if (getaddrinfo(opt_srcaddr, NULL, &hint, &ai))
> + /* not a presentation address - use it */
> + strncpy(nsm_hostname, opt_srcaddr, sizeof(nsm_hostname));
> + else {
> + /* was a presentation address - look it up in
> + * /etc/hosts, so it can be used for my_name */
> + int error;
> +
> + freeaddrinfo(ai);
> + hint.ai_flags = AI_CANONNAME;
> + error = getaddrinfo(opt_srcaddr, NULL, &hint, &ai);
> + if (error != 0) {
> + xlog(L_ERROR, "Bind address %s is unusable: %s",
> + opt_srcaddr, gai_strerror(error));
> + exit(1);
> + }
> + strncpy(nsm_hostname, ai->ai_canonname,
> + sizeof(nsm_hostname));
> + freeaddrinfo(ai);
> + }
>From what I can tell, lockd always uses the utsname()->nodename for the
"caller" field. Am I correct that that's what the server generally
expects to get from the client for my_name on a NSM notification?
If so, wouldn't the above patch pretty much ensure that the kernel and
statd are sending different info here?
> }
>
> (void)nsm_retire_monitored_hosts();
> @@ -535,6 +556,8 @@ notify(const int sock)
> static int
> notify_host(int sock, struct nsm_host *host)
> {
> + const char *my_name = (opt_srcaddr != NULL ?
> + nsm_hostname : host->my_name);
> struct sockaddr *sap;
> socklen_t salen;
>
> @@ -580,8 +603,8 @@ notify_host(int sock, struct nsm_host *host)
> host->xid = nsm_xmit_rpcbind(sock, sap, SM_PROG, SM_VERS);
> else
> host->xid = nsm_xmit_notify(sock, sap, salen,
> - SM_PROG, nsm_hostname, nsm_state);
> -
> + SM_PROG, my_name, nsm_state);
> +
> return 0;
> }
>
> diff --git a/utils/statd/sm-notify.man b/utils/statd/sm-notify.man
> index 163713e..7a1cbfa 100644
> --- a/utils/statd/sm-notify.man
> +++ b/utils/statd/sm-notify.man
> @@ -97,11 +97,9 @@ It uses the
> string as the destination.
> To identify which host has rebooted, the
> .B sm-notify
> -command normally sends the results of
> -.BR gethostname (3)
> -as the
> +command normally sends
> .I my_name
> -string.
> +string recorded when that remote was monitored.
> The remote
> .B rpc.statd
> matches incoming SM_NOTIFY requests using this string,
> @@ -202,15 +200,22 @@ argument to use when sending SM_NOTIFY requests.
> If this option is not specified,
> .B sm-notify
> uses a wildcard address as the transport bind address,
> -and uses the results of
> -.BR gethostname (3)
> -as the
> +and uses the
> +.I my_name
> +recorded when the remote was monitored as the
> .I mon_name
> -argument.
> +argument when sending SM_NOTIFY requests.
> .IP
> The
> .I ipaddr
> form can be expressed as either an IPv4 or an IPv6 presentation address.
> +If the
> +.I ipaddr
> +form is used, the
> +.B sm-notify
> +command converts this address to a hostname for use as the
> +.I mon_name
> +argument when sending SM_NOTIFY requests.
> .IP
> This option can be useful in multi-homed configurations where
> the remote requires notification from a specific network address.
> @@ -252,13 +257,6 @@ consistent
> The hostname the client uses to mount the server should match the server's
> .I mon_name
> in SM_NOTIFY requests it sends
> -.IP
> -The use of network addresses as a
> -.I mon_name
> -or a
> -.I my_name
> -string should be avoided when
> -interoperating with non-Linux NFS implementations.
> .PP
> Unmounting an NFS file system does not necessarily stop
> either the NFS client or server from monitoring each other.
> diff --git a/utils/statd/statd.man b/utils/statd/statd.man
> index ffc5e95..ca00e24 100644
> --- a/utils/statd/statd.man
> +++ b/utils/statd/statd.man
> @@ -100,11 +100,9 @@ It uses the
> string as the destination.
> To identify which host has rebooted, the
> .B sm-notify
> -command normally sends the results of
> -.BR gethostname (3)
> -as the
> +command sends the
> .I my_name
> -string.
> +string recorded when that remote was monitored.
> The remote
> .B rpc.statd
> matches incoming SM_NOTIFY requests using this string,
> @@ -292,7 +290,6 @@ man pages.
> .SH ADDITIONAL NOTES
> Lock recovery after a reboot is critical to maintaining data integrity
> and preventing unnecessary application hangs.
> -.PP
> To help
> .B rpc.statd
> match SM_NOTIFY requests to NLM requests, a number of best practices
> @@ -309,13 +306,6 @@ consistent
> The hostname the client uses to mount the server should match the server's
> .I mon_name
> in SM_NOTIFY requests it sends
> -.IP
> -The use of network addresses as a
> -.I mon_name
> -or a
> -.I my_name
> -string should be avoided when
> -interoperating with non-Linux NFS implementations.
> .PP
> Unmounting an NFS file system does not necessarily stop
> either the NFS client or server from monitoring each other.
>
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--
Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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