Currently, if getaddrinfo(3) fails when trying to resolve a hostname,
sm-notify gives up immediately on that host. If sm-notify is started
before network service is available on a system, that means it quits
without notifying anyone. Or, if DNS service isn't available due to
a network partition or because the DNS server crashed, sm-notify will
simply remove all of its callback files and exit.
Really, sm-notify should try harder. We know that the hostnames
passed in to notify_host() have already been vetted by statd, which
won't monitor a hostname that it can't resolve. So it's likely that
any DNS failure we meet here is a temporary condition. If it isn't,
then sm-notify will stop trying to notify that host in 15 minutes
anyway.
[ The host's file is left in /var/lib/nfs/sm.bak in this case, but
sm.bak is not read again until the next time sm-notify runs. ]
sm-notify already has retry logic for handling RPC timeouts. We can
co-opt that to drive DNS resolution retries.
We also add AI_ADDRCONFIG because on systems whose network startup is
handled by NetworkManager, there appears to be a bug that causes
processes that started calling getaddinfo(3) before the network came
up to continue getting EAI_AGAIN even after the network is fully
operating.
As I understand it, legacy glibc (before AI_ADDRCONFIG was exposed in
headers) sets AI_ADDRCONFIG by default, although I haven't checked
this. In any event, pre-glibc-2.2 systems probably won't run
NetworkManager anyway, so this may not be much of a problem for them.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
utils/statd/sm-notify.c | 39 +++++++++++++++++++++++++++------------
1 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/utils/statd/sm-notify.c b/utils/statd/sm-notify.c
index 78d0a59..72dcff4 100644
--- a/utils/statd/sm-notify.c
+++ b/utils/statd/sm-notify.c
@@ -118,17 +118,33 @@ static void smn_set_port(struct sockaddr *sap, const unsigned short port)
}
}
-static struct addrinfo *smn_lookup(const sa_family_t family, const char *name)
+static struct addrinfo *smn_lookup(const char *name)
{
struct addrinfo *ai, hint = {
- .ai_family = family,
+#if HAVE_DECL_AI_ADDRCONFIG
+ .ai_flags = AI_ADDRCONFIG,
+#endif /* HAVE_DECL_AI_ADDRCONFIG */
+ .ai_family = AF_INET,
.ai_protocol = IPPROTO_UDP,
};
+ int error;
+
+ error = getaddrinfo(name, NULL, &hint, &ai);
+ switch (error) {
+ case 0:
+ return ai;
+ case EAI_SYSTEM:
+ if (opt_debug)
+ nsm_log(LOG_ERR, "getaddrinfo(3): %s",
+ strerror(errno));
+ break;
+ default:
+ if (opt_debug)
+ nsm_log(LOG_ERR, "getaddrinfo(3): %s",
+ gai_strerror(error));
+ }
- if (getaddrinfo(name, NULL, &hint, &ai) != 0)
- return NULL;
-
- return ai;
+ return NULL;
}
static void smn_forget_host(struct nsm_host *host)
@@ -291,7 +307,7 @@ notify(void)
/* Bind source IP if provided on command line */
if (opt_srcaddr) {
- struct addrinfo *ai = smn_lookup(AF_INET, opt_srcaddr);
+ struct addrinfo *ai = smn_lookup(opt_srcaddr);
if (!ai) {
nsm_log(LOG_ERR,
"Not a valid hostname or address: \"%s\"",
@@ -402,13 +418,12 @@ notify_host(int sock, struct nsm_host *host)
host->xid = xid++;
if (host->ai == NULL) {
- host->ai = smn_lookup(AF_UNSPEC, host->name);
+ host->ai = smn_lookup(host->name);
if (host->ai == NULL) {
nsm_log(LOG_WARNING,
- "%s doesn't seem to be a valid address,"
- " skipped", host->name);
- smn_forget_host(host);
- return 1;
+ "DNS resolution of %s failed; "
+ "retrying later", host->name);
+ return 0;
}
}
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
