sm-notify: perform DNS lookup in the background.

If an NFS server has no network connectivity when it reboots,
it will block in sm-notify waiting for DNS lookup for a potentially
large number of hosts.  This is not helpful and just annoys the
sysadmin.

So do the DNS lookup in the backgrounded phase of sm-notify,
before sending off the NOTIFY requests.  If hostname lookup fails,
just drop that host.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/utils/statd/sm-notify.c b/utils/statd/sm-notify.c
index bb67c378e94839254bbb49ec093bef71dda11317..407c5784dd5eeadf872466a5ad038e7e3cd6522a 100644 (file)
--- a/utils/statd/sm-notify.c
+++ b/utils/statd/sm-notify.c
@@ -76,7 +76,7 @@ static int            log_syslog = 0;
 
 static unsigned int    nsm_get_state(int);
 static void            notify(void);
-static void            notify_host(int, struct nsm_host *);
+static int             notify_host(int, struct nsm_host *);
 static void            recv_reply(int);
 static void            backup_hosts(const char *, const char *);
 static void            get_hosts(const char *);
@@ -286,7 +286,13 @@ notify(void)
                        hp = hosts;
                        hosts = hp->next;
 
-                       notify_host(sock, hp);
+                       if (notify_host(sock, hp) < 0) {
+                               unlink(hp->path);
+                               free(hp->name);
+                               free(hp->path);
+                               free(hp);
+                               continue;
+                       }
 
                        /* Set the timeout for this call, using an
                           exponential timeout strategy */
@@ -316,9 +322,10 @@ notify(void)
 }
 
 /*
- * Send notification to a single host
+ * Send notification to a single host.
+ * Return negative if we should give up on this host.
  */
-void
+int
 notify_host(int sock, struct nsm_host *host)
 {
        static unsigned int     xid = 0;
@@ -331,6 +338,17 @@ notify_host(int sock, struct nsm_host *host)
        if (!host->xid)
                host->xid = xid++;
 
+       if (host->ai == NULL) {
+               host->ai = host_lookup(AF_UNSPEC, host->name);
+               if (host->ai == NULL) {
+                       nsm_log(LOG_WARNING,
+                               "%s doesn't seem to be a valid address,"
+                               " skipped",
+                               host->name);
+                       return -1;
+               }
+       }
+
        memset(msgbuf, 0, sizeof(msgbuf));
        p = msgbuf;
        *p++ = htonl(host->xid);
@@ -395,6 +413,8 @@ notify_host(int sock, struct nsm_host *host)
        len = (p - msgbuf) << 2;
 
        sendto(sock, msgbuf, len, 0, (struct sockaddr *) &dest, sizeof(dest));
+
+       return 0;
 }
 
 /*
@@ -504,7 +524,7 @@ backup_hosts(const char *dirname, const char *bakname)
 }
 
 /*
- * Get all entries from sm.bak and convert them to host names
+ * Get all entries from sm.bak and convert them to host entries
  */
 static void
 get_hosts(const char *dirname)
@@ -532,15 +552,6 @@ get_hosts(const char *dirname)
                if (stat(path, &stb) < 0)
                        continue;
 
-               host->ai = host_lookup(AF_UNSPEC, de->d_name);
-               if (! host->ai) {
-                       nsm_log(LOG_WARNING,
-                               "%s doesn't seem to be a valid address, skipped",
-                               de->d_name);
-                       unlink(path);
-                       continue;
-               }
-
                host->last_used = stb.st_mtime;
                host->timeout = NSM_TIMEOUT;
                host->path = strdup(path);