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.

Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/statd/sm-notify.c b/utils/statd/sm-notify.c
index bb67c378e94839254bbb49ec093bef71dda11317..b75f11b365c317a8f4638b6bf4574ab602be86bf 100644 (file)
--- a/utils/statd/sm-notify.c
+++ b/utils/statd/sm-notify.c
@@ -24,6 +24,8 @@
 #include <errno.h>
 #include <grp.h>
 
+#include "config.h"
+
 #ifndef BASEDIR
 # ifdef NFS_STATEDIR
 #  define BASEDIR              NFS_STATEDIR
@@ -76,7 +78,7 @@ 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 *);
@@ -277,7 +279,7 @@ notify(void)
                if (failtime && now >= failtime)
                        break;
 
-               while ((wait = hosts->send_next - now) <= 0) {
+               while (hosts && ((wait = hosts->send_next - now) <= 0)) {
                        /* Never send more than 10 packets at once */
                        if (sent++ >= 10)
                                break;
@@ -286,7 +288,13 @@ notify(void)
                        hp = hosts;
                        hosts = hp->next;
 
-                       notify_host(sock, hp);
+                       if (notify_host(sock, hp)){
+                               unlink(hp->path);
+                               free(hp->name);
+                               free(hp->path);
+                               free(hp);
+                               continue;
+                       }
 
                        /* Set the timeout for this call, using an
                           exponential timeout strategy */
@@ -298,6 +306,8 @@ notify(void)
 
                        insert_host(hp);
                }
+               if (hosts == NULL)
+                       return;
 
                nsm_log(LOG_DEBUG, "Host %s due in %ld seconds",
                                hosts->name, wait);
@@ -318,7 +328,7 @@ notify(void)
 /*
  * Send notification to a single host
  */
-void
+int
 notify_host(int sock, struct nsm_host *host)
 {
        static unsigned int     xid = 0;
@@ -331,6 +341,16 @@ 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);
@@ -343,14 +363,19 @@ notify_host(int sock, struct nsm_host *host)
         * point.
         */
        if (host->retries >= 4) {
-               struct addrinfo *hold = host->ai;
+               struct addrinfo *first = host->ai;
                struct addrinfo **next = &host->ai;
-               *next = hold->ai_next;
+
+               /* remove the first entry from the list */
+               host->ai = first->ai_next;
+               first->ai_next = NULL;
+               /* find the end of the list */
+               next = &first->ai_next;
                while ( *next )
                        next = & (*next)->ai_next;
-               *next = hold;
-               hold->ai_next = NULL;
-               memcpy(&host->addr, hold->ai_addr, hold->ai_addrlen);
+               /* put first entry at end */
+               *next = first;
+               memcpy(&host->addr, first->ai_addr, first->ai_addrlen);
                addr_set_port(&host->addr, 0);
                host->retries = 0;
        }
@@ -394,7 +419,11 @@ notify_host(int sock, struct nsm_host *host)
        }
        len = (p - msgbuf) << 2;
 
-       sendto(sock, msgbuf, len, 0, (struct sockaddr *) &dest, sizeof(dest));
+       if (sendto(sock, msgbuf, len, 0, (struct sockaddr *) &dest, sizeof(dest)) < 0)
+               nsm_log(LOG_WARNING, "Sending Reboot Notification to "
+                       "'%s' failed: errno %d (%s)", host->name, errno, strerror(errno));
+       
+       return 0;
 }
 
 /*
@@ -504,7 +533,7 @@ 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 +561,6 @@ 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);