Envelope-to: root@trofast.sesse.net
Delivery-date: Sun, 17 Apr 2005 04:53:44 +0200
Subject: Bug#304245: patch - NFS mounts occasionally fail
Reply-To: Daniel Andre Vaquero <daniel@vision.ime.usp.br>,
	304245@bugs.debian.org
Resent-From: Daniel Andre Vaquero <daniel@vision.ime.usp.br>
Resent-To: debian-bugs-dist@lists.debian.org
Resent-CC: sesse@debian.org (Steinar H. Gunderson)
Resent-Date: Sun, 17 Apr 2005 02:48:03 UTC
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Date: Sat, 16 Apr 2005 23:38:26 -0300
From: Daniel Andre Vaquero <daniel@vision.ime.usp.br>
To: 304245@bugs.debian.org
Message-ID: <20050417023826.GA4527@vision.ime.usp.br>
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Hi,

After some days of testing with upstream version 4.1.4, I noticed that it
is also broken (although mount failures occur less frequently). My scenario
consists of a single server, with no replicated mounts. Debugging the code,
I found that the problem happens in the function get_best_mount()
of mount_nfs.c. If the server don't respond to rpc_ping() within 0.1 seconds,
winner remains NULL and the function is not called again with the longer
timeout (10 sec), leading to a mount failure because no winner is elected.
Another thing I noticed is that the behavior when there are replicated hosts
is not the described in README.replicated-server. If all pings fail, winner
should be set to the first host in the list, but the current code will return
winner = NULL.

I have made a patch that should solve these problems, and included it below
(maybe this fixes the problem of #297359 too).
It must be applied over upstream version 4.1.4. I'll be testing it for the 
single server scenario in the next few days.

$ diff -upr autofs-4.1.4.orig/modules/mount_nfs.c autofs-4.1.4/modules/mount_nfs.c

--- autofs-4.1.4.orig/modules/mount_nfs.c 2005-04-05 09:42:42.000000000 -0300
+++ autofs-4.1.4/modules/mount_nfs.c   2005-04-16 22:59:05.000000000 -0300
@@ -251,33 +251,28 @@ int get_best_mount(char *what, const cha
 
   debug(MODPREFIX "winner = %s local = %d", winner, local);
 
-  /*
-   * We didn't find a weighted winner or local
-   */
-  if (!local && winner_weight == INT_MAX) {
-     /* We had more than one contender and none responded in time */
-     if (winner_time != 0 && winner_time > 500) {
-        /* We've already tried a longer timeout */
-        if (!longtimeout) {
-           /* Reset string and try again */
-           strcpy(what, original);
-
-           debug(MODPREFIX 
-                 "all hosts timed out for '%s', "
-                 "retrying with longer timeout",
-                 original);
-
-           return get_best_mount(what, original, 1, 1);
-        }
+  /* No winner found */
+  if (!local && !winner) {
+     
+     /* Retry with a longer timeout */
+     if (!longtimeout) {
+        /* Reset string and try again */
+        strcpy(what, original);
+      
+        debug(MODPREFIX 
+              "all hosts timed out for '%s', "
+              "retrying with longer timeout",
+              original);
+        
+        return get_best_mount(what, original, 1, 1);
+     }
+     else {
+        /* No hosts responded, winner = first host */
+        winner = what;
      }
+     
   }
-
-  /* No winner found so bail */
-  if (!winner) {
-     *what = '\0';
-     return 0;
-  }
-
+  
   /*
    * We now have our winner, copy it to the front of the string,
    * followed by the next :string<delim>