commit a5ea57a64a1d70486e8d8ab2da944e50ca51b836
Author: zoulasc <christos@zoulas.com>
Date:   Tue Mar 8 23:31:26 2016 -0500

    - add more debugging in the unmount path
    - if the EXPIRE_MULTI call fails, with EAGAIN, fail back to the EXPIRE call
      seems to fix unmounting with nfsv4 volumes.

diff --git a/conf/autofs/autofs_linux.c b/conf/autofs/autofs_linux.c
index d543979..5b4ac06 100644
--- a/conf/autofs/autofs_linux.c
+++ b/conf/autofs/autofs_linux.c
@@ -365,6 +365,7 @@ autofs_expire_one(am_node *mp, char *name, autofs_wqt_t token)
 
   ap = find_ap(ap_path);
   if (ap == NULL) {
+    dlog("%s: could not find %s", __func__, ap_path);
     /* not found??? not sure what to do here... */
     send_fail(fh->ioctlfd, token);
     goto out;
@@ -376,6 +377,7 @@ autofs_expire_one(am_node *mp, char *name, autofs_wqt_t token)
   p->next = fh->pending_umounts;
   fh->pending_umounts = p;
 
+  dlog("%s: unmount for %s", __func__, ap_path);
   unmount_mp(ap);
 
 out:
@@ -426,6 +428,7 @@ autofs_missing_one(am_node *mp, autofs_wqt_t wait_queue_token, char *name)
       dlog("Mount still pending, not sending autofs reply yet");
       return;
     }
+    dlog("%s: lookup failed for %s/%s", __func__, mp->am_path, name);
     autofs_lookup_failed(mp, name);
   }
   mp->am_stats.s_lookup++;
@@ -872,15 +875,42 @@ autofs_compute_mount_flags(mntent_t *mnt)
   return 0;
 }
 
+static int autofs_expire_4(am_node *mp)
+{
+  struct autofs_packet_expire pkt;
+  autofs_fh_t *fh = mp->am_autofs_fh;
+
+  dlog("Calling AUTOFS_IOC_EXPIRE");
+  if (ioctl(fh->ioctlfd, AUTOFS_IOC_EXPIRE, &pkt) == -1)
+    {
+      dlog("AUTOFS_IOC_EXPIRE for %s failed %d", mp->am_path, errno);
+      return -1;
+    }
+
+  autofs_handle_expire(mp, &pkt);
+  return 0;
+}
+
 
 #if AUTOFS_MAX_PROTO_VERSION >= 4
 static int autofs_timeout_mp_task(void *arg)
 {
   am_node *mp = (am_node *)arg;
   autofs_fh_t *fh = mp->am_autofs_fh;
-  int now = 0;
-
-  while (ioctl(fh->ioctlfd, AUTOFS_IOC_EXPIRE_MULTI, &now) == 0);
+  int how = AUTOFS_EXP_IMMEDIATE;
+
+  for (;;)
+    {
+      dlog("Calling AUTOFS_IOC_EXPIRE_MULTI");
+      if (ioctl(fh->ioctlfd, AUTOFS_IOC_EXPIRE_MULTI, &how) == -1)
+        {
+	  dlog("AUTOFS_IOC_EXPIRE_MULTI for %s failed %d", mp->am_path, errno);
+	  if (errno != EAGAIN)
+	     break;
+	  if (autofs_expire_4(mp) == -1)
+	     break;
+	}
+    }
   return 0;
 }
 #endif /* AUTOFS_MAX_PROTO_VERSION >= 4 */
@@ -895,9 +925,8 @@ void autofs_timeout_mp(am_node *mp)
   mp->am_autofs_ttl = now + gopt.am_timeo_w;
 
   if (fh->version < 4) {
-    struct autofs_packet_expire pkt;
-    while (ioctl(fh->ioctlfd, AUTOFS_IOC_EXPIRE, &pkt) == 0)
-      autofs_handle_expire(mp, &pkt);
+    while (autofs_expire_4(mp) == 0)
+      continue;
     return;
   }