Tests portability: umount(8)

1) Avoid hangs on unmounting NFS on NetBSD

NetBSD umount(8) on a NFS mount whose server is gone will wait forever
because umount(8) calls realpath(3) and tries to access the mount before
it calls unmount(2). The non-portable, NetBSD-specific umount -R flag
prevent that behavior.

We therefore introduce UMOUNT_F, defined as "umount -f" on Linux and
"umount -f -R" on NetBSD to take care of forced unmounts, especially
in the NFS case.

2) Enforce usage of force_umount wrapper with timeout

Whenever umount is used it should be wrapped in force_umount with
tiemout handling. That saves us timing issues, and it handles the
NetBSD NFS case.

3) Cleanup kernel cache flush.

We used (cd $M0 && umount $M0 )	as a portable kernel cache flush
trick, but it does not flush everything we need on Linux. Introduce
a drop_cache() shell function that reverts to previously used
echo 3 > /proc/sys/vm/drop_caches on Linux, and keeps
(cd $M0 && umount $M0 ) on other systems.

BUG: 1129939
Change-Id: Iab1f5a023405f1f7270c42b595573702ca1eb6f3
Signed-off-by: Emmanuel Dreyfus <manu@netbsd.org>
Reviewed-on: http://review.gluster.org/11114
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/tests/volume.rc b/tests/volume.rc
index 5a7d0343a14..b12ba42784e 100644
--- a/tests/volume.rc
+++ b/tests/volume.rc
@@ -435,7 +435,7 @@ function path_exists {
 }
 
 function force_umount {
-        umount -f $*
+        ${UMOUNT_F} $*
         if [ $? -eq 0 ]; then echo "Y"; else echo "N"; fi
 }
 
@@ -543,3 +543,15 @@ function get_scrubd_count {
         ps auxw | grep glusterfs | grep scrub.pid | grep -v grep | wc -l
 }
 
+
+function drop_cache() {
+	case $OSTYPE in
+	Linux)
+		echo 3 > /proc/sys/vm/drop_caches
+		;;
+	*)
+		# fail but flush caches
+		( cd $1 && umount $1 2>/dev/null )
+		;;
+	esac
+}