zdtm: don't create loops of bind mounts

Before this patch crtools/test is bound to crtools/test/dump/crtools.XXXXXXX

It's a main reason why "make clean" deletes all content from crtools/test.

Always when you have a test bind mount. You have a test bind mount, when
a test is executed. You execute a test sometimes. So "make clean"
deletes all content sometimes;).

This patch fixes this problem.

Actually this patch fixes more significan problem. If / is a shared
mount (it's defult in FC19),
$ mount --bind crtools/test crtools/test/dump/crtools.XXXXXXX
will recursively copy all previous bind mounts.

E.g:

cd crtools/test
make -j 4
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.DMoEZv ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA/dump/crtools-root.DMoEZv ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.oLnVTw ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.DMoEZv/dump/crtools-root.oLnVTw ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA/dump/crtools-root.DMoEZv/dump/crtools-root.oLnVTw ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA/dump/crtools-root.oLnVTw ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.oLnVTw/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.DMoEZv/dump/crtools-root.oLnVTw/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA/dump/crtools-root.DMoEZv/dump/crtools-root.oLnVTw/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA/dump/crtools-root.oLnVTw/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.DMoEZv/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA/dump/crtools-root.DMoEZv/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0
/dev/mapper/vg-lv_root /root/crtools/test/dump/crtools-root.b86wVA/dump/crtools-root.7zQrDs ext4 rw,relatime,data=ordered 0 0

make -j 32 generates ~2^32 mounts.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -221,7 +221,7 @@ start_test()
 	else
 		if [ -z "$ZDTM_ROOT" ]; then
 			mkdir dump
-			ZDTM_ROOT=`mktemp -d dump/crtools-root.XXXXXX`
+			ZDTM_ROOT=`mktemp -d /tmp/crtools-root.XXXXXX`
 			ZDTM_ROOT=`readlink -f $ZDTM_ROOT`
 			mount --bind . $ZDTM_ROOT || return 1
 		fi