Cleanup zloop working directory after each pass

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Giuseppe Di Natale <[email protected]>
Reviewed by: John Kennedy <[email protected]>
Reviewed-by: Olaf Faaland <[email protected]>
Signed-off-by: Don Brady <[email protected]>
Issue openzfs#6595 
Closes openzfs#6663

scripts/zloop.sh

@@ -100,6 +100,7 @@ function store_core
 {
 	core="$(core_file)"
 	if [[ $ztrc -ne 0 ]] || [[ -f "$core" ]]; then
+		df -h "$workdir" >>ztest.out
 		coreid=$(date "+zloop-%y%m%d-%H%M%S")
 		foundcrashes=$((foundcrashes + 1))
 
@@ -149,15 +150,16 @@ function store_core
 # parse arguments
 # expected format: zloop [-t timeout] [-c coredir] [-- extra ztest args]
 coredir=$DEFAULTCOREDIR
-workdir=$DEFAULTWORKDIR
+basedir=$DEFAULTWORKDIR
+rundir="zloop-run"
 timeout=0
 size="512m"
 while getopts ":ht:s:c:f:" opt; do
 	case $opt in
 		t ) [[ $OPTARG -gt 0 ]] && timeout=$OPTARG ;;
 		s ) [[ $OPTARG ]] && size=$OPTARG ;;
 		c ) [[ $OPTARG ]] && coredir=$OPTARG ;;
-		f ) [[ $OPTARG ]] && workdir=$(readlink -f "$OPTARG") ;;
+		f ) [[ $OPTARG ]] && basedir=$(readlink -f "$OPTARG") ;;
 		h ) usage
 		    exit 2
 		    ;;
@@ -201,6 +203,11 @@ curtime=$starttime
 while [[ $timeout -eq 0 ]] || [[ $curtime -le $((starttime + timeout)) ]]; do
 	zopt="-VVVVV"
 
+	# start each run with an empty directory
+	workdir="$basedir/$rundir"
+	or_die rm -rf "$workdir"
+	or_die mkdir "$workdir"
+
 	# switch between common arrangements & fully randomized
 	if [[ $((RANDOM % 2)) -eq 0 ]]; then
 		mirrors=2