[PATCH v2] 251: Make fstrim call a bit more random

[Lukas Czerner]

To cover cases when fstrim arguments are not block/block group/file
system size aligned, we can be a bit more random. This commit changes
fstrim argument computing to use $RANDOM bash variable in order to have
different minlen, start, len argument settings and change the full fs
fstrim to be called randomly as well.

Also make kill and wait not complain about non existent process, since
it may have already finished before we attempt to kill it and wait for
it. No reason to fail the test.

Signed-off-by: Lukas Czerner <lczerner at redhat.com>
---
v2: guess maximum minlen so we do not fail if milnen limitation
    of the fs is too small.

 251 |   36 +++++++++++++++++++++++++-----------
 1 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/251 b/251
index fa3d74a..6d87bf4 100755
--- a/251
+++ b/251
@@ -54,21 +54,21 @@ _cleanup()
 
 _destroy()
 {
-	kill $pids $fstrim_pid
-	wait $pids $fstrim_pid
+	kill $pids $fstrim_pid 2> /dev/null
+	wait $pids $fstrim_pid 2> /dev/null
 	rm -rf $tmp
 }
 
 _destroy_fstrim()
 {
-	kill $fpid
-	wait $fpid
+	kill $fpid 2> /dev/null
+	wait $fpid 2> /dev/null
 }
 
 _fail()
 {
 	echo "$1"
-	kill $mypid
+	kill $mypid 2> /dev/null
 }
 
 _check_fstrim_support()
@@ -76,6 +76,16 @@ _check_fstrim_support()
 	$here/src/fstrim -l 10M $SCRATCH_MNT &> /dev/null
 }
 
+_guess_max_minlen()
+{
+	mmlen=100000
+	while [ $mmlen -gt 1 ]; do
+		$here/src/fstrim -l $(($mmlen*2))k -m ${mmlen}k $SCRATCH_MNT &> /dev/null && break
+		mmlen=$(($mmlen/2))
+	done
+	echo $mmlen
+}
+
 ##
 # Background FSTRIM loop. We are trimming the device in the loop and for
 # test coverage, we are doing whole device trim followed by several smaller
@@ -85,15 +95,19 @@ fstrim_loop()
 {
 	trap "_destroy_fstrim; exit \$status" 2 15
 	fsize=$(df | grep $SCRATCH_MNT | grep $SCRATCH_DEV  | awk '{print $2}')
+	mmlen=$(_guess_max_minlen)
 
 	while true ; do
-		step=1048576
-		start=0
-		$here/src/fstrim $SCRATCH_MNT &
-		fpid=$!
-		wait $fpid
+		step=$((RANDOM*$RANDOM))
+		minlen=$(((RANDOM*($RANDOM%2+1))%$mmlen))
+		start=$RANDOM
+		if [ $((RANDOM%10)) -gt 7 ]; then
+			$here/src/fstrim $SCRATCH_MNT &
+			fpid=$!
+			wait $fpid
+		fi
 		while [ $start -lt $fsize ] ; do
-			$here/src/fstrim -s ${start}k -l ${step}k $SCRATCH_MNT &
+			$here/src/fstrim -m ${minlen}k -s ${start}k -l ${step}k $SCRATCH_MNT &
 			fpid=$!
 			wait $fpid
 			start=$(( $start + $step ))
-- 
1.7.4.4