torture: Compress KASAN vmlinux files

The sizes of vmlinux files built with KASAN enabled can approach a full
gigabyte, which can result in disk overflow sooner rather than later.
Fortunately, the xz command compresses them by almost an order of
magnitude.  This commit therefore uses xz to compress vmlinux file built
by torture.sh with KASAN enabled.

However, xz is not the fastest thing in the world.  In fact, it is way
slower than rotating-rust mass storage.  This commit therefore also adds a
--compress-kasan-vmlinux argument to specify the degree of xz concurrency,
which defaults to using all available CPUs if there are that many files in
need of compression.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/bin/torture.sh

@@ -36,7 +36,8 @@ configs_locktorture=
 configs_scftorture=
 kcsan_kmake_args=
 
-# Default duration and apportionment.
+# Default compression, duration, and apportionment.
+compress_kasan_vmlinux="`identify_qemu_vcpus`"
 duration_base=10
 duration_rcutorture_frac=7
 duration_locktorture_frac=1
@@ -65,6 +66,7 @@ function doyesno () {
 
 usage () {
 	echo "Usage: $scriptname optional arguments:"
+	echo "       --compress-kasan-vmlinux concurrency"
 	echo "       --configs-rcutorture \"config-file list w/ repeat factor (3*TINY01)\""
 	echo "       --configs-locktorture \"config-file list w/ repeat factor (10*LOCK01)\""
 	echo "       --configs-scftorture \"config-file list w/ repeat factor (2*CFLIST)\""
@@ -87,6 +89,11 @@ usage () {
 while test $# -gt 0
 do
 	case "$1" in
+	--compress-kasan-vmlinux)
+		checkarg --compress-kasan-vmlinux "(concurrency level)" $# "$2" '^[0-9][0-9]*$' '^error'
+		compress_kasan_vmlinux=$2
+		shift
+		;;
 	--config-rcutorture|--configs-rcutorture)
 		checkarg --configs-rcutorture "(list of config files)" "$#" "$2" '^[^/]\+$' '^--'
 		configs_rcutorture="$configs_rcutorture $2"
@@ -391,8 +398,45 @@ fi
 echo Started at $startdate, ended at `date`, duration `get_starttime_duration $starttime`. | tee -a $T/log
 echo Summary: Successes: $nsuccesses Failures: $nfailures. | tee -a $T/log
 tdir="`cat $T/successes $T/failures | head -1 | awk '{ print $NF }' | sed -e 's,/[^/]\+/*$,,'`"
+if test -n "$tdir" && test $compress_kasan_vmlinux -gt 0
+then
+	# KASAN vmlinux files can approach 1GB in size, so compress them.
+	echo Looking for KASAN files to compress: `date` > "$tdir/log-xz" 2>&1
+	find "$tdir" -type d -name '*-kasan' -print > $T/xz-todo
+	ncompresses=0
+	batchno=1
+	if test -s $T/xz-todo
+	then
+		echo Size before compressing: `du -sh $tdir | awk '{ print $1 }'` `date` 2>&1 | tee -a "$tdir/log-xz" | tee -a $T/log
+		for i in `cat $T/xz-todo`
+		do
+			echo Compressing vmlinux files in ${i}: `date` >> "$tdir/log-xz" 2>&1
+			for j in $i/*/vmlinux
+			do
+				xz "$j" >> "$tdir/log-xz" 2>&1 &
+				ncompresses=$((ncompresses+1))
+				if test $ncompresses -ge $compress_kasan_vmlinux
+				then
+					echo Waiting for batch $batchno of $ncompresses compressions `date` | tee -a "$tdir/log-xz" | tee -a $T/log
+					wait
+					ncompresses=0
+					batchno=$((batchno+1))
+				fi
+			done
+		done
+		if test $ncompresses -gt 0
+		then
+			echo Waiting for final batch $batchno of $ncompresses compressions `date` | tee -a "$tdir/log-xz" | tee -a $T/log
+		fi
+		wait
+		echo Size after compressing: `du -sh $tdir | awk '{ print $1 }'` `date` 2>&1 | tee -a "$tdir/log-xz" | tee -a $T/log
+		echo Total duration `get_starttime_duration $starttime`. | tee -a $T/log
+	else
+		echo No compression needed: `date` >> "$tdir/log-xz" 2>&1
+	fi
+fi
 if test -n "$tdir"
 then
-	cp $T/log $tdir
+	cp $T/log "$tdir"
 fi
 exit $ret