--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/usr/src/test/zfs-tests/tests/functional/cache/cache_012_pos.ksh	Thu Jul 30 18:40:44 2020 -0500
@@ -0,0 +1,110 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2020, George Amanakis. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/cache/cache.cfg
+. $STF_SUITE/tests/functional/cache/cache.kshlib
+
+#
+# DESCRIPTION:
+#	Looping around a cache device with l2arc_write_size exceeding
+#	the device size succeeds.
+#
+# STRATEGY:
+#	1. Create pool with a cache device.
+#	2. Set l2arc_write_max to a value larger than the cache device.
+#	3. Create a file larger than the cache device and random read
+#		for 10 sec.
+#	4. Verify that l2arc_write_max is set back to the default.
+#	5. Set l2arc_write_max to a value less than the cache device size but
+#		larger than the default (64MB).
+#	6. Record the l2_size.
+#	7. Random read for 1 sec.
+#	8. Record the l2_size again.
+#	9. If (6) <= (8) then we have not looped around yet.
+#	10. If (6) > (8) then we looped around. Break out of the loop and test.
+#	11. Destroy pool.
+#
+
+verify_runnable "global"
+
+log_assert "Looping around a cache device succeeds."
+
+function cleanup
+{
+	if poolexists $TESTPOOL ; then
+		destroy_pool $TESTPOOL
+	fi
+
+	log_must set_tunable32 l2arc_write_max $write_max
+	log_must set_tunable32 l2arc_noprefetch $noprefetch
+}
+log_onexit cleanup
+
+typeset write_max=$(get_tunable l2arc_write_max)
+typeset noprefetch=$(get_tunable l2arc_noprefetch)
+log_must set_tunable32 l2arc_noprefetch 0
+
+typeset VDEV="$VDIR/vdev.disk"
+typeset VDEV_SZ=$(( 4 * 1024 * 1024 * 1024 ))
+typeset VCACHE="$VDIR/vdev.cache"
+typeset VCACHE_SZ=$(( $VDEV_SZ / 2 ))
+
+typeset fill_mb=$(( floor($VDEV_SZ * 3 / 4 ) ))
+export DIRECTORY=/$TESTPOOL
+export NUMJOBS=4
+export RUNTIME=10
+export PERF_RANDSEED=1234
+export PERF_COMPPERCENT=66
+export PERF_COMPCHUNK=0
+export BLOCKSIZE=128K
+export SYNC_TYPE=0
+export DIRECT=1
+export FILE_SIZE=$(( floor($fill_mb / $NUMJOBS) ))
+
+log_must set_tunable32 l2arc_write_max $(( $VCACHE_SZ * 2 ))
+
+log_must truncate -s $VCACHE_SZ $VCACHE
+log_must truncate -s $VDEV_SZ $VDEV
+
+log_must zpool create -f $TESTPOOL $VDEV cache $VCACHE
+
+log_must fio $FIO_SCRIPTS/mkfiles.fio
+log_must fio $FIO_SCRIPTS/random_reads.fio
+
+typeset write_max2=$(get_tunable l2arc_write_max)
+
+log_must test $write_max2 -eq $write_max
+
+log_must set_tunable32 l2arc_write_max $(( 64 * 1024 * 1024 ))
+export RUNTIME=1
+
+typeset do_once=true
+while $do_once || [[ $l2_size1 -le $l2_size2 ]]; do
+	typeset l2_size1=$(get_arcstat l2_size)
+	log_must fio $FIO_SCRIPTS/random_reads.fio
+	typeset l2_size2=$(get_arcstat l2_size)
+	do_once=false
+done
+
+log_must test $l2_size1 -gt $l2_size2
+
+log_must zpool destroy $TESTPOOL
+
+log_pass "Looping around a cache device succeeds."