diff --git a/tests/zfs-tests/tests/functional/devices/devices_001_pos.ksh b/tests/zfs-tests/tests/functional/devices/devices_001_pos.ksh
index ac031ed6a52f..2f2802bc65a3 100755
--- a/tests/zfs-tests/tests/functional/devices/devices_001_pos.ksh
+++ b/tests/zfs-tests/tests/functional/devices/devices_001_pos.ksh
@@ -42,7 +42,7 @@
 # 1. Create pool and file system.
 # 2. Set devices=on on this file system.
 # 3. Separately create block device file and character file.
-# 4. Separately read from those two device files.
+# 4. Separately read and write from those two device files.
 # 5. Check the return value, and make sure it succeeds.
 #
 
@@ -55,12 +55,18 @@ log_onexit cleanup
 log_must zfs set devices=on $TESTPOOL/$TESTFS
 
 #
-# Separately create block device file and character device file, then try to
-# open them and make sure it succeed.
+# Create block device file backed by a ZFS volume.
+# Verify it can be opened, written, and read.
 #
-create_dev_file b $TESTDIR/$TESTFILE1
-log_must dd if=$TESTDIR/$TESTFILE1 of=$TESTDIR/$TESTFILE1.out count=1
+create_dev_file b $TESTDIR/$TESTFILE1 $ZVOL_DEVDIR/$TESTPOOL/$TESTVOL
+log_must dd if=/dev/urandom of=$TESTDIR/$TESTFILE1.out1 count=1 bs=128k
+log_must dd if=$TESTDIR/$TESTFILE1.out1 of=$TESTDIR/$TESTFILE1 count=1 bs=128k
+log_must dd if=$TESTDIR/$TESTFILE1 of=$TESTDIR/$TESTFILE1.out2 count=1 bs=128k
+log_must cmp $TESTDIR/$TESTFILE1.out1 $TESTDIR/$TESTFILE1.out2
+
+# Create character device file backed by /dev/null
+# Verify it can be opened and written.
 create_dev_file c $TESTDIR/$TESTFILE2
-log_must dd if=$TESTDIR/$TESTFILE2 of=$TESTDIR/$TESTFILE2.out count=1
+log_must dd if=/dev/urandom of=$TESTDIR/$TESTFILE2 count=1 bs=128k
 
 log_pass "Setting devices=on on file system and testing it pass."
diff --git a/tests/zfs-tests/tests/functional/devices/devices_002_neg.ksh b/tests/zfs-tests/tests/functional/devices/devices_002_neg.ksh
index ce25502b818b..a768c4aa6b34 100755
--- a/tests/zfs-tests/tests/functional/devices/devices_002_neg.ksh
+++ b/tests/zfs-tests/tests/functional/devices/devices_002_neg.ksh
@@ -42,7 +42,7 @@
 # 1. Create pool and file system.
 # 2. Set devices=off on this file system.
 # 3. Separately create block device file and character file.
-# 4. Separately read from those two device files.
+# 4. Separately read and write from those two device files.
 # 5. Check the return value, and make sure it failed.
 #
 
@@ -55,12 +55,16 @@ log_onexit cleanup
 log_must zfs set devices=off $TESTPOOL/$TESTFS
 
 #
-# Separately create block device file and character device file, then try to
-# open them and make sure it failed.
+# Create block device file backed by a ZFS volume.
+# Verify it cannot be opened, written, and read.
 #
-create_dev_file b $TESTDIR/$TESTFILE1
-log_mustnot dd if=$TESTDIR/$TESTFILE1 of=$TESTDIR/$TESTFILE1.out count=1
+create_dev_file b $TESTDIR/$TESTFILE1 $ZVOL_DEVDIR/$TESTPOOL/$TESTVOL
+log_mustnot dd if=/dev/urandom of=$TESTDIR/$TESTFILE1 count=1 bs=128k
+log_mustnot dd if=$TESTDIR/$TESTFILE1 of=/dev/null count=1 bs=128k
+
+# Create character device file backed by /dev/null
+# Verify it cannot be opened and written.
 create_dev_file c $TESTDIR/$TESTFILE2
-log_mustnot dd if=$TESTDIR/$TESTFILE2 of=$TESTDIR/$TESTFILE2.out count=1
+log_mustnot dd if=/dev/urandom of=$TESTDIR/$TESTFILE2 count=1 bs=128k
 
 log_pass "Setting devices=off on file system and testing it pass."
diff --git a/tests/zfs-tests/tests/functional/devices/devices_common.kshlib b/tests/zfs-tests/tests/functional/devices/devices_common.kshlib
index 2c7df8d058c3..fa7fdbecf5fd 100644
--- a/tests/zfs-tests/tests/functional/devices/devices_common.kshlib
+++ b/tests/zfs-tests/tests/functional/devices/devices_common.kshlib
@@ -36,89 +36,74 @@
 #
 # $1 device file type
 # $2 file name
+# $3 device path (used for 'b' device type)
 #
 function create_dev_file
 {
 	typeset filetype=$1
 	typeset filename=$2
+	typeset devstr=$3
 
 	case $filetype in
-		b)
-			if is_linux; then
-				major=$(awk '/[hsv]d/ { print $1; exit }' \
-				    /proc/partitions)
-				minor=$(awk '/[hsv]d/ { print $2; exit }' \
-				    /proc/partitions)
-				log_must mknod $filename b $major $minor
-				return 0
-			fi
-
-			devtype=$(df -n / | awk '{print $3}')
-			case $devtype in
-				zfs)
-					rootpool=$(df / | \
-						awk '{print $2}')
-					rootpool=${rootpool#\(}
-					rootpool=${rootpool%%/*}
-
-					devstr=$(get_disklist $rootpool)
-					devstr=$(echo "$devstr" | \
-						awk '{print $1}')
-					[[ -z $devstr ]] && \
-						log_fail "Can not get block device file."
-					devstr=$DEV_DSKDIR/${devstr}
-					;;
-				ufs)
+	b)
+		case $(uname) in
+		Linux)
 			#
-			# Get the existing block device file in current system.
-			# And bring out the first one.
+			# stat(1) --format=FORMAT tokens
+			# %t - major device type in hex
+			# %T - minor device type in hex
 			#
-					devstr=$(df-lhF ufs | \
-						grep "^${DEV_DSKDIR}" | \
-						awk '{print $1}')
-					devstr=$(echo "$devstr" | \
-						awk '{print $1}')
-					[[ -z $devstr ]] && \
-						log_fail "Can not get block device file."
-					;;
-				*)
-					log_unsupported "Unsupported fstype " \
-						"for / ($devtype)," \
-						"only ufs|zfs is supported."
-					;;
-			esac
-
+			major=$(stat --dereference --format="%t" "$devstr")
+			minor=$(stat --dereference --format="%T" "$devstr")
+			log_must mknod $filename b "0x${major}" "0x${minor}"
+			;;
+		*)
 			#
 			# Get the device file information. i.e:
-			# $DEV_DSKDIR/c0t0d0s0:      block special (28/768)
+			# $devstr:      block special (28/768)
 			#
 			devstr=$(file $devstr)
-
-			#
-			# Bring out major and minor number.
-			#
 			major=${devstr##*\(}
 			major=${major%%/*}
 			minor=${devstr##*/}
 			minor=${minor%\)}
-
 			log_must mknod $filename b $major $minor
 			;;
-		c)
+		esac
+		;;
+	c)
+		#
+		# Create device file '/dev/null', $devstr is unused.
+		#
+		case $(uname) in
+		Linux)
+			#
+			# stat(1) --format=FORMAT tokens
+			# %t - major device type in hex
+			# %T - minor device type in hex
+			#
+			major=$(stat --format="%t" /dev/null)
+			minor=$(stat --format="%T" /dev/null)
+			log_must mknod $filename c "0x${major}" "0x${minor}"
+			;;
+		FreeBSD)
 			#
 			# Create device file '/dev/null'
 			#
-			if is_linux; then
-				major=$(stat -c %t /dev/null)
-				minor=$(stat -c %T /dev/null)
-				log_must mknod $filename c $major $minor
-			else
-				log_must mknod $filename c $(getmajor mm) 2
-			fi
+			major=13
+			minor=2
+			log_must mknod $filename b $major $minor
 			;;
 		*)
-			log_fail "'$filetype' is wrong."
+			major=$(getmajor mm)
+			minor=2
+			log_must mknod $filename b $major $minor
 			;;
+		esac
+		;;
+	*)
+		log_fail "'$filetype' is wrong."
+		;;
 	esac
 
 	return 0
@@ -129,6 +114,6 @@ function cleanup
 	log_must zfs set devices=on $TESTPOOL/$TESTFS
 	log_must rm -f $TESTDIR/$TESTFILE1
 	log_must rm -f $TESTDIR/$TESTFILE2
-	log_must rm -f $TESTDIR/$TESTFILE1.out
-	log_must rm -f $TESTDIR/$TESTFILE2.out
+	log_must rm -f $TESTDIR/$TESTFILE1.out1
+	log_must rm -f $TESTDIR/$TESTFILE1.out2
 }
diff --git a/tests/zfs-tests/tests/functional/devices/setup.ksh b/tests/zfs-tests/tests/functional/devices/setup.ksh
index fc5cec3063a6..ee6cf83acb9e 100755
--- a/tests/zfs-tests/tests/functional/devices/setup.ksh
+++ b/tests/zfs-tests/tests/functional/devices/setup.ksh
@@ -32,4 +32,4 @@
 . $STF_SUITE/include/libtest.shlib
 
 DISK=${DISKS%% *}
-default_setup $DISK
+default_volume_setup $DISK