btrfs-progs: tests: use nullb helper and smaller zone size

With the change of minimal number of zones, mkfs-tests/030-zoned-rst now
fails because the loopback device is 2GB and can contain 8x 256MB zones.

Use the nullb helpers to choose a smaller zone size.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

tests/mkfs-tests/030-zoned-rst/test.sh

@@ -4,22 +4,22 @@
 source "$TEST_TOP/common" || exit
 
 setup_root_helper
-setup_loopdevs 4
-prepare_loopdevs
-TEST_DEV=${loopdevs[1]}
+setup_nullbdevs 4 128 4
+prepare_nullbdevs
+TEST_DEV=${nullb_devs[1]}
 
 profiles="single dup raid1 raid1c3 raid1c4 raid10"
 
 for dprofile in $profiles; do
 	for mprofile in $profiles; do
 		# It's sufficient to specify only 'zoned', the rst will be enabled
-		run_check $SUDO_HELPER "$TOP/mkfs.btrfs" -f -O zoned -d "$dprofile" -m "$mprofile" "${loopdevs[@]}"
+		run_check $SUDO_HELPER "$TOP/mkfs.btrfs" -f -O zoned -d "$dprofile" -m "$mprofile" "${nullb_devs[@]}"
 	done
 done
 
 run_mustfail "unsupported profile raid56 created" \
-	$SUDO_HELPER "$TOP/mkfs.btrfs" -f -O zoned -d raid5 -m raid5 "${loopdevs[@]}"
+	$SUDO_HELPER "$TOP/mkfs.btrfs" -f -O zoned -d raid5 -m raid5 "${nullb_devs[@]}"
 run_mustfail "unsupported profile raid56 created" \
-	$SUDO_HELPER "$TOP/mkfs.btrfs" -f -O zoned -d raid6 -m raid6 "${loopdevs[@]}"
+	$SUDO_HELPER "$TOP/mkfs.btrfs" -f -O zoned -d raid6 -m raid6 "${nullb_devs[@]}"
 
-cleanup_loopdevs
+cleanup_nullbdevs