btrfs-progs: tests: add mkfs/025 to test parallel zone reset

Create a few emulated zoned devices and run mkfs, the zone reset is
expected to be run in parallel. It's using memory-backed devices so it's
too fast to measure the differences and we can't expect availability of
slow zoned devices so this test is very simplistic.

Signed-off-by: David Sterba <dsterba@suse.com>

tests/mkfs-tests/025-zoned-parallel/test.sh

@@ -0,0 +1,55 @@
+#!/bin/bash
+# Test parallel reset of zones.
+# Needs kernel modules: null_blk, configfs and at least 2G of free memory for
+# the devices
+
+source "$TEST_TOP/common"
+
+setup_root_helper
+prepare_test_dev
+
+if ! check_min_kernel_version 5.12; then
+	_not_run "zoned tests need kernel 5.12 and newer"
+fi
+
+nullb="$TEST_TOP/nullb"
+# Create 128M devices with 4M zones, 32 of them
+size=128
+zone=4
+# More than 10 may fail
+count=10
+
+declare -a devices
+declare -a names
+
+run_check $SUDO_HELPER "$nullb" setup
+if [ $? != 0 ]; then
+	_not_run "cannot setup nullb environment for zoned devices"
+fi
+
+# Record any other pre-existing devices in case creation fails
+run_check $SUDO_HELPER "$nullb" ls
+
+for i in `seq $count`; do
+	# Last line has the name of the device node path
+	out=$(run_check_stdout $SUDO_HELPER "$nullb" create -s "$size" -z "$zone")
+	if [ $? != 0 ]; then
+		_fail "cannot create nullb zoned device $i"
+	fi
+	devices[$i]=$(echo "$out" | tail -n 1)
+	names[$i]=$(basename "${devices[$i]}")
+done
+
+run_check $SUDO_HELPER "$nullb" ls
+
+TEST_DEV="${devices[1]}"
+# Use single as it's supported on more kernels
+run_check $SUDO_HELPER "$TOP/mkfs.btrfs" -d single -m single "${devices[@]}"
+run_check_mount_test_dev
+run_check $SUDO_HELPER dd if=/dev/zero of="$TEST_MNT"/file bs=1M count=1
+run_check $SUDO_HELPER "$TOP/btrfs" filesystem usage -T "$TEST_MNT"
+run_check_umount_test_dev
+
+for i in `seq $count`; do
+	run_check $SUDO_HELPER "$nullb" rm "${names[$i]}"
+done