test: reduce number of disks in TEST-64-UDEV-STORAGE-simultaneous_events on Debian/Ubuntu

This test never finishes in Ubuntu autopkgtest with the current values,
and is currently skipped all together on Debian. When running on either,
reduce the number of disks to make the test more reliable.

test/units/TEST-64-UDEV-STORAGE.sh

@@ -386,10 +386,12 @@ EOF
 }
 
 testcase_simultaneous_events_1() {
-    local disk expected i iterations link num_part part partscript rule target timeout
+    local disk expected i iterations link num_disks num_part part partscript prio_disk_index0 prio_disk_index1 rule reduce_num_disks target timeout
     local -a devices symlinks running
 
-    if [[ -v ASAN_OPTIONS || "$(systemd-detect-virt -v)" == "qemu" ]]; then
+    reduce_num_disks="${1:-0}"
+
+    if [[ -v ASAN_OPTIONS || "$(systemd-detect-virt -v)" == "qemu" || "$reduce_num_disks" -eq 1 ]]; then
         num_part=2
         iterations=10
         timeout=240
@@ -399,7 +401,18 @@ testcase_simultaneous_events_1() {
         timeout=60
     fi
 
-    for disk in {0..9}; do
+    # NOTE: num_disks must be even for the later test logic to remain correct.
+    if [[ "$reduce_num_disks" -eq 1 ]]; then
+        num_disks=4
+        prio_disk_index0=3
+        prio_disk_index1=2
+    else
+        num_disks=10
+        prio_disk_index0=5
+        prio_disk_index1=4
+    fi
+
+    for ((disk = 0; disk < num_disks; disk++)); do
         link="/dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_deadbeeftest${disk}"
         target="$(readlink -f "$link")"
         if [[ ! -b "$target" ]]; then
@@ -425,13 +438,13 @@ EOF
     rule=/run/udev/rules.d/50-test.rules
     mkdir -p "${rule%/*}"
     cat >"$rule" <<EOF
-SUBSYSTEM=="block", KERNEL=="${devices[4]##*/}*|${devices[5]##*/}*", OPTIONS="link_priority=10"
+SUBSYSTEM=="block", KERNEL=="${devices[$prio_disk_index1]##*/}*|${devices[$prio_disk_index0]##*/}*", OPTIONS="link_priority=10"
 EOF
 
     udevadm control --reload
 
     # initialize partition table
-    for disk in {0..9}; do
+    for ((disk = 0; disk < num_disks; disk++)); do
         echo 'label: gpt' | udevadm lock --timeout=30 --device="${devices[$disk]}" sfdisk -q "${devices[$disk]}"
     done
 
@@ -443,7 +456,7 @@ EOF
     # leading to dead symlinks in /dev/disk/
     for ((i = 1; i <= iterations; i++)); do
         running=()
-        for disk in {0..9}; do
+        for ((disk = 0; disk < num_disks; disk++)); do
             if ((disk % 2 == i % 2)); then
                 udevadm lock --timeout=30 --device="${devices[$disk]}" sfdisk -q --delete "${devices[$disk]}" &
             else
@@ -466,9 +479,9 @@ EOF
                 link="/dev/disk/by-partlabel/test${part}"
                 target="$(readlink -f "$link")"
                 if ((i % 2 == 0)); then
-                    expected="${devices[5]}$part"
+                    expected="${devices[$prio_disk_index0]}$part"
                 else
-                    expected="${devices[4]}$part"
+                    expected="${devices[$prio_disk_index1]}$part"
                 fi
                 if [[ "$target" != "$expected" ]]; then
                     echo >&2 "ERROR: symlink '/dev/disk/by-partlabel/test${part}' points to '$target' but '$expected' was expected"
@@ -481,7 +494,7 @@ EOF
     helper_check_device_units
 
     # Cleanup and check if unnecessary devlinks are removed.
-    for disk in {0..9}; do
+    for ((disk = 0; disk < num_disks; disk++)); do
         udevadm lock --timeout="$timeout" --device="${devices[$disk]}" sfdisk -q --delete "${devices[$disk]}" || :
     done
     udevadm settle --timeout="$timeout"
@@ -494,14 +507,16 @@ EOF
 }
 
 testcase_simultaneous_events_2() {
-    local disk i iterations link num_part part script_dir target timeout
+    local disk i iterations link num_disks num_part part script_dir reduce_num_disks target timeout
     local -a devices running
 
+    reduce_num_disks="${1:-0}"
+
     script_dir="$(mktemp --directory "/tmp/test-udev-storage.script.XXXXXXXXXX")"
     # shellcheck disable=SC2064
     trap "rm -rf '$script_dir'" RETURN
 
-    if [[ -v ASAN_OPTIONS || "$(systemd-detect-virt -v)" == "qemu" ]]; then
+    if [[ -v ASAN_OPTIONS || "$(systemd-detect-virt -v)" == "qemu" || "$reduce_num_disks" -eq 1 ]]; then
         num_part=10
         iterations=2
         timeout=300
@@ -511,7 +526,13 @@ testcase_simultaneous_events_2() {
         timeout=200
     fi
 
-    for disk in {0..9}; do
+    if [[ "$reduce_num_disks" -eq 1 ]]; then
+        num_disks=4
+    else
+        num_disks=10
+    fi
+
+    for ((disk = 0; disk < num_disks; disk++)); do
         link="/dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_deadbeeftest${disk}"
         target="$(readlink -f "$link")"
         if [[ ! -b "$target" ]]; then
@@ -616,15 +637,16 @@ EOF
 }
 
 testcase_simultaneous_events() {
+    local reduce_num_disks
+
     . /etc/os-release
-    if [[ "$ID" == "debian" ]]; then
-        # See https://github.com/systemd/systemd/issues/39552
-        echo "Simultaneous events test cases are not working on Debian, skipping the test" | tee --append /skipped
-        exit 77
+    reduce_num_disks=0
+    if [[ "$ID" == "ubuntu" || "$ID" == "debian" ]]; then
+        reduce_num_disks=1
     fi
 
-    testcase_simultaneous_events_1
-    testcase_simultaneous_events_2
+    testcase_simultaneous_events_1 "$reduce_num_disks"
+    testcase_simultaneous_events_2 "$reduce_num_disks"
     testcase_simultaneous_events_3
 }