ZTS: Apply small changes for speeding up the tests

The Github Action Runner got some new hardware metrics.  We should use
the provided and empty disk which is pre-mounted at /mnt now.

Disk1: 89GiB -> rootfs + bootfs with ~80MB/s -> don't care
Disk2: 64GiB -> /mnt with 420MB/s -> new testing ssd

This commit will mount the new disk to /var/tmp and provide hopefully
some speedups within our testings.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Andrew Innes <andrew.c12@gmail.com>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #15811

.github/workflows/scripts/setup-dependencies.sh

@@ -55,29 +55,24 @@ function mod_install() {
   cat /proc/spl/kstat/zfs/chksum_bench
   echo "::endgroup::"
 
-  echo "::group::Reclaim and report disk space"
-  # remove 4GiB of images
-  sudo systemd-run docker system prune --force --all --volumes
+  echo "::group::Optimize storage for ZFS testings"
+  # remove swap and umount fast storage
+  # 89GiB -> rootfs + bootfs with ~80MB/s -> don't care
+  # 64GiB -> /mnt with 420MB/s -> new testing ssd
+  sudo swapoff -a
 
-  # remove unused software
-  sudo systemd-run --wait rm -rf \
-    "$AGENT_TOOLSDIRECTORY" \
-    /opt/* \
-    /usr/local/* \
-    /usr/share/az* \
-    /usr/share/dotnet \
-    /usr/share/gradle* \
-    /usr/share/miniconda \
-    /usr/share/swift \
-    /var/lib/gems \
-    /var/lib/mysql \
-    /var/lib/snapd
-
-  # trim the cleaned space
-  sudo fstrim /
+  # this one is fast and mounted @ /mnt
+  # -> we reformat with ext4 + move it to /var/tmp
+  DEV="/dev/disk/azure/resource-part1"
+  sudo umount /mnt
+  sudo mkfs.ext4 -O ^has_journal -F $DEV
+  sudo mount -o noatime,barrier=0 $DEV /var/tmp
+  sudo chmod 1777 /var/tmp
 
   # disk usage afterwards
-  df -h /
+  sudo df -h /
+  sudo df -h /var/tmp
+  sudo fstrim -a
   echo "::endgroup::"
 }