CI: Add logs to zloop workflow

On failure attempt to include the most relevant portions of the
ztest logs in the CI output.  This full logs are still available
for download but often a backtrace and the last output is enough.

Install libunwind to improve the odds of a useful backtrace.

Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #16573

.github/workflows/scripts/qemu-3-deps.sh

@@ -32,9 +32,9 @@ function debian() {
   sudo apt-get install -y \
     acl alien attr autoconf bc cpio curl dbench dh-python dkms fakeroot \
     fio gdb gdebi git ksh lcov isc-dhcp-client jq libacl1-dev libaio-dev \
-    libattr1-dev libblkid-dev libcurl4-openssl-dev libdevmapper-dev \
-    libelf-dev libffi-dev libmount-dev libpam0g-dev libselinux-dev \
-    libssl-dev libtool libtool-bin libudev-dev linux-headers-$(uname -r) \
+    libattr1-dev libblkid-dev libcurl4-openssl-dev libdevmapper-dev libelf-dev \
+    libffi-dev libmount-dev libpam0g-dev libselinux-dev libssl-dev libtool \
+    libtool-bin libudev-dev libunwind-dev linux-headers-$(uname -r) \
     lsscsi nfs-kernel-server pamtester parted python3 python3-all-dev \
     python3-cffi python3-dev python3-distlib python3-packaging \
     python3-setuptools python3-sphinx qemu-guest-agent rng-tools rpm2cpio \

.github/workflows/zloop.yml

@@ -43,11 +43,23 @@ jobs:
         sudo mkdir -p $TEST_DIR
         # run for 10 minutes or at most 6 iterations for a maximum runner
         # time of 60 minutes.
-        sudo /usr/share/zfs/zloop.sh -t 600 -I 6 -l -m1 -- -T 120 -P 60
+        sudo /usr/share/zfs/zloop.sh -t 600 -I 6 -l -m 1 -- -T 120 -P 60
     - name: Prepare artifacts
       if: failure()
       run: |
         sudo chmod +r -R $TEST_DIR/
+    - name: Ztest log
+      if: failure()
+      run: |
+        grep -B10 -A1000 'ASSERT' $TEST_DIR/*/ztest.out || tail -n 1000 $TEST_DIR/*/ztest.out
+    - name: Gdb log
+      if: failure()
+      run: |
+        sed -n '/Backtraces (full)/q;p' $TEST_DIR/*/ztest.gdb
+    - name: Zdb log
+      if: failure()
+      run: |
+        cat $TEST_DIR/*/ztest.zdb
     - uses: actions/upload-artifact@v4
       if: failure()
       with: