CI: use alternative disks if available

src/ci/docker/run.sh

@@ -347,6 +347,7 @@ docker \
   --env DEPLOY \
   --env DEPLOY_ALT \
   --env CI \
+  --env GIT_DISCOVERY_ACROSS_FILESYSTEM=1 \
   --env GITHUB_ACTIONS \
   --env GITHUB_REF \
   --env GITHUB_STEP_SUMMARY="/checkout/obj/${SUMMARY_FILE}" \

src/ci/scripts/free-disk-space-linux.sh

@@ -4,6 +4,11 @@ set -euo pipefail
 # Free disk space on Linux GitHub action runners
 # Script inspired by https://github.com/jlumbroso/free-disk-space
 
+
+# we need ~50GB of space
+space_target_kb=$((50 * 1024 * 1024))
+
+
 isX86() {
     local arch
     arch=$(uname -m)
@@ -247,12 +252,69 @@ cleanSwap() {
     free -h
 }
 
+sufficientSpaceEarlyExit() {
+    local available_space_kb=$(df -k . --output=avail | tail -n 1)
+
+    if [ "$available_space_kb" -ge "$space_target_kb" ]; then
+        echo "Sufficient disk space available (${available_space_kb}KB >= ${space_target_kb}KB). Skipping cleanup."
+        exit 0
+    fi
+}
+
+# Try to find a different drive to put our data on so we don't need to run cleanup.
+# The availability of the disks we're probing isn't guaranteed,
+# so this is opportunistic.
+checkAlternative() {
+    local gha_alt_disk="/mnt"
+
+    local available_space_kb=$(df -k "$gha_alt_disk" --output=avail | tail -n 1)
+
+    # mount options that trade durability for performance
+    # ignore-tidy-linelength
+    local mntopts="defaults,discard,journal_async_commit,barrier=0,noauto_da_alloc,lazytime,data=writeback"
+
+    # GHA has a 2nd disk mounted at /mnt that is almost empty.
+    # Check if it's a valid mountpoint and it has enough available space.
+    if mountpoint "$gha_alt_disk" && [ "$available_space_kb" -ge "$space_target_kb" ]; then
+        local blkdev=$(df -k "$gha_alt_disk" --output=source | tail -n 1)
+        echo "Sufficient space available on $blkdev mounted at $gha_alt_disk"
+        # see cleanSwap(), swapfile may be mounted under /mnt
+        sudo swapoff -a || true
+
+        # unmount from original location
+        sudo umount "$gha_alt_disk"
+
+        # remount under the obj dir which is used by docker scripts to write most
+        # of our build output. And apply optimized mount options while we're at it.
+        mkdir ./obj
+        if ! sudo mount $blkdev ./obj -o $mntopts; then
+            sudo dmesg | tail -n 20 # kernel log should have more details for mount failures
+            echo "::warning::Failed to remount $blkdev to ./obj with options: $mntopts"
+            return
+        fi
+
+        # ensure current user can access everything.
+        # later scripts assume they have recursive access to obj
+        sudo chown -R "$USER":"$USER" ./obj
+
+        # Exit from this script to avoid wasting time removing disk space,
+        # as we already have enough disk space in the alternative drive.
+        exit 0
+    fi
+}
+
+
+
 # Display initial disk space stats
 
 AVAILABLE_INITIAL=$(getAvailableSpace)
 
 printDF "BEFORE CLEAN-UP:"
 echo ""
+
+sufficientSpaceEarlyExit
+checkAlternative
+
 execAndMeasureSpaceChange cleanPackages "Unused packages"
 execAndMeasureSpaceChange cleanDocker "Docker images"
 execAndMeasureSpaceChange cleanSwap "Swap storage"