feat: use btrfs with zstd compression

I specified zstd:13, but I'm not sure that it is the best compression
level.

Author: Theo Paris

action.yml

@@ -23,6 +23,14 @@ inputs:
       You should prefer adjusting root-reserve-mb/temp-reserve-mb over using this option.
     required: false
     default: 'false'
+  filesystem-type:
+    description: 'The filesystem to use'
+    required: false
+    default: 'ext4'
+  btrfs-compression-level:
+    description: 'The compression level to use if the filesystem is btrfs'
+    required: false
+    default: '0'
   build-mount-path:
     description: 'Absolute path to the mount point where the build space will be available, defaults to $GITHUB_WORKSPACE if unset.'
     required: false
@@ -177,12 +185,27 @@ runs:
           echo "Creating build volume"
           # create and mount build volume
           sudo lvcreate -l 100%FREE -n buildlv "${VG_NAME}"
-          if [[ ${{ inputs.overprovision-lvm }} == 'true' ]]; then
-            sudo mkfs.ext4 -m0 "/dev/mapper/${VG_NAME}-buildlv"
+          if [[ ${inputs.filesystem-type} == 'btrfs' ]]; then
+            sudo mkfs.btrfs -m single -d single "/dev/mapper/${VG_NAME}-buildlv"
+
+            mount_options=('space_cache=v2' 'noatime')
+            if [[ ${{ inputs.overprovision-lvm }} == 'true' ]]; then
+              mount_options+=('discard=async')
+            else
+              mount_options+=('nodiscard')
+            fi
+            if [[ ${{ inputs.btrfs-compression-level }} != '0' ]]; then
+              mount_options+=("compress-force=zstd:${inputs.build-compression-level}")
+            fi
+            IFS="," sudo mount -t btrfs -o ${mount_options[*]} "/dev/mapper/${VG_NAME}-buildlv" "${BUILD_MOUNT_PATH}"
           else
-            sudo mkfs.ext4 -Enodiscard -m0 "/dev/mapper/${VG_NAME}-buildlv"
+            if [[ ${{ inputs.overprovision-lvm }} == 'true' ]]; then
+              sudo mkfs.ext4 -m0 "/dev/mapper/${VG_NAME}-buildlv"
+            else
+              sudo mkfs.ext4 -Enodiscard -m0 "/dev/mapper/${VG_NAME}-buildlv"
+            fi
+            IFS="," sudo mount -t ext4 "/dev/mapper/${VG_NAME}-buildlv" "${BUILD_MOUNT_PATH}"
           fi
-          sudo mount "/dev/mapper/${VG_NAME}-buildlv" "${BUILD_MOUNT_PATH}"
           sudo chown -R "${{ inputs.build-mount-path-ownership }}" "${BUILD_MOUNT_PATH}"
 
           # if build mount path is a parent of $GITHUB_WORKSPACE, and has been deleted, recreate it