arc/vm/media-sharing-services/init/arcvm-mount-removable-media.conf

# Copyright 2020 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

description    "Mount the removable media directory using mount-passthrough."
author         "chromium-os-dev@chromium.org"

start on starting arcvm-media-sharing-services
stop on stopping arcvm-media-sharing-services

# Set the same oom score as arcvm-media-sharing-services.
oom score -100

# Set VM size soft limit to 1 GB. See arcvm-mount-myfiles.conf for rationale.
# TODO(b/164936284): Specify a lower limit after improving mount-passthrough.
limit as 1000000000 unlimited

import MEDIA_PROVIDER_UID

env SOURCE=/media/removable
env DEST=/run/arcvm/media/removable
env UMASK=007
env CONCIERGE_NAMESPACE_PATH=/run/namespaces/mnt_concierge
# Android's external_storage GID (not shifted).
env ANDROID_EXTERNAL_STORAGE_GID=1077
# The maximum number of file descriptors mount-passthrough can open.
# The number is taken from vm_concierge.conf, which defines the maximum number
# of fds that can be opened by virtio-fs devices.
# We use the same number here because files opened by this mount-passthrough
# process are expected to be the ones opend by a virtio-fs device, and we'd like
# to let virtio-fs devices open as many files as they like without imposing a
# new restriction on the number of files they can open.
env MAX_NUMBER_OF_OPEN_FDS=262144

pre-start exec nsenter --mount="${CONCIERGE_NAMESPACE_PATH}" --no-fork \
  -- mkdir -p "${DEST}"

exec /usr/sbin/syslog-cat --identifier="${UPSTART_JOB}" -- \
     mount-passthrough-jailed --source="${SOURCE}" --dest="${DEST}" \
       --fuse_umask="${UMASK}" --fuse_uid="${MEDIA_PROVIDER_UID}" \
       --fuse_gid="${ANDROID_EXTERNAL_STORAGE_GID}" \
       --enter_concierge_namespace \
       --max_number_of_open_fds="${MAX_NUMBER_OF_OPEN_FDS}"

post-stop script
  # Termination by SIGKILL can result in a stale mount which needs clean-up.
  nsenter --mount="${CONCIERGE_NAMESPACE_PATH}" --no-fork \
    -- umount "${DEST}" || true
end script