transmission-daemon: Couldn't save file "/tmp/transmission/settings.json": Resource busy (variant.c:1226)

<package-name>: transmission-daemon

OpenWrt 22.03.0
Askey RT4230W REV6 / RAC2V1K

Issue

Couldn't save file "/tmp/transmission/settings.json": Resource busy (variant.c:1226)

When starting daemon.

Removing procd-ujail from the system fixes it temporarily but when added torrent to download it crashes daemon and autostarts it on its own.

Hashing jail part from init script also result same issue of crashing daemon.

Removing package and reinstalling, enabling in config and starting /etc/init.d/transmission start result following in logread

daemon.err transmission-daemon[16422]: [2022-09-15 19:28:11.861] Couldn't save temporary file "/tmp/transmission/settings.json.tmp.XXXXXX": Permission denied (variant.c:1235)

Changing in settings user and group to root

        option user 'root'
        option group 'root'

result in

Thu Sep 15 19:30:00 2022 daemon.err transmission-daemon[16779]: [2022-09-15 19:30:00.803] Couldn't save file "/tmp/transmission/settings.json": Resource busy (variant.c:1226)

The only solution that still working is to comment jail and seccomp from transmission init file like described here

Temporary solution

#       seccomp_path="/etc/seccomp/transmission-daemon.json"
#       if [ -f "$seccomp_path" ]; then
#               procd_set_param seccomp "$seccomp_path"
#       fi

        if [ -z "$USE" ]; then
                procd_set_param limits core="0 0"
        else
                procd_set_param limits core="0 0" as="$USE $USE"
                logger -t transmission "Starting with $USE virt mem"
        fi

        [ -d "$web_home" ] && procd_set_param env TRANSMISSION_WEB_HOME="$web_home"
        [ "$ca_bundle" -gt 0 ] && procd_set_param env CURL_CA_BUNDLE="$ca_bundle_file"

#       procd_add_jail transmission log
#       procd_add_jail_mount "$config_file"
#       procd_add_jail_mount_rw "$config_dir/resume"
#       procd_add_jail_mount_rw "$config_dir/torrents"
#       procd_add_jail_mount_rw "$config_dir/blocklists"
#       procd_add_jail_mount_rw "$config_dir/stats.json"
#       procd_add_jail_mount_rw "$download_dir"
        web_home="${web_home:-/usr/share/transmission/web}"
#       [ -d "$web_home" ] && procd_add_jail_mount "$web_home"
#       [ -f "$ca_bundle_file" ] && procd_add_jail_mount "$ca_bundle_file"
        procd_close_instance
}

Start with the transmission init script, especially its procd-ujail jail mounts and seccomp configuration, and compare them with the workaround and the referenced issue 17674. Reproduce the daemon start and torrent-download sequence on the reported OpenWrt setup; done means settings can be saved and downloads proceed without the daemon crashing while jail and seccomp remain enabled.