tmpdir-setup

#! /usr/bin/bash

usage() {
    cat <<EOF >&2
usage:
    $0 create JOBID SIZE UID  # create SIZE GiB /dev/shm/mxqd/mnt/job/$JOBID
    $0 cleanup JOBID          # cleanup
EOF
    exit 1
}

tmpdir=/scratch/local2/mxqd/tmp
mntdir=/dev/shm/mxqd/mnt/job

cmd_create() {
    (( $# == 3 )) || usage
    MXQ_JOBID=$1
    MXQ_SIZE=$2
    MXQ_UID=$3

    filename=$tmpdir/$MXQ_JOBID.tmp
    mountpoint=$mntdir/$MXQ_JOBID
    dmname=mxq.$MXQ_JOBID
    dmdevice=/dev/mapper/$dmname

    umask 006
    mkdir -p $tmpdir
    mkdir -p $mntdir

    status=1;

    if fallocate -l ${MXQ_SIZE}G $filename; then
        if loopdevice=$(losetup --find --show $filename); then
            if dmsetup create $dmname --table "0 $((MXQ_SIZE*1024*1024*2)) linear $loopdevice 0"; then
                if mkfs.ext4 \
                        -q \
                        -m 0 \
                        -E nodiscard,mmp_update_interval=300,lazy_journal_init=1,root_owner=$MXQ_UID:0 \
                        -O '64bit,ext_attr,filetype,^has_journal,huge_file,inline_data,^mmp,^quota,sparse_super2' \
                        $dmdevice \
                        && mkdir -p $mountpoint && mount -Odata=writeback,barrier=0  $dmdevice $mountpoint; then
                    rmdir $mountpoint/lost+found
                    status=0
                else
                    dmsetup remove --force --deferred $dmname
                fi
            fi
            losetup -d $loopdevice
        fi
        rm $filename
    else
        test -e $filename && rm $filename
    fi
    exit $status
}

cmd_cleanup() {
    (( $# == 1 )) || usage
    MXQ_JOBID=$1

    # Support rolling upgrade: Use old code if loop device is directly mounted without a dm device in between.
    #
    if [[ $(findmnt --output SOURCE --noheadings /dev/shm/mxqd/mnt/job/$MXQ_JOBID) =~ ^/dev/loop ]]; then
        shopt -s dotglob
        rm -rf /dev/shm/mxqd/mnt/job/$MXQ_JOBID/*
        umount /dev/shm/mxqd/mnt/job/$MXQ_JOBID
        rmdir /dev/shm/mxqd/mnt/job/$MXQ_JOBID
        exit
    fi

    mountpoint=$mntdir/$MXQ_JOBID
    dmname=mxq.$MXQ_JOBID
    dmdevice=/dev/mapper/$dmname
    minor=$(( 0x$(stat -c%T $dmdevice) ))
    sectors=$(cat /sys/block/dm-$minor/size)

    # fs/ext4/ext4.h: #define EXT4_IOC_SHUTDOWN _IOR ('X', 125, __u32)
    # (_IOC_READ << 30) + (sizeof(_u32) << 16) + ( 'X' << 8 ) + 125
    # ( 2 << 30 ) + ( 4 << 16 ) + ( 88 << 8 ) + 125 = 2147768445
    # fs/ext4/ext4.h: #define EXT4_GOING_FLAGS_NOLOGFLUSH       0x2 /* don't flush log nor data */

    /usr/local/system/perl/bin/perl -e "open F, '<', '$mountpoint/.' ; \$d=pack('L', 2) ; ioctl (F, 2147768445, \$d)"

    dmsetup reload $dmname --table "0 $sectors zero"
    dmsetup resume $dmname --noflush
    umount --lazy $mountpoint
    dmsetup remove $dmname
    rmdir $mountpoint
}

(( $# > 0 )) || usage
cmd="$1"
shift;
case "$cmd" in
    create)
        cmd_create "$@"
        ;;
    cleanup)
        cmd_cleanup "$@"
        ;;
    *)
        usage
        ;;
esac