core-agent-linux/misc/block_add_change

#!/bin/bash

NAME=${DEVNAME#/dev/}
DESC="${ID_MODEL} (${ID_FS_LABEL})"
SIZE=$[ $(cat /sys/$DEVPATH/size) * 512 ]
MODE=w
XS_KEY="qubes-block-devices/$NAME"

# Ignore mounted...
if fgrep -q $DEVNAME /proc/mounts; then
    xenstore-rm "$XS_KEY"
    exit 0
fi
# ... and used by device-mapper
if [ -n "`ls -A /sys/$DEVPATH/holders 2> /dev/null`" ]; then
    xenstore-rm "$XS_KEY"
    exit 0
fi

# Special case for CD
if [ "$ID_TYPE" = "cd" ]; then
    if [ "$ID_CDROM_MEDIA" != "1" ]; then
        # Hide empty cdrom drive
        xenstore-rm "$XS_KEY"
        exit 0
    fi
    MODE=r
fi
xenstore-write "$XS_KEY/desc" "$DESC" "$XS_KEY/size" "$SIZE" "$XS_KEY/mode" "$MODE"

# Make sure that block backend is loaded
/sbin/modprobe xen-blkback 2> /dev/null || /sbin/modprobe blkbk