1 #!/bin/bash

     2 

     3 set -e

     4 

     5 SNAPSIZE='500M'

     6 

     7 warn() {

     8     echo $@ >&2

     9 }

    10 

    11 die() {

    12     if [ $# -ne 0 ]; then

    13 	echo $@ >&2

    14     else

    15 	echo something went wrong

    16     fi

    17     exit 1

    18 }

    19 

    20 usage() {

    21 

    22 cat <<__U

    23 usage:

    24  $0 [-s snapsize] /dev/<vgname>/<lvname>

    25  or

    26  $0 [-s snapsize] <vgname>/<lvname>

    27  but not (yet?)

    28  $0 [-s snapsize] /dev/mapper/<vgname>-<lvname>

    29 __U

    30 

    31 exit 1

    32 

    33 }

    34 

    35 cleanup() {

    36 

    37     # if you have problems removing volumes then you may have the 'udisks'

    38     # package installed; see:

    39     # http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=549691#74

    40     # https://bugzilla.redhat.com/show_bug.cgi?id=577798#c5

    41     # https://www.redhat.com/archives/linux-lvm/2010-August/msg00029.html

    42     lvs "$vg/$lvs" && lvremove -f "$vg/$lvs"

    43 

    44 }

    45 

    46 while getopts "s:" opt; do

    47   case $opt in

    48     s)

    49       SNAPSIZE="$OPTARG"

    50       ;;

    51     \?)

    52       usage

    53       ;;

    54   esac

    55 done

    56 shift $((OPTIND-1))

    57 

    58 p=${1:?device required}

    59 p=${p#/dev/}

    60 vg=${p%/*}

    61 lv=${p##*/}

    62 lvs="snap.${lv}"

    63 

    64 trap cleanup EXIT

    65 

    66 [ -n "${vg}" -a -n "${lv}" -a "${vg}" != "${p}" -a "${lv}" != "${p}" ] || usage

    67 

    68 d=$(date +%Y%m%d%H%M%S)

    69 lvcreate -n"$lvs" -L"$SNAPSIZE" -s "$vg/$lv"

    70 # fix any noncritical problems automatically and don't make any noise (on

    71 # stderr) about it; note that these problems remain present on the origin

    72 # volume

    73 e2fsck -fp "/dev/$vg/$lvs" 2>&1 || true

    74 if e2fsck -fy "/dev/$vg/$lvs" 2>&1; then

    75     tune2fs -C 1 -T "$d" "/dev/$vg/$lv"

    76 else

    77     die fsck returned nonzero: this may indicate filesystem corruption on the origin volume.

    78 fi