1 #!/bin/bash

     2 

     3 SNAPSIZE='500M'

     4 

     5 warn() {

     6     echo $@ >&2

     7 }

     8 

     9 die() {

    10     if [ $# -ne 0 ]; then

    11 	echo $@ >&2

    12     else

    13 	echo something went wrong

    14     fi

    15     exit -1

    16 }

    17 

    18 usage() {

    19 

    20 cat <<__U

    21 usage:

    22  $0 /dev/<vgname>/<lvname>

    23  or

    24  $0 <vgname>/<lvname>

    25  but not (yet?)

    26  $0 /dev/mapper/<vgname>-<lvname>

    27 __U

    28 

    29 exit -1

    30 

    31 }

    32 

    33 p=${1:?device required}

    34 p=${p#/dev}

    35 vg=${p%%/*}

    36 lv=${p##*/}

    37 lvs="snap.${lv}"

    38 

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

    40 

    41 lvcreate -n"$lvs" -L"$SNAPSIZE" -s "$vg/$lv" || die

    42 if e2fsck -p "/dev/$vg/$lvs"; then

    43     tune2fs -C 1 -T now "/dev/$vg/$lv" || die

    44     # removing /dev/$vg/snap.$lv or just $vg/snap.$lv does not work reliably

    45     # removing /dev/mapper/$vg-snap.$lv does not work reliably either

    46     waittime=1 # second

    47     tries=60

    48     i=1

    49     until lvremove -f "$vg/$lvs"; do

    50         if [ $i -lt $tries ]; then

    51             warn retrying

    52             sleep $waittime

    53             i=$((i+1))

    54         else

    55             die giving up

    56         fi

    57     done

    58 else

    59     die fsck failed

    60 fi