code.delx.au - monosys/blob - borg/bsnap

   1 #!/bin/bash
   2
   3 set -eu
   4
   5 function snap {
   6     unsnap
   7
   8     cat /etc/fstab | awk '{print $5 " " $1 " " $2;}' | while read -r dump dev mnt; do
   9         if [ "$dump" = 1 ]; then
  10             echo "bind mount $mnt"
  11             mount --bind "${mnt}" "/a${mnt}"
  12         elif [ "$dump" = 2 ]; then
  13             read -r lvname vgname _ < <(lvdisplay --noheadings -C "$dev")
  14             echo "snapshot ${vgname}/${lvname}"
  15             lvcreate -L1G --snapshot --name "${lvname}snap" "${vgname}/${lvname}"
  16             mount -o ro "${dev}snap" "/a${mnt}"
  17         fi
  18     done
  19 }
  20
  21 function unsnap {
  22     tac /etc/fstab | awk '{print $5 " " $1 " " $2;}' | while read -r dump dev mnt; do
  23         snapmnt="/a${mnt}"
  24         snapdev="${dev}snap"
  25         if [ "$dump" = 1 ]; then
  26             echo "umount $snapmnt"
  27             mountpoint -q "$snapmnt" && umount "$snapmnt"
  28         elif [ "$dump" = 2 ]; then
  29             echo "umount $snapmnt"
  30             mountpoint -q "$snapmnt" && umount "$snapmnt"
  31
  32             echo "unsnapshot $snapdev"
  33             [ -b "$(readlink -f "$snapdev")" ] && echo y | lvremove "${dev}snap"
  34         fi
  35     done
  36 }
  37
  38 if [ "$(id -u)" -ne 0 ]; then
  39     echo "Must be root"
  40     exit 1
  41 fi
  42
  43 mkdir -p /a
  44
  45 if [ "${1:-}" = "off" ]; then
  46     unsnap
  47 elif [ "${1:-}" = "on" ]; then
  48     snap
  49 else
  50     echo "Usage: $0 on|off"
  51     exit 1
  52 fi