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

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