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

   1 #!/bin/bash
   2
   3 set -eu
   4
   5 function snap {
   6     unsnap
   7
   8     znap-take bsnap 1
   9     mount_snapshots
  10     mkdir -p /a/boot
  11     mount --bind /boot /a/boot
  12 }
  13
  14 function unsnap {
  15     if ! [ -d /a ]; then
  16         return
  17     fi
  18
  19     umount /a/boot || true
  20     rmdir /a/boot || true
  21
  22     if ls &> /dev/null /a/*; then
  23         umount /a/* || true
  24         rmdir /a/* || true
  25     fi
  26     rmdir /a || true
  27 }
  28
  29 function list_snapshots {
  30     local fsname
  31     for fsname in $(zfs list -H -o name); do
  32         zfs list -H -o name -S creation -t snapshot -d 1 -r "$fsname" | \
  33             grep '@znap_....-..-..-...._bsnap' | \
  34             head -n1
  35     done
  36 }
  37
  38 function mount_snapshots {
  39     local snapname
  40     local fsname
  41     local mountpoint
  42
  43     for snapname in $(list_snapshots); do
  44         fsname="${snapname%@*}"
  45         mountpoint="/a/$(echo "$fsname" | cut -d/ -f2- | tr '/' '_')"
  46         mkdir -p "$mountpoint"
  47         mount -t zfs "$snapname" "$mountpoint"
  48     done
  49 }
  50
  51 if [ "$(id -u)" -ne 0 ]; then
  52     echo "Must be root"
  53     exit 1
  54 fi
  55
  56 if [ "${1:-}" = "off" ]; then
  57     unsnap
  58 elif [ "${1:-}" = "on" ]; then
  59     snap
  60 else
  61     echo "Usage: $0 on|off"
  62     exit 1
  63 fi