iankelling.org Git - distro-setup/blob - check-subvol-stale

   1 #!/bin/bash
   2 # Copyright (C) 2016 Ian Kelling
   3 #
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7 #
   8 #     http://www.apache.org/licenses/LICENSE-2.0
   9 #
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15
  16 # usage: $0 SUBVOL_MOUNTPOINT...
  17 #
  18 # In git, this is not not executable because it's meant to be installed
  19 # using ./install-my-scripts
  20 #
  21 # If latest subvols $@ are not mounted, exit 1, print message, and touch
  22 # /nocow/btrfs-stale/$subvol
  23 #
  24 # Either SUBVOL_MOUNTPOINT is a snapshot of the latest, or
  25 # the latest snapshot is snapshot of SUBVOL_MOUNTPOINT.
  26
  27 [[ $EUID == 0 ]] || exec sudo -E "$BASH_SOURCE" "$@"
  28
  29 set -eE -o pipefail
  30 trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR
  31
  32 shopt -s nullglob
  33
  34 if [[ ! $@ ]]; then
  35     echo "$0: error: expected mountpoint argument"
  36 fi
  37
  38 ret=0
  39 for d; do
  40     vol=${d##*/}
  41     cd /mnt/root/btrbk
  42     snaps=($vol.20*) # Assumes we are in the 21st century.
  43     if [[ ! $snaps ]]; then
  44         # no snapshots yet
  45         continue
  46     fi
  47     # when a btrbk bugfix makes it into the distro,
  48     # we might replace this with btrbk list latest /mnt/root/$vol | ...
  49     # note: this is duplicated in mount-latest-subvol
  50     last_snap=$(
  51         for f in ${snaps[@]}; do
  52             printf "%s %s\n" $(date -d $(sed -r  's/(.{4})(..)(.{5})(..)(.*)/\1-\2-\3:\4:\5/' <<<${f#$vol.}) +%s) $f
  53         done | sort -r | head -n 1 | awk '{print $2}'
  54              )
  55     if [[ ! $last_snap ]]; then
  56         # should not happen.
  57         echo "$0: error: could not find latest snapshot for $d among ${snaps[@]}"
  58         ret=1
  59         continue
  60     fi
  61
  62     # check that $d has $last_snap as a snapshot,
  63     # or else $d is a snapshot of $last_snap. In the second
  64     # case, we use a uuid comparison, which if I remember from the
  65     # docs, is a bit more robust, perhaps to renames.
  66     if btrfs sub show $d 2>/dev/null | sed '0,/^\s*Snapshot(s):/d;s/^\s*//' | \
  67             grep -xF btrbk/$last_snap &>/dev/null; then
  68         stale=false
  69     else
  70         last_snap_uuid=$(btrfs sub show $last_snap| awk '$1 == "UUID:" {print $2}')
  71         if btrfs sub show $d| grep "^\s*Parent UUID:\s*$last_snap_uuid$" &>/dev/null; then
  72             stale=false
  73         fi
  74     fi
  75
  76     # check if $d is a snapshot of any of the btrbk backups
  77     if [[ ! $stale ]]; then
  78         for f in ${snaps[@]}; do
  79             if [[ $f == $last_snap ]]; then continue; fi
  80             uuid=$(btrfs sub show $f| awk '$1 == "UUID:" {print $2}')
  81             if btrfs sub show $d| grep "^\s*Parent UUID:\s*$uuid$" &>/dev/null; then
  82                 stale=true
  83                 echo "$d stale: it's a snapshot of $f"
  84                 break
  85             fi
  86         done
  87     fi
  88     # check if $d generation is later than last_snap
  89     if [[ ! $stale ]]; then
  90         last_snap_gen=$(btrfs sub show $last_snap| awk '$1 == "Generation:" {print $2}')
  91         d_gen=$(btrfs sub show $d| awk '$1 == "Generation:" {print $2}')
  92         if (( last_snap_gen < d_gen )); then
  93             stale=false
  94         else
  95             echo "$d stale: it's generation, $d_gen, is earlier than the last snapshot's, $last_snap_gen"
  96             stale=true
  97         fi
  98     fi
  99
 100
 101     stale_dir=/nocow/btrfs-stale
 102     stale_file=$stale_dir/$vol
 103     if $stale; then
 104         mkdir -p $stale_dir
 105         printf "%s\n" $last_snap > $stale_file
 106         ret=1
 107         continue
 108     else
 109         rm -f $stale_file
 110     fi
 111 done
 112 exit $ret