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
  17 [[ $EUID == 0 ]] || exec sudo -E "$BASH_SOURCE" "$@"
  18
  19 set -eE -o pipefail
  20 trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR
  21
  22 shopt -s nullglob
  23
  24 usage() {
  25   cat <<EOF
  26 usage: $0 SUBVOL_MOUNTPOINT...
  27
  28 In git, this is not not executable because it's meant to be installed
  29 using ./install-my-scripts
  30
  31 If latest subvols \$@ are not mounted, exit 1, print message, and touch
  32 /nocow/btrfs-stale/\$subvol
  33
  34 Either SUBVOL_MOUNTPOINT is a snapshot of the latest, or
  35 the latest snapshot is snapshot of SUBVOL_MOUNTPOINT.
  36
  37 -d         Enable debug output
  38 -h|--help  Print help and exit.
  39
  40 Note: Uses GNU getopt options parsing style
  41 EOF
  42   exit $1
  43 }
  44
  45 ##### begin command line parsing ########
  46
  47 debug=false # default
  48 temp=$(getopt -l help,d hd "$@") || usage 1
  49 eval set -- "$temp"
  50 while true; do
  51   case $1 in
  52     -d) debug=true; shift ;;
  53     -h|--help) usage ;;
  54     --) shift; break ;;
  55     *) echo "$0: Internal error! unexpected args: $*" ; exit 1 ;;
  56   esac
  57 done
  58
  59 if [[ ! $@ ]]; then
  60     echo "$0: error: expected mountpoint argument"
  61 fi
  62
  63 stale-file() {
  64     stale_dir=/nocow/btrfs-stale
  65     stale_file=$stale_dir/$vol
  66     if $stale; then
  67         mkdir -p $stale_dir
  68         printf "%s\n" $freshest_snap > $stale_file
  69         ret=1
  70     else
  71         rm -f $stale_file
  72     fi
  73
  74 }
  75 d() {
  76   if $debug; then
  77     printf "%s\n" "$*"
  78     fi
  79 }
  80
  81 ret=0
  82 for d; do
  83     vol=${d##*/}
  84     dev=$(sed -rn "s,^\s*([^#]\S*)\s+$d\s.*,\1,p" /etc/fstab|head -n1)
  85     d dev=$dev
  86     subvol_dir=$(sed -rn "s,^\s*[^#]\S*\s+$d\s.*\bsubvol=([a-zA-A/]+).*,\1,p" /etc/fstab|head -n1)
  87     d subvol_dir=$subvol_dir
  88     # note, we need $dev because $d might not be mounted, and we do this loop
  89     # because the device in fstab for the rootfs can be different.
  90     for devx in $(btrfs fi show $dev| sed -rn 's#.*path (/\S+)$#\1#p'); do
  91         root_dir=$(sed -rn "s,^\s*$devx\s+(\S+).*\bsubvolid=0\b.*,\1,p" /etc/fstab|head -n1)
  92         if [[ $root_dir ]]; then break; fi
  93     done
  94     svp=$root_dir/$subvol_dir # subvolume path
  95     d svp=$svp
  96
  97     snaps=($root_dir/btrbk/$subvol_dir.20*) # Assumes we are in the 21st century.
  98     if [[ ! $snaps ]]; then
  99         # no snapshots yet
 100         echo "$0: warning. no snapshots found. this is expected for a brand new volume"
 101         continue
 102     fi
 103
 104     # get info on last received sub
 105     last_received_cgen=0
 106     for f in ${snaps[@]}; do
 107         show="$(btrfs sub show $f)"
 108         if echo "$show" | grep -E "Received UUID:\s+[[:alnum:]]" &>/dev/null; then
 109             cgen=$(echo "$show" | sed -rn 's,^\s*Gen at creation:\s+([0-9]+).*,\1,p')
 110             if [[ $cgen -gt $last_received_cgen ]]; then
 111                 last_received_cgen=$cgen
 112                 last_received=$f
 113             fi
 114         fi
 115     done
 116     d last_received_cgen=$cgen
 117     d last_received=$f
 118
 119     # Get last_snap by date.
 120     # when a btrbk bugfix makes it into the distro,
 121     # we might replace this with btrbk list latest /mnt/root/$vol | ...
 122     last_snap=$(
 123         for s in ${snaps[@]}; do
 124             f=${s##*/}
 125             unix_time=$(date -d $(sed -r  's/(.{4})(..)(.{5})(..)(.*)/\1-\2-\3:\4:\5/' <<<${f#$vol.}) +%s)
 126             printf "%s %s\n" $unix_time $s
 127         done | sort -r | head -n 1 | awk '{print $2}'
 128              )
 129     if [[ ! $last_snap ]]; then
 130         # should not happen.
 131         echo "$0: error: could not find latest snapshot for $svp among ${snaps[*]}"
 132         ret=1
 133         continue
 134     fi
 135
 136     if [[ ! -e $svp ]]; then
 137         echo "$0: warning: subvol does not exist: $svp"
 138         echo "$0 assuming this host was just for receiving and latest snap is freshest"
 139         freshest_snap=$last_snap
 140         stale=true
 141         stale-file
 142         continue
 143     fi
 144
 145
 146     # if there is a last_received, we can assume stale or fresh if we are newer/older
 147     if [[ $last_received ]]; then
 148         svp_cgen=$(btrfs sub show $svp | sed -rn 's,^\s*Gen at creation:\s+([0-9]+).*,\1,p')
 149         d svp_cgen=$svp_cgen
 150         if [[ $svp_cgen -ge $last_received_cgen ]]; then
 151             stale=false
 152         else
 153             echo "$svp stale: it's gen at creation, $svp_cgen, is earlier than the last received snapshot, $last_received's gen at creation: $last_received_cgen"
 154             freshest_snap=$last_received
 155             stale=true
 156         fi
 157         stale-file
 158         continue
 159     fi
 160
 161     # fallback to using last_snap as the freshest
 162     freshest_snap=$last_snap
 163     stale=true
 164     # fresh if $svp has $last_snap as a snapshot,
 165     if btrfs sub show $svp 2>/dev/null | sed '0,/^\s*Snapshot(s):/d;s/^\s*//' | \
 166             grep -xF btrbk/$last_snap &>/dev/null; then
 167         stale=false
 168     else # or else $svp is a snapshot of $last_snap. we use a uuid
 169         # comparison, which if I remember from the docs, is a bit more
 170         # robust, perhaps to renames.
 171         last_snap_uuid=$(btrfs sub show $last_snap| awk '$1 == "UUID:" {print $2}')
 172         if btrfs sub show $svp| grep "^\s*Parent UUID:\s*$last_snap_uuid$" &>/dev/null; then
 173             stale=false
 174         fi
 175     fi
 176
 177     stale-file
 178
 179 done
 180 exit $ret