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[0]}" "$@"
  18
  19 source /usr/local/lib/err
  20
  21 shopt -s nullglob
  22
  23 usage() {
  24   cat <<EOF
  25 usage: $0 SUBVOL_MOUNTPOINT... | -p SUBVOL_PATH...
  26
  27 In git this is not not executable because it's meant to be installed
  28 using ./install-my-scripts
  29
  30 If latest subvols \$@ are not mounted, print a message, and print
  31 the unstale subvol name into /nocow/btrfs-stale/\$subvol
  32
  33 Fresh is opposite of stale. To be fresh, either SUBVOL_MOUNTPOINT is a
  34 snapshot of the latest, or the latest snapshot is snapshot of
  35 SUBVOL_MOUNTPOINT.
  36
  37 -p            Args are SUBVOL_PATH, not mountpoints from which we derive
  38               that information.
  39 -v|--verbose  Be more verbose
  40 -h|--help  Print help and exit.
  41
  42 Note: Uses GNU getopt options parsing style
  43 EOF
  44   exit $1
  45 }
  46
  47 ##### begin command line parsing ########
  48
  49 subvol_path=false
  50 verbose=false
  51 temp=$(getopt -l help,verbose hpv "$@") || usage 1
  52 eval set -- "$temp"
  53 while true; do
  54   case $1 in
  55     -p) subvol_path=true ;;
  56     -v|--verbose) verbose=true ;;
  57     -h|--help) usage ;;
  58     --) shift; break ;;
  59     *) echo "$0: unexpected args: $*" >&2 ; usage 1 ;;
  60   esac
  61   shift
  62 done
  63
  64 if [[ ! $1 ]]; then
  65   echo "$0: error: expected mountpoint argument"
  66 fi
  67
  68 stale-file() {
  69   stale_dir=/nocow/btrfs-stale
  70   stale_file=$stale_dir/$vol
  71   if $stale; then
  72     mkdir -p $stale_dir
  73     printf "%s\n" $freshest_snap > $stale_file
  74   else
  75     rm -f $stale_file
  76   fi
  77
  78 }
  79 d() {
  80   if $verbose; then
  81     printf "%s\n" "$*"
  82   fi
  83 }
  84
  85 # duplicated in mount-latest-sub
  86 mapper-dev() {
  87   local mapdev
  88   local -n devref=$1
  89   if [[ $devref == /dev/dm-* ]]; then
  90     for mapdev in /dev/mapper/*; do
  91       if [[ $(readlink -f $mapdev) == "$devref" ]]; then
  92         devref=$mapdev
  93         break
  94       fi
  95     done
  96   fi
  97 }
  98
  99 for d; do
 100   if $subvol_path; then
 101     svp=$d
 102     root_dir=${d%/*}
 103     subvol_dir=${d##*/}
 104     vol=$subvol_dir
 105   else
 106     vol=${d##*/}
 107     # second field, non-comment line == $d
 108     dev=$(sed -rn "s,^\s*([^#]\S*)\s+$d\s.*,\1,p" /etc/fstab /etc/mtab|head -n1)
 109
 110     d dev=$dev
 111     subvol_dir=$(sed -rn "s,^\s*[^#]\S*\s+$d\s.*\bsubvol=([a-zA-A/]+).*,\1,p" /etc/fstab /etc/mtab|head -n1)
 112     if [[ ! $subvol_dir ]]; then
 113       continue
 114     fi
 115     d subvol_dir=$subvol_dir
 116
 117     ### begin getting root_dir
 118     ### this is duplicated in mount-latest-subvol
 119     # note, we need $dev because $d might not be mounted, and we do this loop
 120     # because the device in fstab for the rootfs can be different.
 121     for devx in $(btrfs fil show $dev| sed -rn 's#.*path (\S+)$#\1#p'); do
 122       if [[ $devx == dm-* ]]; then
 123         devx=/dev/$devx
 124         d mapper-dev $devx
 125         mapper-dev devx
 126       fi
 127       d devx=$devx
 128       root_dir=$(sed -rn "s,^\s*$devx\s+(\S+).*\bsubvolid=[05]\b.*,\1,p" /etc/mtab /etc/fstab|head -n1)
 129       if [[ $root_dir ]]; then
 130         d root_dir=$root_dir
 131         break
 132       fi
 133     done
 134     if [[ ! $root_dir ]]; then
 135       echo "$0: error could not find root subvol mount for $dev" >&2
 136       exit 1
 137     fi
 138     ### end getting root_dir
 139     svp=$root_dir/$subvol_dir # subvolume path
 140     d "svp=$svp # subvolume path"
 141   fi
 142
 143   snaps=($root_dir/btrbk/$subvol_dir.20*) # Assumes we are in the 21st century.
 144   if [[ ! ${snaps[*]} ]]; then
 145     # no snapshots yet
 146     # TODO: make this an error and override with a cli flag
 147     echo "$0: warning: no snapshots found at $root_dir/btrbk/$subvol_dir.20*. this is expected for a brand new volume"
 148     continue
 149   fi
 150
 151   # get info on last received sub
 152   last_received=
 153   last_received_cgen=0
 154   for f in ${snaps[@]}; do
 155     show="$(btrfs sub show $f)"
 156     if echo "$show" | grep -E "Received UUID:\s+[[:alnum:]]" &>/dev/null; then
 157       d found received uuid in $f
 158       cgen=$(echo "$show" | sed -rn 's,^\s*Gen at creation:\s+([0-9]+).*,\1,p')
 159       if [[ $cgen -gt $last_received_cgen ]]; then
 160         last_received_cgen=$cgen
 161         last_received=$f
 162       fi
 163     fi
 164   done
 165   d last_received_cgen=$last_received_cgen
 166   d last_received=$last_received
 167
 168   # Get last_snap by date.
 169   # when a btrbk bugfix makes it into the distro,
 170   # we might replace this with btrbk list latest /mnt/root/$vol | ...
 171   last_snap=$(
 172     for s in ${snaps[@]}; do
 173       f=${s##*/}
 174       unix_time=$(date -d $(sed -r  's/(.{4})(..)(.{5})(..)(.*)/\1-\2-\3:\4:\5/' <<<${f#$vol.}) +%s)
 175       printf "%s %s\n" $unix_time $s # part of the pipeline
 176       # sort will fail
 177     done | sort -r | head -n 1 | awk '{print $2}' || [[ ${PIPESTATUS[1]} == 141 || ${PIPESTATUS[0]} == 32 ]]
 178            )
 179   if [[ ! $last_snap ]]; then
 180     # should not happen.
 181     echo "$0: error: could not find latest snapshot for $svp among ${snaps[*]}" >&2
 182     exit 1
 183   fi
 184   d last_snap=$last_snap
 185
 186   if [[ ! -e $svp ]]; then
 187     echo "$0: warning: subvol does not exist: $svp"
 188     echo "$0 assuming this host was just for receiving and latest snap is freshest"
 189     freshest_snap=$last_snap
 190     stale=true
 191     stale-file
 192     continue
 193   fi
 194
 195
 196   # if there is a last_received, we can assume stale or fresh if we are newer/older
 197   if [[ $last_received ]]; then
 198     svp_cgen=$(btrfs sub show $svp | sed -rn 's,^\s*Gen at creation:\s+([0-9]+).*,\1,p')
 199     d svp_cgen=$svp_cgen
 200     if [[ $svp_cgen -ge $last_received_cgen ]]; then
 201       stale=false
 202     else
 203       d "$svp stale: it's gen at creation, $svp_cgen, is earlier than the last received snapshot, $last_received's gen at creation: $last_received_cgen"
 204       freshest_snap=$last_received
 205       stale=true
 206     fi
 207     stale-file
 208     continue
 209   fi
 210
 211   # fallback to using last_snap as the freshest
 212   freshest_snap=$last_snap
 213   stale=true
 214   # fresh if $svp has $last_snap as a snapshot,
 215   if btrfs sub show $svp 2>/dev/null | sed '0,/^\s*Snapshot(s):/d;s/^\s*//' | \
 216       grep -xF ${last_snap#$root_dir/} ; then
 217     stale=false
 218   else # or else $svp is a snapshot of $last_snap. we use a uuid
 219     # comparison, which if I remember from the docs, is a bit more
 220     # robust, perhaps to renames.
 221     last_snap_uuid=$(btrfs sub show $last_snap| awk '$1 == "UUID:" {print $2}')
 222     if btrfs sub show $svp| grep "^\s*Parent UUID:\s*$last_snap_uuid$" &>/dev/null; then
 223       stale=false
 224     fi
 225   fi
 226
 227   stale-file
 228 done