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