Take the snapshot of btrfs filesystem

snapshot.sh

#!/bin/bash
#
# usage: snapshot.sh create|delete|list [snapshotname]
#
#

btrfs_root=/
DST_BACKUPDIR=/backup

# **************************************************************************
#   create()
#   ARGS: <no>
#   RC: 0 if OK
#
create()
{
  sync
  if [ -z $1 ]
  then
    path_to_snapshots=${DST_BACKUPDIR}/`date +%Y%m%d_%H%m%S`
  else
    path_to_snapshots=${DST_BACKUPDIR}/$1
  fi
  mkdir -pv ${DST_BACKUPDIR}

  subvolumes="$(/usr/bin/btrfs subvolume list '/' | /usr/bin/awk '{print $NF}' | grep -vE '^backup')" # rescan
  for subvolume in $subvolumes
  do
    snapshot_directory="${btrfs_root}/${path_to_snapshots}/$(/usr/bin/dirname ${subvolume})"
    rm -rf ${btrfs_root}/${path_to_snapshots}/${subvolume}
    if [ ! -d "${snapshot_directory}" ]
    then
      /usr/bin/mkdir -p "${snapshot_directory}"
    fi
    /usr/bin/btrfs subvolume snapshot "${btrfs_root}/${subvolume}" "${btrfs_root}/${path_to_snapshots}/${subvolume}"

    TRANSACTION_ID=`btrfs subvolume find-new "${btrfs_root}/${subvolume}" 9999999`
    TRANSACTION_ID=${TRANSACTION_ID#transid marker was }
    echo "${subvolume};${TRANSACTION_ID}" >> $path_to_snapshots/transaction.db
  done

  return 0
}

# **************************************************************************
#   list()
#   ARGS: <no>
#   RC: 0 if OK
#
list()
{
  cd $DST_BACKUPDIR
  ls -ltrd */
}

# **************************************************************************
#   remove()
#   ARGS: <no>
#   RC: 0 if OK
#
delete()
{
  if [ -z $1 ]
  then
    echo  echo "usage: snapshot.sh delete snapshotname"
    return 1
  else
    path_to_snapshots=${DST_BACKUPDIR}/$1
  fi
  if [ ! -d $path_to_snapshots ]
  then
    echo "$path_to_snapshots : No such directory"
    echo "usage: snapshot.sh delete snapshotname"
    return 1
  fi

  subvolumes=`btrfs subvolume list $path_to_snapshots | /usr/bin/awk '{print $NF}' | tac`
  for subvolume in $subvolumes
  do
      btrfs subvolume delete ${btrfs_root}/${path_to_snapshots}/$subvolume
  done

  rm -rvf  $path_to_snapshots
}

# **************************************************************************
#   diff()
#   ARGS: <no>
#   RC: 0 if OK
#
diff ()
{
  SNAPSHOT_OLD=${DST_BACKUPDIR}/$1;
  SNAPSHOT_NEW=${DST_BACKUPDIR}/$2;

  if [ ! -d $SNAPSHOT_OLD ]
  then
    echo "$SNAPSHOT_OLD does not exist";
    return 1
  fi
  if [ ! -d $SNAPSHOT_NEW ]
  then
    echo "$SNAPSHOT_NEW does not exist";
    return 1
  fi

  cat $SNAPSHOT_OLD/transaction.db | while read line
  do
    OLD_TRANSID=`echo $line | cut -d";" -f2`
    SUBVOL=`echo $line | cut -d";" -f1`

    btrfs subvolume find-new "$SNAPSHOT_NEW/$SUBVOL" $OLD_TRANSID | sed '$d' | cut -f17- -d' ' | sort | uniq | while read file
    do
      echo $SUBVOL/$file
    done
  done
}

case "$1" in
  create)
    create $2
    RC=$?
    ;;
  delete)
    delete $2
    RC=$?
    ;;
  list)
    list
    RC=$?
    ;;
  diff)
    diff $2 $3
    RC=$?
    ;;
  *)
    echo "usage: snapshot.sh create|delete|list [snapshotname]"
    RC=1
    ;;
esac;

/usr/bin/sync

exit $RC