Subversion Repositories zfs_utils

#!/usr/bin/env perl

# Simplified BSD License (FreeBSD License)

#

# Copyright (c) 2025, Daily Data Inc.

# All rights reserved.

#

# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions are met:

#

# 1. Redistributions of source code must retain the above copyright notice, this

#    list of conditions and the following disclaimer.

#

# 2. Redistributions in binary form must reproduce the above copyright notice,

#    this list of conditions and the following disclaimer in the documentation

#    and/or other materials provided with the distribution.

#

# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE

# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# resetSnapshots.pl - Reset a dataset to a previous snapshot state

#

# Usage: resetSnapshots.pl [--force|-f] [--verbose|-v] [--help|-h] [--version|-V] <snapshot_file> <dataset>

#   --force, -f         Actually destroy snapshots (default: dry-run)

#   --verbose, -v       Verbose output

#   --help, -h          Show help and exit

#   --version, -V       Show version and exit

#   snapshot_file       File containing previous snapshot list (one per line)

#   dataset             ZFS dataset to check (e.g., pool/dataset)

#

# Purpose:

#   Reads a file containing a previous list of snapshots for a dataset,

#   compares it with current snapshots, and destroys any new snapshots

#   that have been added since the file was created. This is useful for

#   resetting a test dataset to a previous state.

#

# Usage Example:

# Save current snapshot state

# zfs list -t snapshot -r pool/testdata > snapshots_before.txt

# ... do some testing that creates snapshots ...

# Preview what would be removed (dry-run)

# ./resetSnapshots.pl -v snapshots_before.txt pool/testdata

# Actually remove new snapshots

# ./resetSnapshots.pl -f -v snapshots_before.txt pool/testdata

#

# Author: R. W. Rodolico <rodo@dailydata.net>

# Created: December 2025

#

# Revision History:

# Version: 1.0 RWR 2025-12-19

# Initial release

use strict;

use warnings;

use Getopt::Long qw(GetOptions);

our $VERSION = '1.0';

Getopt::Long::Configure('bundling');

my %opts;

GetOptions(\%opts,

    'force|f',      # force (actually perform destroys)

    'verbose|v',    # verbose

    'help|h',       # help

    'version|V',    # version

) or die "Error parsing command line options\n";

# Show version and exit

if ($opts{'version'} || $opts{'V'}) {

    print "resetSnapshots version $VERSION\n";

    exit 0;

}

# Show help and exit

if ($opts{'help'} || $opts{'h'}) {

    print "Usage: resetSnapshots.pl [--force|-f] [--verbose|-v] [--version|-V] [--help|-h] <snapshot_file> <dataset>\n";

    print "  --force, -f         actually destroy new snapshots (default: dry-run)\n";

    print "  --verbose, -v       verbose logging\n";

    print "  --version, -V       show version and exit\n";

    print "  --help, -h          show this help and exit\n";

    print "  snapshot_file       file containing previous snapshot list (one per line)\n";

    print "  dataset             ZFS dataset to reset (e.g., pool/dataset)\n";

    print "\n";

    print "Purpose: Destroy snapshots that have been added since the snapshot_file was created.\n";

    print "         Used to reset a dataset to a previous snapshot state.\n";

    exit 0;

}

my $FORCE   = $opts{'force'} || $opts{'f'} || 0;

my $VERBOSE = $opts{'verbose'} || $opts{'v'} || 0;

sub logmsg {

    print @_, "\n" if $VERBOSE;

}

# Get command line arguments

my $snapshot_file = shift @ARGV;

my $dataset = shift @ARGV;

# Validate arguments

unless ($snapshot_file && $dataset) {

    die "Error: Both snapshot_file and dataset are required.\n" .

        "Usage: resetSnapshots.pl [options] <snapshot_file> <dataset>\n" .

        "Use --help for more information.\n";

}

unless (-e $snapshot_file) {

    die "Error: Snapshot file '$snapshot_file' does not exist.\n";

}

unless (-r $snapshot_file) {

    die "Error: Cannot read snapshot file '$snapshot_file'.\n";

}

logmsg("Reading previous snapshot list from: $snapshot_file");

logmsg("Target dataset: $dataset");

# Read previous snapshot list from file

my %previous_snapshots;

open my $fh, '<', $snapshot_file or die "Cannot open $snapshot_file: $!\n";

while (my $line = <$fh>) {

    chomp $line;

    next unless $line =~ /\S/;  # Skip empty lines

    # Extract snapshot name from various formats:

    # - Full line from 'zfs list -t snapshot': "pool/dataset@snap   0B   -   123K   -"

    # - Just the snapshot name: "pool/dataset@snap"

    my $snap_name;

    if ($line =~ /^(\S+@\S+)/) {

        $snap_name = $1;

    } else {

        next;  # Skip lines that don't look like snapshots

    }

    # Only include snapshots for the specified dataset

    if ($snap_name =~ /^\Q$dataset\E@/ || $snap_name =~ /^\Q$dataset\E\//) {

        $previous_snapshots{$snap_name} = 1;

        logmsg("Previous: $snap_name");

    }

}

close $fh;

my $prev_count = scalar keys %previous_snapshots;

logmsg("Found $prev_count previous snapshots for dataset $dataset");

# Get current snapshots for the dataset

logmsg("Fetching current snapshots for $dataset...");

my @current_snapshots = `zfs list -H -t snapshot -r -o name $dataset 2>&1`;

my $zfs_exit = $?;

if ($zfs_exit != 0) {

    die "Error: Failed to list snapshots for dataset '$dataset'\n" .

        "Make sure the dataset exists and you have permissions.\n" .

        "ZFS output: @current_snapshots\n";

}

# Find snapshots that are new (in current but not in previous)

my @new_snapshots;

foreach my $snap (@current_snapshots) {

    chomp $snap;

    next unless $snap =~ /\S/;

    next unless $snap =~ /@/;  # Must contain @ to be a snapshot

    unless ($previous_snapshots{$snap}) {

        push @new_snapshots, $snap;

    }

}

my $new_count = scalar @new_snapshots;

my $current_count = scalar @current_snapshots;

print "Current snapshots: $current_count\n";

print "Previous snapshots: $prev_count\n";

print "New snapshots to remove: $new_count\n";

if ($new_count == 0) {

    print "No new snapshots found. Dataset is already in previous state.\n";

    exit 0;

}

print "\nNew snapshots that will be destroyed:\n";

foreach my $snap (@new_snapshots) {

    print "  $snap\n";

}

if ($FORCE) {

    print "\nDestroying new snapshots...\n";

    my $destroyed = 0;

    my $failed = 0;

    foreach my $snap (@new_snapshots) {

        logmsg("Destroying: $snap");

        my $output = `zfs destroy $snap 2>&1`;

        my $exit_code = $?;

        if ($exit_code == 0) {

            print "  ✓ Destroyed: $snap\n" if $VERBOSE;

            $destroyed++;

        } else {

            print "  ✗ Failed to destroy: $snap\n";

            print "    Error: $output\n" if $output;

            $failed++;

        }

    }

    print "\nSummary:\n";

    print "  Destroyed: $destroyed\n";

    print "  Failed: $failed\n";

    if ($failed > 0) {

        print "\nWarning: Some snapshots could not be destroyed.\n";

        exit 1;

    } else {

        print "\nDataset successfully reset to previous snapshot state.\n";

        exit 0;

    }

} else {

    print "\nDry-run mode: No snapshots were destroyed.\n";

    print "Use --force to actually destroy these snapshots.\n";

    exit 0;

}