mirror of https://github.com/digint/btrbk
150 lines
3.6 KiB
Perl
150 lines
3.6 KiB
Perl
#!/usr/bin/perl
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#
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# Linux::ExtentsMap - Read and Manipulate List of Extents
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#
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# Copyright (C) 2014-2019 Axel Burri
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# ---------------------------------------------------------------------
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# The official btrbk website is located at:
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# https://digint.ch/btrbk/
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#
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# Author:
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# Axel Burri <axel@tty0.ch>
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# ---------------------------------------------------------------------
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#
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# Based on work from:
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# Graham Cobb: https://github.com/GrahamCobb/extents-lists
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# ---------------------------------------------------------------------
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package Linux::ExtentsMap;
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our $blocksize = 4096; # default blocksize
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sub new
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{
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my $class = shift;
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my $file = shift;
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my $self = {
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map => defined($file) ? filefrag_extentmap($file) : [],
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};
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bless $self, ref($class) || $class;
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return $self->merge;
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}
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# returns extents range (unsorted array of [start,end], inclusive) from FIEMAP ioctl
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sub filefrag_extentmap($)
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{
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my $file = shift || die;
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# NOTE: this returns exitstatus=0 if file is not found, or no files found
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my $ret = `find '$file' -xdev -type f -print0 | xargs -0 -r filefrag -vs`;
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return undef unless(defined($ret));
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return undef if($?);
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my @range;
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foreach (split(/\n/, $ret))
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{
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# get extents start / end
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push @range, [ $1, $2 ] if(/^\s*[0-9]+:\s*[0-9]+\.\.\s*[0-9]+:\s*([0-9]+)\.\.\s*([0-9]+):/);
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if(/block of ([0-9]+) bytes/) {
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die "filefrag reports blocksize=$1 (expected $blocksize) in: $file" if($1 ne $blocksize);
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}
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}
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return \@range;
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}
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sub total_blocks()
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{
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my $self = shift;
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my $count = 0;
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foreach(@{$self->{map}}) {
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$count += ($_->[1] - $_->[0] + 1);
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}
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return $count;
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}
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sub size()
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{
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my $self = shift;
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my $total_blocks = $self->total_blocks();
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return $total_blocks * $blocksize;
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}
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# merge sorted map
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sub merge($)
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{
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my $self = shift;
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my @merged;
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my $start = -1;
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my $end = -2;
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foreach (sort { $a->[0] <=> $b->[0] } @{$self->{map}})
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{
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if($_->[0] <= $end + 1) {
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# range overlaps the preceeding one, or is adjacent to it
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$end = $_->[1] if($_->[1] > $end);
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}
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else {
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push @merged, [ $start, $end ] if($start >= 0);
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$start = $_->[0];
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$end = $_->[1];
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}
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}
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push @merged, [ $start, $end ] if($start >= 0);
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$self->{map} = \@merged;
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return $self;
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}
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sub diff($)
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{
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my $self = shift;
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my $l = $self->{map};
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my $r = (shift)->{map};
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my $i = 0;
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my $rn = scalar(@$r);
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my @diff;
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foreach(@$l) {
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my $l_start = $_->[0];
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my $l_end = $_->[1];
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while(($i < $rn) && ($r->[$i][1] < $l_start)) { # r_end < l_start
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# advance r to next overlapping
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$i++;
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}
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while(($i < $rn) && ($r->[$i][0] <= $l_end)) { # r_start <= l_end
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# while overlapping, advance l_start
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my $r_start = $r->[$i][0];
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my $r_end = $r->[$i][1];
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push @diff, [ $l_start, $r_start - 1 ] if($l_start < $r_start);
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$l_start = $r_end + 1;
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last if($l_start > $l_end);
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$i++;
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}
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push @diff, [ $l_start, $l_end ] if($l_start <= $l_end);
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}
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my $ret = { map => \@diff };
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bless $ret, ref($self);
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return $ret;
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}
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1;
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