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btrbk: add extentmap_cache (new cache_dir option)

pull/358/head
Axel Burri 2019-08-07 00:26:12 +02:00
parent c6375967b8
commit 7facb44833
2 changed files with 76 additions and 1 deletions
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73
btrbk
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@ -144,6 +144,8 @@ my %config_options = (
archive_exclude => { default => undef, accept_file => { wildcards => 1 }, allow_multiple => 1, context => [ "global" ] },
archive_exclude_older => { default => undef, accept => [ "yes", "no" ] },
cache_dir => { default => undef, accept_file => { absolute => 1 }, allow_multiple => 1, context => [ "global" ] },
# deprecated options
ssh_port => { default => "default", accept => [ "default" ], accept_numeric => 1,
deprecated => { DEFAULT => { warn => 'Please use "ssh://hostname[:port]" notation in the "volume" and "target" configuration lines.' } } },
@ -2257,6 +2259,68 @@ sub system_urandom($;$) {
die "unsupported format";
}
sub read_extentmap_cache($)
{
my $vol = shift;
my $cache_dir = config_key($vol, 'cache_dir');
return undef unless($cache_dir);
my $uuid = $vol->{node}{uuid} // die;
foreach (@$cache_dir) {
my $file = "$_/${uuid}.extentmap.bin";
next unless (-f $file);
DEBUG "Reading extentmap cache: $file";
if(open(my $fh, '<:raw', $file)) {
my @range;
my $buf;
read($fh, $buf, 24 + 8 * 3); # read header
my ($v, $gen, $time, $blocksize) = unpack('a24Q<Q<Q<', $buf);
unless(($v =~ /^btrbk_extentmap_v1/) && $gen && $time && $blocksize) {
ERROR "Ambigous cache file: $file";
next;
}
if($gen != $vol->{node}{gen}) {
INFO "Subvolume generation has changed (cache=$gen, subvol=$vol->{node}{gen}), ignoring cache: $file";
next;
}
while(read $fh, $buf, 8 * 2) { # read / unpack two words
push @range, [ unpack('Q<Q<', $buf) ];
#TRACE "read_extentmap_cache: range " . join("..", @{$range[-1]});
};
DEBUG "Read " . scalar(@range) . " block regions (blocksize=$blocksize, timestamp='" . localtime($time) . "') from: $file";
return { blocksize => $blocksize, rmap => \@range, CACHED => $file };
} else {
ERROR "Failed to open '$file': $!";
}
}
return undef;
}
sub write_extentmap_cache($)
{
my $vol = shift;
my $extmap = $vol->{EXTENTMAP};
my $cache_dir = config_key($vol, 'cache_dir');
return undef unless($extmap && $cache_dir);
my $uuid = $vol->{node}{uuid} // die;
foreach (@$cache_dir) {
unless(-d $_) {
WARN_ONCE "Ignoring cache_dir (not a directory): $_";
next;
}
my $file = "$_/${uuid}.extentmap.bin";
INFO "Writing extentmap cache: $file";
if(open(my $fh, '>:raw', $file)) {
# pack Q: unsigned quad (64bit, Documentation/filesystems/fiemap.txt)
print $fh pack('a24Q<Q<Q<', "btrbk_extentmap_v1", $vol->{node}{gen}, time, $extmap->{blocksize});
print $fh pack('Q<*', map(@{$_}, @{$extmap->{rmap}}));
close($fh);
} else {
ERROR "Failed to create '$file': $!";
}
}
}
# returns extents range (sorted array of [start,end], inclusive) from FIEMAP ioctl
sub filefrag_extentmap($)
@ -5619,7 +5683,16 @@ MAIN:
($a->{node}{readonly} ? $a->{node}{cgen} : $a->{node}{gen}) }
@resolved_vol) {
next if($prev_vol && ($prev_vol->{node}{id} == $_->{node}{id})); # skip duplicates
# read extents map
if($_->{EXTENTMAP} = read_extentmap_cache($_)) {
INFO "Using cached extents map for: $_->{PRINT}";
} else {
$_->{EXTENTMAP} = filefrag_extentmap($_);
write_extentmap_cache($_);
}
next unless($_->{EXTENTMAP});
if($prev_vol) {
my $diff_map = extentmap_diff($prev_vol->{EXTENTMAP}, $_->{EXTENTMAP});

2
doc/btrbk.conf.5.asciidoc
View File

@ -410,6 +410,8 @@ If you want to set this option for regular (non-root) user only, set
can set *compat_local* or *compat_remote*
(e.g. "compat_remote busybox").
*cache_dir* <file>|no _*experimental*_::
If set, cache extent maps for the 'extents-diff' command.
=== Btrfs Specific Options