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btrbk: add btrfs mountpoint resolving functionality

pull/88/head
Axel Burri 2016-03-30 15:32:28 +02:00
parent de96f267b8
commit 06043cf800
1 changed files with 135 additions and 3 deletions
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@ -169,6 +169,7 @@ my %table_formats = (
);
my %url_cache; # map URL to btr_tree node
my %fstab_cache; # map HOST to btrfs mount points
my %uuid_cache; # map UUID to btr_tree node
my %symlink; # map URL to REAL_URL (symlink target)
@ -1074,6 +1075,137 @@ sub btrfs_send_to_file($$$$;@)
}
sub system_list_mounts($)
{
my $vol = shift // die;
my $file = '/proc/self/mounts';
my $ret = run_cmd(cmd => [ qw(cat), $file ],
rsh => $vol->{RSH},
non_destructive => 1,
catch_stderr => 1, # hack for shell-based run_cmd()
);
return undef unless(defined($ret));
my @mounts;
foreach (split(/\n/, $ret))
{
# from fstab(5)
unless(/^(\S+) (\S+) (\S+) (\S+) (\S+) (\S+)$/) {
ERROR "Failed to parse \"$file\" on " . ($vol->{HOST} || "localhost");
DEBUG "Offending line: $_";
return undef;
}
my %line = (
spec => $1,
file => $2,
vfstype => $3,
mntops => $4,
freq => $5,
passno => $6,
);
foreach (split(',', $line{mntops})) {
if(/^(.+?)=(.+)$/) {
$line{MNTOPS}->{$1} = $2;
} else {
$line{MNTOPS}->{$_} = 1;
}
}
push @mounts, \%line;
}
# TRACE(Data::Dumper->Dump([\@mounts], ["mounts"])) if($loglevel >= 4);
return \@mounts;
}
sub system_realpath($)
{
my $vol = shift // die;
my $path = $vol->{PATH} // die;;
my @quiet = ($loglevel < 3) ? ('-q') : ();
my $ret = run_cmd(cmd => [ qw(realpath), '-e', @quiet, $path ],
rsh => $vol->{RSH},
non_destructive => 1,
);
return undef unless(defined($ret));
unless($ret =~ /^$file_match$/) {
ERROR "Failed to parse output of `realpath` for \"$vol->{PRINT}\": \"$ret\"";
return undef;
}
DEBUG "Real path for \"$vol->{PRINT}\" is: $ret";
return $ret;
}
sub btrfs_mountpoint($)
{
my $vol = shift // die;
DEBUG "Resolving btrfs mount point for: $vol->{PRINT}";
my $host = $vol->{HOST} || "localhost";
my $mounts = $fstab_cache{$host};
TRACE "fstab_cache " . ($mounts ? "HIT" : "MISS") . ": $host";
# get real path
my $path = $symlink{$vol->{URL}};
if($path) {
die unless($path =~ s/^\Q$vol->{URL_PREFIX}\E//);
}
else {
$path = system_realpath($vol);
$symlink{$vol->{URL}} = $vol->{URL_PREFIX} . $path;
}
return (undef, undef, undef) unless($path);
unless($mounts) {
$mounts = [];
my $all_mounts = system_list_mounts($vol);
foreach my $mnt (@$all_mounts) {
if($mnt->{vfstype} ne 'btrfs') {
TRACE "non-btrfs mount point: $mnt->{spec} $mnt->{file} $mnt->{vfstype}";
next;
}
my $file = $mnt->{file} // die;
unless($file =~ /^$file_match$/) {
WARN "Skipping non-parseable file in btrfs mounts of $host: \"$file\"";
next;
}
my $id = $mnt->{MNTOPS}->{subvolid};
unless($id) {
WARN "No subvolid provided in btrfs mounts of $host for: $file";
next;
}
unless($id >= 5) {
WARN "Ambiguous subvolid=$id in btrfs mounts of $host for: $file";
next;
}
TRACE "btrfs mount point (spec=$mnt->{spec}, subvolid=$id): $file";
push @$mounts, $mnt;
}
$fstab_cache{$host} = $mounts;
}
# find longest match
$path .= '/' unless($path =~ /\/$/); # correctly handle root path="/"
my $len = 0;
my $longest_match;
foreach(@$mounts) {
my $mnt_path = $_->{file};
$mnt_path .= '/' unless($mnt_path =~ /\/$/); # correctly handle root path="/"
$longest_match = $_ if((length($mnt_path) > $len) && ($path =~ /^\Q$mnt_path\E/));
}
unless($longest_match) {
DEBUG "No btrfs mount point found for: $vol->{PRINT}";
return (undef, undef, undef);
}
DEBUG "Found btrfs mount point for \"$vol->{PRINT}\": $longest_match->{file} (subvolid=$longest_match->{MNTOPS}->{subvolid})";
return ($longest_match->{file}, $path, $longest_match->{MNTOPS}->{subvolid});
}
sub btr_tree($$)
{
my $vol = shift;