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btrbk: add support for btrfs-progs 4.12: do not fail or set realpath_cache for relative paths in btrfs_subvolume_show() 

As of btrfs-progs-v4.12, the "btrfs subvolume show" command does not
print the full (absolute, resolved) path anymore [1]. Instead, it prints
the relative path to btrfs root (or "/" if it is the root).

The impact for btrbk is that we cannot fill our realpath_cache in
btrfs_subvolume_show() anymore. This is not fatal, but has the
following consequences:

  - The "check for duplicate snapshot locations" may now miss
    subvolumes specified by symlinks.

  - If multiple "volume" sections point to the same subvolume (e.g. if
    specified using symlinks) an additional "btrfs subvolume list" is
    called. Note that the subvolume will still be recognized as
    identical, and the btr_tree will not be rebuilt.

  [1] btrfs-progs commit: b7df24aa5cddc4802b9938f56372b73869775cd9
pull/175/head
Axel Burri 2017-07-30 15:25:32 +02:00
parent 26682213e2
commit 6cf5d59644
2 changed files with 25 additions and 20 deletions
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2
ChangeLog
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@ -1,5 +1,7 @@
btrbk-current
* Support for btrfs-progs v4.12: fix parsing of "btrfs sub show"
output, which now prints relative paths (close #171).
* Add "stream_buffer" configuration option (close #154).
* Bugfix: accept "no" for "transaction_log", "transaction_syslog"
and "lockfile" configuration options.

43
btrbk
View File

@ -855,28 +855,37 @@ sub btrfs_subvolume_show($)
return undef unless(defined($ret));
my $real_path;
if($ret =~ /^($file_match)/) {
$real_path = $1;
$real_path = check_file($real_path, { absolute => 1 }, sanitize => 1);
return undef unless(defined($real_path));
DEBUG "Real path for subvolume \"$vol->{PRINT}\" is: $real_path" if($real_path ne $path);
$realpath_cache{$vol->{URL}} = $real_path if($real_path ne $path);
my @ret_lines = split("\n", $ret);
unless(@ret_lines) {
ERROR "Failed to parse subvolume detail (unsupported btrfs-progs) for: $vol->{PRINT}";
return undef;
}
else {
$real_path = $path;
WARN "No real path provided by \"btrfs subvolume show\" for subvolume \"$vol->{PRINT}\", using: $path";
if($ret_lines[0] =~ /^($file_match)/) {
# use the resolved full path for realpath_cache (if present)
# btrfs-progs < 4.12 prints the full (absolute, resolved) path
# btrfs-progs >= 4.12 prints the relative path to btrfs root (or "/" if it is the root)
my $real_or_rel_path = $1;
if($real_or_rel_path ne '/') {
my $real_path = check_file($real_or_rel_path, { absolute => 1 }, sanitize => 1); # returns undef if not absolute
if($real_path && ($real_path ne $path)) {
DEBUG "Real path for subvolume \"$vol->{PRINT}\" is: $real_path";
$realpath_cache{$vol->{URL}} = $real_path;
}
}
else {
DEBUG "No real path provided by \"btrfs subvolume show\" for subvolume \"$vol->{PRINT}\"";
}
}
my %detail;
if($ret =~ /^\Q$real_path\E is (btrfs root|toplevel subvolume)/) {
if($ret_lines[0] =~ / is (btrfs root|toplevel subvolume)$/) {
# btrfs-progs < 4.4 prints: "<subvol> is btrfs root"
# btrfs-progs >= 4.4 prints: "<subvol> is toplevel subvolume"
# btrfs-progs >= 4.8.3 does not enter here, as output shares format with regular subvolumes
$detail{id} = 5;
}
elsif($ret =~ /^\Q$real_path\E/) {
TRACE "btr_detail: found btrfs subvolume: $vol->{PRINT}";
else {
# NOTE: received_uuid is not required here, as btrfs-progs < 4.1 does not give us that information.
# no worries, we get this from btrfs_subvolume_list() for all subvols.
my @required_keys = qw(name uuid parent_uuid id gen cgen top_level readonly);
@ -921,10 +930,6 @@ sub btrfs_subvolume_show($)
}
}
}
else {
ERROR "Failed to parse subvolume detail (unsupported btrfs-progs) for: $vol->{PRINT}";
return undef;
}
if($detail{id} == 5) {
# NOTE: as of btrfs-progs v4.8.3, we get full output for root
@ -934,8 +939,6 @@ sub btrfs_subvolume_show($)
%detail = ( id => 5, is_root => 1 );
}
$detail{REAL_PATH} = $real_path;
return \%detail;
}
@ -966,7 +969,7 @@ sub btrfs_subvolume_list($;@)
{
my $vol = shift || die;
my %opts = @_;
my $path = $vol->{PATH} // die; # deliberately NOT using REAL_PATH here!
my $path = $vol->{PATH} // die;
my @filter_options = ('-a');
push(@filter_options, '-o') if($opts{subvol_only});