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btrbk
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btrbk: btr_tree: always read btrfs root node (id=5), hoping to get its uuid 

Note that the UUID for btrfs root (id=5) is not always present:

 - btrfs-progs < 4.12 does not support rootid lookup
 - UUID can be missing if filesystem was created with btrfs-progs < 4.16

Still we need to always read it, as the whole tree is cached and we
don't know if it will be used.
pull/245/head
Axel Burri 2018-06-29 19:00:12 +02:00
parent cb5e361f7a
commit b0d58fd0f1
1 changed files with 27 additions and 26 deletions
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@ -2101,21 +2101,27 @@ sub btr_tree($$$$)
return $node;
}
# assemble subvolume tree
my %tree = ( id => 5, # top-level subvolume id is always 5 (by btrfs spec)
is_root => 1,
host_spec => $vol_host_spec, # unique identifier, e.g. "localhost:/dev/sda1"
MOUNTPOINTS => $mountpoints, # { file, spec, node }
SUBTREE => []
);
my %id = ( 5 => \%tree );
# btrfs root (id=5) is not provided by btrfs_subvolume_list below, read it separately (best-efford)
my $tree_root = btrfs_subvolume_show($vol, rootid => 5);
unless($tree_root) {
# this is not an error:
# - btrfs-progs < 4.12 does not support rootid lookup
# - UUID can be missing if filesystem was created with btrfs-progs < 4.16
DEBUG "Failed to fetch subvolume detail (old btrfs-progs?) for btrfs root (id=5) on: $vol->{PRINT}";
$tree_root = { id => 5, is_root => 1 };
}
$tree_root->{host_spec} = $vol_host_spec; # unique identifier, e.g. "localhost:/dev/sda1"
my %id = ( 5 => $tree_root );
my %uuid_hash;
my %received_uuid_hash;
$tree{TREE_ROOT} = \%tree;
$tree{ID_HASH} = \%id;
$tree{UUID_HASH} = \%uuid_hash;
$tree{RECEIVED_UUID_HASH} = \%received_uuid_hash;
$tree_root->{TREE_ROOT} = $tree_root;
$tree_root->{SUBTREE} = [];
$tree_root->{MOUNTPOINTS} = $mountpoints; # { file, spec, node }
$tree_root->{ID_HASH} = \%id;
$tree_root->{UUID_HASH} = \%uuid_hash;
$tree_root->{RECEIVED_UUID_HASH} = \%received_uuid_hash;
my $node_list = btrfs_subvolume_list($vol);
return undef unless(ref($node_list) eq "ARRAY");
@ -2151,7 +2157,13 @@ sub btr_tree($$$$)
$uuid_cache{$node->{uuid}} = $node;
$gen_max = $node->{gen} if($node->{gen} > $gen_max);
}
$tree{GEN_MAX} = $gen_max;
$tree_root->{GEN_MAX} = $gen_max;
$vol_root = $id{$vol_root_id};
unless($vol_root) {
ERROR "Failed to resolve tree root for subvolid=$vol_root_id: " . ($vol->{PRINT} // $vol->{id});
return undef;
}
# note: it is possible that id < top_level, e.g. after restoring
foreach my $node (@$node_list)
@ -2162,7 +2174,7 @@ sub btr_tree($$$$)
push(@{$top_level->{SUBTREE}}, $node);
$node->{TOP_LEVEL} = $top_level;
$node->{TREE_ROOT} = \%tree;
$node->{TREE_ROOT} = $tree_root;
# "path" always starts with set REL_PATH
my $rel_path = $node->{path};
@ -2173,17 +2185,6 @@ sub btr_tree($$$$)
$node->{REL_PATH} = $rel_path; # relative to {TOP_LEVEL}->{path}
add_btrbk_filename_info($node);
$vol_root = $node if($vol_root_id == $node->{id});
}
unless($vol_root) {
if($vol_root_id == 5) {
$vol_root = \%tree;
}
else {
ERROR "Failed to resolve tree root for: " . ($vol->{PRINT} // $vol->{id});
return undef;
}
}
# add known mountpoints to nodes
@ -2199,7 +2200,7 @@ sub btr_tree($$$$)
TRACE "btr_tree: returning tree at id=$vol_root->{id}";
VINFO($vol_root, "node") if($loglevel >=4);
$spec_cache{$vol_host_spec} = \%tree;
$spec_cache{$vol_host_spec} = $tree_root;
return $vol_root;
}