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btrbk: check if received subvolume is really garbled before deleting it 

Improve error handling in btrfs_send_receive: on error, always try to
read the target subvolume and only delete it automatically if it is
garbled (read/write, no received_uuid).

This is especially important if the target subvolume was already
present before send/receive.

Reverts: 4c4afe77 btrbk: skip target metadata test if send/receive has errors
pull/245/head
Axel Burri 2018-07-09 19:24:52 +02:00
parent de57efff82
commit faec212324
1 changed files with 30 additions and 28 deletions
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@ -1432,26 +1432,26 @@ sub btrfs_send_receive($$$$)
}
}
unless($send_receive_error) {
# Read in target subvolume metadata (btrfs subvolume show):
# Double checking the output increases robustness against exotic
# revisions of external commands (btrfs-progs, pv, xz, lz4, ...).
#
# NOTE: we cannot rely on the underlying shell to have
# "pipefail" functionality.
#
# NOTE (bug?) (checked with btrfs-progs v4.6.1 and earlier):
# "cat /dev/null | btrfs receive" returns with exitcode=0 and no
# error message, having the effect that silently no subvolume is
# created if any command in @cmd_pipe fail.
if($dryrun) {
INFO "[send/receive] (dryrun, skip) checking target metadata: $vol_received->{PRINT}";
}
else {
INFO "[send/receive] checking target metadata: $vol_received->{PRINT}";
my $detail = btrfs_subvolume_show($vol_received);
if(defined($detail)) {
# Read in target subvolume metadata (btrfs subvolume show):
# Double checking the output increases robustness against exotic
# revisions of external commands (btrfs-progs, pv, xz, lz4, ...).
#
# NOTE: we cannot rely on the underlying shell to have
# "pipefail" functionality.
#
# NOTE: btrfs-progs < 4.11:
# "cat /dev/null | btrfs receive" returns with exitcode=0 and no
# error message, having the effect that silently no subvolume is
# created if any command in @cmd_pipe fail.
my $is_garbled;
if($dryrun) {
INFO "[send/receive] (dryrun, skip) checking target metadata: $vol_received->{PRINT}";
}
else {
INFO "[send/receive] checking target metadata: $vol_received->{PRINT}";
my $detail = btrfs_subvolume_show($vol_received);
if(defined($detail)) {
unless($send_receive_error) {
# plausibility checks on target detail
unless($detail->{readonly}) {
ERROR "[send/receive] target is not readonly: $vol_received->{PRINT}";
@ -1472,9 +1472,12 @@ sub btrfs_send_receive($$$$)
$send_receive_error = 1;
}
}
else {
$send_receive_error = 1;
}
# incomplete received (garbled) subvolumes are not readonly and have no received_uuid
$is_garbled = ((not $detail->{readonly}) && defined($detail->{received_uuid}) && ($detail->{received_uuid} eq '-'));
}
else {
$send_receive_error = 1;
}
}
@ -1482,11 +1485,12 @@ sub btrfs_send_receive($$$$)
if($send_receive_error) {
ERROR "Failed to send/receive btrfs subvolume: $snapshot->{PRINT} " . ($parent_path ? "[$parent_path]" : "") . " -> $target->{PRINT}";
}
# NOTE: btrfs-progs v3.19.1 does not delete garbled received subvolume,
if($is_garbled) {
# NOTE: btrfs-progs does not delete incomplete received (garbled) subvolumes,
# we need to do this by hand.
# TODO: remove this as soon as btrfs-progs handle receive errors correctly.
DEBUG "send/received failed, deleting (possibly present and garbled) received subvolume: $vol_received->{PRINT}";
my @deleted = btrfs_subvolume_delete($vol_received, commit => "after", type => "delete_garbled");
if(scalar(@deleted)) {
WARN "Deleted partially received (garbled) subvolume: $vol_received->{PRINT}";
@ -1494,10 +1498,8 @@ sub btrfs_send_receive($$$$)
else {
WARN "Deletion of partially received (garbled) subvolume failed, assuming clean environment: $vol_received->{PRINT}";
}
return undef;
}
return 1;
return $send_receive_error ? undef : 1;
}