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[thin_check] Support fixing leaked metadata blocks

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- The leaked blocks are defined as allocated but not used ones,
  i.e., expected ref-count == 0 and actual ref-count <= 2.
- Blocks with expected ref-count > 0, or actual ref-count > 2,
  are treated as unrepairable leaks.
- The fixing processing won't be executed if there's any
  unrepairable leak or errors.
- The fixing process implicitly clearing the superblock
  needs_check flag if there's no error.
This commit is contained in:
Ming-Hung Tsai
2020-07-14 17:57:29 +08:00
parent 7be6b91420
commit 49efa06ffa
3 changed files with 232 additions and 61 deletions
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270
thin-provisioning/metadata_checker.cc
View File

@@ -220,23 +220,15 @@ namespace {
return err;
}
error_state check_space_map_counts(transaction_manager::ptr tm,
superblock_detail::superblock const &sb,
nested_output &out) {
out << "checking space map counts" << end_message();
nested_output::nest _ = out.push();
block_counter bc;
count_metadata(tm, sb, bc);
// Finally we need to check the metadata space map agrees
// with the counts we've just calculated.
error_state compare_metadata_space_maps(space_map::ptr actual,
block_counter const &expected,
nested_output &out) {
error_state err = NO_ERROR;
persistent_space_map::ptr metadata_sm =
open_metadata_sm(*tm, static_cast<void const*>(&sb.metadata_space_map_root_));
for (unsigned b = 0; b < metadata_sm->get_nr_blocks(); b++) {
ref_t c_actual = metadata_sm->get_count(b);
ref_t c_expected = bc.get_count(b);
block_address nr_blocks = actual->get_nr_blocks();
for (block_address b = 0; b < nr_blocks; b++) {
ref_t c_actual = actual->get_count(b);
ref_t c_expected = expected.get_count(b);
if (c_actual != c_expected) {
out << "metadata reference counts differ for block " << b
@@ -251,6 +243,67 @@ namespace {
return err;
}
error_state collect_leaked_blocks(space_map::ptr actual,
block_counter const &expected,
std::set<block_address> &leaked) {
error_state err = NO_ERROR;
block_address nr_blocks = actual->get_nr_blocks();
for (block_address b = 0; b < nr_blocks; b++) {
ref_t c_actual = actual->get_count(b);
ref_t c_expected = expected.get_count(b);
if (c_actual == c_expected)
continue;
if (c_actual < c_expected) {
err << FATAL;
break;
}
// Theoretically, the ref-count of a leaked block
// should be only one. Here a leaked ref-count of two
// is allowed.
if (c_expected || c_actual >= 3)
err << NON_FATAL;
else if (c_actual > 0)
leaked.insert(b);
}
return err;
}
error_state clear_leaked_blocks(space_map::ptr actual,
block_counter const &expected) {
error_state err = NO_ERROR;
std::set<block_address> leaked;
err << collect_leaked_blocks(actual, expected, leaked);
if (err != NO_ERROR)
return err;
for (auto const &b : leaked)
actual->set_count(b, 0);
return err;
}
error_state check_metadata_space_map_counts(transaction_manager::ptr tm,
superblock_detail::superblock const &sb,
block_counter &bc,
nested_output &out) {
out << "checking space map counts" << end_message();
nested_output::nest _ = out.push();
count_metadata(tm, sb, bc);
// Finally we need to check the metadata space map agrees
// with the counts we've just calculated.
space_map::ptr metadata_sm =
open_metadata_sm(*tm, static_cast<void const*>(&sb.metadata_space_map_root_));
return compare_metadata_space_maps(metadata_sm, bc, out);
}
error_state compare_space_maps(space_map::ptr actual, space_map::ptr expected,
nested_output &out)
{
@@ -297,40 +350,36 @@ namespace {
class metadata_checker {
public:
metadata_checker(block_manager::ptr bm,
metadata_checker(std::string const &path,
check_options check_opts,
output_options output_opts)
: bm_(bm),
: path_(path),
options_(check_opts),
out_(cerr, 2),
info_out_(cout, 0) {
info_out_(cout, 0),
err_(NO_ERROR) {
if (output_opts == OUTPUT_QUIET) {
out_.disable();
info_out_.disable();
}
sb_location_ = get_superblock_location();
}
error_state check() {
error_state err = NO_ERROR;
auto sb_location = superblock_detail::SUPERBLOCK_LOCATION;
void check() {
block_manager::ptr bm = open_bm(path_, block_manager::READ_ONLY,
!options_.use_metadata_snap_);
if (options_.use_metadata_snap_) {
superblock_detail::superblock sb = read_superblock(bm_, sb_location);
sb_location = sb.metadata_snap_;
if (sb_location == superblock_detail::SUPERBLOCK_LOCATION)
throw runtime_error("No metadata snapshot found.");
}
err << examine_superblock(bm_, sb_location, out_);
if (err == FATAL) {
if (check_for_xml(bm_))
err_ = examine_superblock(bm, sb_location_, out_);
if (err_ == FATAL) {
if (check_for_xml(bm))
out_ << "This looks like XML. thin_check only checks the binary metadata format." << end_message();
return err;
return;
}
superblock_detail::superblock sb = read_superblock(bm_, sb_location);
transaction_manager::ptr tm = open_tm(bm_, sb_location);
transaction_manager::ptr tm = open_tm(bm, sb_location_);
superblock_detail::superblock sb = read_superblock(bm, sb_location_);
sb.data_mapping_root_ = mapping_root(sb, options_);
print_info(tm, sb, info_out_);
@@ -338,24 +387,77 @@ namespace {
if (options_.sm_opts_ == check_options::SPACE_MAP_FULL) {
space_map::ptr data_sm{open_disk_sm(*tm, &sb.data_space_map_root_)};
optional<space_map::ptr> core_sm{create_core_map(data_sm->get_nr_blocks())};
err << examine_data_mappings(tm, sb, options_.data_mapping_opts_, out_, core_sm);
err_ << examine_data_mappings(tm, sb, options_.data_mapping_opts_, out_, core_sm);
if (err_ == FATAL)
return;
// if we're checking everything, and there were no errors,
// then we should check the space maps too.
if (err != FATAL) {
err << examine_metadata_space_map(tm, sb, options_.sm_opts_, out_);
err_ << examine_metadata_space_map(tm, sb, options_.sm_opts_, out_, expected_rc_);
if (core_sm)
err << compare_space_maps(data_sm, *core_sm, out_);
}
// check the data space map
if (core_sm)
err_ << compare_space_maps(data_sm, *core_sm, out_);
} else
err << examine_data_mappings(tm, sb, options_.data_mapping_opts_, out_,
optional<space_map::ptr>());
err_ << examine_data_mappings(tm, sb, options_.data_mapping_opts_, out_,
optional<space_map::ptr>());
}
return err;
bool fix_metadata_leaks() {
if (!verify_preconditions_before_fixing()) {
out_ << "metadata has not been fully examined" << end_message();
return false;
}
// skip if the metadata cannot be fixed, or there's no leaked blocks
if (err_ == FATAL)
return false;
else if (err_ == NO_ERROR)
return true;
block_manager::ptr bm = open_bm(path_, block_manager::READ_WRITE);
superblock_detail::superblock sb = read_superblock(bm, sb_location_);
transaction_manager::ptr tm = open_tm(bm, sb_location_);
persistent_space_map::ptr metadata_sm =
open_metadata_sm(*tm, static_cast<void const*>(&sb.metadata_space_map_root_));
tm->set_sm(metadata_sm);
err_ = clear_leaked_blocks(metadata_sm, expected_rc_);
if (err_ != NO_ERROR)
return false;
metadata_sm->commit();
metadata_sm->copy_root(&sb.metadata_space_map_root_, sizeof(sb.metadata_space_map_root_));
write_superblock(bm, sb);
out_ << "fixed metadata leaks" << end_message();
return true;
}
error_state get_error() const {
return err_;
}
private:
block_address
get_superblock_location() {
block_address sb_location = superblock_detail::SUPERBLOCK_LOCATION;
if (options_.use_metadata_snap_) {
block_manager::ptr bm = open_bm(path_, block_manager::READ_ONLY,
!options_.use_metadata_snap_);
superblock_detail::superblock sb = read_superblock(bm, sb_location);
sb_location = sb.metadata_snap_;
if (sb_location == superblock_detail::SUPERBLOCK_LOCATION)
throw runtime_error("No metadata snapshot found.");
}
return sb_location;
}
error_state
examine_data_mappings(transaction_manager::ptr tm,
superblock_detail::superblock const &sb,
@@ -382,12 +484,13 @@ namespace {
examine_metadata_space_map(transaction_manager::ptr tm,
superblock_detail::superblock const &sb,
check_options::space_map_options option,
nested_output &out) {
nested_output &out,
block_counter &bc) {
error_state err = NO_ERROR;
switch (option) {
case check_options::SPACE_MAP_FULL:
err << check_space_map_counts(tm, sb, out);
err << check_metadata_space_map_counts(tm, sb, bc, out);
break;
default:
break; // do nothing
@@ -396,10 +499,26 @@ namespace {
return err;
}
block_manager::ptr bm_;
bool verify_preconditions_before_fixing() const {
if (options_.use_metadata_snap_ ||
!!options_.override_mapping_root_ ||
options_.sm_opts_ != check_options::SPACE_MAP_FULL ||
options_.data_mapping_opts_ != check_options::DATA_MAPPING_LEVEL2)
return false;
if (!expected_rc_.get_counts().size())
return false;
return true;
}
std::string const &path_;
check_options options_;
nested_output out_;
nested_output info_out_;
block_address sb_location_;
block_counter expected_rc_;
base::error_state err_; // metadata state
};
}
@@ -409,7 +528,8 @@ check_options::check_options()
: use_metadata_snap_(false),
data_mapping_opts_(DATA_MAPPING_LEVEL2),
sm_opts_(SPACE_MAP_FULL),
ignore_non_fatal_(false) {
ignore_non_fatal_(false),
fix_metadata_leaks_(false) {
}
void check_options::set_superblock_only() {
@@ -434,14 +554,52 @@ void check_options::set_metadata_snap() {
void check_options::set_ignore_non_fatal() {
ignore_non_fatal_ = true;
}
base::error_state
thin_provisioning::check_metadata(block_manager::ptr bm,
check_options const &check_opts,
output_options output_opts)
{
metadata_checker checker(bm, check_opts, output_opts);
return checker.check();
void check_options::set_fix_metadata_leaks() {
fix_metadata_leaks_ = true;
}
bool check_options::check_conformance() {
if (fix_metadata_leaks_) {
if (ignore_non_fatal_) {
cerr << "cannot perform fix by ignoring non-fatal errors" << endl;
return false;
}
if (use_metadata_snap_) {
cerr << "cannot perform fix within metadata snap" << endl;
return false;
}
if (!!override_mapping_root_) {
cerr << "cannot perform fix with an overridden mapping root" << endl;
return false;
}
if (data_mapping_opts_ != DATA_MAPPING_LEVEL2 ||
sm_opts_ != SPACE_MAP_FULL) {
cerr << "cannot perform fix without a full examination" << endl;
return false;
}
}
return true;
}
//----------------------------------------------------------------
base::error_state
thin_provisioning::check_metadata(std::string const &path,
check_options const &check_opts,
output_options output_opts)
{
metadata_checker checker(path, check_opts, output_opts);
checker.check();
if (check_opts.fix_metadata_leaks_)
checker.fix_metadata_leaks();
return checker.get_error();
}
//----------------------------------------------------------------

5
thin-provisioning/metadata_checker.h
View File

@@ -40,17 +40,20 @@ namespace thin_provisioning {
check_options();
bool check_conformance();
void set_superblock_only();
void set_skip_mappings();
void set_override_mapping_root(bcache::block_address b);
void set_metadata_snap();
void set_ignore_non_fatal();
void set_fix_metadata_leaks();
bool use_metadata_snap_;
data_mapping_options data_mapping_opts_;
space_map_options sm_opts_;
boost::optional<bcache::block_address> override_mapping_root_;
bool ignore_non_fatal_;
bool fix_metadata_leaks_;
};
enum output_options {
@@ -59,7 +62,7 @@ namespace thin_provisioning {
};
base::error_state
check_metadata(persistent_data::block_manager::ptr bm,
check_metadata(std::string const &path,
check_options const &check_opts,
output_options output_opts);
}

18
thin-provisioning/thin_check.cc
View File

@@ -76,10 +76,8 @@ namespace {
return 1;
}
block_manager::ptr bm = open_bm(path, block_manager::READ_ONLY,
!fs.check_opts.use_metadata_snap_);
output_options output_opts = !fs.quiet ? OUTPUT_NORMAL : OUTPUT_QUIET;
error_state err = check_metadata(bm, fs.check_opts, output_opts);
error_state err = check_metadata(path, fs.check_opts, output_opts);
if (fs.ignore_non_fatal_errors)
success = (err == FATAL) ? false : true;
@@ -116,6 +114,7 @@ thin_check_cmd::usage(std::ostream &out) const
<< " {-h|--help}\n"
<< " {-V|--version}\n"
<< " {-m|--metadata-snap}\n"
<< " {--fix-metadata-leaks}\n"
<< " {--override-mapping-root}\n"
<< " {--clear-needs-check-flag}\n"
<< " {--ignore-non-fatal-errors}\n"
@@ -140,6 +139,7 @@ thin_check_cmd::run(int argc, char **argv)
{ "ignore-non-fatal-errors", no_argument, NULL, 3},
{ "clear-needs-check-flag", no_argument, NULL, 4 },
{ "override-mapping-root", required_argument, NULL, 5},
{ "fix-metadata-leaks", no_argument, NULL, 6},
{ NULL, no_argument, NULL, 0 }
};
@@ -187,6 +187,11 @@ thin_check_cmd::run(int argc, char **argv)
fs.check_opts.set_override_mapping_root(boost::lexical_cast<uint64_t>(optarg));
break;
case 6:
// fix-metadata-leaks
fs.check_opts.set_fix_metadata_leaks();
break;
default:
usage(cerr);
return 1;
@@ -194,7 +199,12 @@ thin_check_cmd::run(int argc, char **argv)
}
if (fs.clear_needs_check_flag_on_success && fs.check_opts.use_metadata_snap_) {
cerr << "--metadata-snap cannot be combined with --clear-needs-check-flag.";
cerr << "--metadata-snap cannot be combined with --clear-needs-check-flag." << endl;
usage(cerr);
exit(1);
}
if (!fs.check_opts.check_conformance()) {
usage(cerr);
exit(1);
}