The first pass of the repair process scans all metadata working out the
largest orphan btrees. This scan doesn't use as much validation as
the btree_walk function which subsequently gets called.
This patch catches any exceptions thrown by the btree walk function
and removes that btree from consideration.
We've had a trickle of users who accidentally activate the same pool on a
VM and host at the same time. Typically the host doesn't do any IO, but
the kernel will still rewrite the superblock on shutdown. This leaves
the superblock pointing to very out of date btree roots and so we get
massive metadata loss.
This patch changes thin_repair, and thin_dump --repair. They now hunt
for the most recent, undamaged and consistent roots of the device and
mapping trees, and use that as the starting point of the repair.
You need to apply doc/bm-journal.patch to create the journal.
thin_journal_check confirms that if the machine had crashed at any time
during the test run no metadata corruption would have occured.
This fixes following build failure with Boost 1.67.0:
```
In file included from /usr/include/boost/optional/optional.hpp:33,
from /usr/include/boost/optional.hpp:15,
from ./thin-provisioning/emitter.h:23,
from contrib/thin_sexp_emitter.cc:2:
/usr/include/boost/optional/optional.hpp: In instantiation of ‘std::basic_ostream<_CharT, _Traits>& boost::operator<<(std::basic_ostream<_CharT, _Traits>&, const boost::optional_detail::optional_tag&) [with CharType = char; CharTrait = std::char_traits<char>]’:
./base/indented_stream.h:31:9: required from ‘{anonymous}::indented_stream& {anonymous}::indented_stream::operator<<(const T&) [with T = boost::optional<unsigned int>]’
contrib/thin_sexp_emitter.cc:105:29: required from ‘void {anonymous}::sexp_emitter::kv(const char*, const T&) [with T = boost::optional<unsigned int>]’
contrib/thin_sexp_emitter.cc:29:21: required from here
/usr/include/boost/optional/optional.hpp:1481:3: error: static assertion failed: If you want to output boost::optional, include header <boost/optional/optional_io.hpp>
BOOST_STATIC_ASSERT_MSG(sizeof(CharType) == 0, "If you want to output boost::optional, include header <boost/optional/optional_io.hpp>");
^~~~~~~~~~~~~~~~~~~~~~~
make: *** [contrib/Makefile:15: contrib/thin_sexp_emitter.o] Error 1
```
boost/optional/optional_io.hpp exists since at least Boost 1.34.0, so it is
safe to include in older versions, too.
* [file_utils] spin-off syscall-related file operations
1. Eliminate the potential circular dependency between
persistent-data/block.h and persistent-data/file_utils.h,
if the former one wants to include the latter.
2. Avoid namespace pollution by removing the "using namespace std"
declaration in block.tcc.
3. Correct the header hierarchy: base/xml_utils.h now no longer
depends on the higher-level persistent-data/file_utils.h
* [file_utils] support block files in get_file_length()
1. fix the damage type for single_mapping_tree_damage_visitor
2. walk_mapping_tree() now requires the device id
3. update metadata_dumper and thin_ls for the new walk_mapping_tree()
