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the superblock pointing to very out of date btree roots and so we get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.
There is a failure while compiling with libc musl:
[snip]
|./block-cache/io_engine.h:18:17: error: expected
unqualified-id before numeric constant
| unsigned const PAGE_SIZE = 4096;
[snip]
The musl defeines macro PAGE_SIZE, undef it conditionally
could fix the issue.
http://musl.openwall.narkive.com/tO8vrHdP/why-musl-define-page-size
Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
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.
Preserve the input block first to avoid reusing it in subsequent
shadow operations, e.g., shadow another block when releasing
a recursive lock. (issue #97)
