LoadRemoteFile now takes dataFileAccessLock (so a live tier upload does
not race the heartbeat's DataBackend read). But load() also runs it, and
CommitCompact calls load() while already holding that lock, so reloading
a remote-tiered volume during a compaction commit re-enters the
non-reentrant lock and deadlocks.
Split the locked bodies out: swapDataBackendLocked and loadRemoteFileLocked
assume the caller holds dataFileAccessLock. load() uses loadRemoteFileLocked;
the public LoadRemoteFile keeps taking the lock for the live tier-upload
handler that does not hold it.
Chris LuandGitHub
0ae1fdcad2