release-2.1: storage: fix possible raft log panic after fsync error #37214
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bdarnell
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Apr 30, 2019
Detected with cockroachdb#36989 applied by running `./bin/roachtest run --local '^system-crash/sync-errors=true$'`. With some slight modification to that test's constants it could repro errors like this within a minute: ``` panic: tocommit(375) is out of range [lastIndex(374)]. Was the raft log corrupted, truncated, or lost? ``` Debugging showed `DBSyncWAL` can be called even after a sync failure. I guess if it returns success any time after it fails it will ack writes that aren't recoverable in WAL. They aren't recoverable because RocksDB stops recovery upon hitting the offset corresponding to the lost write (typically there should be a corruption there). Meanwhile, there are still successfully synced writes at later offsets in the file. The fix is simple. If `DBSyncWAL` returns an error once, keep track of that error and return it for all future writes. Release note (bug fix): Fixed possible panic while recovering from a WAL on which a sync operation failed.
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Backport 1/1 commits from #37102.
/cc @cockroachdb/release
Detected with #36989 applied by running
./bin/roachtest run --local '^system-crash/sync-errors=true$'.With some slight modification to that test's constants it could repro
errors like this within a minute:
Debugging showed
DBSyncWALcan be called even after a sync failure.I guess if it returns success any time after it fails it will ack
writes that aren't recoverable in WAL. They aren't recoverable because
RocksDB stops recovery upon hitting the offset corresponding to the
lost write (typically there should be a corruption there). Meanwhile,
there are still successfully synced writes at later offsets in the
file.
The fix is simple. If
DBSyncWALreturns an error once, keep track ofthat error and return it for all future writes.
Release note (bug fix): Fixed possible panic while recovering from a WAL
on which a sync operation failed.