A FUSE interrupt is not a process kill. Go's async preemption (SIGURG)
makes a close() under load emit an interrupt on nearly every flush, so
deriving the metadata-flush context from the FUSE cancel channel turned
healthy concurrent close()s into EIO: the interrupt cancelled the
in-flight CreateEntry, which surfaced as "input/output error".
Bound the flush with a deadline instead. A healthy CreateEntry finishes
in well under a second, so the deadline only fires against a genuinely
stuck filer -- still keeping close() from hanging forever -- while
benign preemption no longer aborts a good flush.
* operation: bound AssignVolume with a deadline
AssignVolume ran on context.Background(), so when the filer is overwhelmed
the RPC could block indefinitely and wedge every caller holding the
connection. Give it a 30s deadline so a stuck assign fails and the caller's
retry/error path runs instead of hanging forever.
* mount: abort flush when the FUSE request is interrupted
On close(), a killed process blocks in fuse_flush waiting for the mount to
answer. doFlush ran its metadata CreateEntry on context.Background() and
ignored the kernel interrupt channel, so against an overwhelmed filer the
flush never completed and the process stayed in uninterruptible sleep --
making the pod un-killable.
Derive a context from the FUSE cancel channel in Flush/Fsync and thread it
through doFlush -> flushMetadataToFiler -> streamCreateEntry; the retry loop
stops as soon as the context is cancelled. Release and the pre-rename flush
keep a non-cancellable context since they must finish regardless.
* operation: harden the AssignVolume timeout test
Make the test double's signal send non-blocking and bound the receive with a
timeout so a regression can't wedge the test instead of failing it.
* Add FUSE integration tests for POSIX file locking
Test flock() and fcntl() advisory locks over the FUSE mount:
- Exclusive and shared flock with conflict detection
- flock upgrade (shared to exclusive) and release on close
- fcntl F_SETLK write lock conflicts and shared read locks
- fcntl F_GETLK conflict reporting on overlapping byte ranges
- Non-overlapping byte-range locks held independently
- F_SETLKW blocking until conflicting lock is released
- Lock release on file descriptor close
- Concurrent lock contention with multiple workers
* Fix review feedback in POSIX lock integration tests
- Assert specific EAGAIN error on fcntl lock conflicts instead of generic Error
- Use O_APPEND in concurrent contention test so workers append rather than overwrite
- Verify exact line count (numWorkers * writesPerWorker) after concurrent test
- Check unlock error in F_SETLKW blocking test goroutine
* Refactor fcntl tests to use subprocesses for inter-process semantics
POSIX fcntl locks use the process's files_struct as lock owner, so all
fds in the same process share the same owner and never conflict. This
caused the fcntl tests to silently pass without exercising lock conflicts.
Changes:
- Add TestFcntlLockHelper subprocess entry point with hold/try/getlk actions
- Add lockHolder with channel-based coordination (no scanner race)
- Rewrite all fcntl tests to run contenders in separate subprocesses
- Fix F_UNLCK int16 cast in GetLk assertion for type-safe comparison
- Fix concurrent test: use non-blocking flock with retry to avoid
exhausting go-fuse server reader goroutines (blocking FUSE SETLKW
can starve unlock request processing, causing deadlock)
flock tests remain same-process since flock uses per-struct-file owners.
* Fix misleading comment and error handling in lock test subprocess
- Fix comment: tryLockInSubprocess tests a subprocess, not the test process
- Distinguish EAGAIN/EACCES from unexpected errors in subprocess try mode
so real failures aren't silently masked as lock conflicts
* Fix CI race in FcntlReleaseOnClose and increase flock retry budget
- FcntlReleaseOnClose: retry lock acquisition after subprocess exits
since the FUSE server may not process Release immediately
- ConcurrentLockContention: increase retry limit from 500 to 3000
(5s → 30s budget) to handle CI load
* separating flock and fcntl in the in-memory lock table and cleaning them up through the right release path: PID for POSIX locks, lock owner for flock
* ReleasePosixOwner
* weed/mount: flush before releasing posix close owner
* weed/mount: keep woken lock waiters from losing inode state
* test/fuse: make blocking fcntl helper state explicit
* test/fuse: assert flock contention never overlaps
* test/fuse: stabilize concurrent lock contention check
* test/fuse: make concurrent contention writes deterministic
* weed/mount: retry synchronous metadata flushes
Chris Lu