TestPosixFileLocking/ConcurrentLockContention failed in CI (run
24857323067) with ENOENT when re-opening the file after all 8 workers
had successfully written and closed. The 20s openWithRetry budget was
exhausted, pointing at a real but unproven metaCache/parent-cache
coherence issue in the mount under bursts of concurrent Release.
Test: hold the initial fd open for the whole subtest; use it for the
post-workers Sync() and the verification read. Workers still exercise
the concurrent-flock invariant and per-record write correctness; the
re-open path is no longer load-bearing. On Eventually failure, dump
ReadDir of the parent, Stat, and a fresh O_RDONLY open so a future
recurrence has state to debug from. Drop the darwin-only ENOENT
t.Skip branches that hid this same flake.
Mount: in weedfs.lookupEntry, when returning ENOENT from the
"parent cached but child missing" branch, log at Warningf instead of
V(4) when the kernel is still tracking this path's inode. That
combination is the smoking-gun signal for cache drift and is rare
enough in normal use not to spam the log.