* test: reproduce expired directory cache degrading lookup to N RPCs
After cacheMetaTtlSec elapses the kernel can still serve a directory
listing from its page cache, so ReadDir never runs and EnsureVisited is
not called. Metadata lookups then fall through to one LookupEntry RPC
per entry instead of rebuilding the directory cache once.
Issue #11262
* mount: add expired-directory rebuild predicate with cooldown to InodeToPath
ShouldRebuildExpiredDir distinguishes a TTL-expired cached directory from
a never-cached, invalidated, evicted, or read-through one (those clear
isChildrenCached, while a plain TTL expiry keeps it set). It also gates
retries on a cooldown since the last failed rebuild attempt, recorded by
MarkRebuildAttempt, so a transient listing failure does not trigger a
full rebuild on every later lookup.
Issue #11262
* mount: rebuild expired directory cache on entry lookup
When the kernel still serves a directory listing from its page cache past
cacheMetaTtlSec, ReadDir never runs and EnsureVisited is not called, so
lookupEntry issues one LookupEntry RPC per entry. Rebuild the expired
directory once via ensureDirectoryVisited before the cache-hit check so
later lookups are served locally. The EnsureVisited singleflight
deduplicates concurrent rebuilds.
On a non-oversized rebuild failure, record the attempt so the cooldown
suppresses repeated rebuilds while the listing keeps failing; once it
elapses a later lookup retries, recovering without waiting for ReadDir.
Oversized dirs are already marked read-through by ensureDirectoryVisited.
Issue #11262
* test: cover concurrent rebuild dedup and rebuild-cooldown fallback
Add a test that runs concurrent lookups into the same expired directory
behind a gated listing, asserting they share one rebuild via the
EnsureVisited singleflight. Add a test that a failed rebuild records the
attempt so an immediate retry is suppressed (per-entry RPC fallback), and
that once the cooldown elapses and the filer recovers a later lookup
rebuilds the cache.
Issue #11262
* mount: wait for pending async flush before rebuilding parent cache
The rebuild lists the parent directory from the filer, so a pending
async flush of the target entry must land first; otherwise the rebuilt
cache captures pre-flush metadata and the cache-hit path returns it
without the wait that guards the filer-fallback path. waitForPendingAsync
Flush is a no-op when no flush is pending, so the common case is unaffected.
Issue #11262
Chris Lu
2ebfeabfce