* mount: apply cached remote entry without blocking the read
Reading an uncached remote-mounted file hung forever. The read holds the
file-handle shared lock across the on-demand download, then synchronously
waits on the metadata apply loop to apply the cached entry. The filer's
update event for that same object reaches the apply loop first and runs
invalidateFunc, which wants the file-handle exclusive lock — held in shared
mode by the still-running read. The loop blocks on the read; the read blocks
on the loop.
Enqueue the apply without waiting so the read never blocks on the apply loop
while holding the lock. The handle is already updated via SetEntry, and the
filer subscription delivers the same event regardless.
* mount: regression test for uncached remote read deadlock
Drives the real Read path through downloadRemoteEntry with a stub filer that
broadcasts the matching invalidate event before returning, reproducing the
lock-ordering deadlock. Fails (times out) without the fix.
Chris LuandGitHub
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