[LU-11000] Retain cached dentries under directory update lock

Related — Tue, 5 Dec 2023 21:25:15 +0000

In line with LU-10999 we should be able to retain directory entries in cache on the clients even without update locks assuming we have UPDATE lock on the parent directory.

Currently this mostly affects various opens that are routinely answered without any LOOKUP bit set.

We already have the code that iterates all the children when a directory UPDATE lock is canceled in search of negative dentries, so we can use that to also prune all such lockless dentries too.

Whamcloud Community JIRA

[LU-11000] Retain cached dentries under directory update lock