Du ChengEn, I would second Jan's opinion.

This whole chain of fixes that has gone in to fix LP: #2003053, should
be rolled back. There where no heavy arguments to cherry-pick those
changes in the first place. (It is not in upstream LTS either).

Once it was discovered what kind of impact it had, it should have been
rolled back.

As it is also now clear that LP: #2003053 cannot be solved without
impacting other use-cases, and by only introducing an extra mount-
option, this is just another argument for reverting this set of patches.

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https://bugs.launchpad.net/bugs/2015827

Title:
  NFS performance issue while clearing the file access cache upon login

Status in linux package in Ubuntu:
  In Progress

Bug description:
  The performance issue that has been observed may be attributed to an increase 
in NFS ACCESS operations, possibly due to a new mechanism introduced in the 
Linux 6.2-rc3 NFS client side.
  This mechanism clears the access cache as soon as the cache timestamp becomes 
older than the user's login time,
  with the primary objective of preventing the NFS client's access cache from 
becoming stale due to any changes made to the user's group membership on the 
server after the user has already logged in on the client.

  It's worth noting that POSIX only refreshes the user's supplementary group 
information upon login.
  Upstream has taken into consideration that users may reasonably expect the 
access cache to be cleared when they log out and log back in again, with all 
behavior returning to normal after the replacement.

  The performance overhead can be particularly noticeable when applications or 
users switch to other privileged users via commands such as "su" to operate on 
NFS-mounted folders.
  In such cases, the privileged user's login time will be renewed, and NFS 
ACCESS operations will need to be re-sent, potentially leading to performance 
degradation.

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