Bug#1017720: nfs-common: No such file or directory

[Jason Breitman <jbreitman@tildenparkcapital.com>]

Package: nfs-common                        
Version: 1:1.3.4-6
Severity: important

Kernel: 5.10.0-16-amd64 #1 SMP Debian 5.10.127-1 (2022-06-30) x86_64 GNU/Linux

-- Description
    After updating and or creating new files on our file server via rsync, we see many files report the error message below from NFSv4 clients since upgrading from Debian 10.8 to Debian 11.4.
    Clearing the dentry cache resolves the issue right away.
    I am not sure that nfs-common is the package to blame, but listed it based on the bug submission recommendations. 

-- Test
    ls -l /mnt/dir/someOtherDir/* | grep '?'

-- Error message
    ls: cannot access 'filename': No such file or directory
    -????????? ? ?    ?            ?            ? filename

-- Workaround
    /usr/bin/sync && echo 2 > /proc/sys/vm/drop_caches

-- /etc/fstab snippet --
    nfs-server.domain.com:/dir	/mnt/dir	nfs4	lookupcache=pos,noresvport,sec=krb5,hard,rsize=1048576,wsize=1048576	0	0

Jason Breitman