In the past we've seen high CPU in cases where we had a very large number of subdirectories in a directory. This was due to the cost of reconnecting them. In a patch March 9 in Centos 9, "ovl: do not try to reconnect a disconnected origin dentry", an optimization was made to avoid this, but it was only implemented for overlay. Would it make sense to do the same thing in nfsd? in nfsfs.c, it would change the call to exportfs_decode_fh_raw so that when to pass exp->ex_flags & NFSEXP_NOSUBTREECHECK ? NULL : nfsd_acceptable, since nfsd_acceptable will always return true if NOSUBTREECHECK is set.
