On Monday 03 May 2004 23:07, Reinoud Zandijk wrote:
> 1) every vnode/inode describing a directory gets a `number of directory
> entries in cache' counter.
>
> 2) on addition or removal of an entry from the cache, this number is
> maintained. Also when an entry is purged from the LRU.
>
> 3) with this provision, ,VOP_LOOKUP() now can check the number of directory
> entries in the directory with the `number of directory entries in cache'
> and see that the answer of the namecache is authorative if the two are the
> same.

This sounds like a special case.  Most file systems do not have any direct way 
of knowing the number of entries in a directory without searching it anyway.

Ergo, I would suggest that you find a way to put this in the UDF code.