The guts of stat cache.

[Jeremy Allison]

On Tue, Mar 19, 2013 at 04:20:51PM -0500, Christopher R. Hertel wrote:
> Folks,
> 
> I'm looking into a corner case problem, and I need to know more about the
> workings of the stat cache.
> 
> The problem has to do with small file creates.  Seems that whenever a file
> is created (particularly if the create needs to fail if the file exists), we
> have to do some work going through the possible case permutations of the
> given filename.
> 
> Stat cache is supposed to help with that, but I am seeing lots of calls to
> the Samba VFS stat function, asking for info on the same name.
> 
> Is the stat cache above or below the VFS layer?

Above.

> What does the stat cache do to speed up case-insensitive name matching?

It maps whatever case the client sends us into the actual
case found on disk.

Jeremy.