> > if you consider mmap for read as a lazy implementation of read(2),
> > it's appropriate to note it at mmap time.
> 
> It would be, but I don't see a problem with updating it when a page is faulted
> in. 

updating on fault makes it almost unpredictable.

> > talking about mtime, i think it can be noted when the changes are
> > flushed out to backing store.  ie. when we usually notice the dirtiness
> > of the pages.
> 
> Yes, this is appropriate. Otherwise, tools like dump won't work properly.
> 
> > updating mtime in VOP_GETPAGES is somewhat improper, IMO.
> 
> It could be updated in VOP_PUTPAGES(), isn't it ?

yes, i meant so.

YAMAMOTO Takashi