Subject: Re: problem with tmpfs and linux emulation?
To: Steven M. Bellovin <>
From: Andrew Reilly <>
List: current-users
Date: 11/15/2005 10:36:22
On Sun, Nov 13, 2005 at 07:49:38PM -0500, Steven M. Bellovin wrote:
> It seems likely that nothing will make this work short of a real byte 
> offset in d_off.  This in turn suggests that either the linux emulation 
> layer has to have a way of knowing if it needs to do a conversion, or 
> the file system layer needs to do the conversion, possibly as a result 
> of a mount-time flag.  I'd really rather avoid the latter if possible 
> -- how expensive would it be for tmpfs to maintain a real byte count?  
> (Seeking to that point need not be cheap; it's an infrequent operation, 
> I suspect.)

Is it not possible to have the emulated lseek understand the
opaque cookies (perhaps with a hash lookup) and do the right

What is the good of passing an opaque cookie out to user-land if
it's not subsequently useful for something?