contigmalloc() and mmap()

[Christoph Hellwig]

On Mon, Jun 13, 2005 at 12:54:40PM -0700, Julian Elischer wrote:
> though, some people use it for that purpose (e.g. in the original posting).

driver writers do all kinds of odd things ;-)

> it might not be such a bad idea..
> I don't see why the device entrypoints shouldn't have that argument
> available.. (file descriptor by which we are getting here)
> As long as it can take account of the fact that not all accesses come 
> via an FD
> (e.g mounted disks).

disk drivers use a completely different set of entry points in Linux,
and don't have access to per-fd data even in the case they're opened
from userland.  Character drivers to which this applies OTOH always
get a valid struct file, it's guranteed as part of the driver API.