Re: [PATCH 3/3] p9auth: add p9auth driver

ron minnich [off-list ref] writes:

On Fri, Apr 23, 2010 at 8:36 PM, Serge E. Hallyn [off-list ref] wrote:

quoted

An fs actually seems overkill for two write-only files for
process-related information.  Would these actually be candidates
for new /proc files?

       /proc/grantcred - replaces /dev/caphash, for privileged
               tasks to tell the kernel about new setuid
               capabilities
       /proc/self/usecred - replaces /dev/capuse for unprivileged
               tasks to make use of a setuid capability

An fs is fine.

To relate this to Plan 9, where it all began, might be useful. There's
no equivalent in Plan 9 to Linux/Unix devices of the major/minor
number etc. variety. In-kernel drivers and out-of-kernel servers both
end up providing the services (i.e. file name spaces) that we see in a
Linux file system. So the Plan 9 driver for the capability device
really does match closely in function and interface to a Linux
kernel-based file system.

Hence, making devcap a file system is entirely appropriate, because it
best fits the way it works in Plan 9: a kernel driver that provides
two files.

It's pretty easy to write a Linux VFS anyway, so it makes sense from
that point of view.

Eric, that was a great suggestion.

A fs provides user space policy control of naming.  I.e. where the two files go.
That can also be a very big deal.  Especially when files are writable.

You have no idea how much I am frustrated by sysfs right now, because
it does not provide userspace policy control and instead mandates a
sometimes inappropriate naming convention.

Eric