[PATCH 03/17] VFS: Implement handling for pathless pioctls

Andreas Dilger adilger at sun.com
Wed Jun 17 03:47:11 EDT 2009


On Jun 16, 2009  21:39 +0100, David Howells wrote:
> Implement handling for pathless pioctls.  Because these take no path argument,
> there's no way to know for certain which filesystem they're aimed at, so we
> have to switch on command number instead.  This patch allows interested parties
> to register handlers.  Each registered handler function is tried in turn until
> one doesn't return -EOPNOTSUPP.
> 
> This is required because OpenAFS implemented a number of AFS calls that don't
> get given a path as they're aimed at AFS in general, and not at a particular
> file, volume or cell in the AFS world.

Wouldn't it make a lot more sense to create a virtual device, open the
mountpoint, or do _something_ that associates these calls with AFS
directly instead of having the kernel magically route the call to a
specific filesystem?

Not that I agree with having a filesystem-specific syscall either
(sys_reiserfs() was not allowed either :-), but wouldn't even that
be better suited to doing AFS-specific things?

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.




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