On Fri, Aug 01, 2014 at 06:53:05AM -0700, Christoph Hellwig wrote:
> Talking about libhandle: this one has been a bit bitrotted. Maybe it's
> a good time to move everything over to the kernel by handle syscalls
> and deprecated it?
First you need to make the kernel by-handle interfaces handle the
sae functionality as the XFS by-handle ioctls.
1. O_NOCMTIME doesn't exist, and so there's no way to do
invisible IO on files.
2. Can we construct VFs filehandles in userspace from
bulkstat information (dump, xfs_fsr and others rely on
this capability)?
3. The kernel by-handle interfaces cannot manipulate
attributes at all (i.e. attr-list, attr-multi
functionality).
So until the VFS by-handle interfaces can do these things, we can't
change libhandle over to use the newer kernel interfaces.
I'm also pretty sure the incompatible handle format would mean
big problems if someone were to be storing file handles in userspace
and they upgrade their version of libhandle. i.e. such a library
implementation change is not forwards or backwards compatible with
existing applications, but bumping the major shared library version
should solve that problem.
However, these are all solvable problems. It's definitely a low
priority for me to do this, but if you want to do it patches will
definitely be accepted ;)
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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