Re: [PATCH RFC 1/3] vfs: add copy_file_range syscall and vfs helper

From: Christoph Hellwig
Date: Tue Apr 14 2015 - 12:53:52 EST

On Sat, Apr 11, 2015 at 09:04:02AM -0400, Jeff Layton wrote:
> Yuck! How the heck do you clean up the mess if that happens? I guess
> you're just stuck redoing the copy with normal READ/WRITE?
> Maybe we need to have the interface return a hard error in that
> case and not try to give back any sort of offset?

The NFSv4.2 COPY interface is a train wreck. At least for Linux I'd
expect us to simply ignore it and only implement my new CLONE operation
with sane semantics. That is unless someone can show some real life
use case for the inter server copy, in which case we'll have to deal
with that mess. But getting that one right at the VFS level will
be a nightmare anyway.

Make this a vote from me to not support partial copies and just return
and error in that case.
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