Re: [PATCH v1 0/6] no-copy bvec

[Christoph Hellwig]

On Tue, Dec 15, 2020 at 02:05:35PM +0000, Pavel Begunkov wrote:
> > You may find clue from the following link:
> > 
> > https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg2262077.html
> 
> Thanks for the link!
> 
> Al, you mentioned "Zero-length segments are not disallowed", do you have
> a strong opinion on that? Apart from already diverged behaviour from the
> block layer and getting in the way of this series, without it we'd also be
> able to remove some extra ifs, e.g. in iterate_bvec()

I'd prefer not to support zero-length ITER_BVEC and catching them
early, as the block layer can't deal with them either.  From a quick
look at iter_file_splice_write it should be pretty trivial to fix there,
although we'll need to audit other callers as well (even if I don't
expect them to submit this degenerate case).