linux-kernel - Re: [PATCH] sendfile removal (nfsd update)

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Message-ID: <20070601054424.GJ32105@kernel.dk>
Date:	Fri, 1 Jun 2007 07:44:25 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Neil Brown <neilb@...e.de>
Cc:	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, cotte@...ibm.com, hugh@...itas.com,
	zanussi@...ibm.com, Linus Torvalds <torvalds@...l.org>
Subject: Re: [PATCH] sendfile removal (nfsd update)

On Fri, Jun 01 2007, Neil Brown wrote:
> 
> Ok, here is a patch that makes nfsd use splice instead of sendfile.
> It appears to both compile and work.
> 
> Some observations:
>   - __splice_from_pipe wants a "struct file*" and I wanted to pass a
>     "struct svcrqst *".  Maybe it should take a void * ?
>   - It also wants a *ppos which I had no use for.. It that really
>     need?  Cannot &file->f_pos be used?

See:

http://git.kernel.dk/?p=linux-2.6-block.git;a=commitdiff;h=c73a9509ef7877d31e0c97c684ee8b7ed13ecbbe;hp=07f0e716250d4a3a550b2f39bd0a7e4e6566b3c2

I'll rebase the conversion on top of this one, loop will need the same
change.

>   - I copied do_splice_to from splice.c as it wasn't exported, and
>     then found I couldn't compile because rw_verify_area wasn't
>     exported. As nfsd doesn't need that (we never export
>     mandatory-locking files) I just remove it and some other cruft
>     that I didn't need.... Not sure if that was the best approach.
>   - I needed to export alloc_pipe_info.  Maybe there should be a 
>     get_current_pipe instead which does the alloc if needed.
>   - I would much rather have something like free_pipe_info exported
>     than open code it in do_splice_read (which is based heavily on
>     do_splice_direct).

I need the same thing for loop. I think I'll add do_splice_foo() to
fs/splice.c in a way that loop can use instead of do_splice_direct(),
then nfsd should be able to do the same.

Thanks for this Neil!

-- 
Jens Axboe

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