linux-kernel - Re: [PATCH] sendfile removal

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Message-ID: <20070531105321.GQ32105@kernel.dk>
Date:	Thu, 31 May 2007 12:53:22 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Eric Dumazet <dada1@...mosbay.com>
Cc:	linux-kernel@...r.kernel.org, cotte@...ibm.com, hugh@...itas.com,
	neilb@...e.de, zanussi@...ibm.com,
	Linus Torvalds <torvalds@...l.org>, hch@...radead.org
Subject: Re: [PATCH] sendfile removal

On Thu, May 31 2007, Eric Dumazet wrote:
> On Thu, 31 May 2007 12:33:16 +0200
> Jens Axboe <jens.axboe@...cle.com> wrote:
> 
> > Hi,
> > 
> > This patch removes the ->sendfile() hook from the file_operations
> > structure, and replaces the sys_sendfile() mechanism to be based on
> > ->splice_read() instead. There should be no functional changes.
> > 
>   
> > -	retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
> > +	fl = 0;
> > +	if (in_file->f_flags & O_NONBLOCK)
> > +		fl = SPLICE_F_NONBLOCK;
> > +
> > +	retval = do_splice_direct(in_file, ppos, out_file, count, fl);
> 
> I like this, but are you sure it wont break user land ?
> 
> Some applications might react badly if sendfile() returns EAGAIN ?

Yeah, I didn't actually intend for that to sneak in. I'd think that
userspace should handle it if they opened the file O_NONBLOCK (or used
fcntl()), but it's a change in behaviour none the less and probably not
a good idea.

Encourage those people to use splice() instead :-)

-- 
Jens Axboe

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