linux-kernel - Re: [PATCH] sendfile removal

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Message-ID: <20070601054120.GI32105@kernel.dk>
Date:	Fri, 1 Jun 2007 07:41:21 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Eric Dumazet <dada1@...mosbay.com>, 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, H. Peter Anvin wrote:
> Jens Axboe wrote:
> >>   
> >>> -	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.
> > 
> 
> I would personally argue that sendfile() blocking on an O_NONBLOCK
> desriptor, as opposed to returning EAGAIN, is a bug, and a fairly
> serious such.

I agree, but it's still a change in behaviour. Even if we consider the
app buggy (it is), can we potentially break it?

-- 
Jens Axboe

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