linux-kernel - Re: [PATCH 4/4] vfs: remove redundant checks in do

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Message-ID: <20090807170537.7f31b716@tlielax.poochiereds.net>
Date:	Fri, 7 Aug 2009 17:05:37 -0400
From:	Jeff Layton <jlayton@...hat.com>
To:	Mandeep Singh Baines <msb@...gle.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, hch@...radead.org, rlove@...gle.com,
	viro@...iv.linux.org.uk, hannes@...xchg.org
Subject: Re: [PATCH 4/4] vfs: remove redundant checks in do_sendfile

On Fri, 7 Aug 2009 13:58:33 -0700
Mandeep Singh Baines <msb@...gle.com> wrote:

> Jeff Layton (jlayton@...hat.com) wrote:
> > As Johannes Weiner pointed out, a couple of the range checks in do_sendfile
> > are redundant and are already checked in rw_verify_area.
> > 
> > Signed-off-by: Jeff Layton <jlayton@...hat.com>
> > ---
> >  fs/read_write.c |   11 -----------
> >  1 files changed, 0 insertions(+), 11 deletions(-)
> > 
> > diff --git a/fs/read_write.c b/fs/read_write.c
> > index 6c8c55d..9c3d98b 100644
> > --- a/fs/read_write.c
> > +++ b/fs/read_write.c
> > @@ -792,7 +792,6 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> >  {
> >  	struct file * in_file, * out_file;
> >  	struct inode * in_inode, * out_inode;
> > -	loff_t pos;
> >  	ssize_t retval;
> >  	int fput_needed_in, fput_needed_out, fl;
> >  
> > @@ -838,17 +837,7 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> >  	if (!max)
> >  		max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
> >  
> > -	pos = *ppos;
> >  	retval = -EINVAL;
> > -	if (unlikely(pos < 0))
> > -		goto fput_out;
> 
> Agree. This check is redundant.
> 
> > -	if (unlikely(pos + count > max)) {
> 
> rw_verify_area does not check s_maxbytes so aren't the checks against
> max still required?
> 

Good catch. That's what I get for not touching these patches for a few weeks :)

I'll fix and resend in another day or so.

> > -		retval = -EOVERFLOW;
> > -		if (pos >= max)
> > -			goto fput_out;
> > -		count = max - pos;
> > -	}
> > -
> >  	fl = 0;
> >  #if 0
> >  	/*
> > -- 
> > 1.6.0.6
> > 


-- 
Jeff Layton <jlayton@...hat.com>
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