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

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Date:	Fri, 7 Aug 2009 13:58:33 -0700
From:	Mandeep Singh Baines <msb@...gle.com>
To:	Jeff Layton <jlayton@...hat.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

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?

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