Re: [PATCH] stop using uio in the readlink code

[David Chinner <dgc@sgi.com>]

On Sun, Jul 29, 2007 at 11:13:54PM +0200, Christoph Hellwig wrote:
> Simplify the readlink code to get rid of the last user of uio.
> 
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
.....
> --- linux-2.6-xfs.orig/fs/xfs/linux-2.6/xfs_ioctl.c	2007-07-14 16:07:19.000000000 +0200
> +++ linux-2.6-xfs/fs/xfs/linux-2.6/xfs_ioctl.c	2007-07-29 14:28:29.000000000 +0200
> @@ -349,19 +349,44 @@ xfs_open_by_handle(
>  	return new_fd;
>  }
>  
> +/*
> + * This is a copy from fs/namei.c:vfs_readlink(), except for removing it's
> + * unused first argument.
> + */
> +STATIC int
> +do_readlink(
> +	char __user		*buffer,
> +	int			buflen,
> +	const char		*link)
> +{
> +        int len;
> +
> +	len = PTR_ERR(link);
> +	if (IS_ERR(link))
> +		goto out;
> +
> +	len = strlen(link);
> +	if (len > (unsigned) buflen)
> +		len = buflen;
> +	if (copy_to_user(buffer, link, len))
> +		len = -EFAULT;
> + out:
> +	return len;
> +}

Do we really need to copy this code? I guess it doesn't really
matter that much but it would be nice not to have to copy an
exported vfs function just because we don't have a dentry...

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group