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List:       linux-xfs
Subject:    Re: [PATCH, RFC] directory offset overflows in 2.6.28
From:       Dave Chinner <david () fromorbit ! com>
Date:       2008-12-30 0:11:17
Message-ID: 20081230001117.GA5220 () disturbed
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On Mon, Dec 29, 2008 at 05:07:45PM -0500, Christoph Hellwig wrote:
> The patch below is a dumb version of just putting back the masking,
> to make sure we have the same behavior as in 2.6.27 and earlier.
> I think we should at least hide it in a macro that is well-commented,
> but I suspect we also need to make sure that we never ever get bigger
> offsets in directories in some way.

I think we need that macro sooner rather than later ;)

> Index: xfs/fs/xfs/xfs_dir2_block.c
> ===================================================================
> --- xfs.orig/fs/xfs/xfs_dir2_block.c	2008-12-29 21:25:29.680613664 +0100
> +++ xfs/fs/xfs/xfs_dir2_block.c	2008-12-29 21:29:57.341627581 +0100
> @@ -517,9 +517,9 @@ xfs_dir2_block_getdents(
>  		/*
>  		 * If it didn't fit, set the final offset to here & return.
>  		 */
> -		if (filldir(dirent, dep->name, dep->namelen, cook,
> +		if (filldir(dirent, dep->name, dep->namelen, cook & 0x7fffffff,
>  			    ino, DT_UNKNOWN)) {
> -			*offset = cook;
> +			*offset = cook & 0x7fffffff;
>  			xfs_da_brelse(NULL, bp);
>  			return 0;
>  		}

In this case, you can do the masking at the time cook is
assigned. I haven't checked, but I suspect the rest will be the
same. That will make the patch less invasive and with a macro
somewhat cleaner...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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