linux-ext4 - Re: [PATCH 5 2/4] Return 32/64-bit dir name hash according to usage type

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Message-ID: <20120305155939.GE21356@thunk.org>
Date:	Mon, 5 Mar 2012 10:59:39 -0500
From:	Ted Ts'o <tytso@....edu>
To:	Bernd Schubert <bernd.schubert@...m.fraunhofer.de>
Cc:	linux-nfs@...r.kernel.org, linux-ext4@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, Fan Yong <yong.fan@...mcloud.com>,
	bfields@...hat.com, sandeen@...hat.com,
	Andreas Dilger <adilger@...mcloud.com>
Subject: Re: [PATCH 5 2/4] Return 32/64-bit dir name hash according to
 usage type

On Mon, Jan 09, 2012 at 02:21:48PM +0100, Bernd Schubert wrote:
> diff --git a/fs/ext4/hash.c b/fs/ext4/hash.c
> index ac8f168..fa8e491 100644
> --- a/fs/ext4/hash.c
> +++ b/fs/ext4/hash.c
> @@ -200,8 +200,8 @@ int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
>  		return -1;
>  	}
>  	hash = hash & ~1;
> -	if (hash == (EXT4_HTREE_EOF << 1))
> -		hash = (EXT4_HTREE_EOF-1) << 1;
> +	if (hash == (EXT4_HTREE_EOF_32BIT << 1))
> +		hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
>  	hinfo->hash = hash;
>  	hinfo->minor_hash = minor_hash;
>  	return 0;

Is there a reason why we don't need to avoid the collsion with the
64-bit EOF value as well?  i.e., I think we also need to add:

	if (hash == (EXT4_HTREE_EOF_64BIT << 1))
		hash = (EXT4_HTREE_EOF_64BIT - 1) << 1;

		       			       	  - Ted
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