Re: [PATCH 4/5] Fix reading of 32-bit tag descriptors

On Tue, 2006-06-27 at 17:01 +0100, Stephen Tweedie wrote:
> We must never attempt to read the high 32-bits of a descriptor tag on
> a 32-bit journal, even when CONFIG_LBD is set, as we'll end up reading
> garbage from the subsequent tag.
> 
> Signed-off-by: Stephen Tweedie <[email protected]>
> ---
>  fs/jbd/recovery.c |   13 +++++++------
>  1 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/jbd/recovery.c b/fs/jbd/recovery.c
> index ec8a206..a5fb515 100644
> --- a/fs/jbd/recovery.c
> +++ b/fs/jbd/recovery.c
> @@ -308,11 +308,12 @@ #endif
>  	return err;
>  }
>  
> -static inline u64 read_split_be64(__be32 *high, __be32 *low)
> +static inline sector_t read_tag_block(int tag_bytes, journal_block_tag_t *tag)
>  {
> -	u64 ret = be32_to_cpu(*low);
> -	ret |= (u64)be32_to_cpu(*high) << 32;
> -	return ret;
> +	sector_t block = be32_to_cpu(tag->t_blocknr);
> +	if (tag_bytes > JBD_TAG_SIZE32)
> +		block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
> +	return block;
>  }
>  
>  static int do_one_pass(journal_t *journal,
> @@ -454,8 +455,8 @@ static int do_one_pass(journal_t *journa
>  					sector_t blocknr;
>  
>  					J_ASSERT(obh != NULL);
> -					blocknr = read_split_be64(&tag->t_blocknr_high,
> -							&tag->t_blocknr);
> +					blocknr = read_tag_block(tag_bytes,
> +								 tag);
>  
>  					/* If the block has been
>  					 * revoked, then we're all done

Looks good to me :)

Thanks,
Badari


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