Re: [PATCH 02/14] repair: reduce byte swap operations in scanfunc_allocbt

[Eric Sandeen <sandeen@sandeen.net>]

Christoph Hellwig wrote:

> Store native endian version of the extent startblock and length in
> local variables instead of converting them over and over again.
>
>
> Signed-off-by: Barry Naujok <bnaujok@sgi.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

I bet there's a lot more places where this could be done too :)

Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
> Index: xfsprogs-dev/repair/scan.c
> ===================================================================
> --- xfsprogs-dev.orig/repair/scan.c	2009-08-21 18:48:01.000000000 +0000
> +++ xfsprogs-dev/repair/scan.c	2009-08-21 18:54:29.000000000 +0000
> @@ -449,7 +449,6 @@ scanfunc_allocbt(
>  	__uint32_t		magic)
>  {
>  	const char 		*name;
> -	xfs_agblock_t		b, e;
>  	int			i;
>  	xfs_alloc_ptr_t		*pp;
>  	xfs_alloc_rec_t		*rp;
> @@ -509,20 +508,21 @@ _("%s freespace btree block claimed (sta
>  
>  		rp = XFS_ALLOC_REC_ADDR(mp, block, 1);
>  		for (i = 0; i < numrecs; i++) {
> -			if (be32_to_cpu(rp[i].ar_blockcount) == 0 ||
> -			    be32_to_cpu(rp[i].ar_startblock) == 0 ||
> -			    !verify_agbno(mp, agno,
> -				be32_to_cpu(rp[i].ar_startblock)) ||
> -			    be32_to_cpu(rp[i].ar_blockcount) >
> -					MAXEXTLEN)
> -				continue;
> +			xfs_agblock_t		b, end;
> +			xfs_extlen_t		len;
> +
> +			b = be32_to_cpu(rp[i].ar_startblock);
> +			len = be32_to_cpu(rp[i].ar_blockcount);
> +			end = b + len;
>  
> -			e = be32_to_cpu(rp[i].ar_startblock) +
> -				be32_to_cpu(rp[i].ar_blockcount);
> -			if (!verify_agbno(mp, agno, e - 1))
> +			if (b == 0 || !verify_agbno(mp, agno, b))
> +				continue;
> +			if (len == 0 || len > MAXEXTLEN)
>  				continue;
> -			for (b = be32_to_cpu(rp[i].ar_startblock);
> -			     b < e; b++)  {
> +			if (!verify_agbno(mp, agno, end - 1))
> +				continue;
> +
> +			for ( ; b < end; b++)  {
>  				state = get_agbno_state(mp, agno, b);
>  				switch (state) {
>  				case XR_E_UNKNOWN:
> @@ -579,6 +579,8 @@ _("%s freespace btree block claimed (sta
>  	}
>  
>  	for (i = 0; i < numrecs; i++)  {
> +		xfs_agblock_t		bno = be32_to_cpu(pp[i]);
> +
>  		/*
>  		 * XXX - put sibling detection right here.
>  		 * we know our sibling chain is good.  So as we go,
> @@ -588,11 +590,11 @@ _("%s freespace btree block claimed (sta
>  		 * pointer mismatch, try and extract as much data
>  		 * as possible.
>  		 */
> -		if (be32_to_cpu(pp[i]) != 0 && verify_agbno(mp, agno,
> -							be32_to_cpu(pp[i])))
> -			scan_sbtree(be32_to_cpu(pp[i]), level, agno, suspect,
> +		if (bno != 0 && verify_agbno(mp, agno, bno)) {
> +			scan_sbtree(bno, level, agno, suspect,
>  				    (magic == XFS_ABTB_MAGIC) ?
>  				    	scanfunc_bno : scanfunc_cnt, 0);
> +		}
>  	}
>  }
>  
>
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>

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