Re: [PATCH 2/2 V2] xfs: don't take addresses of packed xfs_rmap_key member

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Wed, Jan 29, 2020 at 12:15:06PM -0600, Eric Sandeen wrote:
>  {
>  	uint64_t		off;
> +	xfs_agblock_t		start;
>  	int			adj;
>  
>  	adj = be32_to_cpu(rec->rmap.rm_blockcount) - 1;
>  
>  	key->rmap.rm_startblock = rec->rmap.rm_startblock;
> -	be32_add_cpu(&key->rmap.rm_startblock, adj);
> +	start = be32_to_cpu(key->rmap.rm_startblock) - adj;
> +	key->rmap.rm_startblock = cpu_to_be32(start);

Do we really need the local variable?  Why not:

	key->rmap.rm_startblock =
		cpu_to_be32(be32_to_cpu(key->rmap.rm_startblock) - adj);