Re: [PATCH 4 of 4] sd: Correctly handle 6-byte commands with DIX

[Matthew Wilcox <matthew@wil.cx>]

On Sun, Jan 04, 2009 at 03:04:34AM -0500, Martin K. Petersen wrote:
> @@ -374,7 +374,10 @@ void sd_dif_op(struct scsi_cmnd *scmd, u
>  	else
>  		csum_convert = 0;
>  
> +	BUG_ON(dif && (scmd->cmnd[0] == READ_6 || scmd->cmnd[0] == WRITE_6));

This BUG_ON gave me a 'Huh?' moment.  I immediately wondered if it was
user-triggerable.  The answer is "no, this is kosher".  sd_dif_op() is
only called from sd.c where it has chosen which READ_*/WRITE_* opcode to
set up, and it would indeed be an internal bug for this combination of
conditions to exist.

Reviewed-by: Matthew Wilcox <willy@linux.intel.com>

> +
>  	switch (scmd->cmnd[0]) {
> +	case READ_6:
>  	case READ_10:
>  	case READ_12:
>  	case READ_16:
> @@ -390,6 +393,7 @@ void sd_dif_op(struct scsi_cmnd *scmd, u
>  
>  		break;
>  
> +	case WRITE_6:
>  	case WRITE_10:
>  	case WRITE_12:
>  	case WRITE_16:
> 
> 
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-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."