Re: PATCH; make sr.c respect use_10_for_ms

[James Bottomley <James.Bottomley@steeleye.com>]

In general, you would have been a bit better off just doing a

	if(cd->device->use_10_for_ms) {
		cgc.cmd[0] = MODE_SENSE_10;
		cgc.cmd[8] = 128;
	} else {
		cdc.cmd[0] = MODE_SENSE;
		cgc.cmd[4] = 128;
	}

Rather than duplicating so much code.

This: 

> +	if (cd->device->use_10_for_ms) {
> +		memset(&cgc, 0, sizeof(struct cdrom_generic_command));
> +		cgc.cmd[0] = MODE_SENSE_10;
> +		cgc.cmd[2] = 0x2a;		/* page code */
> +		cgc.cmd[8] = 128;		/* allocation length */
> +		cgc.buffer = buffer;
> +		cgc.buflen = 128;
> +		cgc.quiet = 1;
> +		cgc.data_direction = SCSI_DATA_READ;
> +		cgc.timeout = SR_TIMEOUT;
> +		rc = sr_do_ioctl(cd, &cgc);
> +	}
> +
> +	/* if we got an error, return to old behavior */
> +	if (rc)
> +		cd->device->use_10_for_ms = 0;

Is slightly incorrect.  Mode sense commands can return errors for many
reasons, you need to check for ILLEGAL_REQUEST sense before assuming it
was a problem with the command.

What probably should happen is that the resetting of the flag should be
in scsi_io_completion (like it is for the use_10_for_rw flag), then the
retry and the flag reset would come for free.

James