Re: [PATCH-v2 2/2] target/iblock: Use -EAGAIN/-ENOMEM to propigate SAM BUSY/TASK_SET_FULL

[Christoph Hellwig <hch@lst.de>]

> -	if (atomic_read(&ibr->ib_bio_err_cnt))
> -		status = SAM_STAT_CHECK_CONDITION;
> -	else
> +	/*
> +	 * Propigate use these two bio completion values from raw block
> +	 * drivers to signal up BUSY and TASK_SET_FULL status to the
> +	 * host side initiator.  The latter for Linux/iSCSI initiators
> +	 * means the Linux/SCSI LLD will begin to reduce it's internal
> +	 * per session queue_depth.
> +	 */
> +	if (atomic_read(&ibr->ib_bio_err_cnt)) {
> +		switch (ibr->ib_bio_retry) {
> +		case -EAGAIN:
> +			status = SAM_STAT_BUSY;
> +			break;
> +		case -ENOMEM:
> +			status = SAM_STAT_TASK_SET_FULL;
> +			break;
> +		default:
> +			status = SAM_STAT_CHECK_CONDITION;
> +			break;
> +		}
> +	} else {
>  		status = SAM_STAT_GOOD;
> +	}

I think you;d be much better off killing ib_bio_err_cnt and having
an ib_error that gets set to the last / most server error.