Re: [PATCH v4] sd: Check for unaligned partial completion

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Hi Damien,

this looks reasonable, but we should ask Guilherme and Ram to confirm
it fixes their originally reported issue.  I've added them to Cc.

On Wed, Feb 15, 2017 at 11:12:30AM +0900, Damien Le Moal wrote:
> Commit "mpt3sas: Force request partial completion alignment" was not
> considering the case of REQ_TYPE_FS commands not operating on sector
> size units (e.g. REQ_OP_ZONE_REPORT and its 64B aligned partial
> replies). This could result is incorrectly retrying (forever) those
> commands.
> 
> Move the partial completion alignement check of mpt3sas to a generic
> implementation in sd_done so that the check comes after good_bytes and
> resid corrections done in that function depending on the request
> command. The check is added to the initial command switch so that
> commands with special payload size handling are ignored.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
> 
> ---
> 
> Changes from v3:
> - Moved check to initial switch-case so that commands with special payload
>   handling are ignored.
> 
> Changes from v2:
> - Fixed good_bytes calculation after correction of unaligned resid
>   It should be good_bytes=scsi_buflen() - resid, and not good_bytes-=resid
> 
>  drivers/scsi/mpt3sas/mpt3sas_scsih.c | 15 ---------------
>  drivers/scsi/sd.c                    | 20 ++++++++++++++++++++
>  2 files changed, 20 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> index 0b5b423..1961535 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> @@ -4658,7 +4658,6 @@ _scsih_io_done(struct MPT3SAS_ADAPTER *ioc, u16 smid, u8 msix_index, u32 reply)
>  	struct MPT3SAS_DEVICE *sas_device_priv_data;
>  	u32 response_code = 0;
>  	unsigned long flags;
> -	unsigned int sector_sz;
>  
>  	mpi_reply = mpt3sas_base_get_reply_virt_addr(ioc, reply);
>  	scmd = _scsih_scsi_lookup_get_clear(ioc, smid);
> @@ -4717,20 +4716,6 @@ _scsih_io_done(struct MPT3SAS_ADAPTER *ioc, u16 smid, u8 msix_index, u32 reply)
>  	}
>  
>  	xfer_cnt = le32_to_cpu(mpi_reply->TransferCount);
> -
> -	/* In case of bogus fw or device, we could end up having
> -	 * unaligned partial completion. We can force alignment here,
> -	 * then scsi-ml does not need to handle this misbehavior.
> -	 */
> -	sector_sz = scmd->device->sector_size;
> -	if (unlikely(scmd->request->cmd_type == REQ_TYPE_FS && sector_sz &&
> -		     xfer_cnt % sector_sz)) {
> -		sdev_printk(KERN_INFO, scmd->device,
> -		    "unaligned partial completion avoided (xfer_cnt=%u, sector_sz=%u)\n",
> -			    xfer_cnt, sector_sz);
> -		xfer_cnt = round_down(xfer_cnt, sector_sz);
> -	}
> -
>  	scsi_set_resid(scmd, scsi_bufflen(scmd) - xfer_cnt);
>  	if (ioc_status & MPI2_IOCSTATUS_FLAG_LOG_INFO_AVAILABLE)
>  		log_info =  le32_to_cpu(mpi_reply->IOCLogInfo);
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 1f5d92a..d05a328 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -1790,6 +1790,8 @@ static int sd_done(struct scsi_cmnd *SCpnt)
>  {
>  	int result = SCpnt->result;
>  	unsigned int good_bytes = result ? 0 : scsi_bufflen(SCpnt);
> +	unsigned int sector_size = SCpnt->device->sector_size;
> +	unsigned int resid;
>  	struct scsi_sense_hdr sshdr;
>  	struct scsi_disk *sdkp = scsi_disk(SCpnt->request->rq_disk);
>  	struct request *req = SCpnt->request;
> @@ -1820,6 +1822,24 @@ static int sd_done(struct scsi_cmnd *SCpnt)
>  			scsi_set_resid(SCpnt, blk_rq_bytes(req));
>  		}
>  		break;
> +	default:
> +		/*
> +	 	 * In case of bogus fw or device, we could end up having
> +	 	 * an unaligned partial completion. Check this here and force
> +	 	 * alignment.
> +	 	 */
> +		resid = scsi_get_resid(SCpnt);
> +		if (resid & (sector_size - 1)) {
> +			SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, SCpnt,
> +				"Unaligned partial completion (resid=%u, sector_sz=%u)\n",
> +				resid, sector_size));
> +			resid = round_up(resid, sector_size);
> +			if (resid < good_bytes)
> +				good_bytes -= resid;
> +			else
> +				good_bytes = 0;
> +			scsi_set_resid(SCpnt, resid);
> +		}
>  	}
>  
>  	if (result) {
> -- 
> 2.9.3
> 
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