On 12/13/2011 11:40 PM, Rob Evers wrote:
> When alua targets are transitioning, the scsi midlayer retry mechanism
> continuously retries the scsi commands that are returning with not ready
> transitioning status. The target is not capable of handling the
> commands for time on the order of several seconds during these transistions.
>
> This patch delays the device queue for 2 seconds, which is in the same
> order of aas transition time.
>
> Also, handle all other cases where ADD_TO_MLQUEUE_DELAY could be returned
> instead of ADD_TO_MLQUEUE as if ADD_TO_MLQUEUE were being returned.
>
> Problem found by array partner testing
>
> Signed-off-by: Rob Evers <revers@xxxxxxxxxx>
> ---
> drivers/scsi/device_handler/scsi_dh_alua.c | 7 ++++---
> drivers/scsi/scsi.c | 3 +++
> drivers/scsi/scsi_error.c | 1 +
> drivers/scsi/scsi_lib.c | 9 ++++++++-
> include/scsi/scsi.h | 4 +++-
> 5 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 4ef0212..33b8df7 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -233,7 +233,7 @@ static void stpg_endio(struct request *req, int error)
> goto done;
> }
> err = alua_check_sense(h->sdev, &sense_hdr);
> - if (err == ADD_TO_MLQUEUE) {
> + if (err == ADD_TO_MLQUEUE || err == ADD_TO_MLQUEUE_DELAY) {
> err = SCSI_DH_RETRY;
> goto done;
> }
> @@ -443,7 +443,7 @@ static int alua_check_sense(struct scsi_device *sdev,
> /*
> * LUN Not Accessible - ALUA state transition
> */
> - return ADD_TO_MLQUEUE;
> + return ADD_TO_MLQUEUE_DELAY;
> if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0b)
> /*
> * LUN Not Accessible -- Target port in standby state
> @@ -521,7 +521,8 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
> return SCSI_DH_IO;
>
> err = alua_check_sense(sdev, &sense_hdr);
> - if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry))
> + if ((err == ADD_TO_MLQUEUE || err == ADD_TO_MLQUEUE_DELAY) &&
> + time_before(jiffies, expiry))
> goto retry;
> sdev_printk(KERN_INFO, sdev,
> "%s: rtpg sense code %02x/%02x/%02x\n",
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index 2aeb2e9..ced0085 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -600,6 +600,9 @@ void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
> case ADD_TO_MLQUEUE:
> printk("MLQUEUE\n");
> break;
> + case ADD_TO_MLQUEUE_DELAY:
> + printk("MLQUEUE_DELAY\n");
> + break;
> case FAILED:
> printk("FAILED\n");
> break;
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index dc6131e..775f822 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -812,6 +812,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
> case TARGET_ERROR:
> break;
> case ADD_TO_MLQUEUE:
> + case ADD_TO_MLQUEUE_DELAY:
> rtn = NEEDS_RETRY;
> break;
> default:
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 06bc265..fb35a76 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -139,6 +139,7 @@ static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
> break;
> case SCSI_MLQUEUE_DEVICE_BUSY:
> case SCSI_MLQUEUE_EH_RETRY:
> + case SCSI_MLQUEUE_DEV_DLY_RTY:
> device->device_blocked = device->max_device_blocked;
> break;
> case SCSI_MLQUEUE_TARGET_BUSY:
> @@ -161,7 +162,10 @@ static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
> blk_requeue_request(q, cmd->request);
> spin_unlock_irqrestore(q->queue_lock, flags);
>
> - kblockd_schedule_work(q, &device->requeue_work);
> + if (reason == SCSI_MLQUEUE_DEV_DLY_RTY)
> + blk_delay_queue(q, 2000);
> + else
> + kblockd_schedule_work(q, &device->requeue_work);
>
> return 0;
> }
> @@ -1465,6 +1469,9 @@ static void scsi_softirq_done(struct request *rq)
> case ADD_TO_MLQUEUE:
> scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
> break;
> + case ADD_TO_MLQUEUE_DELAY:
> + scsi_queue_insert(cmd, SCSI_MLQUEUE_DEV_DLY_RTY);
> + break;
> default:
> if (!scsi_eh_scmd_add(cmd, 0))
> scsi_finish_command(cmd);
> diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
> index 8001ae4..df0e353 100644
> --- a/include/scsi/scsi.h
> +++ b/include/scsi/scsi.h
> @@ -466,9 +466,10 @@ static inline int scsi_is_wlun(unsigned int lun)
> #define SOFT_ERROR 0x2005
> #define ADD_TO_MLQUEUE 0x2006
> #define TIMEOUT_ERROR 0x2007
> -#define SCSI_RETURN_NOT_HANDLED 0x2008
> +#define SCSI_RETURN_NOT_HANDLED 0x2008
> #define FAST_IO_FAIL 0x2009
> #define TARGET_ERROR 0x200A
> +#define ADD_TO_MLQUEUE_DELAY 0x200B
>
> /*
> * Midlevel queue return values.
> @@ -477,6 +478,7 @@ static inline int scsi_is_wlun(unsigned int lun)
> #define SCSI_MLQUEUE_DEVICE_BUSY 0x1056
> #define SCSI_MLQUEUE_EH_RETRY 0x1057
> #define SCSI_MLQUEUE_TARGET_BUSY 0x1058
> +#define SCSI_MLQUEUE_DEV_DLY_RTY 0x1059
>
Can't we just name it 'MLQUEUE_DELAYED_RETRY'?
'MLQUEUE_DEV_DLY_RTY' is a bit unwieldy ...
Other than that: Looks good.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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