Adding Hannes to the Cc list as he's been looking into EH improvements
in this area.
On Wed, May 25, 2016 at 02:55:02AM -0500, mchristi@xxxxxxxxxx wrote:
> From: Mike Christie <mchristi@xxxxxxxxxx>
>
> Currently, if the SCSI eh runs then before we do a LUN_RESET
> we stop the host. This patch and the block layer one before it
> begin to add infrastructure to be able to do a LUN_RESET and
> eventually do a transport level recovery without having to stop the
> host.
>
> For LUn-reset, this patch adds a new callout, eh_async_device_reset_handler,
> which works similar to how LLDs handle SG_SCSI_RESET_DEVICE where the
> LLD manages the commands that are affected.
>
> eh_async_device_reset_handler:
>
> The LLD should perform a LUN RESET that affects all commands
> that have been accepted by its queuecommand callout for the
> device passed in to the callout. While the reset handler is running,
> queuecommand will not be running or called for the device.
>
> Unlike eh_device_reset_handler, queuecommand may still be
> called for other devices, and the LLD must call scsi_done for the
> commands that have been affected by the reset.
>
> If SUCCESS or FAST_IO_FAIL is returned, the scsi_cmnds cleaned up
> must be failed with DID_ABORT.
>
> Signed-off-by: Mike Christie <mchristi@xxxxxxxxxx>
> ---
> drivers/scsi/scsi_error.c | 31 ++++++++++++++++++++++++++++---
> drivers/scsi/scsi_lib.c | 6 ++++++
> drivers/scsi/scsi_priv.h | 1 +
> include/scsi/scsi_host.h | 17 +++++++++++++++++
> 4 files changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 984ddcb..cec2dfb 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -853,16 +853,41 @@ static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
> {
> int rtn;
> struct scsi_host_template *hostt = scmd->device->host->hostt;
> + struct scsi_device *sdev = scmd->device;
>
> - if (!hostt->eh_device_reset_handler)
> + if (!hostt->eh_device_reset_handler &&
> + !hostt->eh_async_device_reset_handler)
> return FAILED;
>
> - rtn = hostt->eh_device_reset_handler(scmd);
> + if (hostt->eh_device_reset_handler) {
> + rtn = hostt->eh_device_reset_handler(scmd);
> + } else {
> + if (!blk_reset_queue(sdev->request_queue))
> + rtn = SUCCESS;
> + else
> + rtn = FAILED;
> + }
> if (rtn == SUCCESS)
> - __scsi_report_device_reset(scmd->device, NULL);
> + __scsi_report_device_reset(sdev, NULL);
> return rtn;
> }
>
> +enum blk_eh_timer_return scsi_reset_queue(struct request_queue *q)
> +{
> + struct scsi_device *sdev = q->queuedata;
> + struct scsi_host_template *hostt = sdev->host->hostt;
> + int rtn;
> +
> + if (!hostt->eh_async_device_reset_handler)
> + return -EOPNOTSUPP;
> +
> + rtn = hostt->eh_async_device_reset_handler(sdev);
> + if (rtn == SUCCESS || rtn == FAST_IO_FAIL)
> + return BLK_EH_HANDLED;
> +
> + return BLK_EH_NOT_HANDLED;
> +}
> +
> /**
> * scsi_try_to_abort_cmd - Ask host to abort a SCSI command
> * @hostt: SCSI driver host template
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 8106515..11374dd 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -779,6 +779,10 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
> set_host_byte(cmd, DID_OK);
> error = -ENODATA;
> break;
> + case DID_ABORT:
> + set_host_byte(cmd, DID_OK);
> + error = -EINTR;
> + break;
> default:
> error = -EIO;
> break;
> @@ -2159,6 +2163,7 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
> blk_queue_softirq_done(q, scsi_softirq_done);
> blk_queue_rq_timed_out(q, scsi_times_out);
> blk_queue_lld_busy(q, scsi_lld_busy);
> + blk_queue_reset(q, scsi_reset_queue);
> return q;
> }
>
> @@ -2167,6 +2172,7 @@ static struct blk_mq_ops scsi_mq_ops = {
> .queue_rq = scsi_queue_rq,
> .complete = scsi_softirq_done,
> .timeout = scsi_timeout,
> + .reset = scsi_reset_queue,
> .init_request = scsi_init_request,
> .exit_request = scsi_exit_request,
> };
> diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
> index 27b4d0a..2e03168 100644
> --- a/drivers/scsi/scsi_priv.h
> +++ b/drivers/scsi/scsi_priv.h
> @@ -67,6 +67,7 @@ extern void scsi_exit_devinfo(void);
>
> /* scsi_error.c */
> extern void scmd_eh_abort_handler(struct work_struct *work);
> +extern enum blk_eh_timer_return scsi_reset_queue(struct request_queue *q);
> extern enum blk_eh_timer_return scsi_times_out(struct request *req);
> extern int scsi_error_handler(void *host);
> extern int scsi_decide_disposition(struct scsi_cmnd *cmd);
> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
> index fcfa3d7..532deb5 100644
> --- a/include/scsi/scsi_host.h
> +++ b/include/scsi/scsi_host.h
> @@ -146,6 +146,23 @@ struct scsi_host_template {
> */
> int (* eh_abort_handler)(struct scsi_cmnd *);
> int (* eh_device_reset_handler)(struct scsi_cmnd *);
> + /*
> + * eh_async_device_reset_handler - Perform LUN RESET
> + * @scsi_device: scsi device to reset
> + *
> + * The LLD should perform a LUN RESET that affects all commands
> + * that have been accepted by its queuecommand callout for the
> + * device passed in. While the reset handler is running, queuecommand
> + * will not be called for the device.
> + *
> + * Unlike eh_device_reset_handler, queuecommand may still be called
> + * for other devices, and the LLD must call scsi_done for the commands
> + * that have been affected by the reset.
> + *
> + * If SUCCESS or FAST_IO_FAIL is returned, the scsi_cmnds for
> + * scsi_device must be failed with DID_ABORT.
> + */
> + int (* eh_async_device_reset_handler)(struct scsi_device *);
> int (* eh_target_reset_handler)(struct scsi_cmnd *);
> int (* eh_bus_reset_handler)(struct scsi_cmnd *);
> int (* eh_host_reset_handler)(struct scsi_cmnd *);
> --
> 2.7.2
>
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