[PATCH 0/2] ibmvscsi: dynamic request_limit and device restart

[PATCH 0/2] ibmvscsi: dynamic request_limit and device restart

[Robert Jennings]

There are two fixes for the ibmvscsi client driver in this set.

- Dynamic request_limit
The request_limit for the driver was not properly reflecting the value on
the server side and could cause can_queue to be set to improper values (-1).
The patch corrects this so that request_limit mirrors the value
on the server and sets can_queue appropriately.

- Device restart
When a drive was removed from the server and then re-added the client
would not be able to use that device.  The device would return a unit
attention and then not ready.  By adding a slave_configure function we
can set the "allow_restart" flag for all disk devices.  Now devices will
resume functioning when they are re-added to the server.

---

[PATCH 1/2] ibmvscsi: allow for dynamic adjustment of server request_limit

[Robert Jennings]

The request limit calculations used previously on the client failed to
mirror the state of the server.  Additionally, when a value < 3 was provided
there could be problems setting can_queue and handling abort and reset 
commands.

Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvscsi.c |   58 +++++++++++++++++++++++++--------------
 drivers/scsi/ibmvscsi/ibmvscsi.h |    2 +
 2 files changed, 40 insertions(+), 20 deletions(-)

Index: ibmvscsi-23509/drivers/scsi/ibmvscsi/ibmvscsi.c
===================================================================
--- ibmvscsi-23509.orig/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ ibmvscsi-23509/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -85,7 +85,7 @@
 static int max_id = 64;
 static int max_channel = 3;
 static int init_timeout = 5;
-static int max_requests = 50;
+static int max_requests = IBMVSCSI_MAX_REQUESTS_DEFAULT;
 
 #define IBMVSCSI_VERSION "1.5.8"
 
@@ -538,7 +538,8 @@
 	int request_status;
 	int rc;
 
-	/* If we have exhausted our request limit, just fail this request.
+	/* If we have exhausted our request limit, just fail this request,
+	 * unless it is for a reset or abort.
 	 * Note that there are rare cases involving driver generated requests 
 	 * (such as task management requests) that the mid layer may think we
 	 * can handle more requests (can_queue) when we actually can't
@@ -551,9 +552,30 @@
 		 */
 		if (request_status < -1)
 			goto send_error;
-		/* Otherwise, if we have run out of requests */
-		else if (request_status < 0)
-			goto send_busy;
+		/* Otherwise, we may have run out of requests. */
+		/* Abort and reset calls should make it through.
+		 * Nothing except abort and reset should use the last two
+		 * slots unless we had two or less to begin with.
+		 */
+		else if (request_status < 2 &&
+		         evt_struct->iu.srp.cmd.opcode != SRP_TSK_MGMT) {
+			/* In the case that we have less than two requests
+			 * available, check the server limit as a combination
+			 * of the request limit and the number of requests
+			 * in-flight (the size of the send list).  If the
+			 * server limit is greater than 2, return busy so
+			 * that the last two are reserved for reset and abort.
+			 */
+			int server_limit = request_status;
+			struct srp_event_struct *tmp_evt;
+
+			list_for_each_entry(tmp_evt, &hostdata->sent, list) {
+				server_limit++;
+			}
+
+			if (server_limit > 2)
+				goto send_busy;
+		}
 	}
 
 	/* Copy the IU into the transfer area */
@@ -572,6 +594,7 @@
 
 		printk(KERN_ERR "ibmvscsi: send error %d\n",
 		       rc);
+		atomic_inc(&hostdata->request_limit);
 		goto send_error;
 	}
 
@@ -581,7 +604,8 @@
 	unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);
 
 	free_event_struct(&hostdata->pool, evt_struct);
- 	return SCSI_MLQUEUE_HOST_BUSY;
+	atomic_inc(&hostdata->request_limit);
+	return SCSI_MLQUEUE_HOST_BUSY;
 
  send_error:
 	unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);
@@ -831,23 +855,16 @@
 
 	printk(KERN_INFO "ibmvscsi: SRP_LOGIN succeeded\n");
 
-	if (evt_struct->xfer_iu->srp.login_rsp.req_lim_delta >
-	    (max_requests - 2))
-		evt_struct->xfer_iu->srp.login_rsp.req_lim_delta =
-		    max_requests - 2;
+	if (evt_struct->xfer_iu->srp.login_rsp.req_lim_delta < 0)
+		printk(KERN_ERR "ibmvscsi: Invalid request_limit.\n");
 
-	/* Now we know what the real request-limit is */
+	/* Now we know what the real request-limit is.
+	 * This value is set rather than added to request_limit because
+	 * request_limit could have been set to -1 by this client.
+	 */
 	atomic_set(&hostdata->request_limit,
 		   evt_struct->xfer_iu->srp.login_rsp.req_lim_delta);
 
-	hostdata->host->can_queue =
-	    evt_struct->xfer_iu->srp.login_rsp.req_lim_delta - 2;
-
-	if (hostdata->host->can_queue < 1) {
-		printk(KERN_ERR "ibmvscsi: Invalid request_limit_delta\n");
-		return;
-	}
-
 	/* If we had any pending I/Os, kick them */
 	scsi_unblock_requests(hostdata->host);
 
@@ -1483,7 +1500,7 @@
 	.eh_abort_handler = ibmvscsi_eh_abort_handler,
 	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
 	.cmd_per_lun = 16,
-	.can_queue = 1,		/* Updated after SRP_LOGIN */
+	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,
 	.sg_tablesize = SG_ALL,
 	.use_clustering = ENABLE_CLUSTERING,
@@ -1503,6 +1520,7 @@
 
 	vdev->dev.driver_data = NULL;
 
+	driver_template.can_queue = max_requests;
 	host = scsi_host_alloc(&driver_template, sizeof(*hostdata));
 	if (!host) {
 		printk(KERN_ERR "ibmvscsi: couldn't allocate host data\n");
Index: ibmvscsi-23509/drivers/scsi/ibmvscsi/ibmvscsi.h
===================================================================
--- ibmvscsi-23509.orig/drivers/scsi/ibmvscsi/ibmvscsi.h
+++ ibmvscsi-23509/drivers/scsi/ibmvscsi/ibmvscsi.h
@@ -44,6 +44,8 @@
  */
 #define MAX_INDIRECT_BUFS 10
 
+#define IBMVSCSI_MAX_REQUESTS_DEFAULT 100
+
 /* ------------------------------------------------------------
  * Data Structures
  */

Re: [PATCH 1/2] ibmvscsi: allow for dynamic adjustment of server request_limit

[Santiago Leon]

Robert Jennings wrote:
> The request limit calculations used previously on the client failed to
> mirror the state of the server.  Additionally, when a value < 3 was provided
> there could be problems setting can_queue and handling abort and reset 
> commands.

Signed-off-by: Santiago Leon <santil@us.ibm.com>

> Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>

[PATCH 2/2] ibmvscsi: add slave_configure to allow device restart

[Robert Jennings]

Adding a slave_configure function for the driver. Now the disks can be
restarted by the scsi mid-layer when the are disconnected and reconnected.

Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvscsi.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Index: ibmvscsi-23509/drivers/scsi/ibmvscsi/ibmvscsi.c
===================================================================
--- ibmvscsi-23509.orig/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ ibmvscsi-23509/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -1354,6 +1354,23 @@
 	return rc;
 }
 
+/**
+ * ibmvscsi_slave_configure: For each slave device that is a disk,
+ * ensure that the "allow_restart" flag is enabled.
+ */
+static int ibmvscsi_slave_configure(struct scsi_device *sdev)
+{
+	struct Scsi_Host *shost = sdev->host;
+	int lock_flags = 0;
+
+	spin_lock_irqsave(shost->host_lock, lock_flags);
+	if (sdev->type == TYPE_DISK)
+		sdev->allow_restart = 1;
+	scsi_adjust_queue_depth(sdev, 0, shost->cmd_per_lun);
+	spin_unlock_irqrestore(shost->host_lock, lock_flags);
+	return 0;
+}
+
 /* ------------------------------------------------------------
  * sysfs attributes
  */
@@ -1499,6 +1516,7 @@
 	.queuecommand = ibmvscsi_queuecommand,
 	.eh_abort_handler = ibmvscsi_eh_abort_handler,
 	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
+	.slave_configure = ibmvscsi_slave_configure,
 	.cmd_per_lun = 16,
 	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,

Re: [PATCH 2/2] ibmvscsi: add slave_configure to allow device restart

[Santiago Leon]

Robert Jennings wrote:
> Adding a slave_configure function for the driver. Now the disks can be
> restarted by the scsi mid-layer when the are disconnected and reconnected.

Signed-off-by: Santiago Leon <santil@us.ibm.com>

> Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>

[PATCH 2/2] [v2] ibmvscsi: add slave_configure to allow device restart

[Robert Jennings]

The first version of this patch had the incorrect type for the
lock_flags variable.

Adding a slave_configure function for the driver. Now the disks can be
restarted by the scsi mid-layer when the are disconnected and reconnected.

Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvscsi.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Index: b/drivers/scsi/ibmvscsi/ibmvscsi.c
===================================================================
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -1354,6 +1354,23 @@
 	return rc;
 }
 
+/**
+ * ibmvscsi_slave_configure: For each slave device that is a disk,
+ * ensure that the "allow_restart" flag is enabled.
+ */
+static int ibmvscsi_slave_configure(struct scsi_device *sdev)
+{
+	struct Scsi_Host *shost = sdev->host;
+	unsigned long lock_flags = 0;
+
+	spin_lock_irqsave(shost->host_lock, lock_flags);
+	if (sdev->type == TYPE_DISK)
+		sdev->allow_restart = 1;
+	scsi_adjust_queue_depth(sdev, 0, shost->cmd_per_lun);
+	spin_unlock_irqrestore(shost->host_lock, lock_flags);
+	return 0;
+}
+
 /* ------------------------------------------------------------
  * sysfs attributes
  */
@@ -1499,6 +1516,7 @@
 	.queuecommand = ibmvscsi_queuecommand,
 	.eh_abort_handler = ibmvscsi_eh_abort_handler,
 	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
+	.slave_configure = ibmvscsi_slave_configure,
 	.cmd_per_lun = 16,
 	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,

[PATCH 0/2][resend] ibmvscsi: dynamic request_limit and device restart

[Robert Jennings]

James,

Resending these patches for inclusion in your tree.

There are two fixes for the ibmvscsi client driver in this set.

- Dynamic request_limit
The request_limit for the driver was not properly reflecting the value on
the server side and could cause can_queue to be set to improper values (-1).
The patch corrects this so that request_limit mirrors the value
on the server and sets can_queue appropriately.

- Device restart
When a drive was removed from the server and then re-added the client
would not be able to use that device.  The device would return a unit
attention and then not ready.  By adding a slave_configure function we
can set the "allow_restart" flag for all disk devices.  Now devices will
resume functioning when they are re-added to the server.

---

[PATCH 2/2] ibmvscsi: add slave_configure to allow device restart

[Robert Jennings]

Adding a slave_configure function for the driver. Now the disks can be
restarted by the scsi mid-layer when the are disconnected and reconnected.

Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
Signed-off-by: "Santiago Leon" <santil@us.ibm.com>

---
 drivers/scsi/ibmvscsi/ibmvscsi.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Index: b/drivers/scsi/ibmvscsi/ibmvscsi.c
===================================================================
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -1354,6 +1354,23 @@
 	return rc;
 }
 
+/**
+ * ibmvscsi_slave_configure: For each slave device that is a disk,
+ * ensure that the "allow_restart" flag is enabled.
+ */
+static int ibmvscsi_slave_configure(struct scsi_device *sdev)
+{
+	struct Scsi_Host *shost = sdev->host;
+	unsigned long lock_flags = 0;
+
+	spin_lock_irqsave(shost->host_lock, lock_flags);
+	if (sdev->type == TYPE_DISK)
+		sdev->allow_restart = 1;
+	scsi_adjust_queue_depth(sdev, 0, shost->cmd_per_lun);
+	spin_unlock_irqrestore(shost->host_lock, lock_flags);
+	return 0;
+}
+
 /* ------------------------------------------------------------
  * sysfs attributes
  */
@@ -1499,6 +1516,7 @@
 	.queuecommand = ibmvscsi_queuecommand,
 	.eh_abort_handler = ibmvscsi_eh_abort_handler,
 	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
+	.slave_configure = ibmvscsi_slave_configure,
 	.cmd_per_lun = 16,
 	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,

Re: [PATCH 2/2] ibmvscsi: add slave_configure to allow device restart

[Randy Dunlap]

On Wed, 28 Mar 2007 12:47:04 -0500 Robert Jennings wrote:

> Adding a slave_configure function for the driver. Now the disks can be
> restarted by the scsi mid-layer when the are disconnected and reconnected.
> 
> Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
> Signed-off-by: "Santiago Leon" <santil@us.ibm.com>
> 
> ---
>  drivers/scsi/ibmvscsi/ibmvscsi.c |   18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> Index: b/drivers/scsi/ibmvscsi/ibmvscsi.c
> ===================================================================
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -1354,6 +1354,23 @@
>  	return rc;
>  }
>  
> +/**
> + * ibmvscsi_slave_configure: For each slave device that is a disk,
> + * ensure that the "allow_restart" flag is enabled.

Hi,
Please don't use kernel-doc notation (/**) unless the following
documentation block is in kernel-doc format.  See
Documentation/kernel-doc-nano-HOWTO.txt for more info, or just
ask me questions if you have any.

> + */
> +static int ibmvscsi_slave_configure(struct scsi_device *sdev)
> +{
> +	struct Scsi_Host *shost = sdev->host;
> +	unsigned long lock_flags = 0;
> +
> +	spin_lock_irqsave(shost->host_lock, lock_flags);
> +	if (sdev->type == TYPE_DISK)
> +		sdev->allow_restart = 1;
> +	scsi_adjust_queue_depth(sdev, 0, shost->cmd_per_lun);
> +	spin_unlock_irqrestore(shost->host_lock, lock_flags);
> +	return 0;
> +}
> +
>  /* ------------------------------------------------------------
>   * sysfs attributes
>   */
> @@ -1499,6 +1516,7 @@
>  	.queuecommand = ibmvscsi_queuecommand,
>  	.eh_abort_handler = ibmvscsi_eh_abort_handler,
>  	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
> +	.slave_configure = ibmvscsi_slave_configure,
>  	.cmd_per_lun = 16,
>  	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
>  	.this_id = -1,


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

Re: [PATCH 2/2] ibmvscsi: add slave_configure to allow device restart

[Robert Jennings]

Fixed the kernel-doc comment for ibmvscsi_slave_configure.  Thanks to
Randy Dunlap for catching that.

Adding a slave_configure function for the driver. Now the disks can be
restarted by the scsi mid-layer when the are disconnected and reconnected.

Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
Signed-off-by: "Santiago Leon" <santil@us.ibm.com>

---
 drivers/scsi/ibmvscsi/ibmvscsi.c |   23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

Index: b/drivers/scsi/ibmvscsi/ibmvscsi.c
===================================================================
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -1354,6 +1354,28 @@
 	return rc;
 }
 
+/**
+ * ibmvscsi_slave_configure: Set the "allow_restart" flag for each disk.
+ *
+ * @sdev:	struct scsi_device device to configure
+ *
+ * Enable allow_restart for a device if it is a disk.  Adjust the
+ * queue_depth here also as is required by the documentation for
+ * struct scsi_host_template.
+ */
+static int ibmvscsi_slave_configure(struct scsi_device *sdev)
+{
+	struct Scsi_Host *shost = sdev->host;
+	unsigned long lock_flags = 0;
+
+	spin_lock_irqsave(shost->host_lock, lock_flags);
+	if (sdev->type == TYPE_DISK)
+		sdev->allow_restart = 1;
+	scsi_adjust_queue_depth(sdev, 0, shost->cmd_per_lun);
+	spin_unlock_irqrestore(shost->host_lock, lock_flags);
+	return 0;
+}
+
 /* ------------------------------------------------------------
  * sysfs attributes
  */
@@ -1499,6 +1521,7 @@
 	.queuecommand = ibmvscsi_queuecommand,
 	.eh_abort_handler = ibmvscsi_eh_abort_handler,
 	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
+	.slave_configure = ibmvscsi_slave_configure,
 	.cmd_per_lun = 16,
 	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,

Re: [PATCH 2/2] ibmvscsi: add slave_configure to allow device restart

[Randy Dunlap]

On Thu, 29 Mar 2007 11:28:36 -0500 Robert Jennings wrote:

> Fixed the kernel-doc comment for ibmvscsi_slave_configure.  Thanks to
> Randy Dunlap for catching that.

Sorry, there's still a minor nit below.

> Adding a slave_configure function for the driver. Now the disks can be
> restarted by the scsi mid-layer when the are disconnected and reconnected.
> 
> Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
> Signed-off-by: "Santiago Leon" <santil@us.ibm.com>
> 
> ---
>  drivers/scsi/ibmvscsi/ibmvscsi.c |   23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> Index: b/drivers/scsi/ibmvscsi/ibmvscsi.c
> ===================================================================
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -1354,6 +1354,28 @@
>  	return rc;
>  }
>  
> +/**
> + * ibmvscsi_slave_configure: Set the "allow_restart" flag for each disk.
> + *

No "blank" ("*") line between the function name and its parameters...
it mucks up the generated output.

> + * @sdev:	struct scsi_device device to configure
> + *
> + * Enable allow_restart for a device if it is a disk.  Adjust the
> + * queue_depth here also as is required by the documentation for
> + * struct scsi_host_template.
> + */
> +static int ibmvscsi_slave_configure(struct scsi_device *sdev)
> +{
> +	struct Scsi_Host *shost = sdev->host;
> +	unsigned long lock_flags = 0;
> +
> +	spin_lock_irqsave(shost->host_lock, lock_flags);
> +	if (sdev->type == TYPE_DISK)
> +		sdev->allow_restart = 1;
> +	scsi_adjust_queue_depth(sdev, 0, shost->cmd_per_lun);
> +	spin_unlock_irqrestore(shost->host_lock, lock_flags);
> +	return 0;
> +}
> +
>  /* ------------------------------------------------------------
>   * sysfs attributes
>   */
> @@ -1499,6 +1521,7 @@
>  	.queuecommand = ibmvscsi_queuecommand,
>  	.eh_abort_handler = ibmvscsi_eh_abort_handler,
>  	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
> +	.slave_configure = ibmvscsi_slave_configure,
>  	.cmd_per_lun = 16,
>  	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
>  	.this_id = -1,


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***