[PATCH 2/7] scsi_dh: Add 'dh_state' sysfs attribute

[PATCH 2/7] scsi_dh: Add 'dh_state' sysfs attribute

[Hannes Reinecke]

Implement a 'dh_state' sdev attribute for dynamic device handler
manipulation. A read on the attribute will return the name of
the currently attached device handler or 'detached' if no handler
is attached.
The attribute allows the following strings to be written:
- The name of the device handler to be attached if the state is
  'detached'.
- 'activate' to trigger path activation if a device handler
  is attached.
- 'detach' to detach the currently attached device handler.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/device_handler/scsi_dh.c |   88 +++++++++++++++++++++++++++++++++
 1 files changed, 88 insertions(+), 0 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index 55e5fd2..2dbf84b 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -54,6 +54,55 @@ static struct scsi_device_handler *get_device_handler(const char *name)
 	return found;
 }
 
+static ssize_t
+store_dh_state(struct device *dev, struct device_attribute *attr,
+	       const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct scsi_device_handler *scsi_dh;
+	int err = -EINVAL;
+
+	if (!sdev->scsi_dh_data) {
+		/*
+		 * Attach to a device handler
+		 */
+		if (!(scsi_dh = get_device_handler(buf)))
+			return err;
+		err = scsi_dh_handler_attach(sdev, scsi_dh);
+	} else {
+		/*
+		 * Detach from a device handler
+		 */
+		if (!strncmp(buf, "detach", 6)) {
+			err = scsi_dh_handler_detach(sdev);
+		} else if (!strncmp(buf, "activate", 8)) {
+			scsi_dh = sdev->scsi_dh_data->scsi_dh;
+
+			err = scsi_dh->activate(sdev);
+		}
+	}
+
+	return err<0?err:count;
+}
+
+static ssize_t
+show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct scsi_device_handler *scsi_dh;
+
+	if (!sdev->scsi_dh_data)
+		return snprintf(buf, 20, "detached\n");
+
+	scsi_dh = sdev->scsi_dh_data->scsi_dh;
+
+	return snprintf(buf, 20, "%s\n", scsi_dh->name);
+}
+
+static struct device_attribute scsi_dh_state_attr =
+	__ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
+	       store_dh_state);
+
 /*
  * scsi_dh_handler_attach - Attach a device handler to a device
  * @sdev - SCSI device the device handler should attach to
@@ -115,9 +164,11 @@ static int scsi_dh_notifier(struct notifier_block *nb,
 
 	if (action == BUS_NOTIFY_ADD_DEVICE) {
 		scsi_dh_handler_attach(sdev, devinfo->handler);
+		device_create_file(dev, &scsi_dh_state_attr);
 	} else if (action == BUS_NOTIFY_DEL_DEVICE) {
 		if (sdev->scsi_dh_data == NULL)
 			goto out;
+		device_remove_file(dev, &scsi_dh_state_attr);
 		scsi_dh_handler_detach(sdev);
 	}
 out:
@@ -298,17 +349,54 @@ static struct notifier_block scsi_dh_nb = {
 	.notifier_call = scsi_dh_notifier
 };
 
+static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
+{
+	struct scsi_device *sdev;
+	int err;
+
+	if (!scsi_is_sdev_device(dev))
+		return 0;
+
+	sdev = to_scsi_device(dev);
+
+	err = device_create_file(&sdev->sdev_gendev,
+				 &scsi_dh_state_attr);
+
+	return 0;
+}
+
 static int __init scsi_dh_init(void)
 {
 	int r;
 
 	r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
 
+	if (!r)
+		bus_for_each_dev(&scsi_bus_type, NULL, NULL,
+				 scsi_dh_sysfs_attr_add);
+
 	return r;
 }
 
+static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
+{
+	struct scsi_device *sdev;
+
+	if (!scsi_is_sdev_device(dev))
+		return 0;
+
+	sdev = to_scsi_device(dev);
+
+	device_remove_file(&sdev->sdev_gendev,
+			   &scsi_dh_state_attr);
+
+	return 0;
+}
+
 static void __exit scsi_dh_exit(void)
 {
+	bus_for_each_dev(&scsi_bus_type, NULL, NULL,
+			 scsi_dh_sysfs_attr_remove);
 	bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
 }
 
-- 
1.5.2.4

Re: [PATCH 2/7] scsi_dh: Add 'dh_state' sysfs attribute

[Chandra Seetharaman]

On Wed, 2008-05-14 at 16:43 +0200, Hannes Reinecke wrote:
> Implement a 'dh_state' sdev attribute for dynamic device handler
> manipulation. A read on the attribute will return the name of
> the currently attached device handler or 'detached' if no handler
> is attached.
> The attribute allows the following strings to be written:
> - The name of the device handler to be attached if the state is
>   'detached'.
> - 'activate' to trigger path activation if a device handler
>   is attached.
> - 'detach' to detach the currently attached device handler.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---

All the sysfs functions can be grouped together. Helps in readability.

>  drivers/scsi/device_handler/scsi_dh.c |   88 +++++++++++++++++++++++++++++++++
>  1 files changed, 88 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
> index 55e5fd2..2dbf84b 100644
> --- a/drivers/scsi/device_handler/scsi_dh.c
> +++ b/drivers/scsi/device_handler/scsi_dh.c
> @@ -54,6 +54,55 @@ static struct scsi_device_handler *get_device_handler(const char *name)
>  	return found;
>  }
> 
> +static ssize_t
> +store_dh_state(struct device *dev, struct device_attribute *attr,
> +	       const char *buf, size_t count)
> +{
> +	struct scsi_device *sdev = to_scsi_device(dev);
> +	struct scsi_device_handler *scsi_dh;
> +	int err = -EINVAL;
> +
> +	if (!sdev->scsi_dh_data) {
> +		/*
> +		 * Attach to a device handler
> +		 */ 
> +		if (!(scsi_dh = get_device_handler(buf)))
> +			return err;
> +		err = scsi_dh_handler_attach(sdev, scsi_dh);
> +	} else {
> +		/*
> +		 * Detach from a device handler
> +		 */
> +		if (!strncmp(buf, "detach", 6)) {
> +			err = scsi_dh_handler_detach(sdev);
> +		} else if (!strncmp(buf, "activate", 8)) {
> +			scsi_dh = sdev->scsi_dh_data->scsi_dh;
> +
> +			err = scsi_dh->activate(sdev);
> +		}
> +	}
> +
> +	return err<0?err:count;
> +}
> +
> +static ssize_t
> +show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct scsi_device *sdev = to_scsi_device(dev);
> +	struct scsi_device_handler *scsi_dh;
> +
> +	if (!sdev->scsi_dh_data)
> +		return snprintf(buf, 20, "detached\n");
> +
> +	scsi_dh = sdev->scsi_dh_data->scsi_dh;

we can use it directly instead of this variable ?

> +
> +	return snprintf(buf, 20, "%s\n", scsi_dh->name);
> +}
> +
> +static struct device_attribute scsi_dh_state_attr =
> +	__ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
> +	       store_dh_state);
> +
>  /*
>   * scsi_dh_handler_attach - Attach a device handler to a device
>   * @sdev - SCSI device the device handler should attach to
> @@ -115,9 +164,11 @@ static int scsi_dh_notifier(struct notifier_block *nb,
> 
>  	if (action == BUS_NOTIFY_ADD_DEVICE) {
>  		scsi_dh_handler_attach(sdev, devinfo->handler);
> +		device_create_file(dev, &scsi_dh_state_attr);

A later patch checks for the return status of scsi_dh_handler_attach(),
should be moved here.

>  	} else if (action == BUS_NOTIFY_DEL_DEVICE) {
>  		if (sdev->scsi_dh_data == NULL)
>  			goto out;
> +		device_remove_file(dev, &scsi_dh_state_attr);
>  		scsi_dh_handler_detach(sdev);
>  	}
>  out:
> @@ -298,17 +349,54 @@ static struct notifier_block scsi_dh_nb = {
>  	.notifier_call = scsi_dh_notifier
>  };
> 
> +static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
> +{
> +	struct scsi_device *sdev;
> +	int err;
> +
> +	if (!scsi_is_sdev_device(dev))
> +		return 0;
> +
> +	sdev = to_scsi_device(dev);
> +
> +	err = device_create_file(&sdev->sdev_gendev,
> +				 &scsi_dh_state_attr);
> +
> +	return 0;
> +}
> +
>  static int __init scsi_dh_init(void)
>  {
>  	int r;
> 
>  	r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
> 
> +	if (!r)
> +		bus_for_each_dev(&scsi_bus_type, NULL, NULL,
> +				 scsi_dh_sysfs_attr_add);
> +
>  	return r;
>  }
> 
> +static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
> +{
> +	struct scsi_device *sdev;
> +
> +	if (!scsi_is_sdev_device(dev))
> +		return 0;
> +
> +	sdev = to_scsi_device(dev);
> +
> +	device_remove_file(&sdev->sdev_gendev,
> +			   &scsi_dh_state_attr);
> +
> +	return 0;
> +}
> +
>  static void __exit scsi_dh_exit(void)
>  {
> +	bus_for_each_dev(&scsi_bus_type, NULL, NULL,
> +			 scsi_dh_sysfs_attr_remove);
>  	bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
>  }
> 

Re: [PATCH 2/7] scsi_dh: Add 'dh_state' sysfs attribute

[Hannes Reinecke]

Chandra Seetharaman wrote:
> On Wed, 2008-05-14 at 16:43 +0200, Hannes Reinecke wrote:
>> Implement a 'dh_state' sdev attribute for dynamic device handler
>> manipulation. A read on the attribute will return the name of
>> the currently attached device handler or 'detached' if no handler
>> is attached.
>> The attribute allows the following strings to be written:
>> - The name of the device handler to be attached if the state is
>>   'detached'.
>> - 'activate' to trigger path activation if a device handler
>>   is attached.
>> - 'detach' to detach the currently attached device handler.
>>
>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>> ---
> 
> All the sysfs functions can be grouped together. Helps in readability.
> 
?? But I did ... Or thought so, anyway. Checking.

>>  drivers/scsi/device_handler/scsi_dh.c |   88 +++++++++++++++++++++++++++++++++
>>  1 files changed, 88 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
>> index 55e5fd2..2dbf84b 100644
>> --- a/drivers/scsi/device_handler/scsi_dh.c
>> +++ b/drivers/scsi/device_handler/scsi_dh.c
>> @@ -54,6 +54,55 @@ static struct scsi_device_handler *get_device_handler(const char *name)
>>  	return found;
>>  }
>>
>> +static ssize_t
>> +store_dh_state(struct device *dev, struct device_attribute *attr,
>> +	       const char *buf, size_t count)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +	struct scsi_device_handler *scsi_dh;
>> +	int err = -EINVAL;
>> +
>> +	if (!sdev->scsi_dh_data) {
>> +		/*
>> +		 * Attach to a device handler
>> +		 */ 
>> +		if (!(scsi_dh = get_device_handler(buf)))
>> +			return err;
>> +		err = scsi_dh_handler_attach(sdev, scsi_dh);
>> +	} else {
>> +		/*
>> +		 * Detach from a device handler
>> +		 */
>> +		if (!strncmp(buf, "detach", 6)) {
>> +			err = scsi_dh_handler_detach(sdev);
>> +		} else if (!strncmp(buf, "activate", 8)) {
>> +			scsi_dh = sdev->scsi_dh_data->scsi_dh;
>> +
>> +			err = scsi_dh->activate(sdev);
>> +		}
>> +	}
>> +
>> +	return err<0?err:count;
>> +}
>> +
>> +static ssize_t
>> +show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +	struct scsi_device_handler *scsi_dh;
>> +
>> +	if (!sdev->scsi_dh_data)
>> +		return snprintf(buf, 20, "detached\n");
>> +
>> +	scsi_dh = sdev->scsi_dh_data->scsi_dh;
> 
> we can use it directly instead of this variable ?
> 
Yes.

>> +
>> +	return snprintf(buf, 20, "%s\n", scsi_dh->name);
>> +}
>> +
>> +static struct device_attribute scsi_dh_state_attr =
>> +	__ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
>> +	       store_dh_state);
>> +
>>  /*
>>   * scsi_dh_handler_attach - Attach a device handler to a device
>>   * @sdev - SCSI device the device handler should attach to
>> @@ -115,9 +164,11 @@ static int scsi_dh_notifier(struct notifier_block *nb,
>>
>>  	if (action == BUS_NOTIFY_ADD_DEVICE) {
>>  		scsi_dh_handler_attach(sdev, devinfo->handler);
>> +		device_create_file(dev, &scsi_dh_state_attr);
> 
> A later patch checks for the return status of scsi_dh_handler_attach(),
> should be moved here.
> 
Ok.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 2/7] scsi_dh: Add 'dh_state' sysfs attribute

[Hannes Reinecke]

Implement a 'dh_state' sdev attribute for dynamic device handler
manipulation. A read on the attribute will return the name of
the currently attached device handler or 'detached' if no handler
is attached.
The attribute allows the following strings to be written:
- The name of the device handler to be attached if the state is
  'detached'.
- 'activate' to trigger path activation if a device handler
  is attached.
- 'detach' to detach the currently attached device handler.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/device_handler/scsi_dh.c |  107 ++++++++++++++++++++++++++++++++-
 1 files changed, 105 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index 0b5c457..b80fae7 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -79,6 +79,98 @@ static void scsi_dh_handler_detach(struct scsi_device *sdev)
 }
 
 /*
+ * Functions for sysfs attribute 'dh_state'
+ */
+static ssize_t
+store_dh_state(struct device *dev, struct device_attribute *attr,
+	       const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct scsi_device_handler *scsi_dh;
+	int err = -EINVAL;
+
+	if (!sdev->scsi_dh_data) {
+		/*
+		 * Attach to a device handler
+		 */
+		if (!(scsi_dh = get_device_handler(buf)))
+			return err;
+		err = scsi_dh_handler_attach(sdev, scsi_dh);
+	} else {
+		if (!strncmp(buf, "detach", 6)) {
+			/*
+			 * Detach from a device handler
+			 */
+			scsi_dh_handler_detach(sdev);
+			err = 0;
+		} else if (!strncmp(buf, "activate", 8)) {
+			/*
+			 * Activate a device handler
+			 */
+			scsi_dh = sdev->scsi_dh_data->scsi_dh;
+			if (scsi_dh->activate)
+				err = scsi_dh->activate(sdev);
+			else
+				err = 0;
+		}
+	}
+
+	return err<0?err:count;
+}
+
+static ssize_t
+show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+
+	if (!sdev->scsi_dh_data)
+		return snprintf(buf, 20, "detached\n");
+
+	return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
+}
+
+static struct device_attribute scsi_dh_state_attr =
+	__ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
+	       store_dh_state);
+
+/*
+ * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
+ */
+static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
+{
+	struct scsi_device *sdev;
+	int err;
+
+	if (!scsi_is_sdev_device(dev))
+		return 0;
+
+	sdev = to_scsi_device(dev);
+
+	err = device_create_file(&sdev->sdev_gendev,
+				 &scsi_dh_state_attr);
+
+	return 0;
+}
+
+/*
+ * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
+ */
+static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
+{
+	struct scsi_device *sdev;
+
+	if (!scsi_is_sdev_device(dev))
+		return 0;
+
+	sdev = to_scsi_device(dev);
+
+	device_remove_file(&sdev->sdev_gendev,
+			   &scsi_dh_state_attr);
+
+	return 0;
+}
+
+/*
  * scsi_dh_notifier - notifier chain callback
  */
 static int scsi_dh_notifier(struct notifier_block *nb,
@@ -86,7 +178,7 @@ static int scsi_dh_notifier(struct notifier_block *nb,
 {
 	struct device *dev = data;
 	struct scsi_device *sdev;
-	int i, err = 0;
+	int i;
 	struct scsi_device_handler *tmp, *devinfo = NULL;
 
 	if (!scsi_is_sdev_device(dev))
@@ -114,14 +206,19 @@ static int scsi_dh_notifier(struct notifier_block *nb,
 		goto out;
 
 	if (action == BUS_NOTIFY_ADD_DEVICE) {
+		int err;
+
 		err = scsi_dh_handler_attach(sdev, devinfo);
+		if (!err)
+			err = device_create_file(dev, &scsi_dh_state_attr);
 	} else if (action == BUS_NOTIFY_DEL_DEVICE) {
 		if (sdev->scsi_dh_data == NULL)
 			goto out;
+		device_remove_file(dev, &scsi_dh_state_attr);
 		scsi_dh_handler_detach(sdev);
 	}
 out:
-	return err;
+	return 0;
 }
 
 /*
@@ -275,11 +372,17 @@ static int __init scsi_dh_init(void)
 
 	r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
 
+	if (!r)
+		bus_for_each_dev(&scsi_bus_type, NULL, NULL,
+				 scsi_dh_sysfs_attr_add);
+
 	return r;
 }
 
 static void __exit scsi_dh_exit(void)
 {
+	bus_for_each_dev(&scsi_bus_type, NULL, NULL,
+			 scsi_dh_sysfs_attr_remove);
 	bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
 }
 
-- 
1.5.2.4