diff mbox

[3/5] scsi: Add 'access_state' attribute

Message ID 1436353788-104911-4-git-send-email-hare@suse.de (mailing list archive)
State New, archived
Headers show

Commit Message

Hannes Reinecke July 8, 2015, 11:09 a.m. UTC 
Add an 'access_state' attribute to display the LUN access state.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/scsi_sysfs.c  | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 include/scsi/scsi_device.h | 13 ++++++++++++
 include/scsi/scsi_dh.h     |  1 +
 3 files changed, 67 insertions(+)

Comments

Christoph Hellwig July 9, 2015, 8:22 a.m. UTC | #1 
On Wed, Jul 08, 2015 at 01:09:46PM +0200, Hannes Reinecke wrote:
> Add an 'access_state' attribute to display the LUN access state.

Should we just reuse the ALUA values here as they part of the spec
and map the legacy implemetation values to it?

I'd also really love to store the access_state variable in
struct scsi_device so we can perform the checks for it in core code
instead of the device handlers.
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Hannes Reinecke July 9, 2015, 8:43 a.m. UTC | #2 
On 07/09/2015 10:22 AM, Christoph Hellwig wrote:
> On Wed, Jul 08, 2015 at 01:09:46PM +0200, Hannes Reinecke wrote:
>> Add an 'access_state' attribute to display the LUN access state.
> 
> Should we just reuse the ALUA values here as they part of the spec
> and map the legacy implemetation values to it?
> 
That's what I've attempted to; only I've displayed them as text,
not as a numeric value.
But sure, the idea was to take the ALUA values and map legacy
implementation onto it.

> I'd also really love to store the access_state variable in
> struct scsi_device so we can perform the checks for it in core code
> instead of the device handlers.
> 
That would be a good idea indeed. I had been pondering the idea of a
revamped multipath integration, where this would be come in handy.

I can easily adapt the patches here.

Cheers,

Hannes
diff mbox

Patch

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index b4de776..5f1a981 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -81,6 +81,34 @@  const char *scsi_host_state_name(enum scsi_host_state state)
 	return name;
 }
 
+static const struct {
+	enum scsi_access_state	value;
+	char			*name;
+} sdev_access_states[] = {
+	{ SCSI_ACCESS_STATE_UNKNOWN, "unknown" },
+	{ SCSI_ACCESS_STATE_OPTIMAL, "optimal" },
+	{ SCSI_ACCESS_STATE_ACTIVE, "active" },
+	{ SCSI_ACCESS_STATE_PASSIVE, "passive" },
+	{ SCSI_ACCESS_STATE_UNAVAILABLE, "unavailable" },
+	{ SCSI_ACCESS_STATE_LBA, "lba-dependent" },
+	{ SCSI_ACCESS_STATE_OFFLINE, "offline" },
+	{ SCSI_ACCESS_STATE_TRANSITIONING, "transitioning" },
+	{ SCSI_ACCESS_STATE_PREFERRED, "preferred" },
+};
+const char *scsi_access_state_name(enum scsi_access_state state)
+{
+	int i;
+	char *name = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(sdev_access_states); i++) {
+		if (sdev_access_states[i].value == state) {
+			name = sdev_access_states[i].name;
+			break;
+		}
+	}
+	return name;
+}
+
 static int check_set(unsigned long long *val, char *src)
 {
 	char *last;
@@ -934,6 +962,30 @@  sdev_store_dh_state(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(dh_state, S_IRUGO | S_IWUSR, sdev_show_dh_state,
 		   sdev_store_dh_state);
+
+static ssize_t
+sdev_show_access_state(struct device *dev,
+		       struct device_attribute *attr,
+		       char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	enum scsi_access_state access_state = SCSI_ACCESS_STATE_UNKNOWN;
+	bool pref = false;
+
+	if (sdev->handler && sdev->handler->state) {
+		int state = sdev->handler->state(sdev);
+
+		if (state & SCSI_ACCESS_STATE_PREFERRED)
+			pref = true;
+
+		access_state = (state & SCSI_ACCESS_STATE_MASK);
+	}
+
+	return snprintf(buf, 32, "%s%s\n",
+			scsi_access_state_name(access_state),
+			pref ? " preferred" :"");
+}
+static DEVICE_ATTR(access_state, S_IRUGO, sdev_show_access_state, NULL);
 #endif
 
 static ssize_t
@@ -1007,6 +1059,7 @@  static struct attribute *scsi_sdev_attrs[] = {
 	&dev_attr_queue_type.attr,
 #ifdef CONFIG_SCSI_DH
 	&dev_attr_dh_state.attr,
+	&dev_attr_access_state.attr,
 #endif
 	&dev_attr_queue_ramp_up_period.attr,
 	REF_EVT(media_change),
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index d2f8b7a..4a10737 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -50,6 +50,19 @@  enum scsi_device_state {
 	SDEV_CREATED_BLOCK,	/* same as above but for created devices */
 };
 
+enum scsi_access_state {
+	SCSI_ACCESS_STATE_UNKNOWN = 0,
+	SCSI_ACCESS_STATE_OPTIMAL,
+	SCSI_ACCESS_STATE_ACTIVE,
+	SCSI_ACCESS_STATE_PASSIVE,
+	SCSI_ACCESS_STATE_UNAVAILABLE,
+	SCSI_ACCESS_STATE_LBA,
+	SCSI_ACCESS_STATE_OFFLINE,
+	SCSI_ACCESS_STATE_TRANSITIONING,
+	SCSI_ACCESS_STATE_PREFERRED = 0x80
+};
+#define SCSI_ACCESS_STATE_MASK 0x7f
+
 enum scsi_device_event {
 	SDEV_EVT_MEDIA_CHANGE	= 1,	/* media has changed */
 	SDEV_EVT_INQUIRY_CHANGE_REPORTED,		/* 3F 03  UA reported */
diff --git a/include/scsi/scsi_dh.h b/include/scsi/scsi_dh.h
index 5c73062..bc1b9f0 100644
--- a/include/scsi/scsi_dh.h
+++ b/include/scsi/scsi_dh.h
@@ -71,6 +71,7 @@  struct scsi_device_handler {
 	int (*prep_fn)(struct scsi_device *, struct request *);
 	int (*set_params)(struct scsi_device *, const char *);
 	void (*rescan)(struct scsi_device *);
+	int (*state)(struct scsi_device *);
 };
 
 #ifdef CONFIG_SCSI_DH