enclosure: handle non-unique element descriptors

Some SES devices give non-unique Element Descriptors as part of the
Element Descriptor diag page. Since we use these for creating sysfs
entries, they need to be unique. The specification doesn't require
these to be unique.

Eg:
$ sg_ses -p 7 /dev/sg0
  FTS CORP  TXS6_SAS20BPX12   0500
    enclosure services device
Element descriptor In diagnostic page:
  generation code: 0x0
  element descriptor by type list
    Element type: Array device, subenclosure id: 0
      Overall descriptor: ArrayDevicesInSubEnclsr0
      Element 1 descriptor: ArrayDevice00
      Element 2 descriptor: ArrayDevice01
      Element 3 descriptor: ArrayDevice02
      Element 4 descriptor: ArrayDevice03
      Element 5 descriptor: ArrayDevice03
      Element 6 descriptor: ArrayDevice03
      Element 7 descriptor: ArrayDevice03
      Element 8 descriptor: ArrayDevice03
      Element 9 descriptor: ArrayDevice03
      Element 10 descriptor: ArrayDevice03
      Element 11 descriptor: ArrayDevice03
      Element 12 descriptor: ArrayDevice03

Based on http://thread.gmane.org/gmane.linux.scsi/69289. This
version implements James' ideas about the naming convention

Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Acked-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/misc/enclosure.c

@@ -187,6 +187,7 @@ void enclosure_unregister(struct enclosure_device *edev)
 EXPORT_SYMBOL_GPL(enclosure_unregister);
 
 #define ENCLOSURE_NAME_SIZE	64
+#define COMPONENT_NAME_SIZE	64
 
 static void enclosure_link_name(struct enclosure_component *cdev, char *name)
 {
@@ -246,6 +247,29 @@ static void enclosure_component_release(struct device *dev)
 	put_device(dev->parent);
 }
 
+static struct enclosure_component *
+enclosure_component_find_by_name(struct enclosure_device *edev,
+				const char *name)
+{
+	int i;
+	const char *cname;
+	struct enclosure_component *ecomp;
+
+	if (!edev || !name || !name[0])
+		return NULL;
+
+	for (i = 0; i < edev->components; i++) {
+		ecomp = &edev->component[i];
+		cname = dev_name(&ecomp->cdev);
+		if (ecomp->number != -1 &&
+		    cname && cname[0] &&
+		    !strcmp(cname, name))
+			return ecomp;
+	}
+
+	return NULL;
+}
+
 static const struct attribute_group *enclosure_component_groups[];
 
 /**
@@ -269,7 +293,8 @@ enclosure_component_register(struct enclosure_device *edev,
 {
 	struct enclosure_component *ecomp;
 	struct device *cdev;
-	int err;
+	int err, i;
+	char newname[COMPONENT_NAME_SIZE];
 
 	if (number >= edev->components)
 		return ERR_PTR(-EINVAL);
@@ -283,9 +308,20 @@ enclosure_component_register(struct enclosure_device *edev,
 	ecomp->number = number;
 	cdev = &ecomp->cdev;
 	cdev->parent = get_device(&edev->edev);
-	if (name && name[0])
-		dev_set_name(cdev, "%s", name);
-	else
+
+	if (name && name[0]) {
+		/* Some hardware (e.g. enclosure in RX300 S6) has components
+		 * with non unique names. Registering duplicates in sysfs
+		 * will lead to warnings during bootup. So make the names
+		 * unique by appending consecutive numbers -1, -2, ... */
+		i = 1;
+		snprintf(newname, COMPONENT_NAME_SIZE,
+			 "%s", name);
+		while (enclosure_component_find_by_name(edev, newname))
+			snprintf(newname, COMPONENT_NAME_SIZE,
+				 "%s-%i", name, i++);
+		dev_set_name(cdev, "%s", newname);
+	} else
 		dev_set_name(cdev, "%u", number);
 
 	cdev->release = enclosure_component_release;