SCSI: revamp target scanning routines

The basic change is to allow target scans to be done
by generic device (which need only have a scsi host
as a parent).  Also changes most target functions to
take a struct scsi_target instead of the H/C/T numbers.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/hosts.c

@@ -216,6 +216,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 	spin_lock_init(&shost->default_lock);
 	scsi_assign_lock(shost, &shost->default_lock);
 	INIT_LIST_HEAD(&shost->__devices);
+	INIT_LIST_HEAD(&shost->__targets);
 	INIT_LIST_HEAD(&shost->eh_cmd_q);
 	INIT_LIST_HEAD(&shost->starved_list);
 	init_waitqueue_head(&shost->host_wait);

drivers/scsi/scsi.c

@@ -1115,6 +1115,60 @@ void starget_for_each_device(struct scsi_target *starget, void * data,
 }
 EXPORT_SYMBOL(starget_for_each_device);
 
+/**
+ * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
+ * @starget:	SCSI target pointer
+ * @lun:	SCSI Logical Unit Number
+ *
+ * Looks up the scsi_device with the specified @lun for a give
+ * @starget. The returned scsi_device does not have an additional
+ * reference.  You must hold the host's host_lock over this call and
+ * any access to the returned scsi_device.
+ *
+ * Note:  The only reason why drivers would want to use this is because
+ * they're need to access the device list in irq context.  Otherwise you
+ * really want to use scsi_device_lookup_by_target instead.
+ **/
+struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
+						   uint lun)
+{
+	struct scsi_device *sdev;
+
+	list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
+		if (sdev->lun ==lun)
+			return sdev;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(__scsi_device_lookup_by_target);
+
+/**
+ * scsi_device_lookup_by_target - find a device given the target
+ * @starget:	SCSI target pointer
+ * @lun:	SCSI Logical Unit Number
+ *
+ * Looks up the scsi_device with the specified @channel, @id, @lun for a
+ * give host.  The returned scsi_device has an additional reference that
+ * needs to be release with scsi_host_put once you're done with it.
+ **/
+struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
+						 uint lun)
+{
+	struct scsi_device *sdev;
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+	unsigned long flags;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	sdev = __scsi_device_lookup_by_target(starget, lun);
+	if (sdev && scsi_device_get(sdev))
+		sdev = NULL;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	return sdev;
+}
+EXPORT_SYMBOL(scsi_device_lookup_by_target);
+
 /**
  * scsi_device_lookup - find a device given the host (UNLOCKED)
  * @shost:	SCSI host pointer

drivers/scsi/scsi_lib.c

@@ -365,10 +365,11 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev)
 {
 	struct Scsi_Host *shost = current_sdev->host;
 	struct scsi_device *sdev, *tmp;
+	struct scsi_target *starget = scsi_target(current_sdev);
 	unsigned long flags;
 
 	spin_lock_irqsave(shost->host_lock, flags);
-	scsi_target(current_sdev)->starget_sdev_user = NULL;
+	starget->starget_sdev_user = NULL;
 	spin_unlock_irqrestore(shost->host_lock, flags);
 
 	/*
@@ -380,10 +381,12 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev)
 	blk_run_queue(current_sdev->request_queue);
 
 	spin_lock_irqsave(shost->host_lock, flags);
-	if (scsi_target(current_sdev)->starget_sdev_user)
+	if (starget->starget_sdev_user)
 		goto out;
-	list_for_each_entry_safe(sdev, tmp, &current_sdev->same_target_siblings,
+	list_for_each_entry_safe(sdev, tmp, &starget->devices,
 			same_target_siblings) {
+		if (sdev == current_sdev)
+			continue;
 		if (scsi_device_get(sdev))
 			continue;
 

drivers/scsi/scsi_sysfs.c

@@ -154,33 +154,25 @@ void scsi_device_dev_release(struct device *dev)
 {
 	struct scsi_device *sdev;
 	struct device *parent;
+	struct scsi_target *starget;
 	unsigned long flags;
-	int delete;
 
 	parent = dev->parent;
 	sdev = to_scsi_device(dev);
+	starget = to_scsi_target(parent);
 
 	spin_lock_irqsave(sdev->host->host_lock, flags);
-	/* If we're the last LUN on the target, destroy the target */
-	delete = list_empty(&sdev->same_target_siblings);
+	starget->reap_ref++;
 	list_del(&sdev->siblings);
 	list_del(&sdev->same_target_siblings);
 	list_del(&sdev->starved_entry);
 	spin_unlock_irqrestore(sdev->host->host_lock, flags);
 
-	if (delete) {
-		struct scsi_target *starget = to_scsi_target(parent);
-		if (!starget->create) {
-			transport_remove_device(&starget->dev);
-			device_del(parent);
-		}
-		transport_destroy_device(&starget->dev);
-
-		put_device(parent);
-	}
 	if (sdev->request_queue)
 		scsi_free_queue(sdev->request_queue);
 
+	scsi_target_reap(scsi_target(sdev));
+
 	kfree(sdev->inquiry);
 	kfree(sdev);
 
@@ -560,14 +552,6 @@ static int attr_add(struct device *dev, struct device_attribute *attr)
 	return device_create_file(dev, attr);
 }
 
-static void scsi_target_dev_release(struct device *dev)
-{
-	struct scsi_target *starget = to_scsi_target(dev);
-	struct device *parent = dev->parent;
-	kfree(starget);
-	put_device(parent);
-}
-
 /**
  * scsi_sysfs_add_sdev - add scsi device to sysfs
  * @sdev:	scsi_device to add
@@ -577,25 +561,16 @@ static void scsi_target_dev_release(struct device *dev)
  **/
 int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 {
-	struct scsi_target *starget = sdev->sdev_target;
 	struct Scsi_Host *shost = sdev->host;
-	int error, i, create;
+	struct scsi_target *starget = scsi_target(sdev);
+	int error, i;
 	unsigned long flags;
 
 	spin_lock_irqsave(shost->host_lock, flags);
-	create = starget->create;
-	starget->create = 0;
+	list_add_tail(&sdev->same_target_siblings, &starget->devices);
+	list_add_tail(&sdev->siblings, &shost->__devices);
 	spin_unlock_irqrestore(shost->host_lock, flags);
 
-	if (create) {
-		error = device_add(&starget->dev);
-		if (error) {
-			printk(KERN_ERR "Target device_add failed\n");
-			return error;
-		}
-		transport_add_device(&starget->dev);
-	}
-
 	if ((error = scsi_device_set_state(sdev, SDEV_RUNNING)) != 0)
 		return error;
 
@@ -643,7 +618,6 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
  out:
 	return error;
 
-	class_device_del(&sdev->sdev_classdev);
  clean_device:
 	scsi_device_set_state(sdev, SDEV_CANCEL);
 
@@ -673,12 +647,40 @@ void scsi_remove_device(struct scsi_device *sdev)
 		sdev->host->hostt->slave_destroy(sdev);
 	transport_unregister_device(&sdev->sdev_gendev);
 	put_device(&sdev->sdev_gendev);
-
 out:
 	up(&shost->scan_mutex);
 }
 EXPORT_SYMBOL(scsi_remove_device);
 
+/**
+ * scsi_remove_target - try to remove a target and all its devices
+ * @starget: the target to remove
+ *
+ * Note: This is slightly racy.  It is possible that if the user
+ * requests the addition of another device then the target won't be
+ * removed.
+ */
+void scsi_remove_target(struct scsi_target *starget)
+{
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+	unsigned long flags;
+	struct scsi_device *sdev, *tmp;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	starget->reap_ref++;
+	list_for_each_entry_safe(sdev, tmp, &shost->__devices, siblings) {
+		if (sdev->channel != starget->channel ||
+		    sdev->id != starget->id)
+			continue;
+		spin_unlock_irqrestore(shost->host_lock, flags);
+		scsi_remove_device(sdev);
+		spin_lock_irqsave(shost->host_lock, flags);
+	}
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	scsi_target_reap(starget);
+}
+EXPORT_SYMBOL(scsi_remove_target);
+
 int scsi_register_driver(struct device_driver *drv)
 {
 	drv->bus = &scsi_bus_type;
@@ -780,7 +782,7 @@ void scsi_sysfs_device_initialize(struct scsi_device *sdev)
 	snprintf(sdev->sdev_classdev.class_id, BUS_ID_SIZE,
 		 "%d:%d:%d:%d", sdev->host->host_no,
 		 sdev->channel, sdev->id, sdev->lun);
-
+	sdev->scsi_level = SCSI_2;
 	transport_setup_device(&sdev->sdev_gendev);
 }
 
@@ -790,73 +792,6 @@ int scsi_is_sdev_device(const struct device *dev)
 }
 EXPORT_SYMBOL(scsi_is_sdev_device);
 
-int scsi_sysfs_target_initialize(struct scsi_device *sdev)
-{
-	struct scsi_target *starget = NULL;
-	struct Scsi_Host *shost = sdev->host;
-	struct scsi_device *device;
-	struct device *dev = NULL;
-	unsigned long flags;
-	int create = 0;
-
-	spin_lock_irqsave(shost->host_lock, flags);
-	/*
-	 * Search for an existing target for this sdev.
-	 */
-	list_for_each_entry(device, &shost->__devices, siblings) {
-		if (device->id == sdev->id &&
-		    device->channel == sdev->channel) {
-			list_add_tail(&sdev->same_target_siblings,
-				      &device->same_target_siblings);
-			sdev->scsi_level = device->scsi_level;
-			starget = device->sdev_target;
-			break;
-		}
-	}
-			
-	if (!starget) {
-		const int size = sizeof(*starget) +
-			shost->transportt->target_size;
-		starget = kmalloc(size, GFP_ATOMIC);
-		if (!starget) {
-			printk(KERN_ERR "%s: allocation failure\n", __FUNCTION__);
-			spin_unlock_irqrestore(shost->host_lock,
-					       flags);
-			return -ENOMEM;
-		}
-		memset(starget, 0, size);
-		dev = &starget->dev;
-		device_initialize(dev);
-		dev->parent = get_device(&shost->shost_gendev);
-		dev->release = scsi_target_dev_release;
-		sprintf(dev->bus_id, "target%d:%d:%d",
-			shost->host_no, sdev->channel, sdev->id);
-		starget->id = sdev->id;
-		starget->channel = sdev->channel;
-		create = starget->create = 1;
-		/*
-		 * If there wasn't another lun already configured at
-		 * this target, then default this device to SCSI_2
-		 * until we know better
-		 */
-		sdev->scsi_level = SCSI_2;
-	}
-	get_device(&starget->dev);
-	sdev->sdev_gendev.parent = &starget->dev;
-	sdev->sdev_target = starget;
-	list_add_tail(&sdev->siblings, &shost->__devices);
-	spin_unlock_irqrestore(shost->host_lock, flags);
-	if (create)
-		transport_setup_device(&starget->dev);
-	return 0;
-}
-
-int scsi_is_target_device(const struct device *dev)
-{
-	return dev->release == scsi_target_dev_release;
-}
-EXPORT_SYMBOL(scsi_is_target_device);
-
 /* A blank transport template that is used in drivers that don't
  * yet implement Transport Attributes */
 struct scsi_transport_template blank_transport_template = { NULL, };

include/scsi/scsi_device.h

@@ -144,7 +144,10 @@ struct scsi_device {
  */
 struct scsi_target {
 	struct scsi_device	*starget_sdev_user;
+	struct list_head	siblings;
+	struct list_head	devices;
 	struct device		dev;
+	unsigned int		reap_ref; /* protected by the host lock */
 	unsigned int		channel;
 	unsigned int		id; /* target id ... replace
 				     * scsi_device.id eventually */
@@ -173,6 +176,10 @@ extern struct scsi_device *scsi_device_lookup(struct Scsi_Host *,
 					      uint, uint, uint);
 extern struct scsi_device *__scsi_device_lookup(struct Scsi_Host *,
 						uint, uint, uint);
+extern struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *,
+							uint);
+extern struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *,
+							  uint);
 extern void starget_for_each_device(struct scsi_target *, void *,
 		     void (*fn)(struct scsi_device *, void *));
 
@@ -226,6 +233,10 @@ extern int scsi_device_quiesce(struct scsi_device *sdev);
 extern void scsi_device_resume(struct scsi_device *sdev);
 extern void scsi_target_quiesce(struct scsi_target *);
 extern void scsi_target_resume(struct scsi_target *);
+extern void scsi_scan_target(struct device *parent, unsigned int channel,
+			     unsigned int id, unsigned int lun, int rescan);
+extern void scsi_target_reap(struct scsi_target *);
+extern void scsi_remove_target(struct scsi_target *);
 extern const char *scsi_device_state_name(enum scsi_device_state);
 extern int scsi_is_sdev_device(const struct device *);
 extern int scsi_is_target_device(const struct device *);

include/scsi/scsi_host.h

@@ -416,6 +416,7 @@ struct Scsi_Host {
 	 * access this list directly from a driver.
 	 */
 	struct list_head	__devices;
+	struct list_head	__targets;
 	
 	struct scsi_host_cmd_pool *cmd_pool;
 	spinlock_t		free_list_lock;
@@ -553,11 +554,21 @@ struct Scsi_Host {
 	unsigned long hostdata[0]  /* Used for storage of host specific stuff */
 		__attribute__ ((aligned (sizeof(unsigned long))));
 };
-#define		dev_to_shost(d)		\
-	container_of(d, struct Scsi_Host, shost_gendev)
+
 #define		class_to_shost(d)	\
 	container_of(d, struct Scsi_Host, shost_classdev)
 
+int scsi_is_host_device(const struct device *);
+
+static inline struct Scsi_Host *dev_to_shost(struct device *dev)
+{
+	while (!scsi_is_host_device(dev)) {
+		if (!dev->parent)
+			return NULL;
+		dev = dev->parent;
+	}
+	return container_of(dev, struct Scsi_Host, shost_gendev);
+}
 
 extern struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *, int);
 extern int __must_check scsi_add_host(struct Scsi_Host *, struct device *);
@@ -601,8 +612,6 @@ struct class_container;
  */
 extern void scsi_free_host_dev(struct scsi_device *);
 extern struct scsi_device *scsi_get_host_dev(struct Scsi_Host *);
-int scsi_is_host_device(const struct device *);
-
 
 /* legacy interfaces */
 extern struct Scsi_Host *scsi_register(struct scsi_host_template *, int);