Allow device rescan to be triggered via sysfs.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Mike Miller <mikem@beardog.cce.hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/scsi/hpsa.c

@@ -147,10 +147,13 @@ static ssize_t lunid_show(struct device *dev,
 static ssize_t unique_id_show(struct device *dev,
 	struct device_attribute *attr, char *buf);
 static void hpsa_update_scsi_devices(struct ctlr_info *h, int hostno);
+static ssize_t host_store_rescan(struct device *dev,
+	 struct device_attribute *attr, const char *buf, size_t count);
 
 DEVICE_ATTR(raid_level, S_IRUGO, raid_level_show, NULL);
 DEVICE_ATTR(lunid, S_IRUGO, lunid_show, NULL);
 DEVICE_ATTR(unique_id, S_IRUGO, unique_id_show, NULL);
+DEVICE_ATTR(rescan, S_IWUSR, NULL, host_store_rescan);
 
 struct device_attribute *hpsa_sdev_attrs[] = {
 	&dev_attr_raid_level,
@@ -159,6 +162,11 @@ struct device_attribute *hpsa_sdev_attrs[] = {
 	NULL,
 };
 
+static struct device_attribute *hpsa_shost_attrs[] = {
+	&dev_attr_rescan,
+	NULL,
+};
+
 static struct scsi_host_template hpsa_driver_template = {
 	.module			= THIS_MODULE,
 	.name			= "hpsa",
@@ -177,6 +185,7 @@ static struct scsi_host_template hpsa_driver_template = {
 	.compat_ioctl		= hpsa_compat_ioctl,
 #endif
 	.sdev_attrs = hpsa_sdev_attrs,
+	.shost_attrs = hpsa_shost_attrs,
 };
 
 static inline struct ctlr_info *sdev_to_hba(struct scsi_device *sdev)
@@ -308,6 +317,21 @@ static int scan_thread(__attribute__((unused)) void *data)
 	return 0;
 }
 
+static ssize_t host_store_rescan(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct ctlr_info *h;
+	struct Scsi_Host *shost = class_to_shost(dev);
+	unsigned long *priv = shost_priv(shost);
+	h = (struct ctlr_info *) *priv;
+	if (add_to_scan_list(h)) {
+		wake_up_process(hpsa_scan_thread);
+		wait_for_completion_interruptible(&h->scan_wait);
+	}
+	return count;
+}
+
 /* Enqueuing and dequeuing functions for cmdlists. */
 static inline void addQ(struct hlist_head *list, struct CommandList *c)
 {