storvsc: force discovery of LUNs that may have been removed.

{

	struct storvsc_scan_work *wrk;

	struct Scsi_Host *host;

	struct scsi_device *sdev;

	unsigned long flags;

	wrk = container_of(work, struct storvsc_scan_work, work);

	host = wrk->host;

	/*

	 * Before scanning the host, first check to see if any of the

	 * currrently known devices have been hot removed. We issue a

	 * "unit ready" command against all currently known devices.

	 * This I/O will result in an error for devices that have been

	 * removed. As part of handling the I/O error, we remove the device.

	 *

	 * When a LUN is added or removed, the host sends us a signal to

	 * scan the host. Thus we are forced to discover the LUNs that

	 * may have been removed this way.

	 */

	mutex_lock(&host->scan_mutex);

	spin_lock_irqsave(host->host_lock, flags);

	list_for_each_entry(sdev, &host->__devices, siblings) {

		spin_unlock_irqrestore(host->host_lock, flags);

		scsi_test_unit_ready(sdev, 1, 1, NULL);

		spin_lock_irqsave(host->host_lock, flags);

		continue;

	}

	spin_unlock_irqrestore(host->host_lock, flags);

	mutex_unlock(&host->scan_mutex);

	/*

	 * Now scan the host to discover LUNs that may have been added.

	 */

	scsi_scan_host(host);

	kfree(wrk);