diff --git a/drivers/md/dm-hw-handler.c b/drivers/md/dm-hw-handler.c
new file mode 100644
index 0000000..ae63772
--- /dev/null
+++ b/drivers/md/dm-hw-handler.c
@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ *
+ * Multipath hardware handler registration.
+ */
+
+#include "dm.h"
+#include "dm-hw-handler.h"
+
+#include <linux/slab.h>
+
+struct hwh_internal {
+	struct hw_handler_type hwht;
+
+	struct list_head list;
+	long use;
+};
+
+#define hwht_to_hwhi(__hwht) container_of((__hwht), struct hwh_internal, hwht)
+
+static LIST_HEAD(_hw_handlers);
+static DECLARE_RWSEM(_hwh_lock);
+
+struct hwh_internal *__find_hw_handler_type(const char *name)
+{
+	struct hwh_internal *hwhi;
+
+	list_for_each_entry(hwhi, &_hw_handlers, list) {
+		if (!strcmp(name, hwhi->hwht.name))
+			return hwhi;
+	}
+
+	return NULL;
+}
+
+static struct hwh_internal *get_hw_handler(const char *name)
+{
+	struct hwh_internal *hwhi;
+
+	down_read(&_hwh_lock);
+	hwhi = __find_hw_handler_type(name);
+	if (hwhi) {
+		if ((hwhi->use == 0) && !try_module_get(hwhi->hwht.module))
+			hwhi = NULL;
+		else
+			hwhi->use++;
+	}
+	up_read(&_hwh_lock);
+
+	return hwhi;
+}
+
+struct hw_handler_type *dm_get_hw_handler(const char *name)
+{
+	struct hwh_internal *hwhi;
+
+	if (!name)
+		return NULL;
+
+	hwhi = get_hw_handler(name);
+	if (!hwhi) {
+		request_module("dm-%s", name);
+		hwhi = get_hw_handler(name);
+	}
+
+	return hwhi ? &hwhi->hwht : NULL;
+}
+
+void dm_put_hw_handler(struct hw_handler_type *hwht)
+{
+	struct hwh_internal *hwhi;
+
+	if (!hwht)
+		return;
+
+	down_read(&_hwh_lock);
+	hwhi = __find_hw_handler_type(hwht->name);
+	if (!hwhi)
+		goto out;
+
+	if (--hwhi->use == 0)
+		module_put(hwhi->hwht.module);
+
+	if (hwhi->use < 0)
+		BUG();
+
+      out:
+	up_read(&_hwh_lock);
+}
+
+static struct hwh_internal *_alloc_hw_handler(struct hw_handler_type *hwht)
+{
+	struct hwh_internal *hwhi = kmalloc(sizeof(*hwhi), GFP_KERNEL);
+
+	if (hwhi) {
+		memset(hwhi, 0, sizeof(*hwhi));
+		hwhi->hwht = *hwht;
+	}
+
+	return hwhi;
+}
+
+int dm_register_hw_handler(struct hw_handler_type *hwht)
+{
+	int r = 0;
+	struct hwh_internal *hwhi = _alloc_hw_handler(hwht);
+
+	if (!hwhi)
+		return -ENOMEM;
+
+	down_write(&_hwh_lock);
+
+	if (__find_hw_handler_type(hwht->name)) {
+		kfree(hwhi);
+		r = -EEXIST;
+	} else
+		list_add(&hwhi->list, &_hw_handlers);
+
+	up_write(&_hwh_lock);
+
+	return r;
+}
+
+int dm_unregister_hw_handler(struct hw_handler_type *hwht)
+{
+	struct hwh_internal *hwhi;
+
+	down_write(&_hwh_lock);
+
+	hwhi = __find_hw_handler_type(hwht->name);
+	if (!hwhi) {
+		up_write(&_hwh_lock);
+		return -EINVAL;
+	}
+
+	if (hwhi->use) {
+		up_write(&_hwh_lock);
+		return -ETXTBSY;
+	}
+
+	list_del(&hwhi->list);
+
+	up_write(&_hwh_lock);
+
+	kfree(hwhi);
+
+	return 0;
+}
+
+unsigned dm_scsi_err_handler(struct hw_handler *hwh, struct bio *bio)
+{
+#if 0
+	int sense_key, asc, ascq;
+
+	if (bio->bi_error & BIO_SENSE) {
+		/* FIXME: This is just an initial guess. */
+		/* key / asc / ascq */
+		sense_key = (bio->bi_error >> 16) & 0xff;
+		asc = (bio->bi_error >> 8) & 0xff;
+		ascq = bio->bi_error & 0xff;
+
+		switch (sense_key) {
+			/* This block as a whole comes from the device.
+			 * So no point retrying on another path. */
+		case 0x03:	/* Medium error */
+		case 0x05:	/* Illegal request */
+		case 0x07:	/* Data protect */
+		case 0x08:	/* Blank check */
+		case 0x0a:	/* copy aborted */
+		case 0x0c:	/* obsolete - no clue ;-) */
+		case 0x0d:	/* volume overflow */
+		case 0x0e:	/* data miscompare */
+		case 0x0f:	/* reserved - no idea either. */
+			return MP_ERROR_IO;
+
+			/* For these errors it's unclear whether they
+			 * come from the device or the controller.
+			 * So just lets try a different path, and if
+			 * it eventually succeeds, user-space will clear
+			 * the paths again... */
+		case 0x02:	/* Not ready */
+		case 0x04:	/* Hardware error */
+		case 0x09:	/* vendor specific */
+		case 0x0b:	/* Aborted command */
+			return MP_FAIL_PATH;
+
+		case 0x06:	/* Unit attention - might want to decode */
+			if (asc == 0x04 && ascq == 0x01)
+				/* "Unit in the process of
+				 * becoming ready" */
+				return 0;
+			return MP_FAIL_PATH;
+
+			/* FIXME: For Unit Not Ready we may want
+			 * to have a generic pg activation
+			 * feature (START_UNIT). */
+
+			/* Should these two ever end up in the
+			 * error path? I don't think so. */
+		case 0x00:	/* No sense */
+		case 0x01:	/* Recovered error */
+			return 0;
+		}
+	}
+#endif
+
+	/* We got no idea how to decode the other kinds of errors ->
+	 * assume generic error condition. */
+	return MP_FAIL_PATH;
+}
+
+EXPORT_SYMBOL_GPL(dm_register_hw_handler);
+EXPORT_SYMBOL_GPL(dm_unregister_hw_handler);
+EXPORT_SYMBOL_GPL(dm_scsi_err_handler);