diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 2378ee8..2d9e755 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -549,6 +549,7 @@
  */
 struct thin_c {
 	struct dm_dev *pool_dev;
+	struct dm_dev *origin_dev;
 	dm_thin_id dev_id;
 
 	struct pool *pool;
@@ -666,14 +667,16 @@
 		(bio->bi_sector & pool->offset_mask);
 }
 
-static void remap_and_issue(struct thin_c *tc, struct bio *bio,
-			    dm_block_t block)
+static void remap_to_origin(struct thin_c *tc, struct bio *bio)
+{
+	bio->bi_bdev = tc->origin_dev->bdev;
+}
+
+static void issue(struct thin_c *tc, struct bio *bio)
 {
 	struct pool *pool = tc->pool;
 	unsigned long flags;
 
-	remap(tc, bio, block);
-
 	/*
 	 * Batch together any FUA/FLUSH bios we find and then issue
 	 * a single commit for them in process_deferred_bios().
@@ -686,6 +689,19 @@
 		generic_make_request(bio);
 }
 
+static void remap_to_origin_and_issue(struct thin_c *tc, struct bio *bio)
+{
+	remap_to_origin(tc, bio);
+	issue(tc, bio);
+}
+
+static void remap_and_issue(struct thin_c *tc, struct bio *bio,
+			    dm_block_t block)
+{
+	remap(tc, bio, block);
+	issue(tc, bio);
+}
+
 /*
  * wake_worker() is used when new work is queued and when pool_resume is
  * ready to continue deferred IO processing.
@@ -932,7 +948,8 @@
 }
 
 static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
-			  dm_block_t data_origin, dm_block_t data_dest,
+			  struct dm_dev *origin, dm_block_t data_origin,
+			  dm_block_t data_dest,
 			  struct cell *cell, struct bio *bio)
 {
 	int r;
@@ -964,7 +981,7 @@
 	} else {
 		struct dm_io_region from, to;
 
-		from.bdev = tc->pool_dev->bdev;
+		from.bdev = origin->bdev;
 		from.sector = data_origin * pool->sectors_per_block;
 		from.count = pool->sectors_per_block;
 
@@ -982,6 +999,22 @@
 	}
 }
 
+static void schedule_internal_copy(struct thin_c *tc, dm_block_t virt_block,
+				   dm_block_t data_origin, dm_block_t data_dest,
+				   struct cell *cell, struct bio *bio)
+{
+	schedule_copy(tc, virt_block, tc->pool_dev,
+		      data_origin, data_dest, cell, bio);
+}
+
+static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,
+				   dm_block_t data_dest,
+				   struct cell *cell, struct bio *bio)
+{
+	schedule_copy(tc, virt_block, tc->origin_dev,
+		      virt_block, data_dest, cell, bio);
+}
+
 static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
 			  dm_block_t data_block, struct cell *cell,
 			  struct bio *bio)
@@ -1128,8 +1161,8 @@
 	r = alloc_data_block(tc, &data_block);
 	switch (r) {
 	case 0:
-		schedule_copy(tc, block, lookup_result->block,
-			      data_block, cell, bio);
+		schedule_internal_copy(tc, block, lookup_result->block,
+				       data_block, cell, bio);
 		break;
 
 	case -ENOSPC:
@@ -1203,7 +1236,10 @@
 	r = alloc_data_block(tc, &data_block);
 	switch (r) {
 	case 0:
-		schedule_zero(tc, block, data_block, cell, bio);
+		if (tc->origin_dev)
+			schedule_external_copy(tc, block, data_block, cell, bio);
+		else
+			schedule_zero(tc, block, data_block, cell, bio);
 		break;
 
 	case -ENOSPC:
@@ -1254,7 +1290,11 @@
 		break;
 
 	case -ENODATA:
-		provision_block(tc, bio, block, cell);
+		if (bio_data_dir(bio) == READ && tc->origin_dev) {
+			cell_release_singleton(cell, bio);
+			remap_to_origin_and_issue(tc, bio);
+		} else
+			provision_block(tc, bio, block, cell);
 		break;
 
 	default:
@@ -2237,6 +2277,8 @@
 	__pool_dec(tc->pool);
 	dm_pool_close_thin_device(tc->td);
 	dm_put_device(ti, tc->pool_dev);
+	if (tc->origin_dev)
+		dm_put_device(ti, tc->origin_dev);
 	kfree(tc);
 
 	mutex_unlock(&dm_thin_pool_table.mutex);
@@ -2245,21 +2287,22 @@
 /*
  * Thin target parameters:
  *
- * <pool_dev> <dev_id>
+ * <pool_dev> <dev_id> [origin_dev]
  *
  * pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
  * dev_id: the internal device identifier
+ * origin_dev: a device external to the pool that should act as the origin
  */
 static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
 	int r;
 	struct thin_c *tc;
-	struct dm_dev *pool_dev;
+	struct dm_dev *pool_dev, *origin_dev;
 	struct mapped_device *pool_md;
 
 	mutex_lock(&dm_thin_pool_table.mutex);
 
-	if (argc != 2) {
+	if (argc != 2 && argc != 3) {
 		ti->error = "Invalid argument count";
 		r = -EINVAL;
 		goto out_unlock;
@@ -2272,6 +2315,15 @@
 		goto out_unlock;
 	}
 
+	if (argc == 3) {
+		r = dm_get_device(ti, argv[2], FMODE_READ, &origin_dev);
+		if (r) {
+			ti->error = "Error opening origin device";
+			goto bad_origin_dev;
+		}
+		tc->origin_dev = origin_dev;
+	}
+
 	r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &pool_dev);
 	if (r) {
 		ti->error = "Error opening pool device";
@@ -2324,6 +2376,9 @@
 bad_common:
 	dm_put_device(ti, tc->pool_dev);
 bad_pool_dev:
+	if (tc->origin_dev)
+		dm_put_device(ti, tc->origin_dev);
+bad_origin_dev:
 	kfree(tc);
 out_unlock:
 	mutex_unlock(&dm_thin_pool_table.mutex);
@@ -2382,6 +2437,8 @@
 			DMEMIT("%s %lu",
 			       format_dev_t(buf, tc->pool_dev->bdev->bd_dev),
 			       (unsigned long) tc->dev_id);
+			if (tc->origin_dev)
+				DMEMIT(" %s", format_dev_t(buf, tc->origin_dev->bdev->bd_dev));
 			break;
 		}
 	}
@@ -2419,7 +2476,7 @@
 
 static struct target_type thin_target = {
 	.name = "thin",
-	.version = {1, 0, 0},
+	.version = {1, 1, 0},
 	.module	= THIS_MODULE,
 	.ctr = thin_ctr,
 	.dtr = thin_dtr,