diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index 9fb18c147825..b280c433e4a0 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -323,7 +323,7 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 	 * Corrupt successful READs while in down state.
 	 * If flags were specified, only corrupt those that match.
 	 */
-	if (!error && bio_submitted_while_down &&
+	if (fc->corrupt_bio_byte && !error && bio_submitted_while_down &&
 	    (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
 	    all_corrupt_bio_flags_match(bio, fc))
 		corrupt_bio_data(bio, fc);
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index ad2eba40e319..ea5dd289fe2a 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -296,6 +296,8 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
 	unsigned offset;
 	unsigned num_bvecs;
 	sector_t remaining = where->count;
+	struct request_queue *q = bdev_get_queue(where->bdev);
+	sector_t discard_sectors;
 
 	/*
 	 * where->count may be zero if rw holds a flush and we need to
@@ -305,9 +307,12 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
 		/*
 		 * Allocate a suitably sized-bio.
 		 */
-		num_bvecs = dm_sector_div_up(remaining,
-					     (PAGE_SIZE >> SECTOR_SHIFT));
-		num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev), num_bvecs);
+		if (rw & REQ_DISCARD)
+			num_bvecs = 1;
+		else
+			num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
+					  dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
+
 		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
 		bio->bi_sector = where->sector + (where->count - remaining);
 		bio->bi_bdev = where->bdev;
@@ -315,10 +320,14 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
 		bio->bi_destructor = dm_bio_destructor;
 		store_io_and_region_in_bio(bio, io, region);
 
-		/*
-		 * Try and add as many pages as possible.
-		 */
-		while (remaining) {
+		if (rw & REQ_DISCARD) {
+			discard_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
+			bio->bi_size = discard_sectors << SECTOR_SHIFT;
+			remaining -= discard_sectors;
+		} else while (remaining) {
+			/*
+			 * Try and add as many pages as possible.
+			 */
 			dp->get_page(dp, &page, &len, &offset);
 			len = min(len, to_bytes(remaining));
 			if (!bio_add_page(bio, page, len, offset))
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 31c2dc25886d..1ce84ed0b765 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1437,7 +1437,7 @@ static int target_message(struct dm_ioctl *param, size_t param_size)
 
 	if (!argc) {
 		DMWARN("Empty message received.");
-		goto out;
+		goto out_argv;
 	}
 
 	table = dm_get_live_table(md);
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 86cb7e5d83d5..787022c18187 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -668,7 +668,14 @@ static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
 		return ret;
 
 	sb = page_address(rdev->sb_page);
-	if (sb->magic != cpu_to_le32(DM_RAID_MAGIC)) {
+
+	/*
+	 * Two cases that we want to write new superblocks and rebuild:
+	 * 1) New device (no matching magic number)
+	 * 2) Device specified for rebuild (!In_sync w/ offset == 0)
+	 */
+	if ((sb->magic != cpu_to_le32(DM_RAID_MAGIC)) ||
+	    (!test_bit(In_sync, &rdev->flags) && !rdev->recovery_offset)) {
 		super_sync(rdev->mddev, rdev);
 
 		set_bit(FirstUse, &rdev->flags);
@@ -745,11 +752,8 @@ static int super_init_validation(struct mddev *mddev, struct md_rdev *rdev)
 	 */
 	rdev_for_each(r, t, mddev) {
 		if (!test_bit(In_sync, &r->flags)) {
-			if (!test_bit(FirstUse, &r->flags))
-				DMERR("Superblock area of "
-				      "rebuild device %d should have been "
-				      "cleared.", r->raid_disk);
-			set_bit(FirstUse, &r->flags);
+			DMINFO("Device %d specified for rebuild: "
+			       "Clearing superblock", r->raid_disk);
 			rebuilds++;
 		} else if (test_bit(FirstUse, &r->flags))
 			new_devs++;
@@ -971,6 +975,7 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
 	INIT_WORK(&rs->md.event_work, do_table_event);
 	ti->private = rs;
+	ti->num_flush_requests = 1;
 
 	mutex_lock(&rs->md.reconfig_mutex);
 	ret = md_run(&rs->md);
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 59c4f0446ffa..237571af77fd 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -385,6 +385,7 @@ static int init_pmd(struct dm_pool_metadata *pmd,
 		data_sm = dm_sm_disk_create(tm, nr_blocks);
 		if (IS_ERR(data_sm)) {
 			DMERR("sm_disk_create failed");
+			dm_tm_unlock(tm, sblock);
 			r = PTR_ERR(data_sm);
 			goto bad;
 		}
@@ -789,6 +790,11 @@ int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
 	return 0;
 }
 
+/*
+ * __open_device: Returns @td corresponding to device with id @dev,
+ * creating it if @create is set and incrementing @td->open_count.
+ * On failure, @td is undefined.
+ */
 static int __open_device(struct dm_pool_metadata *pmd,
 			 dm_thin_id dev, int create,
 			 struct dm_thin_device **td)
@@ -799,10 +805,16 @@ static int __open_device(struct dm_pool_metadata *pmd,
 	struct disk_device_details details_le;
 
 	/*
-	 * Check the device isn't already open.
+	 * If the device is already open, return it.
 	 */
 	list_for_each_entry(td2, &pmd->thin_devices, list)
 		if (td2->id == dev) {
+			/*
+			 * May not create an already-open device.
+			 */
+			if (create)
+				return -EEXIST;
+
 			td2->open_count++;
 			*td = td2;
 			return 0;
@@ -817,6 +829,9 @@ static int __open_device(struct dm_pool_metadata *pmd,
 		if (r != -ENODATA || !create)
 			return r;
 
+		/*
+		 * Create new device.
+		 */
 		changed = 1;
 		details_le.mapped_blocks = 0;
 		details_le.transaction_id = cpu_to_le64(pmd->trans_id);
@@ -882,12 +897,10 @@ static int __create_thin(struct dm_pool_metadata *pmd,
 
 	r = __open_device(pmd, dev, 1, &td);
 	if (r) {
-		__close_device(td);
 		dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
 		dm_btree_del(&pmd->bl_info, dev_root);
 		return r;
 	}
-	td->changed = 1;
 	__close_device(td);
 
 	return r;
@@ -967,14 +980,14 @@ static int __create_snap(struct dm_pool_metadata *pmd,
 		goto bad;
 
 	r = __set_snapshot_details(pmd, td, origin, pmd->time);
+	__close_device(td);
+
 	if (r)
 		goto bad;
 
-	__close_device(td);
 	return 0;
 
 bad:
-	__close_device(td);
 	dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
 	dm_btree_remove(&pmd->details_info, pmd->details_root,
 			&key, &pmd->details_root);
@@ -1211,6 +1224,8 @@ static int __remove(struct dm_thin_device *td, dm_block_t block)
 	if (r)
 		return r;
 
+	td->mapped_blocks--;
+	td->changed = 1;
 	pmd->need_commit = 1;
 
 	return 0;