diff --git a/drivers/md/dm-era-target.c b/drivers/md/dm-era-target.c
index 854b1be8b452..62f679faf9e7 100644
--- a/drivers/md/dm-era-target.c
+++ b/drivers/md/dm-era-target.c
@@ -134,7 +134,7 @@ static int writeset_test_and_set(struct dm_disk_bitset *info,
 {
 	int r;
 
-	if (!test_and_set_bit(block, ws->bits)) {
+	if (!test_bit(block, ws->bits)) {
 		r = dm_bitset_set_bit(info, ws->md.root, block, &ws->md.root);
 		if (r) {
 			/* FIXME: fail mode */
@@ -1226,8 +1226,10 @@ static void process_deferred_bios(struct era *era)
 	int r;
 	struct bio_list deferred_bios, marked_bios;
 	struct bio *bio;
+	struct blk_plug plug;
 	bool commit_needed = false;
 	bool failed = false;
+	struct writeset *ws = era->md->current_writeset;
 
 	bio_list_init(&deferred_bios);
 	bio_list_init(&marked_bios);
@@ -1237,9 +1239,11 @@ static void process_deferred_bios(struct era *era)
 	bio_list_init(&era->deferred_bios);
 	spin_unlock(&era->deferred_lock);
 
+	if (bio_list_empty(&deferred_bios))
+		return;
+
 	while ((bio = bio_list_pop(&deferred_bios))) {
-		r = writeset_test_and_set(&era->md->bitset_info,
-					  era->md->current_writeset,
+		r = writeset_test_and_set(&era->md->bitset_info, ws,
 					  get_block(era, bio));
 		if (r < 0) {
 			/*
@@ -1247,7 +1251,6 @@ static void process_deferred_bios(struct era *era)
 			 * FIXME: finish.
 			 */
 			failed = true;
-
 		} else if (r == 0)
 			commit_needed = true;
 
@@ -1263,9 +1266,19 @@ static void process_deferred_bios(struct era *era)
 	if (failed)
 		while ((bio = bio_list_pop(&marked_bios)))
 			bio_io_error(bio);
-	else
-		while ((bio = bio_list_pop(&marked_bios)))
+	else {
+		blk_start_plug(&plug);
+		while ((bio = bio_list_pop(&marked_bios))) {
+			/*
+			 * Only update the in-core writeset if the on-disk one
+			 * was updated too.
+			 */
+			if (commit_needed)
+				set_bit(get_block(era, bio), ws->bits);
 			submit_bio_noacct(bio);
+		}
+		blk_finish_plug(&plug);
+	}
 }
 
 static void process_rpc_calls(struct era *era)