diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index 4ef1bf5..a9625b8 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -167,6 +167,20 @@ static struct nvm_dev *nvm_find_nvm_dev(const char *name)
 	return NULL;
 }
 
+struct nvm_block *nvm_get_blk_unlocked(struct nvm_dev *dev, struct nvm_lun *lun,
+							unsigned long flags)
+{
+	return dev->mt->get_blk_unlocked(dev, lun, flags);
+}
+EXPORT_SYMBOL(nvm_get_blk_unlocked);
+
+/* Assumes that all valid pages have already been moved on release to bm */
+void nvm_put_blk_unlocked(struct nvm_dev *dev, struct nvm_block *blk)
+{
+	return dev->mt->put_blk_unlocked(dev, blk);
+}
+EXPORT_SYMBOL(nvm_put_blk_unlocked);
+
 struct nvm_block *nvm_get_blk(struct nvm_dev *dev, struct nvm_lun *lun,
 							unsigned long flags)
 {
diff --git a/drivers/lightnvm/gennvm.c b/drivers/lightnvm/gennvm.c
index 12ddcaa..154ac03 100644
--- a/drivers/lightnvm/gennvm.c
+++ b/drivers/lightnvm/gennvm.c
@@ -60,7 +60,8 @@ static int gennvm_luns_init(struct nvm_dev *dev, struct gen_nvm *gn)
 		lun->vlun.lun_id = i % dev->luns_per_chnl;
 		lun->vlun.chnl_id = i / dev->luns_per_chnl;
 		lun->vlun.nr_free_blocks = dev->blks_per_lun;
-		lun->vlun.nr_inuse_blocks = 0;
+		lun->vlun.nr_open_blocks = 0;
+		lun->vlun.nr_closed_blocks = 0;
 		lun->vlun.nr_bad_blocks = 0;
 	}
 	return 0;
@@ -134,15 +135,15 @@ static int gennvm_block_map(u64 slba, u32 nlb, __le64 *entries, void *private)
 		pba = pba - (dev->sec_per_lun * lun_id);
 		blk = &lun->vlun.blocks[div_u64(pba, dev->sec_per_blk)];
 
-		if (!blk->type) {
+		if (!blk->state) {
 			/* at this point, we don't know anything about the
 			 * block. It's up to the FTL on top to re-etablish the
-			 * block state
+			 * block state. The block is assumed to be open.
 			 */
 			list_move_tail(&blk->list, &lun->used_list);
-			blk->type = 1;
+			blk->state = NVM_BLK_ST_OPEN;
 			lun->vlun.nr_free_blocks--;
-			lun->vlun.nr_inuse_blocks++;
+			lun->vlun.nr_open_blocks++;
 		}
 	}
 
@@ -256,14 +257,14 @@ static void gennvm_unregister(struct nvm_dev *dev)
 	module_put(THIS_MODULE);
 }
 
-static struct nvm_block *gennvm_get_blk(struct nvm_dev *dev,
+static struct nvm_block *gennvm_get_blk_unlocked(struct nvm_dev *dev,
 				struct nvm_lun *vlun, unsigned long flags)
 {
 	struct gen_lun *lun = container_of(vlun, struct gen_lun, vlun);
 	struct nvm_block *blk = NULL;
 	int is_gc = flags & NVM_IOTYPE_GC;
 
-	spin_lock(&vlun->lock);
+	assert_spin_locked(&vlun->lock);
 
 	if (list_empty(&lun->free_list)) {
 		pr_err_ratelimited("gennvm: lun %u have no free pages available",
@@ -276,44 +277,63 @@ static struct nvm_block *gennvm_get_blk(struct nvm_dev *dev,
 
 	blk = list_first_entry(&lun->free_list, struct nvm_block, list);
 	list_move_tail(&blk->list, &lun->used_list);
-	blk->type = 1;
+	blk->state = NVM_BLK_ST_OPEN;
 
 	lun->vlun.nr_free_blocks--;
-	lun->vlun.nr_inuse_blocks++;
+	lun->vlun.nr_open_blocks++;
 
 out:
+	return blk;
+}
+
+static struct nvm_block *gennvm_get_blk(struct nvm_dev *dev,
+				struct nvm_lun *vlun, unsigned long flags)
+{
+	struct nvm_block *blk;
+
+	spin_lock(&vlun->lock);
+	blk = gennvm_get_blk_unlocked(dev, vlun, flags);
 	spin_unlock(&vlun->lock);
 	return blk;
 }
 
-static void gennvm_put_blk(struct nvm_dev *dev, struct nvm_block *blk)
+static void gennvm_put_blk_unlocked(struct nvm_dev *dev, struct nvm_block *blk)
 {
 	struct nvm_lun *vlun = blk->lun;
 	struct gen_lun *lun = container_of(vlun, struct gen_lun, vlun);
 
-	spin_lock(&vlun->lock);
+	assert_spin_locked(&vlun->lock);
 
-	switch (blk->type) {
-	case 1:
+	if (blk->state & NVM_BLK_ST_OPEN) {
 		list_move_tail(&blk->list, &lun->free_list);
+		lun->vlun.nr_open_blocks--;
 		lun->vlun.nr_free_blocks++;
-		lun->vlun.nr_inuse_blocks--;
-		blk->type = 0;
-		break;
-	case 2:
+		blk->state = NVM_BLK_ST_FREE;
+	} else if (blk->state & NVM_BLK_ST_CLOSED) {
+		list_move_tail(&blk->list, &lun->free_list);
+		lun->vlun.nr_closed_blocks--;
+		lun->vlun.nr_free_blocks++;
+		blk->state = NVM_BLK_ST_FREE;
+	} else if (blk->state & NVM_BLK_ST_BAD) {
 		list_move_tail(&blk->list, &lun->bb_list);
 		lun->vlun.nr_bad_blocks++;
-		lun->vlun.nr_inuse_blocks--;
-		break;
-	default:
+		blk->state = NVM_BLK_ST_BAD;
+	} else {
 		WARN_ON_ONCE(1);
 		pr_err("gennvm: erroneous block type (%lu -> %u)\n",
-							blk->id, blk->type);
+							blk->id, blk->state);
 		list_move_tail(&blk->list, &lun->bb_list);
 		lun->vlun.nr_bad_blocks++;
-		lun->vlun.nr_inuse_blocks--;
+		blk->state = NVM_BLK_ST_BAD;
 	}
+}
 
+static void gennvm_put_blk(struct nvm_dev *dev, struct nvm_block *blk)
+{
+	struct nvm_lun *vlun = blk->lun;
+
+	spin_lock(&vlun->lock);
+	gennvm_put_blk_unlocked(dev, blk);
 	spin_unlock(&vlun->lock);
 }
 
@@ -339,7 +359,7 @@ static void gennvm_blk_set_type(struct nvm_dev *dev, struct ppa_addr *ppa,
 	blk = &lun->vlun.blocks[ppa->g.blk];
 
 	/* will be moved to bb list on put_blk from target */
-	blk->type = type;
+	blk->state = type;
 }
 
 /* mark block bad. It is expected the target recover from the error. */
@@ -358,9 +378,10 @@ static void gennvm_mark_blk_bad(struct nvm_dev *dev, struct nvm_rq *rqd)
 	/* look up blocks and mark them as bad */
 	if (rqd->nr_pages > 1)
 		for (i = 0; i < rqd->nr_pages; i++)
-			gennvm_blk_set_type(dev, &rqd->ppa_list[i], 2);
+			gennvm_blk_set_type(dev, &rqd->ppa_list[i],
+						NVM_BLK_ST_BAD);
 	else
-		gennvm_blk_set_type(dev, &rqd->ppa_addr, 2);
+		gennvm_blk_set_type(dev, &rqd->ppa_addr, NVM_BLK_ST_BAD);
 }
 
 static void gennvm_end_io(struct nvm_rq *rqd, int error)
@@ -416,10 +437,11 @@ static void gennvm_lun_info_print(struct nvm_dev *dev)
 	gennvm_for_each_lun(gn, lun, i) {
 		spin_lock(&lun->vlun.lock);
 
-		pr_info("%s: lun%8u\t%u\t%u\t%u\n",
+		pr_info("%s: lun%8u\t%u\t%u\t%u\t%u\n",
 				dev->name, i,
 				lun->vlun.nr_free_blocks,
-				lun->vlun.nr_inuse_blocks,
+				lun->vlun.nr_open_blocks,
+				lun->vlun.nr_closed_blocks,
 				lun->vlun.nr_bad_blocks);
 
 		spin_unlock(&lun->vlun.lock);
@@ -427,20 +449,23 @@ static void gennvm_lun_info_print(struct nvm_dev *dev)
 }
 
 static struct nvmm_type gennvm = {
-	.name		= "gennvm",
-	.version	= {0, 1, 0},
+	.name			= "gennvm",
+	.version		= {0, 1, 0},
 
-	.register_mgr	= gennvm_register,
-	.unregister_mgr	= gennvm_unregister,
+	.register_mgr		= gennvm_register,
+	.unregister_mgr		= gennvm_unregister,
 
-	.get_blk	= gennvm_get_blk,
-	.put_blk	= gennvm_put_blk,
+	.get_blk_unlocked	= gennvm_get_blk_unlocked,
+	.put_blk_unlocked	= gennvm_put_blk_unlocked,
 
-	.submit_io	= gennvm_submit_io,
-	.erase_blk	= gennvm_erase_blk,
+	.get_blk		= gennvm_get_blk,
+	.put_blk		= gennvm_put_blk,
 
-	.get_lun	= gennvm_get_lun,
-	.lun_info_print = gennvm_lun_info_print,
+	.submit_io		= gennvm_submit_io,
+	.erase_blk		= gennvm_erase_blk,
+
+	.get_lun		= gennvm_get_lun,
+	.lun_info_print		= gennvm_lun_info_print,
 };
 
 static int __init gennvm_module_init(void)
diff --git a/drivers/lightnvm/rrpc.c b/drivers/lightnvm/rrpc.c
index 1bea346..77ca14a 100644
--- a/drivers/lightnvm/rrpc.c
+++ b/drivers/lightnvm/rrpc.c
@@ -179,16 +179,20 @@ static void rrpc_set_lun_cur(struct rrpc_lun *rlun, struct rrpc_block *rblk)
 static struct rrpc_block *rrpc_get_blk(struct rrpc *rrpc, struct rrpc_lun *rlun,
 							unsigned long flags)
 {
+	struct nvm_lun *lun = rlun->parent;
 	struct nvm_block *blk;
 	struct rrpc_block *rblk;
 
-	blk = nvm_get_blk(rrpc->dev, rlun->parent, flags);
+	spin_lock(&lun->lock);
+	blk = nvm_get_blk_unlocked(rrpc->dev, rlun->parent, flags);
 	if (!blk)
 		return NULL;
 
 	rblk = &rlun->blocks[blk->id];
+	list_add_tail(&rblk->list, &rlun->open_list);
+	spin_unlock(&lun->lock);
+
 	blk->priv = rblk;
-
 	bitmap_zero(rblk->invalid_pages, rrpc->dev->pgs_per_blk);
 	rblk->next_page = 0;
 	rblk->nr_invalid_pages = 0;
@@ -199,7 +203,13 @@ static struct rrpc_block *rrpc_get_blk(struct rrpc *rrpc, struct rrpc_lun *rlun,
 
 static void rrpc_put_blk(struct rrpc *rrpc, struct rrpc_block *rblk)
 {
-	nvm_put_blk(rrpc->dev, rblk->parent);
+	struct rrpc_lun *rlun = rblk->rlun;
+	struct nvm_lun *lun = rlun->parent;
+
+	spin_lock(&lun->lock);
+	nvm_put_blk_unlocked(rrpc->dev, rblk->parent);
+	list_del(&rblk->list);
+	spin_unlock(&lun->lock);
 }
 
 static void rrpc_put_blks(struct rrpc *rrpc)
@@ -653,8 +663,20 @@ static void rrpc_end_io_write(struct rrpc *rrpc, struct rrpc_rq *rrqd,
 		lun = rblk->parent->lun;
 
 		cmnt_size = atomic_inc_return(&rblk->data_cmnt_size);
-		if (unlikely(cmnt_size == rrpc->dev->pgs_per_blk))
+		if (unlikely(cmnt_size == rrpc->dev->pgs_per_blk)) {
+			struct nvm_block *blk = rblk->parent;
+			struct rrpc_lun *rlun = rblk->rlun;
+
+			spin_lock(&lun->lock);
+			lun->nr_open_blocks--;
+			lun->nr_closed_blocks++;
+			blk->state &= ~NVM_BLK_ST_OPEN;
+			blk->state |= NVM_BLK_ST_CLOSED;
+			list_move_tail(&rblk->list, &rlun->closed_list);
+			spin_unlock(&lun->lock);
+
 			rrpc_run_gc(rrpc, rblk);
+		}
 	}
 }
 
@@ -1134,6 +1156,9 @@ static int rrpc_luns_init(struct rrpc *rrpc, int lun_begin, int lun_end)
 		rlun->rrpc = rrpc;
 		rlun->parent = lun;
 		INIT_LIST_HEAD(&rlun->prio_list);
+		INIT_LIST_HEAD(&rlun->open_list);
+		INIT_LIST_HEAD(&rlun->closed_list);
+
 		INIT_WORK(&rlun->ws_gc, rrpc_lun_gc);
 		spin_lock_init(&rlun->lock);
 
diff --git a/drivers/lightnvm/rrpc.h b/drivers/lightnvm/rrpc.h
index 7c5fa4d..a5082d3 100644
--- a/drivers/lightnvm/rrpc.h
+++ b/drivers/lightnvm/rrpc.h
@@ -56,6 +56,7 @@ struct rrpc_block {
 	struct nvm_block *parent;
 	struct rrpc_lun *rlun;
 	struct list_head prio;
+	struct list_head list;
 
 #define MAX_INVALID_PAGES_STORAGE 8
 	/* Bitmap for invalid page intries */
@@ -74,7 +75,14 @@ struct rrpc_lun {
 	struct nvm_lun *parent;
 	struct rrpc_block *cur, *gc_cur;
 	struct rrpc_block *blocks;	/* Reference to block allocation */
-	struct list_head prio_list;		/* Blocks that may be GC'ed */
+
+	struct list_head prio_list;	/* Blocks that may be GC'ed */
+	struct list_head open_list;	/* In-use open blocks. These are blocks
+					   that can be both written to and read
+					   from */
+	struct list_head closed_list;	/* In-use closed blocks. These are
+					   blocks that can _only_ be read from */
+
 	struct work_struct ws_gc;
 
 	spinlock_t lock;
diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h
index 995fe90..9470a86 100644
--- a/include/linux/lightnvm.h
+++ b/include/linux/lightnvm.h
@@ -226,12 +226,24 @@ struct nvm_lun {
 	int lun_id;
 	int chnl_id;
 
-	unsigned int nr_inuse_blocks;	/* Number of used blocks */
+	/* It is up to the target to mark blocks as closed. If the target does
+	 * not do it, all blocks are marked as open, and nr_open_blocks
+	 * represents the number of blocks in use */
+	unsigned int nr_open_blocks;	/* Number of used, writable blocks */
+	unsigned int nr_closed_blocks;	/* Number of used, non-writable blocks */
 	unsigned int nr_free_blocks;	/* Number of unused blocks */
 	unsigned int nr_bad_blocks;	/* Number of bad blocks */
-	struct nvm_block *blocks;
 
 	spinlock_t lock;
+
+	struct nvm_block *blocks;
+};
+
+enum {
+	NVM_BLK_ST_FREE =	0x1,	/* Free block */
+	NVM_BLK_ST_OPEN =	0x2,	/* Open block - read-write */
+	NVM_BLK_ST_CLOSED =	0x4,	/* Closed block - read-only */
+	NVM_BLK_ST_BAD =	0x8,	/* Bad block */
 };
 
 struct nvm_block {
@@ -240,7 +252,7 @@ struct nvm_block {
 	unsigned long id;
 
 	void *priv;
-	int type;
+	int state;
 };
 
 struct nvm_dev {
@@ -401,6 +413,8 @@ struct nvmm_type {
 	nvmm_unregister_fn *unregister_mgr;
 
 	/* Block administration callbacks */
+	nvmm_get_blk_fn *get_blk_unlocked;
+	nvmm_put_blk_fn *put_blk_unlocked;
 	nvmm_get_blk_fn *get_blk;
 	nvmm_put_blk_fn *put_blk;
 	nvmm_open_blk_fn *open_blk;
@@ -421,6 +435,10 @@ struct nvmm_type {
 extern int nvm_register_mgr(struct nvmm_type *);
 extern void nvm_unregister_mgr(struct nvmm_type *);
 
+extern struct nvm_block *nvm_get_blk_unlocked(struct nvm_dev *, struct nvm_lun *,
+								unsigned long);
+extern void nvm_put_blk_unlocked(struct nvm_dev *, struct nvm_block *);
+
 extern struct nvm_block *nvm_get_blk(struct nvm_dev *, struct nvm_lun *,
 								unsigned long);
 extern void nvm_put_blk(struct nvm_dev *, struct nvm_block *);
