3 files changed, 17 insertions, 5 deletions

diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index e5239aba806b..13822594647c 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -193,8 +193,9 @@ static int pblk_rwb_init(struct pblk *pblk)
 	struct nvm_tgt_dev *dev = pblk->dev;
 	struct nvm_geo *geo = &dev->geo;
 	unsigned long buffer_size;
-	int pgs_in_buffer;
+	int pgs_in_buffer, threshold;
 
+	threshold = geo->mw_cunits * geo->all_luns;
 	pgs_in_buffer = (max(geo->mw_cunits, geo->ws_opt) + geo->ws_opt)
 								* geo->all_luns;
 
@@ -203,7 +204,7 @@ static int pblk_rwb_init(struct pblk *pblk)
 	else
 		buffer_size = pgs_in_buffer;
 
-	return pblk_rb_init(&pblk->rwb, buffer_size, geo->csecs);
+	return pblk_rb_init(&pblk->rwb, buffer_size, threshold, geo->csecs);
 }
 
 /* Minimum pages needed within a lun */
diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c
index f653faa6a9ed..b1f4b51783f4 100644
--- a/drivers/lightnvm/pblk-rb.c
+++ b/drivers/lightnvm/pblk-rb.c
@@ -56,7 +56,8 @@ static unsigned int pblk_rb_calculate_size(unsigned int nr_entries)
  * allocated and their size must be a power of two
  * (Documentation/core-api/circular-buffers.rst)
  */
-int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int seg_size)
+int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int threshold,
+		 unsigned int seg_size)
 {
 	struct pblk *pblk = container_of(rb, struct pblk, rwb);
 	struct pblk_rb_entry *entries;
@@ -79,6 +80,7 @@ int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int seg_size)
 	rb->seg_size = (1 << power_seg_sz);
 	rb->nr_entries = (1 << power_size);
 	rb->mem = rb->subm = rb->sync = rb->l2p_update = 0;
+	rb->back_thres = threshold;
 	rb->flush_point = EMPTY_ENTRY;
 
 	spin_lock_init(&rb->w_lock);
@@ -404,11 +406,14 @@ static int __pblk_rb_may_write(struct pblk_rb *rb, unsigned int nr_entries,
 {
 	unsigned int mem;
 	unsigned int sync;
+	unsigned int threshold;
 
 	sync = READ_ONCE(rb->sync);
 	mem = READ_ONCE(rb->mem);
 
-	if (pblk_rb_ring_space(rb, mem, sync, rb->nr_entries) < nr_entries)
+	threshold = nr_entries + rb->back_thres;
+
+	if (pblk_rb_ring_space(rb, mem, sync, rb->nr_entries) < threshold)
 		return 0;
 
 	if (pblk_rb_update_l2p(rb, nr_entries, mem, sync))
diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 0f98ea24ee59..02bb2e98f8a9 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -203,6 +203,11 @@ struct pblk_rb {
 					 * will be 4KB
 					 */
 
+	unsigned int back_thres;	/* Threshold that shall be maintained by
+					 * the backpointer in order to respect
+					 * geo->mw_cunits on a per chunk basis
+					 */
+
 	struct list_head pages;		/* List of data pages */
 
 	spinlock_t w_lock;		/* Write lock */
@@ -734,7 +739,8 @@ struct pblk_line_ws {
 /*
  * pblk ring buffer operations
  */
-int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int seg_sz);
+int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int threshold,
+		 unsigned int seg_sz);
 int pblk_rb_may_write_user(struct pblk_rb *rb, struct bio *bio,
 			   unsigned int nr_entries, unsigned int *pos);
 int pblk_rb_may_write_gc(struct pblk_rb *rb, unsigned int nr_entries,