1 files changed, 257 insertions, 182 deletions

diff --git a/drivers/lightnvm/pblk-gc.c b/drivers/lightnvm/pblk-gc.c
index f811e4ca63f4..1d289242ab92 100644
--- a/drivers/lightnvm/pblk-gc.c
+++ b/drivers/lightnvm/pblk-gc.c
@@ -21,7 +21,6 @@
 static void pblk_gc_free_gc_rq(struct pblk_gc_rq *gc_rq)
 {
 	kfree(gc_rq->data);
-	kfree(gc_rq->lba_list);
 	kfree(gc_rq);
 }
 
@@ -37,10 +36,8 @@ static int pblk_gc_write(struct pblk *pblk)
 		return 1;
 	}
 
-	list_for_each_entry_safe(gc_rq, tgc_rq, &gc->w_list, list) {
-		list_move_tail(&gc_rq->list, &w_list);
-		gc->w_entries--;
-	}
+	list_cut_position(&w_list, &gc->w_list, gc->w_list.prev);
+	gc->w_entries = 0;
 	spin_unlock(&gc->w_lock);
 
 	list_for_each_entry_safe(gc_rq, tgc_rq, &w_list, list) {
@@ -48,9 +45,8 @@ static int pblk_gc_write(struct pblk *pblk)
 				gc_rq->nr_secs, gc_rq->secs_to_gc,
 				gc_rq->line, PBLK_IOTYPE_GC);
 
-		kref_put(&gc_rq->line->ref, pblk_line_put);
-
 		list_del(&gc_rq->list);
+		kref_put(&gc_rq->line->ref, pblk_line_put);
 		pblk_gc_free_gc_rq(gc_rq);
 	}
 
@@ -66,52 +62,41 @@ static void pblk_gc_writer_kick(struct pblk_gc *gc)
  * Responsible for managing all memory related to a gc request. Also in case of
  * failure
  */
-static int pblk_gc_move_valid_secs(struct pblk *pblk, struct pblk_line *line,
-				   u64 *lba_list, unsigned int nr_secs)
+static int pblk_gc_move_valid_secs(struct pblk *pblk, struct pblk_gc_rq *gc_rq)
 {
 	struct nvm_tgt_dev *dev = pblk->dev;
 	struct nvm_geo *geo = &dev->geo;
 	struct pblk_gc *gc = &pblk->gc;
-	struct pblk_gc_rq *gc_rq;
+	struct pblk_line *line = gc_rq->line;
 	void *data;
 	unsigned int secs_to_gc;
-	int ret = NVM_IO_OK;
+	int ret = 0;
 
-	data = kmalloc(nr_secs * geo->sec_size, GFP_KERNEL);
+	data = kmalloc(gc_rq->nr_secs * geo->sec_size, GFP_KERNEL);
 	if (!data) {
-		ret = NVM_IO_ERR;
-		goto free_lba_list;
+		ret = -ENOMEM;
+		goto out;
 	}
 
 	/* Read from GC victim block */
-	if (pblk_submit_read_gc(pblk, lba_list, data, nr_secs,
+	if (pblk_submit_read_gc(pblk, gc_rq->lba_list, data, gc_rq->nr_secs,
 							&secs_to_gc, line)) {
-		ret = NVM_IO_ERR;
+		ret = -EFAULT;
 		goto free_data;
 	}
 
 	if (!secs_to_gc)
-		goto free_data;
-
-	gc_rq = kmalloc(sizeof(struct pblk_gc_rq), GFP_KERNEL);
-	if (!gc_rq) {
-		ret = NVM_IO_ERR;
-		goto free_data;
-	}
+		goto free_rq;
 
-	gc_rq->line = line;
 	gc_rq->data = data;
-	gc_rq->lba_list = lba_list;
-	gc_rq->nr_secs = nr_secs;
 	gc_rq->secs_to_gc = secs_to_gc;
 
-	kref_get(&line->ref);
-
 retry:
 	spin_lock(&gc->w_lock);
-	if (gc->w_entries > 256) {
+	if (gc->w_entries >= PBLK_GC_W_QD) {
 		spin_unlock(&gc->w_lock);
-		usleep_range(256, 1024);
+		pblk_gc_writer_kick(&pblk->gc);
+		usleep_range(128, 256);
 		goto retry;
 	}
 	gc->w_entries++;
@@ -120,13 +105,14 @@ retry:
 
 	pblk_gc_writer_kick(&pblk->gc);
 
-	return NVM_IO_OK;
+	return 0;
 
+free_rq:
+	kfree(gc_rq);
 free_data:
 	kfree(data);
-free_lba_list:
-	kfree(lba_list);
-
+out:
+	kref_put(&line->ref, pblk_line_put);
 	return ret;
 }
 
@@ -150,20 +136,52 @@ static void pblk_put_line_back(struct pblk *pblk, struct pblk_line *line)
 
 static void pblk_gc_line_ws(struct work_struct *work)
 {
+	struct pblk_line_ws *line_rq_ws = container_of(work,
+						struct pblk_line_ws, ws);
+	struct pblk *pblk = line_rq_ws->pblk;
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_line *line = line_rq_ws->line;
+	struct pblk_gc_rq *gc_rq = line_rq_ws->priv;
+
+	up(&gc->gc_sem);
+
+	if (pblk_gc_move_valid_secs(pblk, gc_rq)) {
+		pr_err("pblk: could not GC all sectors: line:%d (%d/%d)\n",
+						line->id, *line->vsc,
+						gc_rq->nr_secs);
+	}
+
+	mempool_free(line_rq_ws, pblk->line_ws_pool);
+}
+
+static void pblk_gc_line_prepare_ws(struct work_struct *work)
+{
 	struct pblk_line_ws *line_ws = container_of(work, struct pblk_line_ws,
 									ws);
 	struct pblk *pblk = line_ws->pblk;
-	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 	struct pblk_line *line = line_ws->line;
+	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 	struct pblk_line_meta *lm = &pblk->lm;
-	struct line_emeta *emeta_buf = line_ws->priv;
+	struct pblk_gc *gc = &pblk->gc;
+	struct line_emeta *emeta_buf;
+	struct pblk_line_ws *line_rq_ws;
+	struct pblk_gc_rq *gc_rq;
 	__le64 *lba_list;
-	u64 *gc_list;
-	int sec_left;
-	int nr_ppas, bit;
-	int put_line = 1;
+	int sec_left, nr_secs, bit;
+	int ret;
 
-	pr_debug("pblk: line '%d' being reclaimed for GC\n", line->id);
+	emeta_buf = pblk_malloc(lm->emeta_len[0], l_mg->emeta_alloc_type,
+								GFP_KERNEL);
+	if (!emeta_buf) {
+		pr_err("pblk: cannot use GC emeta\n");
+		return;
+	}
+
+	ret = pblk_line_read_emeta(pblk, line, emeta_buf);
+	if (ret) {
+		pr_err("pblk: line %d read emeta failed (%d)\n", line->id, ret);
+		goto fail_free_emeta;
+	}
 
 	/* If this read fails, it means that emeta is corrupted. For now, leave
 	 * the line untouched. TODO: Implement a recovery routine that scans and
@@ -172,119 +190,124 @@ static void pblk_gc_line_ws(struct work_struct *work)
 	lba_list = pblk_recov_get_lba_list(pblk, emeta_buf);
 	if (!lba_list) {
 		pr_err("pblk: could not interpret emeta (line %d)\n", line->id);
-		goto out;
-	}
-
-	spin_lock(&line->lock);
-	sec_left = le32_to_cpu(*line->vsc);
-	if (!sec_left) {
-		/* Lines are erased before being used (l_mg->data_/log_next) */
-		spin_unlock(&line->lock);
-		goto out;
+		goto fail_free_emeta;
 	}
-	spin_unlock(&line->lock);
 
+	sec_left = pblk_line_vsc(line);
 	if (sec_left < 0) {
 		pr_err("pblk: corrupted GC line (%d)\n", line->id);
-		put_line = 0;
-		pblk_put_line_back(pblk, line);
-		goto out;
+		goto fail_free_emeta;
 	}
 
 	bit = -1;
 next_rq:
-	gc_list = kmalloc_array(pblk->max_write_pgs, sizeof(u64), GFP_KERNEL);
-	if (!gc_list) {
-		put_line = 0;
-		pblk_put_line_back(pblk, line);
-		goto out;
-	}
+	gc_rq = kmalloc(sizeof(struct pblk_gc_rq), GFP_KERNEL);
+	if (!gc_rq)
+		goto fail_free_emeta;
 
-	nr_ppas = 0;
+	nr_secs = 0;
 	do {
 		bit = find_next_zero_bit(line->invalid_bitmap, lm->sec_per_line,
 								bit + 1);
 		if (bit > line->emeta_ssec)
 			break;
 
-		gc_list[nr_ppas++] = le64_to_cpu(lba_list[bit]);
-	} while (nr_ppas < pblk->max_write_pgs);
+		gc_rq->lba_list[nr_secs++] = le64_to_cpu(lba_list[bit]);
+	} while (nr_secs < pblk->max_write_pgs);
 
-	if (unlikely(!nr_ppas)) {
-		kfree(gc_list);
+	if (unlikely(!nr_secs)) {
+		kfree(gc_rq);
 		goto out;
 	}
 
-	if (pblk_gc_move_valid_secs(pblk, line, gc_list, nr_ppas)) {
-		pr_err("pblk: could not GC all sectors: line:%d (%d/%d/%d)\n",
-						line->id, *line->vsc,
-						nr_ppas, nr_ppas);
-		put_line = 0;
-		pblk_put_line_back(pblk, line);
-		goto out;
-	}
+	gc_rq->nr_secs = nr_secs;
+	gc_rq->line = line;
+
+	line_rq_ws = mempool_alloc(pblk->line_ws_pool, GFP_KERNEL);
+	if (!line_rq_ws)
+		goto fail_free_gc_rq;
+
+	line_rq_ws->pblk = pblk;
+	line_rq_ws->line = line;
+	line_rq_ws->priv = gc_rq;
+
+	down(&gc->gc_sem);
+	kref_get(&line->ref);
+
+	INIT_WORK(&line_rq_ws->ws, pblk_gc_line_ws);
+	queue_work(gc->gc_line_reader_wq, &line_rq_ws->ws);
 
-	sec_left -= nr_ppas;
+	sec_left -= nr_secs;
 	if (sec_left > 0)
 		goto next_rq;
 
 out:
 	pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
 	mempool_free(line_ws, pblk->line_ws_pool);
-	atomic_dec(&pblk->gc.inflight_gc);
-	if (put_line)
-		kref_put(&line->ref, pblk_line_put);
+
+	kref_put(&line->ref, pblk_line_put);
+	atomic_dec(&gc->inflight_gc);
+
+	return;
+
+fail_free_gc_rq:
+	kfree(gc_rq);
+fail_free_emeta:
+	pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
+	pblk_put_line_back(pblk, line);
+	kref_put(&line->ref, pblk_line_put);
+	mempool_free(line_ws, pblk->line_ws_pool);
+	atomic_dec(&gc->inflight_gc);
+
+	pr_err("pblk: Failed to GC line %d\n", line->id);
 }
 
 static int pblk_gc_line(struct pblk *pblk, struct pblk_line *line)
 {
-	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
-	struct pblk_line_meta *lm = &pblk->lm;
-	struct line_emeta *emeta_buf;
+	struct pblk_gc *gc = &pblk->gc;
 	struct pblk_line_ws *line_ws;
-	int ret;
 
-	line_ws = mempool_alloc(pblk->line_ws_pool, GFP_KERNEL);
-	emeta_buf = pblk_malloc(lm->emeta_len[0], l_mg->emeta_alloc_type,
-								GFP_KERNEL);
-	if (!emeta_buf) {
-		pr_err("pblk: cannot use GC emeta\n");
-		goto fail_free_ws;
-	}
+	pr_debug("pblk: line '%d' being reclaimed for GC\n", line->id);
 
-	ret = pblk_line_read_emeta(pblk, line, emeta_buf);
-	if (ret) {
-		pr_err("pblk: line %d read emeta failed (%d)\n", line->id, ret);
-		goto fail_free_emeta;
-	}
+	line_ws = mempool_alloc(pblk->line_ws_pool, GFP_KERNEL);
+	if (!line_ws)
+		return -ENOMEM;
 
 	line_ws->pblk = pblk;
 	line_ws->line = line;
-	line_ws->priv = emeta_buf;
 
-	INIT_WORK(&line_ws->ws, pblk_gc_line_ws);
-	queue_work(pblk->gc.gc_reader_wq, &line_ws->ws);
+	INIT_WORK(&line_ws->ws, pblk_gc_line_prepare_ws);
+	queue_work(gc->gc_reader_wq, &line_ws->ws);
 
 	return 0;
-
-fail_free_emeta:
-	pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
-fail_free_ws:
-	mempool_free(line_ws, pblk->line_ws_pool);
-	pblk_put_line_back(pblk, line);
-
-	return 1;
 }
 
-static void pblk_gc_lines(struct pblk *pblk, struct list_head *gc_list)
+static int pblk_gc_read(struct pblk *pblk)
 {
-	struct pblk_line *line, *tline;
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_line *line;
 
-	list_for_each_entry_safe(line, tline, gc_list, list) {
-		if (pblk_gc_line(pblk, line))
-			pr_err("pblk: failed to GC line %d\n", line->id);
-		list_del(&line->list);
+	spin_lock(&gc->r_lock);
+	if (list_empty(&gc->r_list)) {
+		spin_unlock(&gc->r_lock);
+		return 1;
 	}
+
+	line = list_first_entry(&gc->r_list, struct pblk_line, list);
+	list_del(&line->list);
+	spin_unlock(&gc->r_lock);
+
+	pblk_gc_kick(pblk);
+
+	if (pblk_gc_line(pblk, line))
+		pr_err("pblk: failed to GC line %d\n", line->id);
+
+	return 0;
+}
+
+static void pblk_gc_reader_kick(struct pblk_gc *gc)
+{
+	wake_up_process(gc->gc_reader_ts);
 }
 
 static struct pblk_line *pblk_gc_get_victim_line(struct pblk *pblk,
@@ -301,6 +324,17 @@ static struct pblk_line *pblk_gc_get_victim_line(struct pblk *pblk,
 	return victim;
 }
 
+static bool pblk_gc_should_run(struct pblk_gc *gc, struct pblk_rl *rl)
+{
+	unsigned int nr_blocks_free, nr_blocks_need;
+
+	nr_blocks_need = pblk_rl_high_thrs(rl);
+	nr_blocks_free = pblk_rl_nr_free_blks(rl);
+
+	/* This is not critical, no need to take lock here */
+	return ((gc->gc_active) && (nr_blocks_need > nr_blocks_free));
+}
+
 /*
  * Lines with no valid sectors will be returned to the free list immediately. If
  * GC is activated - either because the free block count is under the determined
@@ -311,71 +345,83 @@ static void pblk_gc_run(struct pblk *pblk)
 {
 	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 	struct pblk_gc *gc = &pblk->gc;
-	struct pblk_line *line, *tline;
-	unsigned int nr_blocks_free, nr_blocks_need;
+	struct pblk_line *line;
 	struct list_head *group_list;
-	int run_gc, gc_group = 0;
-	int prev_gc = 0;
-	int inflight_gc = atomic_read(&gc->inflight_gc);
-	LIST_HEAD(gc_list);
+	bool run_gc;
+	int inflight_gc, gc_group = 0, prev_group = 0;
+
+	do {
+		spin_lock(&l_mg->gc_lock);
+		if (list_empty(&l_mg->gc_full_list)) {
+			spin_unlock(&l_mg->gc_lock);
+			break;
+		}
+
+		line = list_first_entry(&l_mg->gc_full_list,
+							struct pblk_line, list);
 
-	spin_lock(&l_mg->gc_lock);
-	list_for_each_entry_safe(line, tline, &l_mg->gc_full_list, list) {
 		spin_lock(&line->lock);
 		WARN_ON(line->state != PBLK_LINESTATE_CLOSED);
 		line->state = PBLK_LINESTATE_GC;
 		spin_unlock(&line->lock);
 
 		list_del(&line->list);
+		spin_unlock(&l_mg->gc_lock);
+
 		kref_put(&line->ref, pblk_line_put);
-	}
-	spin_unlock(&l_mg->gc_lock);
+	} while (1);
 
-	nr_blocks_need = pblk_rl_gc_thrs(&pblk->rl);
-	nr_blocks_free = pblk_rl_nr_free_blks(&pblk->rl);
-	run_gc = (nr_blocks_need > nr_blocks_free || gc->gc_forced);
+	run_gc = pblk_gc_should_run(&pblk->gc, &pblk->rl);
+	if (!run_gc || (atomic_read(&gc->inflight_gc) >= PBLK_GC_L_QD))
+		return;
 
 next_gc_group:
 	group_list = l_mg->gc_lists[gc_group++];
-	spin_lock(&l_mg->gc_lock);
-	while (run_gc && !list_empty(group_list)) {
-		/* No need to queue up more GC lines than we can handle */
-		if (!run_gc || inflight_gc > gc->gc_jobs_active) {
+
+	do {
+		spin_lock(&l_mg->gc_lock);
+		if (list_empty(group_list)) {
 			spin_unlock(&l_mg->gc_lock);
-			pblk_gc_lines(pblk, &gc_list);
-			return;
+			break;
 		}
 
 		line = pblk_gc_get_victim_line(pblk, group_list);
-		nr_blocks_free += atomic_read(&line->blk_in_line);
 
 		spin_lock(&line->lock);
 		WARN_ON(line->state != PBLK_LINESTATE_CLOSED);
 		line->state = PBLK_LINESTATE_GC;
-		list_move_tail(&line->list, &gc_list);
-		atomic_inc(&gc->inflight_gc);
-		inflight_gc++;
 		spin_unlock(&line->lock);
 
-		prev_gc = 1;
-		run_gc = (nr_blocks_need > nr_blocks_free || gc->gc_forced);
-	}
-	spin_unlock(&l_mg->gc_lock);
+		list_del(&line->list);
+		spin_unlock(&l_mg->gc_lock);
+
+		spin_lock(&gc->r_lock);
+		list_add_tail(&line->list, &gc->r_list);
+		spin_unlock(&gc->r_lock);
+
+		inflight_gc = atomic_inc_return(&gc->inflight_gc);
+		pblk_gc_reader_kick(gc);
 
-	pblk_gc_lines(pblk, &gc_list);
+		prev_group = 1;
 
-	if (!prev_gc && pblk->rl.rb_state > gc_group &&
-						gc_group < PBLK_NR_GC_LISTS)
+		/* No need to queue up more GC lines than we can handle */
+		run_gc = pblk_gc_should_run(&pblk->gc, &pblk->rl);
+		if (!run_gc || inflight_gc >= PBLK_GC_L_QD)
+			break;
+	} while (1);
+
+	if (!prev_group && pblk->rl.rb_state > gc_group &&
+						gc_group < PBLK_GC_NR_LISTS)
 		goto next_gc_group;
 }
 
-
-static void pblk_gc_kick(struct pblk *pblk)
+void pblk_gc_kick(struct pblk *pblk)
 {
 	struct pblk_gc *gc = &pblk->gc;
 
 	wake_up_process(gc->gc_ts);
 	pblk_gc_writer_kick(gc);
+	pblk_gc_reader_kick(gc);
 	mod_timer(&gc->gc_timer, jiffies + msecs_to_jiffies(GC_TIME_MSECS));
 }
 
@@ -413,42 +459,34 @@ static int pblk_gc_writer_ts(void *data)
 	return 0;
 }
 
-static void pblk_gc_start(struct pblk *pblk)
+static int pblk_gc_reader_ts(void *data)
 {
-	pblk->gc.gc_active = 1;
+	struct pblk *pblk = data;
 
-	pr_debug("pblk: gc start\n");
+	while (!kthread_should_stop()) {
+		if (!pblk_gc_read(pblk))
+			continue;
+		set_current_state(TASK_INTERRUPTIBLE);
+		io_schedule();
+	}
+
+	return 0;
 }
 
-int pblk_gc_status(struct pblk *pblk)
+static void pblk_gc_start(struct pblk *pblk)
 {
-	struct pblk_gc *gc = &pblk->gc;
-	int ret;
-
-	spin_lock(&gc->lock);
-	ret = gc->gc_active;
-	spin_unlock(&gc->lock);
-
-	return ret;
+	pblk->gc.gc_active = 1;
+	pr_debug("pblk: gc start\n");
 }
 
-static void __pblk_gc_should_start(struct pblk *pblk)
+void pblk_gc_should_start(struct pblk *pblk)
 {
 	struct pblk_gc *gc = &pblk->gc;
 
-	lockdep_assert_held(&gc->lock);
-
 	if (gc->gc_enabled && !gc->gc_active)
 		pblk_gc_start(pblk);
-}
-
-void pblk_gc_should_start(struct pblk *pblk)
-{
-	struct pblk_gc *gc = &pblk->gc;
 
-	spin_lock(&gc->lock);
-	__pblk_gc_should_start(pblk);
-	spin_unlock(&gc->lock);
+	pblk_gc_kick(pblk);
 }
 
 /*
@@ -457,10 +495,7 @@ void pblk_gc_should_start(struct pblk *pblk)
  */
 static void pblk_gc_stop(struct pblk *pblk, int flush_wq)
 {
-	spin_lock(&pblk->gc.lock);
 	pblk->gc.gc_active = 0;
-	spin_unlock(&pblk->gc.lock);
-
 	pr_debug("pblk: gc stop\n");
 }
 
@@ -483,20 +518,25 @@ void pblk_gc_sysfs_state_show(struct pblk *pblk, int *gc_enabled,
 	spin_unlock(&gc->lock);
 }
 
-void pblk_gc_sysfs_force(struct pblk *pblk, int force)
+int pblk_gc_sysfs_force(struct pblk *pblk, int force)
 {
 	struct pblk_gc *gc = &pblk->gc;
-	int rsv = 0;
+
+	if (force < 0 || force > 1)
+		return -EINVAL;
 
 	spin_lock(&gc->lock);
-	if (force) {
-		gc->gc_enabled = 1;
-		rsv = 64;
-	}
-	pblk_rl_set_gc_rsc(&pblk->rl, rsv);
 	gc->gc_forced = force;
-	__pblk_gc_should_start(pblk);
+
+	if (force)
+		gc->gc_enabled = 1;
+	else
+		gc->gc_enabled = 0;
 	spin_unlock(&gc->lock);
+
+	pblk_gc_should_start(pblk);
+
+	return 0;
 }
 
 int pblk_gc_init(struct pblk *pblk)
@@ -518,30 +558,58 @@ int pblk_gc_init(struct pblk *pblk)
 		goto fail_free_main_kthread;
 	}
 
+	gc->gc_reader_ts = kthread_create(pblk_gc_reader_ts, pblk,
+							"pblk-gc-reader-ts");
+	if (IS_ERR(gc->gc_reader_ts)) {
+		pr_err("pblk: could not allocate GC reader kthread\n");
+		ret = PTR_ERR(gc->gc_reader_ts);
+		goto fail_free_writer_kthread;
+	}
+
 	setup_timer(&gc->gc_timer, pblk_gc_timer, (unsigned long)pblk);
 	mod_timer(&gc->gc_timer, jiffies + msecs_to_jiffies(GC_TIME_MSECS));
 
 	gc->gc_active = 0;
 	gc->gc_forced = 0;
 	gc->gc_enabled = 1;
-	gc->gc_jobs_active = 8;
 	gc->w_entries = 0;
 	atomic_set(&gc->inflight_gc, 0);
 
-	gc->gc_reader_wq = alloc_workqueue("pblk-gc-reader-wq",
-			WQ_MEM_RECLAIM | WQ_UNBOUND, gc->gc_jobs_active);
+	/* Workqueue that reads valid sectors from a line and submit them to the
+	 * GC writer to be recycled.
+	 */
+	gc->gc_line_reader_wq = alloc_workqueue("pblk-gc-line-reader-wq",
+			WQ_MEM_RECLAIM | WQ_UNBOUND, PBLK_GC_MAX_READERS);
+	if (!gc->gc_line_reader_wq) {
+		pr_err("pblk: could not allocate GC line reader workqueue\n");
+		ret = -ENOMEM;
+		goto fail_free_reader_kthread;
+	}
+
+	/* Workqueue that prepare lines for GC */
+	gc->gc_reader_wq = alloc_workqueue("pblk-gc-line_wq",
+					WQ_MEM_RECLAIM | WQ_UNBOUND, 1);
 	if (!gc->gc_reader_wq) {
 		pr_err("pblk: could not allocate GC reader workqueue\n");
 		ret = -ENOMEM;
-		goto fail_free_writer_kthread;
+		goto fail_free_reader_line_wq;
 	}
 
 	spin_lock_init(&gc->lock);
 	spin_lock_init(&gc->w_lock);
+	spin_lock_init(&gc->r_lock);
+
+	sema_init(&gc->gc_sem, 128);
+
 	INIT_LIST_HEAD(&gc->w_list);
+	INIT_LIST_HEAD(&gc->r_list);
 
 	return 0;
 
+fail_free_reader_line_wq:
+	destroy_workqueue(gc->gc_line_reader_wq);
+fail_free_reader_kthread:
+	kthread_stop(gc->gc_reader_ts);
 fail_free_writer_kthread:
 	kthread_stop(gc->gc_writer_ts);
 fail_free_main_kthread:
@@ -555,6 +623,7 @@ void pblk_gc_exit(struct pblk *pblk)
 	struct pblk_gc *gc = &pblk->gc;
 
 	flush_workqueue(gc->gc_reader_wq);
+	flush_workqueue(gc->gc_line_reader_wq);
 
 	del_timer(&gc->gc_timer);
 	pblk_gc_stop(pblk, 1);
@@ -562,9 +631,15 @@ void pblk_gc_exit(struct pblk *pblk)
 	if (gc->gc_ts)
 		kthread_stop(gc->gc_ts);
 
-	if (pblk->gc.gc_reader_wq)
-		destroy_workqueue(pblk->gc.gc_reader_wq);
+	if (gc->gc_reader_wq)
+		destroy_workqueue(gc->gc_reader_wq);
+
+	if (gc->gc_line_reader_wq)
+		destroy_workqueue(gc->gc_line_reader_wq);
 
 	if (gc->gc_writer_ts)
 		kthread_stop(gc->gc_writer_ts);
+
+	if (gc->gc_reader_ts)
+		kthread_stop(gc->gc_reader_ts);
 }