Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 705 insertions, 0 deletions

diff --git a/drivers/lightnvm/pblk-gc.c b/drivers/lightnvm/pblk-gc.c
new file mode 100644
index 000000000..157c2567c
--- /dev/null
+++ b/drivers/lightnvm/pblk-gc.c
@@ -0,0 +1,705 @@
+/*
+ * Copyright (C) 2016 CNEX Labs
+ * Initial release: Javier Gonzalez <javier@cnexlabs.com>
+ *                  Matias Bjorling <matias@cnexlabs.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * pblk-gc.c - pblk's garbage collector
+ */
+
+#include "pblk.h"
+#include <linux/delay.h>
+
+static void pblk_gc_free_gc_rq(struct pblk_gc_rq *gc_rq)
+{
+	if (gc_rq->data)
+		vfree(gc_rq->data);
+	kfree(gc_rq);
+}
+
+static int pblk_gc_write(struct pblk *pblk)
+{
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_gc_rq *gc_rq, *tgc_rq;
+	LIST_HEAD(w_list);
+
+	spin_lock(&gc->w_lock);
+	if (list_empty(&gc->w_list)) {
+		spin_unlock(&gc->w_lock);
+		return 1;
+	}
+
+	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) {
+		pblk_write_gc_to_cache(pblk, gc_rq);
+		list_del(&gc_rq->list);
+		kref_put(&gc_rq->line->ref, pblk_line_put);
+		pblk_gc_free_gc_rq(gc_rq);
+	}
+
+	return 0;
+}
+
+static void pblk_gc_writer_kick(struct pblk_gc *gc)
+{
+	wake_up_process(gc->gc_writer_ts);
+}
+
+static void pblk_put_line_back(struct pblk *pblk, struct pblk_line *line)
+{
+	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
+	struct list_head *move_list;
+
+	spin_lock(&line->lock);
+	WARN_ON(line->state != PBLK_LINESTATE_GC);
+	line->state = PBLK_LINESTATE_CLOSED;
+	move_list = pblk_line_gc_list(pblk, line);
+	spin_unlock(&line->lock);
+
+	if (move_list) {
+		spin_lock(&l_mg->gc_lock);
+		list_add_tail(&line->list, move_list);
+		spin_unlock(&l_mg->gc_lock);
+	}
+}
+
+static void pblk_gc_line_ws(struct work_struct *work)
+{
+	struct pblk_line_ws *gc_rq_ws = container_of(work,
+						struct pblk_line_ws, ws);
+	struct pblk *pblk = gc_rq_ws->pblk;
+	struct nvm_tgt_dev *dev = pblk->dev;
+	struct nvm_geo *geo = &dev->geo;
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_line *line = gc_rq_ws->line;
+	struct pblk_gc_rq *gc_rq = gc_rq_ws->priv;
+	int ret;
+
+	up(&gc->gc_sem);
+
+	gc_rq->data = vmalloc(array_size(gc_rq->nr_secs, geo->csecs));
+	if (!gc_rq->data) {
+		pblk_err(pblk, "could not GC line:%d (%d/%d)\n",
+					line->id, *line->vsc, gc_rq->nr_secs);
+		goto out;
+	}
+
+	/* Read from GC victim block */
+	ret = pblk_submit_read_gc(pblk, gc_rq);
+	if (ret) {
+		pblk_err(pblk, "failed GC read in line:%d (err:%d)\n",
+								line->id, ret);
+		goto out;
+	}
+
+	if (!gc_rq->secs_to_gc)
+		goto out;
+
+retry:
+	spin_lock(&gc->w_lock);
+	if (gc->w_entries >= PBLK_GC_RQ_QD) {
+		spin_unlock(&gc->w_lock);
+		pblk_gc_writer_kick(&pblk->gc);
+		usleep_range(128, 256);
+		goto retry;
+	}
+	gc->w_entries++;
+	list_add_tail(&gc_rq->list, &gc->w_list);
+	spin_unlock(&gc->w_lock);
+
+	pblk_gc_writer_kick(&pblk->gc);
+
+	kfree(gc_rq_ws);
+	return;
+
+out:
+	pblk_gc_free_gc_rq(gc_rq);
+	kref_put(&line->ref, pblk_line_put);
+	kfree(gc_rq_ws);
+}
+
+static __le64 *get_lba_list_from_emeta(struct pblk *pblk,
+				       struct pblk_line *line)
+{
+	struct line_emeta *emeta_buf;
+	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
+	struct pblk_line_meta *lm = &pblk->lm;
+	unsigned int lba_list_size = lm->emeta_len[2];
+	__le64 *lba_list;
+	int ret;
+
+	emeta_buf = pblk_malloc(lm->emeta_len[0],
+				l_mg->emeta_alloc_type, GFP_KERNEL);
+	if (!emeta_buf)
+		return NULL;
+
+	ret = pblk_line_read_emeta(pblk, line, emeta_buf);
+	if (ret) {
+		pblk_err(pblk, "line %d read emeta failed (%d)\n",
+				line->id, ret);
+		pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
+		return NULL;
+	}
+
+	/* If this read fails, it means that emeta is corrupted.
+	 * For now, leave the line untouched.
+	 * TODO: Implement a recovery routine that scans and moves
+	 * all sectors on the line.
+	 */
+
+	ret = pblk_recov_check_emeta(pblk, emeta_buf);
+	if (ret) {
+		pblk_err(pblk, "inconsistent emeta (line %d)\n",
+				line->id);
+		pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
+		return NULL;
+	}
+
+	lba_list = pblk_malloc(lba_list_size,
+			       l_mg->emeta_alloc_type, GFP_KERNEL);
+	if (lba_list)
+		memcpy(lba_list, emeta_to_lbas(pblk, emeta_buf), lba_list_size);
+
+	pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
+
+	return lba_list;
+}
+
+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 *line = line_ws->line;
+	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
+	struct pblk_line_meta *lm = &pblk->lm;
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_line_ws *gc_rq_ws;
+	struct pblk_gc_rq *gc_rq;
+	__le64 *lba_list;
+	unsigned long *invalid_bitmap;
+	int sec_left, nr_secs, bit;
+
+	invalid_bitmap = kmalloc(lm->sec_bitmap_len, GFP_KERNEL);
+	if (!invalid_bitmap)
+		goto fail_free_ws;
+
+	if (line->w_err_gc->has_write_err) {
+		lba_list = line->w_err_gc->lba_list;
+		line->w_err_gc->lba_list = NULL;
+	} else {
+		lba_list = get_lba_list_from_emeta(pblk, line);
+		if (!lba_list) {
+			pblk_err(pblk, "could not interpret emeta (line %d)\n",
+					line->id);
+			goto fail_free_invalid_bitmap;
+		}
+	}
+
+	spin_lock(&line->lock);
+	bitmap_copy(invalid_bitmap, line->invalid_bitmap, lm->sec_per_line);
+	sec_left = pblk_line_vsc(line);
+	spin_unlock(&line->lock);
+
+	if (sec_left < 0) {
+		pblk_err(pblk, "corrupted GC line (%d)\n", line->id);
+		goto fail_free_lba_list;
+	}
+
+	bit = -1;
+next_rq:
+	gc_rq = kmalloc(sizeof(struct pblk_gc_rq), GFP_KERNEL);
+	if (!gc_rq)
+		goto fail_free_lba_list;
+
+	nr_secs = 0;
+	do {
+		bit = find_next_zero_bit(invalid_bitmap, lm->sec_per_line,
+								bit + 1);
+		if (bit > line->emeta_ssec)
+			break;
+
+		gc_rq->paddr_list[nr_secs] = bit;
+		gc_rq->lba_list[nr_secs++] = le64_to_cpu(lba_list[bit]);
+	} while (nr_secs < pblk->max_write_pgs);
+
+	if (unlikely(!nr_secs)) {
+		kfree(gc_rq);
+		goto out;
+	}
+
+	gc_rq->nr_secs = nr_secs;
+	gc_rq->line = line;
+
+	gc_rq_ws = kmalloc(sizeof(struct pblk_line_ws), GFP_KERNEL);
+	if (!gc_rq_ws)
+		goto fail_free_gc_rq;
+
+	gc_rq_ws->pblk = pblk;
+	gc_rq_ws->line = line;
+	gc_rq_ws->priv = gc_rq;
+
+	/* The write GC path can be much slower than the read GC one due to
+	 * the budget imposed by the rate-limiter. Balance in case that we get
+	 * back pressure from the write GC path.
+	 */
+	while (down_timeout(&gc->gc_sem, msecs_to_jiffies(30000)))
+		io_schedule();
+
+	kref_get(&line->ref);
+
+	INIT_WORK(&gc_rq_ws->ws, pblk_gc_line_ws);
+	queue_work(gc->gc_line_reader_wq, &gc_rq_ws->ws);
+
+	sec_left -= nr_secs;
+	if (sec_left > 0)
+		goto next_rq;
+
+out:
+	pblk_mfree(lba_list, l_mg->emeta_alloc_type);
+	kfree(line_ws);
+	kfree(invalid_bitmap);
+
+	kref_put(&line->ref, pblk_line_put);
+	atomic_dec(&gc->read_inflight_gc);
+
+	return;
+
+fail_free_gc_rq:
+	kfree(gc_rq);
+fail_free_lba_list:
+	pblk_mfree(lba_list, l_mg->emeta_alloc_type);
+fail_free_invalid_bitmap:
+	kfree(invalid_bitmap);
+fail_free_ws:
+	kfree(line_ws);
+
+	pblk_put_line_back(pblk, line);
+	kref_put(&line->ref, pblk_line_put);
+	atomic_dec(&gc->read_inflight_gc);
+
+	pblk_err(pblk, "failed to GC line %d\n", line->id);
+}
+
+static int pblk_gc_line(struct pblk *pblk, struct pblk_line *line)
+{
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_line_ws *line_ws;
+
+	pblk_debug(pblk, "line '%d' being reclaimed for GC\n", line->id);
+
+	line_ws = kmalloc(sizeof(struct pblk_line_ws), GFP_KERNEL);
+	if (!line_ws)
+		return -ENOMEM;
+
+	line_ws->pblk = pblk;
+	line_ws->line = line;
+
+	atomic_inc(&gc->pipeline_gc);
+	INIT_WORK(&line_ws->ws, pblk_gc_line_prepare_ws);
+	queue_work(gc->gc_reader_wq, &line_ws->ws);
+
+	return 0;
+}
+
+static void pblk_gc_reader_kick(struct pblk_gc *gc)
+{
+	wake_up_process(gc->gc_reader_ts);
+}
+
+static void pblk_gc_kick(struct pblk *pblk)
+{
+	struct pblk_gc *gc = &pblk->gc;
+
+	pblk_gc_writer_kick(gc);
+	pblk_gc_reader_kick(gc);
+
+	/* If we're shutting down GC, let's not start it up again */
+	if (gc->gc_enabled) {
+		wake_up_process(gc->gc_ts);
+		mod_timer(&gc->gc_timer,
+			  jiffies + msecs_to_jiffies(GC_TIME_MSECS));
+	}
+}
+
+static int pblk_gc_read(struct pblk *pblk)
+{
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_line *line;
+
+	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))
+		pblk_err(pblk, "failed to GC line %d\n", line->id);
+
+	return 0;
+}
+
+static struct pblk_line *pblk_gc_get_victim_line(struct pblk *pblk,
+						 struct list_head *group_list)
+{
+	struct pblk_line *line, *victim;
+	int line_vsc, victim_vsc;
+
+	victim = list_first_entry(group_list, struct pblk_line, list);
+	list_for_each_entry(line, group_list, list) {
+		line_vsc = le32_to_cpu(*line->vsc);
+		victim_vsc = le32_to_cpu(*victim->vsc);
+		if (line_vsc < victim_vsc)
+			victim = line;
+	}
+
+	return victim;
+}
+
+static bool pblk_gc_should_run(struct pblk_gc *gc, struct pblk_rl *rl)
+{
+	unsigned int nr_blocks_free, nr_blocks_need;
+	unsigned int werr_lines = atomic_read(&rl->werr_lines);
+
+	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 ((werr_lines > 0) ||
+		((gc->gc_active) && (nr_blocks_need > nr_blocks_free)));
+}
+
+void pblk_gc_free_full_lines(struct pblk *pblk)
+{
+	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
+	struct pblk_gc *gc = &pblk->gc;
+	struct pblk_line *line;
+
+	do {
+		spin_lock(&l_mg->gc_lock);
+		if (list_empty(&l_mg->gc_full_list)) {
+			spin_unlock(&l_mg->gc_lock);
+			return;
+		}
+
+		line = list_first_entry(&l_mg->gc_full_list,
+							struct pblk_line, 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);
+
+		atomic_inc(&gc->pipeline_gc);
+		kref_put(&line->ref, pblk_line_put);
+	} while (1);
+}
+
+/*
+ * 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
+ * threshold, or because it is being forced from user space - only lines with a
+ * high count of invalid sectors will be recycled.
+ */
+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;
+	struct list_head *group_list;
+	bool run_gc;
+	int read_inflight_gc, gc_group = 0, prev_group = 0;
+
+	pblk_gc_free_full_lines(pblk);
+
+	run_gc = pblk_gc_should_run(&pblk->gc, &pblk->rl);
+	if (!run_gc || (atomic_read(&gc->read_inflight_gc) >= PBLK_GC_L_QD))
+		return;
+
+next_gc_group:
+	group_list = l_mg->gc_lists[gc_group++];
+
+	do {
+		spin_lock(&l_mg->gc_lock);
+		if (list_empty(group_list)) {
+			spin_unlock(&l_mg->gc_lock);
+			break;
+		}
+
+		line = pblk_gc_get_victim_line(pblk, group_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);
+
+		spin_lock(&gc->r_lock);
+		list_add_tail(&line->list, &gc->r_list);
+		spin_unlock(&gc->r_lock);
+
+		read_inflight_gc = atomic_inc_return(&gc->read_inflight_gc);
+		pblk_gc_reader_kick(gc);
+
+		prev_group = 1;
+
+		/* 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 || read_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_timer(struct timer_list *t)
+{
+	struct pblk *pblk = from_timer(pblk, t, gc.gc_timer);
+
+	pblk_gc_kick(pblk);
+}
+
+static int pblk_gc_ts(void *data)
+{
+	struct pblk *pblk = data;
+
+	while (!kthread_should_stop()) {
+		pblk_gc_run(pblk);
+		set_current_state(TASK_INTERRUPTIBLE);
+		io_schedule();
+	}
+
+	return 0;
+}
+
+static int pblk_gc_writer_ts(void *data)
+{
+	struct pblk *pblk = data;
+
+	while (!kthread_should_stop()) {
+		if (!pblk_gc_write(pblk))
+			continue;
+		set_current_state(TASK_INTERRUPTIBLE);
+		io_schedule();
+	}
+
+	return 0;
+}
+
+static int pblk_gc_reader_ts(void *data)
+{
+	struct pblk *pblk = data;
+	struct pblk_gc *gc = &pblk->gc;
+
+	while (!kthread_should_stop()) {
+		if (!pblk_gc_read(pblk))
+			continue;
+		set_current_state(TASK_INTERRUPTIBLE);
+		io_schedule();
+	}
+
+#ifdef CONFIG_NVM_PBLK_DEBUG
+	pblk_info(pblk, "flushing gc pipeline, %d lines left\n",
+		atomic_read(&gc->pipeline_gc));
+#endif
+
+	do {
+		if (!atomic_read(&gc->pipeline_gc))
+			break;
+
+		schedule();
+	} while (1);
+
+	return 0;
+}
+
+static void pblk_gc_start(struct pblk *pblk)
+{
+	pblk->gc.gc_active = 1;
+	pblk_debug(pblk, "gc start\n");
+}
+
+void pblk_gc_should_start(struct pblk *pblk)
+{
+	struct pblk_gc *gc = &pblk->gc;
+
+	if (gc->gc_enabled && !gc->gc_active) {
+		pblk_gc_start(pblk);
+		pblk_gc_kick(pblk);
+	}
+}
+
+void pblk_gc_should_stop(struct pblk *pblk)
+{
+	struct pblk_gc *gc = &pblk->gc;
+
+	if (gc->gc_active && !gc->gc_forced)
+		gc->gc_active = 0;
+}
+
+void pblk_gc_should_kick(struct pblk *pblk)
+{
+	pblk_rl_update_rates(&pblk->rl);
+}
+
+void pblk_gc_sysfs_state_show(struct pblk *pblk, int *gc_enabled,
+			      int *gc_active)
+{
+	struct pblk_gc *gc = &pblk->gc;
+
+	spin_lock(&gc->lock);
+	*gc_enabled = gc->gc_enabled;
+	*gc_active = gc->gc_active;
+	spin_unlock(&gc->lock);
+}
+
+int pblk_gc_sysfs_force(struct pblk *pblk, int force)
+{
+	struct pblk_gc *gc = &pblk->gc;
+
+	if (force < 0 || force > 1)
+		return -EINVAL;
+
+	spin_lock(&gc->lock);
+	gc->gc_forced = force;
+
+	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)
+{
+	struct pblk_gc *gc = &pblk->gc;
+	int ret;
+
+	gc->gc_ts = kthread_create(pblk_gc_ts, pblk, "pblk-gc-ts");
+	if (IS_ERR(gc->gc_ts)) {
+		pblk_err(pblk, "could not allocate GC main kthread\n");
+		return PTR_ERR(gc->gc_ts);
+	}
+
+	gc->gc_writer_ts = kthread_create(pblk_gc_writer_ts, pblk,
+							"pblk-gc-writer-ts");
+	if (IS_ERR(gc->gc_writer_ts)) {
+		pblk_err(pblk, "could not allocate GC writer kthread\n");
+		ret = PTR_ERR(gc->gc_writer_ts);
+		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)) {
+		pblk_err(pblk, "could not allocate GC reader kthread\n");
+		ret = PTR_ERR(gc->gc_reader_ts);
+		goto fail_free_writer_kthread;
+	}
+
+	timer_setup(&gc->gc_timer, pblk_gc_timer, 0);
+	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->w_entries = 0;
+	atomic_set(&gc->read_inflight_gc, 0);
+	atomic_set(&gc->pipeline_gc, 0);
+
+	/* 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) {
+		pblk_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) {
+		pblk_err(pblk, "could not allocate GC reader workqueue\n");
+		ret = -ENOMEM;
+		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, PBLK_GC_RQ_QD);
+
+	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:
+	kthread_stop(gc->gc_ts);
+
+	return ret;
+}
+
+void pblk_gc_exit(struct pblk *pblk, bool graceful)
+{
+	struct pblk_gc *gc = &pblk->gc;
+
+	gc->gc_enabled = 0;
+	del_timer_sync(&gc->gc_timer);
+	gc->gc_active = 0;
+
+	if (gc->gc_ts)
+		kthread_stop(gc->gc_ts);
+
+	if (gc->gc_reader_ts)
+		kthread_stop(gc->gc_reader_ts);
+
+	if (graceful) {
+		flush_workqueue(gc->gc_reader_wq);
+		flush_workqueue(gc->gc_line_reader_wq);
+	}
+
+	destroy_workqueue(gc->gc_reader_wq);
+	destroy_workqueue(gc->gc_line_reader_wq);
+
+	if (gc->gc_writer_ts)
+		kthread_stop(gc->gc_writer_ts);
+}