]> asedeno.scripts.mit.edu Git - linux.git/blobdiff - drivers/lightnvm/pblk-gc.c
lightnvm: pblk: use vmalloc for GC data buffer
[linux.git] / drivers / lightnvm / pblk-gc.c
index eaf479c6b63c8088c872e4cd724e4144f7be07d4..6090d28f7995a51f4d5972bf965457f1388874f7 100644 (file)
@@ -20,8 +20,7 @@
 
 static void pblk_gc_free_gc_rq(struct pblk_gc_rq *gc_rq)
 {
-       kfree(gc_rq->data);
-       kfree(gc_rq->lba_list);
+       vfree(gc_rq->data);
        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 = vmalloc(gc_rq->nr_secs * geo->sec_size);
        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 @@ static int pblk_gc_move_valid_secs(struct pblk *pblk, struct pblk_line *line,
 
        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);
-
+       vfree(data);
+out:
+       kref_put(&line->ref, pblk_line_put);
        return ret;
 }
 
@@ -149,141 +135,207 @@ 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;
-       __le64 *lba_list = line_ws->priv;
-       u64 *gc_list;
-       int sec_left;
-       int nr_ppas, bit;
-       int put_line = 1;
+       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;
+       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;
+       }
 
-       spin_lock(&line->lock);
-       sec_left = line->vsc;
-       if (!sec_left) {
-               /* Lines are erased before being used (l_mg->data_/log_next) */
-               spin_unlock(&line->lock);
-               goto out;
+       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
+        * moves all sectors on the line.
+        */
+       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 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;
 
-       sec_left -= nr_ppas;
+       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_secs;
        if (sec_left > 0)
                goto next_rq;
 
 out:
-       pblk_mfree(line->emeta, l_mg->emeta_alloc_type);
+       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 pblk_gc *gc = &pblk->gc;
        struct pblk_line_ws *line_ws;
-       __le64 *lba_list;
-       int ret;
 
-       line_ws = mempool_alloc(pblk->line_ws_pool, GFP_KERNEL);
-       line->emeta = pblk_malloc(lm->emeta_len, l_mg->emeta_alloc_type,
-                                                               GFP_KERNEL);
-       if (!line->emeta) {
-               pr_err("pblk: cannot use GC emeta\n");
-               goto fail_free_ws;
-       }
-
-       ret = pblk_line_read_emeta(pblk, line);
-       if (ret) {
-               pr_err("pblk: line %d read emeta failed (%d)\n", line->id, ret);
-               goto fail_free_emeta;
-       }
+       pr_debug("pblk: line '%d' being reclaimed for GC\n", line->id);
 
-       /* 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.
-        */
-       lba_list = pblk_recov_get_lba_list(pblk, line->emeta);
-       if (!lba_list) {
-               pr_err("pblk: could not interpret emeta (line %d)\n", line->id);
-               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 = lba_list;
 
-       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(line->emeta, l_mg->emeta_alloc_type);
-fail_free_ws:
-       mempool_free(line_ws, pblk->line_ws_pool);
-       pblk_put_line_back(pblk, line);
+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);
 
-       return 1;
+       if (pblk_gc_line(pblk, line))
+               pr_err("pblk: failed to GC line %d\n", line->id);
+
+       return 0;
 }
 
-static void pblk_gc_lines(struct pblk *pblk, struct list_head *gc_list)
+static void pblk_gc_reader_kick(struct pblk_gc *gc)
 {
-       struct pblk_line *line, *tline;
+       wake_up_process(gc->gc_reader_ts);
+}
 
-       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);
+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;
+
+       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));
 }
 
 /*
@@ -296,71 +348,83 @@ 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 = list_first_entry(group_list, struct pblk_line, list);
-               nr_blocks_free += atomic_read(&line->blk_in_line);
+               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;
-               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);
 
-       pblk_gc_lines(pblk, &gc_list);
+               inflight_gc = atomic_inc_return(&gc->inflight_gc);
+               pblk_gc_reader_kick(gc);
 
-       if (!prev_gc && pblk->rl.rb_state > gc_group &&
-                                               gc_group < PBLK_NR_GC_LISTS)
+               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 || 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));
 }
 
@@ -398,42 +462,34 @@ 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);
 }
 
 /*
@@ -442,10 +498,7 @@ 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");
 }
 
@@ -468,20 +521,25 @@ 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)
@@ -503,30 +561,58 @@ 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:
@@ -540,6 +626,7 @@ 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);
@@ -547,9 +634,15 @@ 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);
 }