lightnvm: pblk: allocate line map bitmaps using a mempool

Line map bitmap allocations are fairly large and can fail. Allocation
failures are fatal to pblk, stopping the write pipeline. To avoid this,
allocate the bitmaps using a mempool instead.

Mempool allocations never fail if called from a process context,
and pblk *should* only allocate map bitmaps in process context,
but keep the failure handling for robustness sake.

Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

4 files changed, 38 insertions, 8 deletions

diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
index a31417682c90..e1207a4f9d54 100644
--- a/drivers/lightnvm/pblk-core.c
+++ b/drivers/lightnvm/pblk-core.c
@@ -1049,15 +1049,18 @@ static int pblk_line_init_metadata(struct pblk *pblk, struct pblk_line *line,
 static int pblk_line_alloc_bitmaps(struct pblk *pblk, struct pblk_line *line)
 {
         struct pblk_line_meta *lm = &pblk->lm;
+        struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 
-        line->map_bitmap = kzalloc(lm->sec_bitmap_len, GFP_KERNEL);
+        line->map_bitmap = mempool_alloc(l_mg->bitmap_pool, GFP_KERNEL);
         if (!line->map_bitmap)
                 return -ENOMEM;
 
+        memset(line->map_bitmap, 0, lm->sec_bitmap_len);
+
         /* will be initialized using bb info from map_bitmap */
-        line->invalid_bitmap = kmalloc(lm->sec_bitmap_len, GFP_KERNEL);
+        line->invalid_bitmap = mempool_alloc(l_mg->bitmap_pool, GFP_KERNEL);
         if (!line->invalid_bitmap) {
-                kfree(line->map_bitmap);
+                mempool_free(line->map_bitmap, l_mg->bitmap_pool);
                 line->map_bitmap = NULL;
                 return -ENOMEM;
         }
@@ -1243,7 +1246,9 @@ int pblk_line_recov_alloc(struct pblk *pblk, struct pblk_line *line)
 
 void pblk_line_recov_close(struct pblk *pblk, struct pblk_line *line)
 {
-        kfree(line->map_bitmap);
+        struct pblk_line_mgmt *l_mg = &pblk->l_mg;
+
+        mempool_free(line->map_bitmap, l_mg->bitmap_pool);
         line->map_bitmap = NULL;
         line->smeta = NULL;
         line->emeta = NULL;
@@ -1261,8 +1266,11 @@ static void pblk_line_reinit(struct pblk_line *line)
 
 void pblk_line_free(struct pblk_line *line)
 {
-        kfree(line->map_bitmap);
-        kfree(line->invalid_bitmap);
+        struct pblk *pblk = line->pblk;
+        struct pblk_line_mgmt *l_mg = &pblk->l_mg;
+
+        mempool_free(line->map_bitmap, l_mg->bitmap_pool);
+        mempool_free(line->invalid_bitmap, l_mg->bitmap_pool);
 
         pblk_line_reinit(line);
 }
@@ -1741,7 +1749,7 @@ void pblk_line_close(struct pblk *pblk, struct pblk_line *line)
 
         list_add_tail(&line->list, move_list);
 
-        kfree(line->map_bitmap);
+        mempool_free(line->map_bitmap, l_mg->bitmap_pool);
         line->map_bitmap = NULL;
         line->smeta = NULL;
         line->emeta = NULL;
diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index 8adc8ac8b03c..76a4a271b9cf 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -498,6 +498,9 @@ static void pblk_line_mg_free(struct pblk *pblk)
                 pblk_mfree(l_mg->eline_meta[i]->buf, l_mg->emeta_alloc_type);
                 kfree(l_mg->eline_meta[i]);
         }
+
+        mempool_destroy(l_mg->bitmap_pool);
+        kmem_cache_destroy(l_mg->bitmap_cache);
 }
 
 static void pblk_line_meta_free(struct pblk_line_mgmt *l_mg,
@@ -797,6 +800,17 @@ static int pblk_line_mg_init(struct pblk *pblk)
                         goto fail_free_smeta;
         }
 
+        l_mg->bitmap_cache = kmem_cache_create("pblk_lm_bitmap",
+                        lm->sec_bitmap_len, 0, 0, NULL);
+        if (!l_mg->bitmap_cache)
+                goto fail_free_smeta;
+
+        /* the bitmap pool is used for both valid and map bitmaps */
+        l_mg->bitmap_pool = mempool_create_slab_pool(PBLK_DATA_LINES * 2,
+                                l_mg->bitmap_cache);
+        if (!l_mg->bitmap_pool)
+                goto fail_destroy_bitmap_cache;
+
         /* emeta allocates three different buffers for managing metadata with
          * in-memory and in-media layouts
          */
@@ -849,6 +863,10 @@ fail_free_emeta:
                         kfree(l_mg->eline_meta[i]->buf);
                 kfree(l_mg->eline_meta[i]);
         }
+
+        mempool_destroy(l_mg->bitmap_pool);
+fail_destroy_bitmap_cache:
+        kmem_cache_destroy(l_mg->bitmap_cache);
 fail_free_smeta:
         for (i = 0; i < PBLK_DATA_LINES; i++)
                 kfree(l_mg->sline_meta[i]);
diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
index 3bd2b6b0a359..eea901d7cebc 100644
--- a/drivers/lightnvm/pblk-recovery.c
+++ b/drivers/lightnvm/pblk-recovery.c
@@ -939,7 +939,7 @@ next:
                         list_move_tail(&line->list, move_list);
                         spin_unlock(&l_mg->gc_lock);
 
-                        kfree(line->map_bitmap);
+                        mempool_free(line->map_bitmap, l_mg->bitmap_pool);
                         line->map_bitmap = NULL;
                         line->smeta = NULL;
                         line->emeta = NULL;
diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 60c509a00574..9068b158de22 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -530,6 +530,10 @@ struct pblk_line_mgmt {
         struct pblk_emeta *eline_meta[PBLK_DATA_LINES];
         unsigned long meta_bitmap;
 
+        /* Cache and mempool for map/invalid bitmaps */
+        struct kmem_cache *bitmap_cache;
+        mempool_t *bitmap_pool;
+
         /* Helpers for fast bitmap calculations */
         unsigned long *bb_template;
         unsigned long *bb_aux;