[PATCH 3/7] lightnvm: pblk: allocate line map bitmaps using a mempool

From: Hans Holmberg
Date: Wed Aug 29 2018 - 08:24:00 EST


From: Hans Holmberg <hans.holmberg@xxxxxxxxxxxx>

Line map bitmap allocations are fairly large and can fail. Allocation
failures are fatal to pblk, stoping 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@xxxxxxxxxxxx>
---
drivers/lightnvm/pblk-core.c | 22 +++++++++++++++-------
drivers/lightnvm/pblk-init.c | 18 ++++++++++++++++++
drivers/lightnvm/pblk-recovery.c | 2 +-
drivers/lightnvm/pblk.h | 4 ++++
4 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
index 36ac9eff8ebd..a1033d82b9cc 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 @@ static int pblk_line_mg_init(struct pblk *pblk)
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 @@ struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
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 fd274985aa82..1a31fda3a9f2 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;
--
2.7.4