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Subject[PATCH V2] lightnvm: pblk: stop recreating global caches
Date
From: Hans Holmberg <hans.holmberg@cnexlabs.com>

Pblk should not create a set of global caches every time
a pblk instance is created. The global caches should be
made available only when there is one or more pblk instances.

This patch bundles the global caches together with a kref
keeping track of whether the caches should be available or not.

Also, turn the global pblk lock into a mutex that explicitly
protects the caches (as this was the only purpose of the lock).

Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
---

Changes in V2:
* Turned the pblk global lock into a mutex protecting the
caches struct.
* Renamed the global caches to pblk_caches
* Refactored pblk_get_global_caches to handle only refcounting
and locking.

drivers/lightnvm/pblk-init.c | 132 ++++++++++++++++++++++++++++---------------
1 file changed, 86 insertions(+), 46 deletions(-)

diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index 9aebdee8e4c9..fb66bc84d5ca 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -26,9 +26,24 @@ static unsigned int write_buffer_size;
module_param(write_buffer_size, uint, 0644);
MODULE_PARM_DESC(write_buffer_size, "number of entries in a write buffer");

-static struct kmem_cache *pblk_ws_cache, *pblk_rec_cache, *pblk_g_rq_cache,
- *pblk_w_rq_cache;
-static DECLARE_RWSEM(pblk_lock);
+struct pblk_global_caches {
+ struct kmem_cache *ws;
+ struct kmem_cache *rec;
+ struct kmem_cache *g_rq;
+ struct kmem_cache *w_rq;
+
+ struct kref kref;
+
+ struct mutex mutex; /* Ensures consistency between
+ * caches and kref
+ */
+};
+
+static struct pblk_global_caches pblk_caches = {
+ .mutex = __MUTEX_INITIALIZER(pblk_caches.mutex),
+ .kref = KREF_INIT(0),
+};
+
struct bio_set pblk_bio_set;

static int pblk_rw_io(struct request_queue *q, struct pblk *pblk,
@@ -307,53 +322,80 @@ static int pblk_set_addrf(struct pblk *pblk)
return 0;
}

-static int pblk_init_global_caches(struct pblk *pblk)
+static int pblk_create_global_caches(void)
{
- down_write(&pblk_lock);
- pblk_ws_cache = kmem_cache_create("pblk_blk_ws",
+
+ pblk_caches.ws = kmem_cache_create("pblk_blk_ws",
sizeof(struct pblk_line_ws), 0, 0, NULL);
- if (!pblk_ws_cache) {
- up_write(&pblk_lock);
+ if (!pblk_caches.ws)
return -ENOMEM;
- }

- pblk_rec_cache = kmem_cache_create("pblk_rec",
+ pblk_caches.rec = kmem_cache_create("pblk_rec",
sizeof(struct pblk_rec_ctx), 0, 0, NULL);
- if (!pblk_rec_cache) {
- kmem_cache_destroy(pblk_ws_cache);
- up_write(&pblk_lock);
- return -ENOMEM;
- }
+ if (!pblk_caches.rec)
+ goto fail_destroy_ws;

- pblk_g_rq_cache = kmem_cache_create("pblk_g_rq", pblk_g_rq_size,
+ pblk_caches.g_rq = kmem_cache_create("pblk_g_rq", pblk_g_rq_size,
0, 0, NULL);
- if (!pblk_g_rq_cache) {
- kmem_cache_destroy(pblk_ws_cache);
- kmem_cache_destroy(pblk_rec_cache);
- up_write(&pblk_lock);
- return -ENOMEM;
- }
+ if (!pblk_caches.g_rq)
+ goto fail_destroy_rec;

- pblk_w_rq_cache = kmem_cache_create("pblk_w_rq", pblk_w_rq_size,
+ pblk_caches.w_rq = kmem_cache_create("pblk_w_rq", pblk_w_rq_size,
0, 0, NULL);
- if (!pblk_w_rq_cache) {
- kmem_cache_destroy(pblk_ws_cache);
- kmem_cache_destroy(pblk_rec_cache);
- kmem_cache_destroy(pblk_g_rq_cache);
- up_write(&pblk_lock);
- return -ENOMEM;
- }
- up_write(&pblk_lock);
+ if (!pblk_caches.w_rq)
+ goto fail_destroy_g_rq;

return 0;
+
+fail_destroy_g_rq:
+ kmem_cache_destroy(pblk_caches.g_rq);
+fail_destroy_rec:
+ kmem_cache_destroy(pblk_caches.rec);
+fail_destroy_ws:
+ kmem_cache_destroy(pblk_caches.ws);
+
+ return -ENOMEM;
+}
+
+static int pblk_get_global_caches(void)
+{
+ int ret;
+
+ mutex_lock(&pblk_caches.mutex);
+
+ if (kref_read(&pblk_caches.kref) > 0) {
+ kref_get(&pblk_caches.kref);
+ mutex_unlock(&pblk_caches.mutex);
+ return 0;
+ }
+
+ ret = pblk_create_global_caches();
+
+ if (!ret)
+ kref_get(&pblk_caches.kref);
+
+ mutex_unlock(&pblk_caches.mutex);
+
+ return ret;
+}
+
+static void pblk_destroy_global_caches(struct kref *ref)
+{
+ struct pblk_global_caches *c;
+
+ c = container_of(ref, struct pblk_global_caches, kref);
+
+ kmem_cache_destroy(c->ws);
+ kmem_cache_destroy(c->rec);
+ kmem_cache_destroy(c->g_rq);
+ kmem_cache_destroy(c->w_rq);
}

-static void pblk_free_global_caches(struct pblk *pblk)
+static void pblk_put_global_caches(void)
{
- kmem_cache_destroy(pblk_ws_cache);
- kmem_cache_destroy(pblk_rec_cache);
- kmem_cache_destroy(pblk_g_rq_cache);
- kmem_cache_destroy(pblk_w_rq_cache);
+ mutex_lock(&pblk_caches.mutex);
+ kref_put(&pblk_caches.kref, pblk_destroy_global_caches);
+ mutex_unlock(&pblk_caches.mutex);
}

static int pblk_core_init(struct pblk *pblk)
@@ -382,7 +424,7 @@ static int pblk_core_init(struct pblk *pblk)
if (!pblk->pad_dist)
return -ENOMEM;

- if (pblk_init_global_caches(pblk))
+ if (pblk_get_global_caches())
goto fail_free_pad_dist;

/* Internal bios can be at most the sectors signaled by the device. */
@@ -391,27 +433,27 @@ static int pblk_core_init(struct pblk *pblk)
goto free_global_caches;

ret = mempool_init_slab_pool(&pblk->gen_ws_pool, PBLK_GEN_WS_POOL_SIZE,
- pblk_ws_cache);
+ pblk_caches.ws);
if (ret)
goto free_page_bio_pool;

ret = mempool_init_slab_pool(&pblk->rec_pool, geo->all_luns,
- pblk_rec_cache);
+ pblk_caches.rec);
if (ret)
goto free_gen_ws_pool;

ret = mempool_init_slab_pool(&pblk->r_rq_pool, geo->all_luns,
- pblk_g_rq_cache);
+ pblk_caches.g_rq);
if (ret)
goto free_rec_pool;

ret = mempool_init_slab_pool(&pblk->e_rq_pool, geo->all_luns,
- pblk_g_rq_cache);
+ pblk_caches.g_rq);
if (ret)
goto free_r_rq_pool;

ret = mempool_init_slab_pool(&pblk->w_rq_pool, geo->all_luns,
- pblk_w_rq_cache);
+ pblk_caches.w_rq);
if (ret)
goto free_e_rq_pool;

@@ -457,7 +499,7 @@ static int pblk_core_init(struct pblk *pblk)
free_page_bio_pool:
mempool_exit(&pblk->page_bio_pool);
free_global_caches:
- pblk_free_global_caches(pblk);
+ pblk_put_global_caches();
fail_free_pad_dist:
kfree(pblk->pad_dist);
return -ENOMEM;
@@ -481,7 +523,7 @@ static void pblk_core_free(struct pblk *pblk)
mempool_exit(&pblk->e_rq_pool);
mempool_exit(&pblk->w_rq_pool);

- pblk_free_global_caches(pblk);
+ pblk_put_global_caches();
kfree(pblk->pad_dist);
}

@@ -1074,7 +1116,6 @@ static void pblk_exit(void *private, bool graceful)
{
struct pblk *pblk = private;

- down_write(&pblk_lock);
pblk_gc_exit(pblk, graceful);
pblk_tear_down(pblk, graceful);

@@ -1083,7 +1124,6 @@ static void pblk_exit(void *private, bool graceful)
#endif

pblk_free(pblk);
- up_write(&pblk_lock);
}

static sector_t pblk_capacity(void *private)
--
2.7.4
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