dm bufio: remove code that merges slab caches

All slab allocators can merge duplicate caches.  So dm-bufio doesn't
need extra slab merging logic.  Instead it can just allocate one slab
cache per client and let the allocator merge them.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 6dd465fa90a7333076df102be4818be6e8d32098..ef6365ed2af098c1c30b61ddf5a407be3d4298c1 100644 (file)
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -57,10 +57,9 @@
 #define DM_BUFIO_INLINE_VECS           16
 
 /*
- * Don't try to use kmem_cache_alloc for blocks larger than this.
+ * Don't try to use alloc_pages for blocks larger than this.
  * For explanation, see alloc_buffer_data below.
  */
-#define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT (PAGE_SIZE >> 1)
 #define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT  (PAGE_SIZE << (MAX_ORDER - 1))
 
 /*
@@ -101,11 +100,11 @@ struct dm_bufio_client {
        unsigned block_size;
        unsigned char sectors_per_block_bits;
        unsigned char pages_per_block_bits;
-       unsigned char blocks_per_page_bits;
        unsigned aux_size;
        void (*alloc_callback)(struct dm_buffer *);
        void (*write_callback)(struct dm_buffer *);
 
+       struct kmem_cache *slab_cache;
        struct dm_io_client *dm_io;
 
        struct list_head reserved_buffers;
@@ -172,19 +171,6 @@ struct dm_buffer {
 
 /*----------------------------------------------------------------*/
 
-static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
-
-static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
-{
-       unsigned ret = c->blocks_per_page_bits - 1;
-
-       BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
-
-       return ret;
-}
-
-#define DM_BUFIO_CACHE(c)      (dm_bufio_caches[dm_bufio_cache_index(c)])
-
 #define dm_bufio_in_request()  (!!current->bio_list)
 
 static void dm_bufio_lock(struct dm_bufio_client *c)
@@ -384,9 +370,9 @@ static void __cache_size_refresh(void)
 static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
                               enum data_mode *data_mode)
 {
-       if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
+       if (unlikely(c->slab_cache != NULL)) {
                *data_mode = DATA_MODE_SLAB;
-               return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
+               return kmem_cache_alloc(c->slab_cache, gfp_mask);
        }
 
        if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
@@ -426,7 +412,7 @@ static void free_buffer_data(struct dm_bufio_client *c,
 {
        switch (data_mode) {
        case DATA_MODE_SLAB:
-               kmem_cache_free(DM_BUFIO_CACHE(c), data);
+               kmem_cache_free(c->slab_cache, data);
                break;
 
        case DATA_MODE_GET_FREE_PAGES:
@@ -1672,8 +1658,6 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
        c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
        c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ?
                                  __ffs(block_size) - PAGE_SHIFT : 0;
-       c->blocks_per_page_bits = (__ffs(block_size) < PAGE_SHIFT ?
-                                 PAGE_SHIFT - __ffs(block_size) : 0);
 
        c->aux_size = aux_size;
        c->alloc_callback = alloc_callback;
@@ -1699,20 +1683,15 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
                goto bad_dm_io;
        }
 
-       mutex_lock(&dm_bufio_clients_lock);
-       if (c->blocks_per_page_bits) {
-               if (!DM_BUFIO_CACHE(c)) {
-                       char name[26];
-                       snprintf(name, sizeof name, "dm_bufio_cache-%u", c->block_size);
-                       DM_BUFIO_CACHE(c) = kmem_cache_create(name, c->block_size, c->block_size, 0, NULL);
-                       if (!DM_BUFIO_CACHE(c)) {
-                               r = -ENOMEM;
-                               mutex_unlock(&dm_bufio_clients_lock);
-                               goto bad;
-                       }
+       if (block_size < PAGE_SIZE) {
+               char name[26];
+               snprintf(name, sizeof name, "dm_bufio_cache-%u", c->block_size);
+               c->slab_cache = kmem_cache_create(name, c->block_size, c->block_size, 0, NULL);
+               if (!c->slab_cache) {
+                       r = -ENOMEM;
+                       goto bad;
                }
        }
-       mutex_unlock(&dm_bufio_clients_lock);
 
        while (c->need_reserved_buffers) {
                struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
@@ -1747,6 +1726,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
                list_del(&b->lru_list);
                free_buffer(b);
        }
+       kmem_cache_destroy(c->slab_cache);
        dm_io_client_destroy(c->dm_io);
 bad_dm_io:
        mutex_destroy(&c->lock);
@@ -1793,6 +1773,7 @@ void dm_bufio_client_destroy(struct dm_bufio_client *c)
        for (i = 0; i < LIST_SIZE; i++)
                BUG_ON(c->n_buffers[i]);
 
+       kmem_cache_destroy(c->slab_cache);
        dm_io_client_destroy(c->dm_io);
        mutex_destroy(&c->lock);
        kfree(c);
@@ -1896,8 +1877,6 @@ static int __init dm_bufio_init(void)
        dm_bufio_allocated_vmalloc = 0;
        dm_bufio_current_allocated = 0;
 
-       memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
-
        mem = (__u64)mult_frac(totalram_pages - totalhigh_pages,
                               DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT;
 
@@ -1932,14 +1911,10 @@ static int __init dm_bufio_init(void)
 static void __exit dm_bufio_exit(void)
 {
        int bug = 0;
-       int i;
 
        cancel_delayed_work_sync(&dm_bufio_work);
        destroy_workqueue(dm_bufio_wq);
 
-       for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++)
-               kmem_cache_destroy(dm_bufio_caches[i]);
-
        if (dm_bufio_client_count) {
                DMCRIT("%s: dm_bufio_client_count leaked: %d",
                        __func__, dm_bufio_client_count);