dm bufio: get rid of slab cache name allocations

dm-bufio keeps the dm_bufio_cache_names array that holds names of the
slab caches.

Since the commit db265eca ("mm/sl[aou]b: Move duping of slab name to
slab_common.c"), the kernel automatically duplicates the slab cache name
when creating the slab cache, so we no longer have to keep the name
allocated.

Remove the code that allocates the slab names and keeps them around.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-bufio.c

@@ -173,7 +173,6 @@ struct dm_buffer {
 /*----------------------------------------------------------------*/
 
 static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
-static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
 
 static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
 {
@@ -185,7 +184,6 @@ static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
 }
 
 #define DM_BUFIO_CACHE(c)	(dm_bufio_caches[dm_bufio_cache_index(c)])
-#define DM_BUFIO_CACHE_NAME(c)	(dm_bufio_cache_names[dm_bufio_cache_index(c)])
 
 #define dm_bufio_in_request()	(!!current->bio_list)
 
@@ -1703,19 +1701,10 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 
 	mutex_lock(&dm_bufio_clients_lock);
 	if (c->blocks_per_page_bits) {
-		if (!DM_BUFIO_CACHE_NAME(c)) {
-			DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size);
-			if (!DM_BUFIO_CACHE_NAME(c)) {
-				r = -ENOMEM;
-				mutex_unlock(&dm_bufio_clients_lock);
-				goto bad;
-			}
-		}
-
 		if (!DM_BUFIO_CACHE(c)) {
-			DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c),
-							      c->block_size,
-							      c->block_size, 0, NULL);
+			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);
@@ -1908,7 +1897,6 @@ static int __init dm_bufio_init(void)
 	dm_bufio_current_allocated = 0;
 
 	memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
-	memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
 
 	mem = (__u64)mult_frac(totalram_pages - totalhigh_pages,
 			       DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT;
@@ -1952,9 +1940,6 @@ static void __exit dm_bufio_exit(void)
 	for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++)
 		kmem_cache_destroy(dm_bufio_caches[i]);
 
-	for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
-		kfree(dm_bufio_cache_names[i]);
-
 	if (dm_bufio_client_count) {
 		DMCRIT("%s: dm_bufio_client_count leaked: %d",
 			__func__, dm_bufio_client_count);