dm bufio: intelligently size dm_buffer_cache's buffer_trees

Size the dm_buffer_cache's number of buffer_tree structs using
dm_num_hash_locks().

Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 2250799..c1126ad 100644 (file)
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -21,6 +21,8 @@
 #include <linux/stacktrace.h>
 #include <linux/jump_label.h>
 
+#include "dm.h"
+
 #define DM_MSG_PREFIX "bufio"
 
 /*
@@ -379,8 +381,6 @@ struct dm_buffer {
  * only enough to ensure get/put are threadsafe.
  */
 
-#define NR_LOCKS 64
-
 struct buffer_tree {
        struct rw_semaphore lock;
        struct rb_root root;
@@ -393,7 +393,7 @@ struct dm_buffer_cache {
         * on the locks.
         */
        unsigned int num_locks;
-       struct buffer_tree trees[NR_LOCKS];
+       struct buffer_tree trees[];
 };
 
 static inline unsigned int cache_index(sector_t block, unsigned int num_locks)
@@ -976,7 +976,7 @@ struct dm_bufio_client {
         */
        unsigned long oldest_buffer;
 
-       struct dm_buffer_cache cache;
+       struct dm_buffer_cache cache; /* must be last member */
 };
 
 static DEFINE_STATIC_KEY_FALSE(no_sleep_enabled);
@@ -2422,6 +2422,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
                                               unsigned int flags)
 {
        int r;
+       unsigned int num_locks;
        struct dm_bufio_client *c;
        char slab_name[27];
 
@@ -2431,12 +2432,13 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
                goto bad_client;
        }
 
-       c = kzalloc(sizeof(*c), GFP_KERNEL);
+       num_locks = dm_num_hash_locks();
+       c = kzalloc(sizeof(*c) + (num_locks * sizeof(struct buffer_tree)), GFP_KERNEL);
        if (!c) {
                r = -ENOMEM;
                goto bad_client;
        }
-       cache_init(&c->cache, NR_LOCKS);
+       cache_init(&c->cache, num_locks);
 
        c->bdev = bdev;
        c->block_size = block_size;