[dm-devel] [dm-6.4 PATCH v3 18/20] dm bufio: intelligently size dm_buffer_cache's buffer_trees

Mike Snitzer
2023-03-27T20:14:23Z

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

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---
drivers/md/dm-bufio.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 2250799a70e4..7dc53f3d0739 100644
--- 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_sharded_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;