dm delay: use per-bio data instead of a mempool and slab cache

Starting with commit c0820cf5ad095 ("dm: introduce per_bio_data"),
device mapper has the capability to pre-allocate a target-specific
structure with the bio.

This patch changes dm-delay to use this facility instead of a slab cache
and mempool.

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

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index 2f91d6d..a8a511c 100644 (file)
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -24,7 +24,6 @@ struct delay_c {
        struct work_struct flush_expired_bios;
        struct list_head delayed_bios;
        atomic_t may_delay;
-       mempool_t *delayed_pool;
 
        struct dm_dev *dev_read;
        sector_t start_read;
@@ -40,14 +39,11 @@ struct delay_c {
 struct dm_delay_info {
        struct delay_c *context;
        struct list_head list;
-       struct bio *bio;
        unsigned long expires;
 };
 
 static DEFINE_MUTEX(delayed_bios_lock);
 
-static struct kmem_cache *delayed_cache;
-
 static void handle_delayed_timer(unsigned long data)
 {
        struct delay_c *dc = (struct delay_c *)data;
@@ -87,13 +83,14 @@ static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
        mutex_lock(&delayed_bios_lock);
        list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
                if (flush_all || time_after_eq(jiffies, delayed->expires)) {
+                       struct bio *bio = dm_bio_from_per_bio_data(delayed,
+                                               sizeof(struct dm_delay_info));
                        list_del(&delayed->list);
-                       bio_list_add(&flush_bios, delayed->bio);
-                       if ((bio_data_dir(delayed->bio) == WRITE))
+                       bio_list_add(&flush_bios, bio);
+                       if ((bio_data_dir(bio) == WRITE))
                                delayed->context->writes--;
                        else
                                delayed->context->reads--;
-                       mempool_free(delayed, dc->delayed_pool);
                        continue;
                }
 
@@ -185,12 +182,6 @@ static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
        }
 
 out:
-       dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
-       if (!dc->delayed_pool) {
-               DMERR("Couldn't create delayed bio pool.");
-               goto bad_dev_write;
-       }
-
        dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
        if (!dc->kdelayd_wq) {
                DMERR("Couldn't start kdelayd");
@@ -206,12 +197,11 @@ out:
 
        ti->num_flush_bios = 1;
        ti->num_discard_bios = 1;
+       ti->per_bio_data_size = sizeof(struct dm_delay_info);
        ti->private = dc;
        return 0;
 
 bad_queue:
-       mempool_destroy(dc->delayed_pool);
-bad_dev_write:
        if (dc->dev_write)
                dm_put_device(ti, dc->dev_write);
 bad_dev_read:
@@ -232,7 +222,6 @@ static void delay_dtr(struct dm_target *ti)
        if (dc->dev_write)
                dm_put_device(ti, dc->dev_write);
 
-       mempool_destroy(dc->delayed_pool);
        kfree(dc);
 }
 
@@ -244,10 +233,9 @@ static int delay_bio(struct delay_c *dc, int delay, struct bio *bio)
        if (!delay || !atomic_read(&dc->may_delay))
                return 1;
 
-       delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
+       delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
 
        delayed->context = dc;
-       delayed->bio = bio;
        delayed->expires = expires = jiffies + (delay * HZ / 1000);
 
        mutex_lock(&delayed_bios_lock);
@@ -356,13 +344,7 @@ static struct target_type delay_target = {
 
 static int __init dm_delay_init(void)
 {
-       int r = -ENOMEM;
-
-       delayed_cache = KMEM_CACHE(dm_delay_info, 0);
-       if (!delayed_cache) {
-               DMERR("Couldn't create delayed bio cache.");
-               goto bad_memcache;
-       }
+       int r;
 
        r = dm_register_target(&delay_target);
        if (r < 0) {
@@ -373,15 +355,12 @@ static int __init dm_delay_init(void)
        return 0;
 
 bad_register:
-       kmem_cache_destroy(delayed_cache);
-bad_memcache:
        return r;
 }
 
 static void __exit dm_delay_exit(void)
 {
        dm_unregister_target(&delay_target);
-       kmem_cache_destroy(delayed_cache);
 }
 
 /* Module hooks */