dm thin: dont use map_context

This patch removes endio_hook_pool from dm-thin and uses per-bio data instead.

This patch removes any use of map_info in preparation for the next patch
that removes map_info from bio-based device mapper.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 13 insertions, 36 deletions

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 4b940745ba9e..e7743c69a24c 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -186,7 +186,6 @@ struct pool {
 
         struct dm_thin_new_mapping *next_mapping;
         mempool_t *mapping_pool;
-        mempool_t *endio_hook_pool;
 
         process_bio_fn process_bio;
         process_bio_fn process_discard;
@@ -304,7 +303,7 @@ static void __requeue_bio_list(struct thin_c *tc, struct bio_list *master)
         bio_list_init(master);
 
         while ((bio = bio_list_pop(&bios))) {
-                struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
                 if (h->tc == tc)
                         bio_endio(bio, DM_ENDIO_REQUEUE);
@@ -375,7 +374,7 @@ static void inc_all_io_entry(struct pool *pool, struct bio *bio)
         if (bio->bi_rw & REQ_DISCARD)
                 return;
 
-        h = dm_get_mapinfo(bio)->ptr;
+        h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
         h->all_io_entry = dm_deferred_entry_inc(pool->all_io_ds);
 }
 
@@ -485,7 +484,7 @@ static void copy_complete(int read_err, unsigned long write_err, void *context)
 static void overwrite_endio(struct bio *bio, int err)
 {
         unsigned long flags;
-        struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
         struct dm_thin_new_mapping *m = h->overwrite_mapping;
         struct pool *pool = m->tc->pool;
 
@@ -714,7 +713,7 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
          * bio immediately. Otherwise we use kcopyd to clone the data first.
          */
         if (io_overwrites_block(pool, bio)) {
-                struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
                 h->overwrite_mapping = m;
                 m->bio = bio;
@@ -784,7 +783,7 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
                 process_prepared_mapping(m);
 
         else if (io_overwrites_block(pool, bio)) {
-                struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
                 h->overwrite_mapping = m;
                 m->bio = bio;
@@ -899,7 +898,7 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
  */
 static void retry_on_resume(struct bio *bio)
 {
-        struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
         struct thin_c *tc = h->tc;
         struct pool *pool = tc->pool;
         unsigned long flags;
@@ -1051,7 +1050,7 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
         if (bio_data_dir(bio) == WRITE && bio->bi_size)
                 break_sharing(tc, bio, block, &key, lookup_result, cell);
         else {
-                struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
                 h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
                 inc_all_io_entry(pool, bio);
@@ -1226,7 +1225,7 @@ static void process_deferred_bios(struct pool *pool)
         spin_unlock_irqrestore(&pool->lock, flags);
 
         while ((bio = bio_list_pop(&bios))) {
-                struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
                 struct thin_c *tc = h->tc;
 
                 /*
@@ -1359,17 +1358,14 @@ static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
         wake_worker(pool);
 }
 
-static struct dm_thin_endio_hook *thin_hook_bio(struct thin_c *tc, struct bio *bio)
+static void thin_hook_bio(struct thin_c *tc, struct bio *bio)
 {
-        struct pool *pool = tc->pool;
-        struct dm_thin_endio_hook *h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO);
+        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
         h->tc = tc;
         h->shared_read_entry = NULL;
         h->all_io_entry = NULL;
         h->overwrite_mapping = NULL;
-
-        return h;
 }
 
 /*
@@ -1386,7 +1382,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio,
         struct dm_bio_prison_cell *cell1, *cell2;
         struct dm_cell_key key;
 
-        map_context->ptr = thin_hook_bio(tc, bio);
+        thin_hook_bio(tc, bio);
 
         if (get_pool_mode(tc->pool) == PM_FAIL) {
                 bio_io_error(bio);
@@ -1595,14 +1591,12 @@ static void __pool_destroy(struct pool *pool)
         if (pool->next_mapping)
                 mempool_free(pool->next_mapping, pool->mapping_pool);
         mempool_destroy(pool->mapping_pool);
-        mempool_destroy(pool->endio_hook_pool);
         dm_deferred_set_destroy(pool->shared_read_ds);
         dm_deferred_set_destroy(pool->all_io_ds);
         kfree(pool);
 }
 
 static struct kmem_cache *_new_mapping_cache;
-static struct kmem_cache *_endio_hook_cache;
 
 static struct pool *pool_create(struct mapped_device *pool_md,
                                 struct block_device *metadata_dev,
@@ -1696,13 +1690,6 @@ static struct pool *pool_create(struct mapped_device *pool_md,
                 goto bad_mapping_pool;
         }
 
-        pool->endio_hook_pool = mempool_create_slab_pool(ENDIO_HOOK_POOL_SIZE,
-                                                         _endio_hook_cache);
-        if (!pool->endio_hook_pool) {
-                *error = "Error creating pool's endio_hook mempool";
-                err_p = ERR_PTR(-ENOMEM);
-                goto bad_endio_hook_pool;
-        }
         pool->ref_count = 1;
         pool->last_commit_jiffies = jiffies;
         pool->pool_md = pool_md;
@@ -1711,8 +1698,6 @@ static struct pool *pool_create(struct mapped_device *pool_md,
 
         return pool;
 
-bad_endio_hook_pool:
-        mempool_destroy(pool->mapping_pool);
 bad_mapping_pool:
         dm_deferred_set_destroy(pool->all_io_ds);
 bad_all_io_ds:
@@ -2607,6 +2592,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
         ti->num_flush_requests = 1;
         ti->flush_supported = true;
+        ti->per_bio_data_size = sizeof(struct dm_thin_endio_hook);
 
         /* In case the pool supports discards, pass them on. */
         if (tc->pool->pf.discard_enabled) {
@@ -2653,7 +2639,7 @@ static int thin_endio(struct dm_target *ti,
                       union map_info *map_context)
 {
         unsigned long flags;
-        struct dm_thin_endio_hook *h = map_context->ptr;
+        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
         struct list_head work;
         struct dm_thin_new_mapping *m, *tmp;
         struct pool *pool = h->tc->pool;
@@ -2683,8 +2669,6 @@ static int thin_endio(struct dm_target *ti,
                 }
         }
 
-        mempool_free(h, pool->endio_hook_pool);
-
         return 0;
 }
 
@@ -2813,14 +2797,8 @@ static int __init dm_thin_init(void)
         if (!_new_mapping_cache)
                 goto bad_new_mapping_cache;
 
-        _endio_hook_cache = KMEM_CACHE(dm_thin_endio_hook, 0);
-        if (!_endio_hook_cache)
-                goto bad_endio_hook_cache;
-
         return 0;
 
-bad_endio_hook_cache:
-        kmem_cache_destroy(_new_mapping_cache);
 bad_new_mapping_cache:
         dm_unregister_target(&pool_target);
 bad_pool_target:
@@ -2835,7 +2813,6 @@ static void dm_thin_exit(void)
         dm_unregister_target(&pool_target);
 
         kmem_cache_destroy(_new_mapping_cache);
-        kmem_cache_destroy(_endio_hook_cache);
 }
 
 module_init(dm_thin_init);