From 94818742316e27d01506240cf8b07d69844d31af Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Fri, 7 Sep 2012 13:44:01 -0700 Subject: [PATCH 3/8] dm: Use bioset's front_pad for dm_rq_clone_bio_info Previously, dm_rq_clone_bio_info needed to be freed by the bio's destructor to avoid a memory leak in the blk_rq_prep_clone() error path. This gets rid of a memory allocation and means we can kill dm_rq_bio_destructor. The _rq_bio_info_cache kmem cache is unused now and needs to be deleted, but due to the way io_pool is used and overloaded this looks not quite trivial so I'm leaving it for a later patch. v6: Fix comment on struct dm_rq_clone_bio_info, per Tejun Signed-off-by: Kent Overstreet CC: Alasdair Kergon Acked-by: Tejun Heo Signed-off-by: Jens Axboe --- drivers/md/dm.c | 46 ++++++++++++++++++---------------------------- 1 file changed, 18 insertions(+), 28 deletions(-) Index: linux/drivers/md/dm.c =================================================================== --- linux.orig/drivers/md/dm.c +++ linux/drivers/md/dm.c @@ -86,12 +86,17 @@ struct dm_rq_target_io { }; /* - * For request-based dm. - * One of these is allocated per bio. + * For request-based dm - the bio clones we allocate are embedded in these + * structs. + * + * We allocate these with bio_alloc_bioset, using the front_pad parameter when + * the bioset is created - this means the bio has to come at the end of the + * struct. */ struct dm_rq_clone_bio_info { struct bio *orig; struct dm_rq_target_io *tio; + struct bio clone; }; union map_info *dm_get_mapinfo(struct bio *bio) @@ -211,6 +216,11 @@ struct dm_md_mempools { static struct kmem_cache *_io_cache; static struct kmem_cache *_tio_cache; static struct kmem_cache *_rq_tio_cache; + +/* + * Unused now, and needs to be deleted. But since io_pool is overloaded and it's + * still used for _io_cache, I'm leaving this for a later cleanup + */ static struct kmem_cache *_rq_bio_info_cache; static int __init local_init(void) @@ -467,16 +477,6 @@ static void free_rq_tio(struct dm_rq_tar mempool_free(tio, tio->md->tio_pool); } -static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md) -{ - return mempool_alloc(md->io_pool, GFP_ATOMIC); -} - -static void free_bio_info(struct dm_rq_clone_bio_info *info) -{ - mempool_free(info, info->tio->md->io_pool); -} - static int md_in_flight(struct mapped_device *md) { return atomic_read(&md->pending[READ]) + @@ -1464,30 +1464,17 @@ void dm_dispatch_request(struct request } EXPORT_SYMBOL_GPL(dm_dispatch_request); -static void dm_rq_bio_destructor(struct bio *bio) -{ - struct dm_rq_clone_bio_info *info = bio->bi_private; - struct mapped_device *md = info->tio->md; - - free_bio_info(info); - bio_free(bio, md->bs); -} - static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig, void *data) { struct dm_rq_target_io *tio = data; - struct mapped_device *md = tio->md; - struct dm_rq_clone_bio_info *info = alloc_bio_info(md); - - if (!info) - return -ENOMEM; + struct dm_rq_clone_bio_info *info = + container_of(bio, struct dm_rq_clone_bio_info, clone); info->orig = bio_orig; info->tio = tio; bio->bi_end_io = end_clone_bio; bio->bi_private = info; - bio->bi_destructor = dm_rq_bio_destructor; return 0; } @@ -2751,7 +2738,10 @@ struct dm_md_mempools *dm_alloc_md_mempo if (!pools->tio_pool) goto free_io_pool_and_out; - pools->bs = bioset_create(pool_size, 0); + pools->bs = (type == DM_TYPE_BIO_BASED) ? + bioset_create(pool_size, 0) : + bioset_create(pool_size, + offsetof(struct dm_rq_clone_bio_info, clone)); if (!pools->bs) goto free_tio_pool_and_out;