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dm: Use bioset's front_pad for dm_rq_clone_bio_info

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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 <koverstreet@google.com>
CC: Alasdair Kergon <agk@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Kent Overstreet 2012-09-07 13:44:01 -07:00 committed by Jens Axboe
parent 1e2a410ff7
commit 9481874231
1 changed files with 18 additions and 28 deletions
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46
drivers/md/dm.c
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@ -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_target_io *tio)
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]) +
@ -1460,30 +1460,17 @@ void dm_dispatch_request(struct request *rq)
}
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;
}
@ -2718,7 +2705,10 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity)
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;