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>
---
drivers/md/dm.c | 44 ++++++++++++++++----------------------------
1 file changed, 16 insertions(+), 28 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 0c3d6dd..9206781 100644
--- a/drivers/md/dm.c
+++ b/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_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 +2705,8 @@ 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 = bioset_create(pool_size,
+ offsetof(struct dm_rq_clone_bio_info, clone));
if (!pools->bs)
goto free_tio_pool_and_out;
--
1.7.12
--
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dm: Use bioset's front_pad for dm_rq_clone_bio_info
