[dm-devel] [PATCH v3 6/8] dm: split request structure out from dm_rq_target_io structure
Mike Snitzer
snitzer at redhat.com
Wed Dec 17 04:00:02 UTC 2014
Request-based DM support for blk-mq devices requires that
dm_rq_target_io structures not be allocated with an embedded request
structure. The request-based DM target (e.g. dm-multipath) must
allocate the request from the blk-mq devices' request_queue using
blk_get_request().
The unfortunate side-effect of this change is old-style request-based DM
support will no longer use contiguous memory for the dm_rq_target_io and
request structures for each clone.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 61 insertions(+), 9 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 1c69fcb..ca5eed2 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -78,7 +78,7 @@ struct dm_io {
struct dm_rq_target_io {
struct mapped_device *md;
struct dm_target *ti;
- struct request *orig, clone;
+ struct request *orig, *clone;
int error;
union map_info info;
};
@@ -179,6 +179,7 @@ struct mapped_device {
* io objects are allocated from here.
*/
mempool_t *io_pool;
+ mempool_t *rq_pool;
struct bio_set *bs;
@@ -214,6 +215,7 @@ struct mapped_device {
*/
struct dm_md_mempools {
mempool_t *io_pool;
+ mempool_t *rq_pool;
struct bio_set *bs;
};
@@ -228,6 +230,7 @@ struct table_device {
#define RESERVED_MAX_IOS 1024
static struct kmem_cache *_io_cache;
static struct kmem_cache *_rq_tio_cache;
+static struct kmem_cache *_rq_cache;
/*
* Bio-based DM's mempools' reserved IOs set by the user.
@@ -285,9 +288,14 @@ static int __init local_init(void)
if (!_rq_tio_cache)
goto out_free_io_cache;
+ _rq_cache = kmem_cache_create("dm_clone_request", sizeof(struct request),
+ __alignof__(struct request), 0, NULL);
+ if (!_rq_cache)
+ goto out_free_rq_tio_cache;
+
r = dm_uevent_init();
if (r)
- goto out_free_rq_tio_cache;
+ goto out_free_rq_cache;
deferred_remove_workqueue = alloc_workqueue("kdmremove", WQ_UNBOUND, 1);
if (!deferred_remove_workqueue) {
@@ -309,6 +317,8 @@ out_free_workqueue:
destroy_workqueue(deferred_remove_workqueue);
out_uevent_exit:
dm_uevent_exit();
+out_free_rq_cache:
+ kmem_cache_destroy(_rq_cache);
out_free_rq_tio_cache:
kmem_cache_destroy(_rq_tio_cache);
out_free_io_cache:
@@ -322,6 +332,7 @@ static void local_exit(void)
flush_scheduled_work();
destroy_workqueue(deferred_remove_workqueue);
+ kmem_cache_destroy(_rq_cache);
kmem_cache_destroy(_rq_tio_cache);
kmem_cache_destroy(_io_cache);
unregister_blkdev(_major, _name);
@@ -574,6 +585,17 @@ static void free_rq_tio(struct dm_rq_target_io *tio)
mempool_free(tio, tio->md->io_pool);
}
+static struct request *alloc_clone_request(struct mapped_device *md,
+ gfp_t gfp_mask)
+{
+ return mempool_alloc(md->rq_pool, gfp_mask);
+}
+
+static void free_clone_request(struct mapped_device *md, struct request *rq)
+{
+ mempool_free(rq, md->rq_pool);
+}
+
static int md_in_flight(struct mapped_device *md)
{
return atomic_read(&md->pending[READ]) +
@@ -1017,6 +1039,7 @@ static void free_rq_clone(struct request *clone)
struct dm_rq_target_io *tio = clone->end_io_data;
blk_rq_unprep_clone(clone);
+ free_clone_request(tio->md, clone);
free_rq_tio(tio);
}
@@ -1712,12 +1735,11 @@ static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
}
static int setup_clone(struct request *clone, struct request *rq,
- struct dm_rq_target_io *tio)
+ struct dm_rq_target_io *tio, gfp_t gfp_mask)
{
int r;
- blk_rq_init(NULL, rq);
- r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
+ r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
dm_rq_bio_constructor, tio);
if (r)
return r;
@@ -1728,9 +1750,29 @@ static int setup_clone(struct request *clone, struct request *rq,
clone->end_io = end_clone_request;
clone->end_io_data = tio;
+ tio->clone = clone;
+
return 0;
}
+static struct request *__clone_rq(struct request *rq, struct mapped_device *md,
+ struct dm_rq_target_io *tio, gfp_t gfp_mask)
+{
+ struct request *clone = alloc_clone_request(md, gfp_mask);
+
+ if (!clone)
+ return NULL;
+
+ blk_rq_init(NULL, clone);
+ if (setup_clone(clone, rq, tio, gfp_mask)) {
+ /* -ENOMEM */
+ free_clone_request(md, clone);
+ return NULL;
+ }
+
+ return clone;
+}
+
static struct request *clone_rq(struct request *rq, struct mapped_device *md,
gfp_t gfp_mask)
{
@@ -1743,13 +1785,13 @@ static struct request *clone_rq(struct request *rq, struct mapped_device *md,
tio->md = md;
tio->ti = NULL;
+ tio->clone = NULL;
tio->orig = rq;
tio->error = 0;
memset(&tio->info, 0, sizeof(tio->info));
- clone = &tio->clone;
- if (setup_clone(clone, rq, tio)) {
- /* -ENOMEM */
+ clone = __clone_rq(rq, md, tio, GFP_ATOMIC);
+ if (!clone) {
free_rq_tio(tio);
return NULL;
}
@@ -2149,6 +2191,8 @@ static void free_dev(struct mapped_device *md)
destroy_workqueue(md->wq);
if (md->io_pool)
mempool_destroy(md->io_pool);
+ if (md->rq_pool)
+ mempool_destroy(md->rq_pool);
if (md->bs)
bioset_free(md->bs);
blk_integrity_unregister(md->disk);
@@ -2195,10 +2239,12 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
goto out;
}
- BUG_ON(!p || md->io_pool || md->bs);
+ BUG_ON(!p || md->io_pool || md->rq_pool || md->bs);
md->io_pool = p->io_pool;
p->io_pool = NULL;
+ md->rq_pool = p->rq_pool;
+ p->rq_pool = NULL;
md->bs = p->bs;
p->bs = NULL;
@@ -3129,6 +3175,9 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
} else if (type == DM_TYPE_REQUEST_BASED) {
cachep = _rq_tio_cache;
pool_size = dm_get_reserved_rq_based_ios();
+ pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);
+ if (!pools->rq_pool)
+ goto out;
front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
/* per_bio_data_size is not used. See __bind_mempools(). */
WARN_ON(per_bio_data_size != 0);
@@ -3162,6 +3211,9 @@ void dm_free_md_mempools(struct dm_md_mempools *pools)
if (pools->io_pool)
mempool_destroy(pools->io_pool);
+ if (pools->rq_pool)
+ mempool_destroy(pools->rq_pool);
+
if (pools->bs)
bioset_free(pools->bs);
--
1.9.3
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