dm: allow immutable request-based targets to use blk-mq pdu
This will allow DM multipath to use a portion of the blk-mq pdu space
for target data (e.g. struct dm_mpath_io).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 89aa961..92c2fee 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -224,7 +224,8 @@
/* for blk-mq request-based DM support */
struct blk_mq_tag_set *tag_set;
- bool use_blk_mq;
+ bool use_blk_mq:1;
+ bool init_tio_pdu:1;
};
#ifdef CONFIG_DM_MQ_DEFAULT
@@ -243,6 +244,7 @@
{
return md->use_blk_mq;
}
+EXPORT_SYMBOL_GPL(dm_use_blk_mq);
/*
* For mempools pre-allocation at the table loading time.
@@ -1889,7 +1891,13 @@
tio->clone = NULL;
tio->orig = rq;
tio->error = 0;
- memset(&tio->info, 0, sizeof(tio->info));
+ /*
+ * Avoid initializing info for blk-mq; it passes
+ * target-specific data through info.ptr
+ * (see: dm_mq_init_request)
+ */
+ if (!md->init_tio_pdu)
+ memset(&tio->info, 0, sizeof(tio->info));
if (md->kworker_task)
init_kthread_work(&tio->work, map_tio_request);
}
@@ -2313,6 +2321,7 @@
goto bad_io_barrier;
md->use_blk_mq = use_blk_mq;
+ md->init_tio_pdu = false;
md->type = DM_TYPE_NONE;
mutex_init(&md->suspend_lock);
mutex_init(&md->type_lock);
@@ -2653,6 +2662,11 @@
*/
tio->md = md;
+ if (md->init_tio_pdu) {
+ /* target-specific per-io data is immediately after the tio */
+ tio->info.ptr = tio + 1;
+ }
+
return 0;
}
@@ -2704,7 +2718,8 @@
.init_request = dm_mq_init_request,
};
-static int dm_mq_init_request_queue(struct mapped_device *md)
+static int dm_mq_init_request_queue(struct mapped_device *md,
+ struct dm_target *immutable_tgt)
{
struct request_queue *q;
int err;
@@ -2726,6 +2741,11 @@
md->tag_set->driver_data = md;
md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
+ if (immutable_tgt && immutable_tgt->per_io_data_size) {
+ /* any target-specific per-io data is immediately after the tio */
+ md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
+ md->init_tio_pdu = true;
+ }
err = blk_mq_alloc_tag_set(md->tag_set);
if (err)
@@ -2763,7 +2783,7 @@
/*
* Setup the DM device's queue based on md's type
*/
-int dm_setup_md_queue(struct mapped_device *md)
+int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
{
int r;
unsigned md_type = filter_md_type(dm_get_md_type(md), md);
@@ -2777,7 +2797,7 @@
}
break;
case DM_TYPE_MQ_REQUEST_BASED:
- r = dm_mq_init_request_queue(md);
+ r = dm_mq_init_request_queue(md, dm_table_get_immutable_target(t));
if (r) {
DMERR("Cannot initialize queue for request-based dm-mq mapped device");
return r;
@@ -3505,8 +3525,7 @@
if (!pool_size)
pool_size = dm_get_reserved_rq_based_ios();
front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
- /* per_io_data_size is not used. */
- WARN_ON(per_io_data_size != 0);
+ /* per_io_data_size is used for blk-mq pdu at queue allocation */
break;
default:
BUG();