[dm-devel] [dm-4.6 PATCH v2 10/15] dm: allow immutable request-based targets to use blk-mq pdu
Mike Snitzer
snitzer at redhat.com
Sun Feb 7 15:53:32 UTC 2016
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 at redhat.com>
---
drivers/md/dm-ioctl.c | 2 +-
drivers/md/dm.c | 45 +++++++++++++++++++++++++++++++++++++--------
drivers/md/dm.h | 2 +-
3 files changed, 39 insertions(+), 10 deletions(-)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 4763c4a..2adf81d 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1304,7 +1304,7 @@ static int table_load(struct dm_ioctl *param, size_t param_size)
dm_set_md_type(md, dm_table_get_type(t));
/* setup md->queue to reflect md's type (may block) */
- r = dm_setup_md_queue(md);
+ r = dm_setup_md_queue(md, t);
if (r) {
DMWARN("unable to set up device queue for new table.");
goto err_unlock_md_type;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 8bc798c..6b7e80e 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -225,6 +225,7 @@ struct mapped_device {
/* for blk-mq request-based DM support */
struct blk_mq_tag_set *tag_set;
bool use_blk_mq;
+ bool init_tio_pdu;
};
#ifdef CONFIG_DM_MQ_DEFAULT
@@ -243,6 +244,7 @@ bool dm_use_blk_mq(struct mapped_device *md)
{
return md->use_blk_mq;
}
+EXPORT_SYMBOL_GPL(dm_use_blk_mq);
/*
* For mempools pre-allocation at the table loading time.
@@ -1850,6 +1852,8 @@ static struct request *clone_rq(struct request *rq, struct mapped_device *md,
struct dm_rq_target_io *tio, gfp_t gfp_mask)
{
/*
+ * Create clone for use with .request_fn request_queue
+ *
* Do not allocate a clone if tio->clone was already set
* (see: dm_mq_queue_rq).
*/
@@ -1884,7 +1888,13 @@ static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
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);
}
@@ -2303,6 +2313,7 @@ static struct mapped_device *alloc_dev(int minor)
goto bad_io_barrier;
md->use_blk_mq = use_blk_mq;
+ md->init_tio_pdu = true;
md->type = DM_TYPE_NONE;
mutex_init(&md->suspend_lock);
mutex_init(&md->type_lock);
@@ -2643,6 +2654,16 @@ static int dm_mq_init_request(void *data, struct request *rq,
*/
tio->md = md;
+ /*
+ * FIXME: If/when there is another blk-mq request-based DM target
+ * other than multipath: make conditional on ti->per_bio_data_size
+ * but it is a serious pain to get target here.
+ */
+ {
+ /* target-specific per-io data is immediately after the tio */
+ tio->info.ptr = tio + 1;
+ }
+
return 0;
}
@@ -2680,8 +2701,11 @@ static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
* Both the table and md type cannot change after initial table load
*/
if (dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) {
- /* clone request is allocated at the end of the pdu */
- tio->clone = (void *)blk_mq_rq_to_pdu(rq) + sizeof(struct dm_rq_target_io);
+ /*
+ * Clone the request if underlying devices aren't blk-mq
+ * - clone request is allocated at the end of the pdu
+ */
+ tio->clone = blk_mq_rq_to_pdu(rq) + sizeof(*tio) + ti->per_io_data_size;
(void) clone_rq(rq, md, tio, GFP_ATOMIC);
queue_kthread_work(&md->kworker, &tio->work);
} else {
@@ -2704,7 +2728,8 @@ static struct blk_mq_ops dm_mq_ops = {
.init_request = dm_mq_init_request,
};
-static int dm_init_request_based_blk_mq_queue(struct mapped_device *md)
+static int dm_init_request_based_blk_mq_queue(struct mapped_device *md,
+ struct dm_target *immutable_tgt)
{
unsigned md_type = dm_get_md_type(md);
struct request_queue *q;
@@ -2719,6 +2744,11 @@ static int dm_init_request_based_blk_mq_queue(struct mapped_device *md)
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 = false;
+ }
if (md_type == DM_TYPE_REQUEST_BASED) {
/* put the memory for non-blk-mq clone at the end of the pdu */
md->tag_set->cmd_size += sizeof(struct request);
@@ -2763,7 +2793,7 @@ static unsigned filter_md_type(unsigned type, struct mapped_device *md)
/*
* 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 +2807,7 @@ int dm_setup_md_queue(struct mapped_device *md)
}
break;
case DM_TYPE_MQ_REQUEST_BASED:
- r = dm_init_request_based_blk_mq_queue(md);
+ r = dm_init_request_based_blk_mq_queue(md, dm_table_get_immutable_target(t));
if (r) {
DMWARN("Cannot initialize queue for request-based blk-mq mapped device");
return r;
@@ -3505,8 +3535,7 @@ struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned t
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();
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 4305a51..13a758e 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -86,7 +86,7 @@ void dm_set_md_type(struct mapped_device *md, unsigned type);
unsigned dm_get_md_type(struct mapped_device *md);
struct target_type *dm_get_immutable_target_type(struct mapped_device *md);
-int dm_setup_md_queue(struct mapped_device *md);
+int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t);
/*
* To check the return value from dm_table_find_target().
--
2.5.4 (Apple Git-61)
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