[PATCH V6 10/14] block: mq-deadline: Add zoned block device data

[Damien Le Moal]

Introduce a zone bitmap field in mq-deadline private data to support
zoned block devices. The zone bitmap is used to implement per zone
write locking. Modify mq-deadline init_queue() and exit_queue()
elevator methods to handle initialization and cleanup of the zone write
lock bitmap.

Signed-off-by: Damien Le Moal <damien.lem...@wdc.com>
---
 block/mq-deadline.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)

diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index a1cad4331edd..f0c01ef934b4 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -60,6 +60,8 @@ struct deadline_data {
 
        spinlock_t lock;
        struct list_head dispatch;
+
+       unsigned long *zones_wlock;
 };
 
 static inline struct rb_root *
@@ -300,6 +302,34 @@ static struct request *dd_dispatch_request(struct 
blk_mq_hw_ctx *hctx)
        return rq;
 }
 
+static int deadline_init_zones_wlock(struct request_queue *q,
+                                    struct deadline_data *dd)
+{
+       /*
+        * For regular drives or non-conforming zoned block device,
+        * do not use zone write locking.
+        */
+       if (!blk_queue_nr_zones(q))
+               return 0;
+
+       /*
+        * Treat host aware drives as regular disks.
+        */
+       if (blk_queue_zoned_model(q) != BLK_ZONED_HM)
+               return 0;
+
+       dd->zones_wlock = kzalloc_node(BITS_TO_LONGS(blk_queue_nr_zones(q))
+                                      * sizeof(unsigned long),
+                                      GFP_KERNEL, q->node);
+       if (!dd->zones_wlock)
+               return -ENOMEM;
+
+       pr_info("mq-deadline: %s: zones write locking enabled\n",
+               dev_name(q->backing_dev_info->dev));
+
+       return 0;
+}
+
 static void dd_exit_queue(struct elevator_queue *e)
 {
        struct deadline_data *dd = e->elevator_data;
@@ -307,6 +337,7 @@ static void dd_exit_queue(struct elevator_queue *e)
        BUG_ON(!list_empty(&dd->fifo_list[READ]));
        BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 
+       kfree(dd->zones_wlock);
        kfree(dd);
 }
 
@@ -317,16 +348,15 @@ static int dd_init_queue(struct request_queue *q, struct 
elevator_type *e)
 {
        struct deadline_data *dd;
        struct elevator_queue *eq;
+       int ret = -ENOMEM;
 
        eq = elevator_alloc(q, e);
        if (!eq)
                return -ENOMEM;
 
        dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
-       if (!dd) {
-               kobject_put(&eq->kobj);
-               return -ENOMEM;
-       }
+       if (!dd)
+               goto out_put_elv;
        eq->elevator_data = dd;
 
        INIT_LIST_HEAD(&dd->fifo_list[READ]);
@@ -341,8 +371,18 @@ static int dd_init_queue(struct request_queue *q, struct 
elevator_type *e)
        spin_lock_init(&dd->lock);
        INIT_LIST_HEAD(&dd->dispatch);
 
+       ret = deadline_init_zones_wlock(q, dd);
+       if (ret)
+               goto out_free_dd;
+
        q->elevator = eq;
        return 0;
+
+out_free_dd:
+       kfree(dd);
+out_put_elv:
+       kobject_put(&eq->kobj);
+       return ret;
 }
 
 static int dd_request_merge(struct request_queue *q, struct request **rq,
-- 
2.13.6