| Message ID | 20170925061454.5533-11-damien.lemoal@wdc.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Mon, 2017-09-25 at 15:14 +0900, Damien Le Moal wrote: > Modify mq-dealine init_queue and exit_queue elevator methods to handle ^^^^^^^^^^ mq-deadline ? > +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); A request queue is created before disk validation occurs and before the number of zones is initialized (sd_probe_async()). If a scheduler is assigned to a ZBC drive through a udev rule, can it happen that deadline_init_zones_wlock() is called before the number of zones has been initialized? Bart.
Bart, On Mon, 2017-09-25 at 21:34 +0000, Bart Van Assche wrote: > On Mon, 2017-09-25 at 15:14 +0900, Damien Le Moal wrote: > > Modify mq-dealine init_queue and exit_queue elevator methods to handle > > ^^^^^^^^^^ > mq-deadline ? > > > +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); > > A request queue is created before disk validation occurs and before the > number of zones is initialized (sd_probe_async()). If a scheduler is > assigned to a ZBC drive through a udev rule, can it happen that > deadline_init_zones_wlock() is called before the number of zones has been > initialized? Yes indeed. I am aware of this, hence the last patch of the series which disables setting a default scheduler for blk-mq devices. That is however a little extreme. So for V6, I am looking at diferring the default elevator setup after device information is gathered. Not sure where the right place to do so is though. Looking. Best regards. -- Damien Le Moal Western Digital
diff --git a/block/mq-deadline.c b/block/mq-deadline.c index a1cad4331edd..af2eb9b3936e 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -60,6 +60,9 @@ struct deadline_data { spinlock_t lock; struct list_head dispatch; + + spinlock_t zone_lock; + unsigned long *zones_wlock; }; static inline struct rb_root * @@ -300,6 +303,34 @@ 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 +338,7 @@ 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 +349,15 @@ 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]); @@ -340,9 +371,20 @@ static int dd_init_queue(struct request_queue *q, struct elevator_type *e) dd->fifo_batch = fifo_batch; spin_lock_init(&dd->lock); INIT_LIST_HEAD(&dd->dispatch); + spin_lock_init(&dd->zone_lock); + + 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,
Introduce new fields to mq-deadline private data to support zoned block devices. The fields are a zone bitmap used to implement zone write locking and a spinlock to atomically handle zone write locking with other processing. Modify mq-dealine 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.lemoal@wdc.com> --- block/mq-deadline.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 46 insertions(+), 4 deletions(-)