From: Yu Kuai <yukuai3@huawei.com>

Prepare to refator async_depth for mq-deadline and kyber.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 block/blk-sysfs.c      | 35 +++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h |  6 ++++++
 2 files changed, 41 insertions(+)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 64f70c713d2f..3ee2fb8a5077 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -76,6 +76,39 @@ queue_requests_store(struct gendisk *disk, const char *page, size_t count)
 	return ret;
 }
 
+static ssize_t queue_async_depth_show(struct gendisk *disk, char *page)
+{
+	if (disk->queue->async_depth)
+		return queue_var_show(disk->queue->async_depth, page);
+
+	return queue_requests_show(disk, page);
+}
+
+static ssize_t
+queue_async_depth_store(struct gendisk *disk, const char *page, size_t count)
+{
+	struct request_queue *q = disk->queue;
+	struct elevator_queue *e = q->elevator;
+	unsigned long nr;
+	int ret, err;
+
+	if (!e || !e->type->ops.async_depth_updated)
+		return -EINVAL;
+
+	ret = queue_var_store(&nr, page, count);
+	if (ret < 0)
+		return ret;
+
+	if (nr < 0 || nr >= q->nr_requests)
+		nr = 0;
+
+	err = e->type->ops.async_depth_updated(q, nr);
+	if (err)
+		return err;
+
+	return ret;
+}
+
 static ssize_t queue_ra_show(struct gendisk *disk, char *page)
 {
 	return queue_var_show(disk->bdi->ra_pages << (PAGE_SHIFT - 10), page);
@@ -440,6 +473,7 @@ static struct queue_sysfs_entry _prefix##_entry = {		\
 }
 
 QUEUE_RW_ENTRY(queue_requests, "nr_requests");
+QUEUE_RW_ENTRY(queue_async_depth, "async_depth");
 QUEUE_RW_ENTRY(queue_ra, "read_ahead_kb");
 QUEUE_RW_ENTRY(queue_max_sectors, "max_sectors_kb");
 QUEUE_RO_ENTRY(queue_max_hw_sectors, "max_hw_sectors_kb");
@@ -621,6 +655,7 @@ static struct attribute *queue_attrs[] = {
 /* Request-based queue attributes that are not relevant for bio-based queues. */
 static struct attribute *blk_mq_queue_attrs[] = {
 	&queue_requests_entry.attr,
+	&queue_async_depth_entry.attr,
 	&elv_iosched_entry.attr,
 	&queue_rq_affinity_entry.attr,
 	&queue_io_timeout_entry.attr,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8656ac4c3069..2fcc1ba39a28 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -524,6 +524,12 @@ struct request_queue {
 	 * queue settings
 	 */
 	unsigned int		nr_requests;	/* Max # of requests */
+	/*
+	 * Max number of async requests, used by elevator.
+	 * Value range: [0, nr_requests)
+	 * 0 is the default value, means unlimited.
+	 */
+	unsigned int		async_depth;
 
 #ifdef CONFIG_BLK_INLINE_ENCRYPTION
 	struct blk_crypto_profile *crypto_profile;
-- 
2.39.2