blk-iocost: cleanup ioc_qos_write

Use a local disk variable instead of retrieving the disk and
request_queue over and over by various means.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-12-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-iocost.c

@@ -3167,6 +3167,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 			     size_t nbytes, loff_t off)
 {
 	struct block_device *bdev;
+	struct gendisk *disk;
 	struct ioc *ioc;
 	u32 qos[NR_QOS_PARAMS];
 	bool enable, user;
@@ -3177,12 +3178,13 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 	if (IS_ERR(bdev))
 		return PTR_ERR(bdev);
 
-	ioc = q_to_ioc(bdev_get_queue(bdev));
+	disk = bdev->bd_disk;
+	ioc = q_to_ioc(disk->queue);
 	if (!ioc) {
-		ret = blk_iocost_init(bdev->bd_disk);
+		ret = blk_iocost_init(disk);
 		if (ret)
 			goto err;
-		ioc = q_to_ioc(bdev_get_queue(bdev));
+		ioc = q_to_ioc(disk->queue);
 	}
 
 	spin_lock_irq(&ioc->lock);
@@ -3259,11 +3261,11 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 	spin_lock_irq(&ioc->lock);
 
 	if (enable) {
-		blk_stat_enable_accounting(ioc->rqos.q);
-		blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q);
+		blk_stat_enable_accounting(disk->queue);
+		blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
 		ioc->enabled = true;
 	} else {
-		blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q);
+		blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
 		ioc->enabled = false;
 	}