zram: remove request_queue from struct zram

`struct zram' contains both `struct gendisk' and `struct request_queue'.
the latter can be deleted, because zram->disk carries ->queue pointer, and
->queue carries zram pointer:

create_device()
	zram->queue->queuedata = zram
	zram->disk->queue = zram->queue
	zram->disk->private_data = zram

so zram->queue is not needed, we can access all necessary data anyway.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/zram/zram_drv.c

@@ -1061,19 +1061,19 @@ static struct attribute_group zram_disk_attr_group = {
 
 static int create_device(struct zram *zram, int device_id)
 {
+	struct request_queue *queue;
 	int ret = -ENOMEM;
 
 	init_rwsem(&zram->init_lock);
 
-	zram->queue = blk_alloc_queue(GFP_KERNEL);
-	if (!zram->queue) {
+	queue = blk_alloc_queue(GFP_KERNEL);
+	if (!queue) {
 		pr_err("Error allocating disk queue for device %d\n",
 			device_id);
 		goto out;
 	}
 
-	blk_queue_make_request(zram->queue, zram_make_request);
-	zram->queue->queuedata = zram;
+	blk_queue_make_request(queue, zram_make_request);
 
 	 /* gendisk structure */
 	zram->disk = alloc_disk(1);
@@ -1086,7 +1086,8 @@ static int create_device(struct zram *zram, int device_id)
 	zram->disk->major = zram_major;
 	zram->disk->first_minor = device_id;
 	zram->disk->fops = &zram_devops;
-	zram->disk->queue = zram->queue;
+	zram->disk->queue = queue;
+	zram->disk->queue->queuedata = zram;
 	zram->disk->private_data = zram;
 	snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 
@@ -1137,7 +1138,7 @@ static int create_device(struct zram *zram, int device_id)
 	del_gendisk(zram->disk);
 	put_disk(zram->disk);
 out_free_queue:
-	blk_cleanup_queue(zram->queue);
+	blk_cleanup_queue(queue);
 out:
 	return ret;
 }
@@ -1158,10 +1159,9 @@ static void destroy_devices(unsigned int nr)
 
 		zram_reset_device(zram);
 
+		blk_cleanup_queue(zram->disk->queue);
 		del_gendisk(zram->disk);
 		put_disk(zram->disk);
-
-		blk_cleanup_queue(zram->queue);
 	}
 
 	kfree(zram_devices);

drivers/block/zram/zram_drv.h

@@ -101,7 +101,6 @@ struct zram_meta {
 struct zram {
 	struct zram_meta *meta;
 	struct zcomp *comp;
-	struct request_queue *queue;
 	struct gendisk *disk;
 	/* Prevent concurrent execution of device init */
 	struct rw_semaphore init_lock;