block: disable entropy contributions for nonrot devices

Clear QUEUE_FLAG_ADD_RANDOM in all block drivers that set
QUEUE_FLAG_NONROT.

Historically, all block devices have automatically made entropy
contributions. But as previously stated in commit e2e1a148 ("block: add
sysfs knob for turning off disk entropy contributions"):
- On SSD disks, the completion times aren't as random as they
are for rotational drives. So it's questionable whether they
should contribute to the random pool in the first place.
- Calling add_disk_randomness() has a lot of overhead.

There are more reliable sources for randomness than non-rotational block
devices. From a security perspective it is better to err on the side of
caution than to allow entropy contributions from unreliable "random"
sources.

Signed-off-by: Mike Snitzer <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/mtip32xx/mtip32xx.c

···
 
 	/* Set device limits. */
 	set_bit(QUEUE_FLAG_NONROT, &dd->queue->queue_flags);
+	clear_bit(QUEUE_FLAG_ADD_RANDOM, &dd->queue->queue_flags);
 	blk_queue_max_segments(dd->queue, MTIP_MAX_SG);
 	blk_queue_physical_block_size(dd->queue, 4096);
 	blk_queue_max_hw_sectors(dd->queue, 0xffff);

drivers/block/nbd.c

···
 		 * Tell the block layer that we are not a rotational device
 		 */
 		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
+		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue);
 		disk->queue->limits.discard_granularity = 512;
 		disk->queue->limits.max_discard_sectors = UINT_MAX;
 		disk->queue->limits.discard_zeroes_data = 0;

drivers/block/null_blk.c

···
 
 	nullb->q->queuedata = nullb;
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
 
 	disk = nullb->disk = alloc_disk_node(1, home_node);
 	if (!disk)

drivers/block/nvme-core.c

···
 	ns->queue->queue_flags = QUEUE_FLAG_DEFAULT;
 	queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, ns->queue);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, ns->queue);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, ns->queue);
 	blk_queue_make_request(ns->queue, nvme_make_request);
 	ns->dev = dev;
 	ns->queue->queuedata = ns;

drivers/block/rsxx/dev.c

···
 	blk_queue_physical_block_size(card->queue, RSXX_HW_BLK_SIZE);
 
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, card->queue);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, card->queue);
 	if (rsxx_discard_supported(card)) {
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, card->queue);
 		blk_queue_max_discard_sectors(card->queue,

drivers/block/skd_main.c

···
 	q->limits.discard_zeroes_data = 1;
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, q);
 
 	spin_lock_irqsave(&skdev->lock, flags);
 	pr_debug("%s:%s:%d stopping %s queue\n",

drivers/block/zram/zram_drv.c

···
 	set_capacity(zram->disk, 0);
 	/* zram devices sort of resembles non-rotational disks */
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
 	/*
 	 * To ensure that we always get PAGE_SIZE aligned
 	 * and n*PAGE_SIZED sized I/O requests.

drivers/ide/ide-disk.c

···
 	printk(KERN_INFO "%s: max request size: %dKiB\n", drive->name,
 	       queue_max_sectors(q) / 2);
 
-	if (ata_id_is_ssd(id))
+	if (ata_id_is_ssd(id)) {
 		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
+		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, q);
+	}
 
 	/* calculate drive capacity, and select LBA if possible */
 	ide_disk_get_capacity(drive);

drivers/md/bcache/super.c

···
 	q->limits.logical_block_size	= block_size;
 	q->limits.physical_block_size	= block_size;
 	set_bit(QUEUE_FLAG_NONROT,	&d->disk->queue->queue_flags);
+	clear_bit(QUEUE_FLAG_ADD_RANDOM, &d->disk->queue->queue_flags);
 	set_bit(QUEUE_FLAG_DISCARD,	&d->disk->queue->queue_flags);
 
 	blk_queue_flush(q, REQ_FLUSH|REQ_FUA);

drivers/mmc/card/queue.c

···
 
 	blk_queue_prep_rq(mq->queue, mmc_prep_request);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, mq->queue);
 	if (mmc_can_erase(card))
 		mmc_queue_setup_discard(mq->queue, card);
 

drivers/mtd/mtd_blkdevs.c

···
 	blk_queue_logical_block_size(new->rq, tr->blksize);
 
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, new->rq);
 
 	if (tr->discard) {
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);

drivers/s390/block/scm_blk.c

···
 	blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
 	blk_queue_max_segments(rq, nr_max_blk);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, rq);
 	scm_blk_dev_cluster_setup(bdev);
 
 	bdev->gendisk = alloc_disk(SCM_NR_PARTS);

drivers/s390/block/xpram.c

···
 			goto out;
 		}
 		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, xpram_queues[i]);
+		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, xpram_queues[i]);
 		blk_queue_make_request(xpram_queues[i], xpram_make_request);
 		blk_queue_logical_block_size(xpram_queues[i], 4096);
 	}

drivers/scsi/sd.c

···
 
 	rot = get_unaligned_be16(&buffer[4]);
 
-	if (rot == 1)
+	if (rot == 1) {
 		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, sdkp->disk->queue);
+		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, sdkp->disk->queue);
+	}
 
  out:
 	kfree(buffer);