UPSTREAM: block: disable entropy contributions for nonrot devices

(cherry picked from commit b277da0a8a594308e17881f4926879bd5fca2a2d)

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 <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Mister Oyster <oysterized@gmail.com>

11 files changed, 15 insertions, 2 deletions

diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index 0d94e0922..2a6fe4f9f 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -4039,6 +4039,7 @@ skip_create_disk:
 
 	/* 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);
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index d593fa524..be7328661 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -859,6 +859,7 @@ static int __init nbd_init(void)
 		 * 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;
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index ce79a590b..5db38d607 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1575,6 +1575,7 @@ static struct nvme_ns *nvme_alloc_ns(struct nvme_dev *dev, int nsid,
 	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;
diff --git a/drivers/block/rsxx/dev.c b/drivers/block/rsxx/dev.c
index 4346d17d2..ce443cd1e 100644
--- a/drivers/block/rsxx/dev.c
+++ b/drivers/block/rsxx/dev.c
@@ -315,6 +315,7 @@ int rsxx_setup_dev(struct rsxx_cardinfo *card)
 	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,
diff --git a/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c
index 16f69be82..121071f9d 100644
--- a/drivers/ide/ide-disk.c
+++ b/drivers/ide/ide-disk.c
@@ -686,8 +686,10 @@ static void ide_disk_setup(ide_drive_t *drive)
 	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);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 2a4c13af4..f690500da 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -780,6 +780,7 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size)
 	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);
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 07247279d..e3b64bb94 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -240,6 +240,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 
 	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);
 
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 03e0669d8..8588fe6cc 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -420,6 +420,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	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);
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index 5d73e6e49..88c641b9e 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -394,6 +394,7 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
 	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);
diff --git a/drivers/s390/block/xpram.c b/drivers/s390/block/xpram.c
index 464dd29d0..324a8cd94 100644
--- a/drivers/s390/block/xpram.c
+++ b/drivers/s390/block/xpram.c
@@ -344,6 +344,7 @@ static int __init xpram_setup_blkdev(void)
 			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);
 	}
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b97268942..1b1f47c66 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2627,8 +2627,10 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 
 	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);