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authorMike Snitzer <snitzer@redhat.com>2014-10-04 10:55:32 -0600
committerJens Axboe <axboe@fb.com>2014-10-04 10:55:32 -0600
commitb277da0a8a594308e17881f4926879bd5fca2a2d (patch)
tree1af7df6ade218a4b246dd43a0771701a672c6cb8 /drivers/md/bcache
parent7b7b7f7e024460cb7d77f8f96b6eb1a8803f94d9 (diff)
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 <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/md/bcache')
-rw-r--r--drivers/md/bcache/super.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index d4713d098a39..4dd2bb7167f0 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -842,6 +842,7 @@ 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);