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UPSTREAM: block: disable entropy contributions for nonrot devices 

(cherry picked from commit b277da0a8a)

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.

Change-Id: I8e9005feeedf301e486cf1aa13c804e322a3591b
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Artem Borisov <dedsa2002@gmail.com>
This commit is contained in:
Mike Snitzer 2014-10-04 10:55:32 -06:00 committed by Artem Borisov
parent bf67753ca2
commit efc542e8fd
6 changed files with 10 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/block/mtip32xx/mtip32xx.c
View File

@ -3632,6 +3632,7 @@ 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_io_min(dd->queue, 4096);

1
drivers/block/zram/zram_drv.c
View File

@ -1150,6 +1150,7 @@ static int create_device(struct zram *zram, int device_id)
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.

4
drivers/ide/ide-disk.c
View File

@ -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);

1
drivers/mmc/card/queue.c
View File

@ -202,6 +202,7 @@ 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);

1
drivers/mtd/mtd_blkdevs.c
View File

@ -441,6 +441,7 @@ 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);

4
drivers/scsi/sd.c
View File

@ -2398,8 +2398,10 @@ 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);