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authorXuewei Zhang <xueweiz@google.com>2018-09-06 13:37:19 -0700
committerMartin K. Petersen <martin.petersen@oracle.com>2018-09-17 02:57:10 -0400
commit83e32a5910772e1475d3640a429b7686695f04d1 (patch)
treebded4bee164404584632e082179544f243791a8f /drivers/scsi
parentadad633af7b970bfa5dd1b624a4afc83cac9b235 (diff)
scsi: sd: Contribute to randomness when running rotational device
Currently a scsi device won't contribute to kernel randomness when it uses blk-mq. Since we commonly use scsi on rotational device with blk-mq, it make sense to keep contributing to kernel randomness in these cases. This is especially important for virtual machines. commit b5b6e8c8d3b4 ("scsi: virtio_scsi: fix IO hang caused by automatic irq vector affinity") made all virtio-scsi device to use blk-mq, which does not contribute to randomness today. So for a virtual machine only having virtio-scsi disk (which is common), it will simple stop getting randomness from its disks in today's implementation. With this patch, if the above VM has rotational virtio-scsi device, then it can still benefit from the entropy generated from the disk. Reported-by: Xuewei Zhang <xueweiz@google.com> Signed-off-by: Xuewei Zhang <xueweiz@google.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Maciej Żenczykowski <maze@google.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/sd.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b79b366a94f7..5e4f10d28065 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2959,6 +2959,9 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
if (rot == 1) {
blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, q);
+ } else {
+ blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
+ blk_queue_flag_set(QUEUE_FLAG_ADD_RANDOM, q);
}
if (sdkp->device->type == TYPE_ZBC) {