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-rw-r--r--block/elevator.c3
-rw-r--r--drivers/block/loop.c2
-rw-r--r--include/linux/blk-mq.h6
3 files changed, 10 insertions, 1 deletions
diff --git a/block/elevator.c b/block/elevator.c
index 2f962662c32a..f762b2af1d2a 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -622,6 +622,9 @@ static inline bool elv_support_iosched(struct request_queue *q)
*/
static struct elevator_type *elevator_get_default(struct request_queue *q)
{
+ if (q->tag_set && q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT)
+ return NULL;
+
if (q->nr_hw_queues != 1)
return NULL;
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 0cdeeb0c5ece..ad3f06d5e986 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -2128,7 +2128,7 @@ static int loop_add(struct loop_device **l, int i)
lo->tag_set.numa_node = NUMA_NO_NODE;
lo->tag_set.cmd_size = sizeof(struct loop_cmd);
lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
- BLK_MQ_F_NO_SCHED;
+ BLK_MQ_F_NO_SCHED_BY_DEFAULT;
lo->tag_set.driver_data = lo;
err = blk_mq_alloc_tag_set(&lo->tag_set);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index f8ea27423d1d..39526279fbd3 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -398,7 +398,13 @@ enum {
BLK_MQ_F_STACKING = 1 << 2,
BLK_MQ_F_TAG_HCTX_SHARED = 1 << 3,
BLK_MQ_F_BLOCKING = 1 << 5,
+ /* Do not allow an I/O scheduler to be configured. */
BLK_MQ_F_NO_SCHED = 1 << 6,
+ /*
+ * Select 'none' during queue registration in case of a single hwq
+ * or shared hwqs instead of 'mq-deadline'.
+ */
+ BLK_MQ_F_NO_SCHED_BY_DEFAULT = 1 << 7,
BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,
BLK_MQ_F_ALLOC_POLICY_BITS = 1,