blk-mq: add flag for drivers wanting blocking ->queue_rq()
If a driver sets BLK_MQ_F_BLOCKING, it is allowed to block in its
->queue_rq() handler. For that case, blk-mq ensures that we always
calls it from a safe context.
Signed-off-by: Jens Axboe <axboe@fb.com>
Tested-by: Josef Bacik <jbacik@fb.com>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 80d4838..e9ebe98 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -908,7 +908,7 @@
!blk_mq_hw_queue_mapped(hctx)))
return;
- if (!async) {
+ if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
int cpu = get_cpu();
if (cpumask_test_cpu(cpu, hctx->cpumask)) {
__blk_mq_run_hw_queue(hctx);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index fbcfdf3..5daa0ef 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -155,6 +155,7 @@
BLK_MQ_F_TAG_SHARED = 1 << 1,
BLK_MQ_F_SG_MERGE = 1 << 2,
BLK_MQ_F_DEFER_ISSUE = 1 << 4,
+ BLK_MQ_F_BLOCKING = 1 << 5,
BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,
BLK_MQ_F_ALLOC_POLICY_BITS = 1,