blk-mq-sched: bypass the scheduler for flushes entirely
There's a weird inconsistency that flushes are mostly hidden from the
scheduler, but it needs to be aware of them in ->insert_requests().
Instead of having every scheduler call blk_mq_sched_bypass_insert(),
let's do it in the common framework.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 114814e..3ec52f4 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -289,7 +289,8 @@ void blk_mq_sched_request_inserted(struct request *rq)
}
EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
-bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, struct request *rq)
+static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
+ struct request *rq)
{
if (rq->tag == -1) {
rq->rq_flags |= RQF_SORTED;
@@ -305,7 +306,6 @@ bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, struct request *rq)
spin_unlock(&hctx->lock);
return true;
}
-EXPORT_SYMBOL_GPL(blk_mq_sched_bypass_insert);
static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
{
@@ -363,6 +363,9 @@ void blk_mq_sched_insert_request(struct request *rq, bool at_head,
return;
}
+ if (e && blk_mq_sched_bypass_insert(hctx, rq))
+ goto run;
+
if (e && e->type->ops.mq.insert_requests) {
LIST_HEAD(list);
@@ -374,6 +377,7 @@ void blk_mq_sched_insert_request(struct request *rq, bool at_head,
spin_unlock(&ctx->lock);
}
+run:
if (run_queue)
blk_mq_run_hw_queue(hctx, async);
}
@@ -385,6 +389,23 @@ void blk_mq_sched_insert_requests(struct request_queue *q,
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
struct elevator_queue *e = hctx->queue->elevator;
+ if (e) {
+ struct request *rq, *next;
+
+ /*
+ * We bypass requests that already have a driver tag assigned,
+ * which should only be flushes. Flushes are only ever inserted
+ * as single requests, so we shouldn't ever hit the
+ * WARN_ON_ONCE() below (but let's handle it just in case).
+ */
+ list_for_each_entry_safe(rq, next, list, queuelist) {
+ if (WARN_ON_ONCE(rq->tag != -1)) {
+ list_del_init(&rq->queuelist);
+ blk_mq_sched_bypass_insert(hctx, rq);
+ }
+ }
+ }
+
if (e && e->type->ops.mq.insert_requests)
e->type->ops.mq.insert_requests(hctx, list, false);
else
