From 339318080b028fe347c279672da63c1cd5e52044 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@fb.com>
Date: Thu, 27 Apr 2017 07:45:46 -0600
Subject: [PATCH] blk-mq-sched: alloate reserved tags out of normal pool
At least one driver, mtip32xx, has a hard coded dependency on
the value of the reserved tag used for internal commands. While
that should really be fixed up, for now let's ensure that we just
bypass the scheduler tags an allocation marked as reserved. They
are used for house keeping or error handling, so we can safely
ignore them in the scheduler.
Tested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---
block/blk-mq-sched.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index e79e9f18d7c25..8b361e192e8a9 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -82,7 +82,11 @@ struct request *blk_mq_sched_get_request(struct request_queue *q,
if (likely(!data->hctx))
data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
- if (e) {
+ /*
+ * For a reserved tag, allocate a normal request since we might
+ * have driver dependencies on the value of the internal tag.
+ */
+ if (e && !(data->flags & BLK_MQ_REQ_RESERVED)) {
data->flags |= BLK_MQ_REQ_INTERNAL;
/*
--
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