[1/3] blk-mq: make blk_mq_alloc_request_hctx() allocate a scheduler request

Commit Message

Omar Sandoval Feb. 27, 2017, 5:53 p.m. UTC

On Mon, Feb 27, 2017 at 09:47:53AM -0800, Omar Sandoval wrote:
> From: Omar Sandoval <[e-mail]>
> 
> blk_mq_alloc_request_hctx() allocates a driver request directly, unlike
> its blk_mq_alloc_request() counterpart. It also crashes because it
> doesn't update the tags->rqs map.
> 
> Fix it by making it allocate a scheduler request.
> 
> Reported-by: Sagi Grimberg <[e-mail]>
> Signed-off-by: Omar Sandoval <[e-mail]>
> ---
> I think this should do it. Verified that normal operation still works
> for me, but I'm not sure how to test the actual _hctx() alloc path.
> Sagi, could you please test this series out?

Hm, Sagi, your mail server seems to have rejected patches 2 and 3
because git-send-email duplicated the in-reply-to header for some
reason. I've attached the patches instead.

Patch

From 4715cce107df8b579734a074093a34001efd01d0 Mon Sep 17 00:00:00 2001
Message-Id: <[e-mail]>
In-Reply-To: <[e-mail]>
References: <[e-mail]>
From: Omar Sandoval <[e-mail]>
Date: Mon, 27 Feb 2017 09:40:34 -0800
Subject: [PATCH 3/3] blk-mq: move update of tags->rqs to
 __blk_mq_alloc_request()

No functional difference, it just makes a little more sense to update
the tag map where we actually allocate the tag.

Signed-off-by: Omar Sandoval <[e-mail]>
---
Optional cleanup, since there's only one place that does this.

 block/blk-mq-sched.c | 2 --
 block/blk-mq.c       | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 5697b23412a1..09af8ff18719 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -134,8 +134,6 @@  struct request *blk_mq_sched_get_request(struct request_queue *q,
 			rq = __blk_mq_alloc_request(data, op);
 	} else {
 		rq = __blk_mq_alloc_request(data, op);
-		if (rq)
-			data->hctx->tags->rqs[rq->tag] = rq;
 	}
 
 	if (rq) {
diff --git a/block/blk-mq.c b/block/blk-mq.c
index cc9713f574a5..452c1caf978f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -234,6 +234,7 @@  struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
 			}
 			rq->tag = tag;
 			rq->internal_tag = -1;
+			data->hctx->tags->rqs[rq->tag] = rq;
 		}
 
 		blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
-- 
2.12.0