From: Jens Axboe <axboe@fb.com>
Date: Thu, 27 Oct 2016 15:49:19 +0000 (-0600)
Subject: blk-mq: update hardware and software queues for sleeping alloc
X-Git-Tag: v4.9-rc3~35^2
X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=7fe311302f7d52601cd799ad508a6f92cb3d748d

blk-mq: update hardware and software queues for sleeping alloc

If we end up sleeping due to running out of requests, we should
update the hardware and software queues in the map ctx structure.
Otherwise we could end up having rq->mq_ctx point to the pre-sleep
context, and risk corrupting ctx->rq_list since we'll be
grabbing the wrong lock when inserting the request.

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Chris Mason <clm@fb.com>
Fixes: 63581af3f31e ("blk-mq: remove non-blocking pass in blk_mq_map_request")
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index ddc2eed64771..f3d27a6dee09 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1217,9 +1217,9 @@ static struct request *blk_mq_map_request(struct request_queue *q,
 	blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx);
 	rq = __blk_mq_alloc_request(&alloc_data, op, op_flags);
 
-	hctx->queued++;
-	data->hctx = hctx;
-	data->ctx = ctx;
+	data->hctx = alloc_data.hctx;
+	data->ctx = alloc_data.ctx;
+	data->hctx->queued++;
 	return rq;
 }