From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 21 Nov 2018 02:12:46 +0000 (-0700)
Subject: block: fix attempt to assign NULL io_context
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0c62bff1fd633774756be6d88d71002cd37615e0;p=linux.git

block: fix attempt to assign NULL io_context

If the first request allocated and issued by a process is a passhthrough
request, we don't set up an IO context for it. Ensure that
blk_mq_sched_assign_ioc() ignores a NULL io_context.

Fixes: e2b3fa5af70c ("block: Remove bio->bi_ioc")
Reported-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 13b8dc3325417..f096d89897738 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -34,9 +34,16 @@ EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
 void blk_mq_sched_assign_ioc(struct request *rq)
 {
 	struct request_queue *q = rq->q;
-	struct io_context *ioc = current->io_context;
+	struct io_context *ioc;
 	struct io_cq *icq;
 
+	/*
+	 * May not have an IO context if it's a passthrough request
+	 */
+	ioc = current->io_context;
+	if (!ioc)
+		return;
+
 	spin_lock_irq(&q->queue_lock);
 	icq = ioc_lookup_icq(ioc, q);
 	spin_unlock_irq(&q->queue_lock);