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 13b8dc332541758f2fb661282fe79d8be4855944..f096d89897738ab9946ac2cccc781cf357273610 100644 (file)
--- 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);