blk-mq: protect completion path with RCU

Currently, blk-mq protects only the issue path with RCU.  This patch
puts the completion path under the same RCU protection.  This will be
used to synchronize issue/completion against timeout by later patches,
which will also add the comments.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index bd7c47eb2923719fa07fe0de6ad65abdf523a8f6..f5e57c80a82be7406c1b9a6b4becf7fd52246c9f 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -584,11 +584,16 @@ static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
 void blk_mq_complete_request(struct request *rq)
 {
        struct request_queue *q = rq->q;
+       struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
+       int srcu_idx;
 
        if (unlikely(blk_should_fake_timeout(q)))
                return;
+
+       hctx_lock(hctx, &srcu_idx);
        if (!blk_mark_rq_complete(rq))
                __blk_mq_complete_request(rq);
+       hctx_unlock(hctx, srcu_idx);
 }
 EXPORT_SYMBOL(blk_mq_complete_request);