blk-mq: ensure that we set REQ_IO_STAT so diskstats work

If disk stats are enabled on the queue, a request needs to
be marked with REQ_IO_STAT for accounting to be active on
that request. This fixes an issue with virtio-blk not
showing up in /proc/diskstats after the conversion to
blk-mq.

Add QUEUE_FLAG_MQ_DEFAULT, setting stats and same cpu-group
completion on by default.

Reported-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 862f458..32593db 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -171,9 +171,12 @@ bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 }
 EXPORT_SYMBOL(blk_mq_can_queue);
 
-static void blk_mq_rq_ctx_init(struct blk_mq_ctx *ctx, struct request *rq,
-                              unsigned int rw_flags)
+static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
+                              struct request *rq, unsigned int rw_flags)
 {
+       if (blk_queue_io_stat(q))
+               rw_flags |= REQ_IO_STAT;
+
        rq->mq_ctx = ctx;
        rq->cmd_flags = rw_flags;
        ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
@@ -197,7 +200,7 @@ static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
 
                rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
                if (rq) {
-                       blk_mq_rq_ctx_init(ctx, rq, rw);
+                       blk_mq_rq_ctx_init(q, ctx, rq, rw);
                        break;
                } else if (!(gfp & __GFP_WAIT))
                        break;
@@ -921,7 +924,7 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
        trace_block_getrq(q, bio, rw);
        rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
        if (likely(rq))
-               blk_mq_rq_ctx_init(ctx, rq, rw);
+               blk_mq_rq_ctx_init(q, ctx, rq, rw);
        else {
                blk_mq_put_ctx(ctx);
                trace_block_sleeprq(q, bio, rw);
@@ -1377,6 +1380,7 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
        q->queue_hw_ctx = hctxs;
 
        q->mq_ops = reg->ops;
+       q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 
        blk_queue_make_request(q, blk_mq_make_request);
        blk_queue_rq_timed_out(q, reg->ops->timeout);

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f26ec20..1b135d4 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -505,6 +505,9 @@ struct request_queue {
                                 (1 << QUEUE_FLAG_SAME_COMP)    |       \
                                 (1 << QUEUE_FLAG_ADD_RANDOM))
 
+#define QUEUE_FLAG_MQ_DEFAULT  ((1 << QUEUE_FLAG_IO_STAT) |            \
+                                (1 << QUEUE_FLAG_SAME_COMP))
+
 static inline void queue_lockdep_assert_held(struct request_queue *q)
 {
        if (q->queue_lock)