On Tue, Nov 19 2013, Christoph Hellwig wrote:
> On Tue, Nov 19, 2013 at 07:02:18PM +1100, Dave Chinner wrote:
> > I have no idea if it's related to the above hang, but either way
> > breaking iostat is a major regression....
>
> Both of them are most likely due to the conversion of virtio_blk
> to the blk-mq code.
>
> I've not seen the hang in my heavy xfstests testing, but that was a
> slightly different codebase than what finally got in, so I'll try
> to reproduce it once I get some spare QA cycles.
Thanks! Dave, if you still have it in that state, can you dump the
contents of /sys/block/<devs>/mq/ for the device/devices that are hung?
> The missing stats should be solved by something like the patch below
> (untested so far):
>
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 862f458..41e3b85 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -175,7 +175,7 @@ static void blk_mq_rq_ctx_init(struct blk_mq_ctx *ctx,
> struct request *rq,
> unsigned int rw_flags)
> {
> rq->mq_ctx = ctx;
> - rq->cmd_flags = rw_flags;
> + rq->cmd_flags = rw_flags | REQ_IO_STAT;
> ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
> }
I have queued up the below.
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 862f458..ef90f18 100644
--- 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);
--
Jens Axboe
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