Re: [PATCH 1/8] blk-mq: add blk_mq_alloc_request_hctx
From: Jens Axboe <axboe@kernel.dk>
Date: 2016-06-08 04:49:30
Also in:
linux-nvme, lkml
On 06/06/2016 03:21 PM, Christoph Hellwig wrote:
quoted hunk ↗ jump to hunk
From: Ming Lin <redacted> For some protocols like NVMe over Fabrics we need to be able to send initialization commands to a specific queue. Based on an earlier patch from Christoph Hellwig [off-list ref]. Signed-off-by: Ming Lin <redacted> Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/blk-mq.c | 33 +++++++++++++++++++++++++++++++++ include/linux/blk-mq.h | 2 ++ 2 files changed, 35 insertions(+)diff --git a/block/blk-mq.c b/block/blk-mq.c index 29cbc1b..7bb45ed 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c@@ -266,6 +266,39 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, } EXPORT_SYMBOL(blk_mq_alloc_request); +struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw, + unsigned int flags, unsigned int hctx_idx) +{ + struct blk_mq_hw_ctx *hctx; + struct blk_mq_ctx *ctx; + struct request *rq; + struct blk_mq_alloc_data alloc_data; + int ret; + + ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT); + if (ret) + return ERR_PTR(ret); + + hctx = q->queue_hw_ctx[hctx_idx]; + ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask)); + + blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx); + + rq = __blk_mq_alloc_request(&alloc_data, rw); + if (!rq && !(flags & BLK_MQ_REQ_NOWAIT)) { + __blk_mq_run_hw_queue(hctx); + + rq = __blk_mq_alloc_request(&alloc_data, rw); + }
Why are we duplicating this code here? If NOWAIT isn't set, then we'll always return a request. bt_get() will run the queue for us, if it needs to. blk_mq_alloc_request() does this too, and I'm guessing that code was just copied. I'll fix that up. Looks like this should just be: rq = __blk_mq_alloc_request(&alloc_data, rw); if (rq) return rq; blk_queue_exit(q); return ERR_PTR(-EWOULDBLOCK); for this case. -- Jens Axboe