On 06/06/2016 03:21 PM, Christoph Hellwig wrote:
From: Ming Lin <ming.l@xxxxxxxxxxxxxxx>
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 <hch@xxxxxx>.
Signed-off-by: Ming Lin <ming.l@xxxxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
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
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