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blk-mq: skip unmapped queues in blk_mq_alloc_request_hctx

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This provides the caller a feedback that a given hctx is not mapped and thus
no command can be sent on it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2016-09-23 10:25:48 -06:00 committed by Jens Axboe
parent 3b4ac78610
commit c8712c6a67
1 changed files with 14 additions and 2 deletions
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16
block/blk-mq.c
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@ -296,17 +296,29 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
if (ret)
return ERR_PTR(ret);
/*
* Check if the hardware context is actually mapped to anything.
* If not tell the caller that it should skip this queue.
*/
hctx = q->queue_hw_ctx[hctx_idx];
if (!blk_mq_hw_queue_mapped(hctx)) {
ret = -EXDEV;
goto out_queue_exit;
}
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, 0);
if (!rq) {
blk_queue_exit(q);
return ERR_PTR(-EWOULDBLOCK);
ret = -EWOULDBLOCK;
goto out_queue_exit;
}
return rq;
out_queue_exit:
blk_queue_exit(q);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);