On 09/22/16 07:52, Jens Axboe wrote:
Two patches that add the ability for a driver to flag itself
as wanting the ->queue_rq() invoked in a manner that allows
it to block. We'll need that for the nbd conversion, to avoid
having to add workqueue offload. We can use this in the current
loop mq path as well.
Hello Jens,
How can this work since there is code that calls blk_mq_run_hw_queue()
with a spin lock held? From mq_flush_data_end_io():
spin_lock_irqsave(&fq->mq_flush_lock, flags);
if (blk_flush_complete_seq(rq, fq, REQ_FSEQ_DATA, error))
blk_mq_run_hw_queue(hctx, true);
spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
Sorry that I hadn't noticed this before.
Bart.
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