Re: [PATCH v4 02/10] block: introduce blk_init_flush and its pair

From: Ming Lei
Date: Wed Sep 24 2014 - 10:46:12 EST

On Wed, Sep 24, 2014 at 6:18 PM, Christoph Hellwig <hch@xxxxxx> wrote:
> On Mon, Sep 15, 2014 at 09:11:06PM +0800, Ming Lei wrote:
>> These two temporary functions are introduced for holding flush
>> initialization and de-initialization, so that we can
>> introduce 'flush queue' easier in the following patch. And
>> once 'flush queue' and its allocation/free functions are ready,
>> they will be removed for sake of code readability.
> Shouldn't we just do the mq work in this helper as well? blk_mq_init_flush
> does exactly the same work, plus initializing a lock, which is harmless
> for the !mq case as well.

The initialization handler is just introduced for putting all initialization
into one place, then all will be put into blk_alloc_flush_queue() once
flush queue is introduced.

It is harmless to initialize mq lock for !mq, but may lose one benefit
of detecting misusing mq lock for !mq.

Ming Lei
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