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Date:   Thu, 18 May 2023 15:06:32 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        linux-block@vger.kernel.org
Subject: Re: [PATCH 2/3] blk-mq: remove RQF_ELVPRIV
Message-ID: <20230518130632.GA31791@lst.de>
References: <20230518053101.760632-1-hch@lst.de> <20230518053101.760632-3-hch@lst.de> <ZGXPkFOWOuoLWglR@ovpn-8-21.pek2.redhat.com>
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On Thu, May 18, 2023 at 03:11:12PM +0800, Ming Lei wrote:
> > -		if ((rq->rq_flags & RQF_ELVPRIV) && e->type->ops.requeue_request)
> > +		if (e->type->ops.requeue_request)
> >  			e->type->ops.requeue_request(rq);
> 
> The above actually changes current behavior since RQF_ELVPRIV is only set
> iff the following condition is true:
> 
> 	(rq->rq_flags & RQF_ELV) && !op_is_flush(rq->cmd_flags) &&
> 		e->type->ops.prepare_request.

It would require an I/O scheduler that implements .requeue_request but
not .prepare_request, which doesn't exist and also is rather pointless as
this .requeue_request method would never get called in the current code.

So no, no behavior change in practice.