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Message-ID: <cacc3f7b-c8be-0f72-1c52-562c15b468a4@huawei.com>
Date: Tue, 22 Mar 2022 11:33:17 +0000
From: John Garry <john.garry@...wei.com>
To: Christoph Hellwig <hch@....de>
CC: <axboe@...nel.dk>, <damien.lemoal@...nsource.wdc.com>,
<bvanassche@....org>, <jejb@...ux.ibm.com>,
<martin.petersen@...cle.com>, <ming.lei@...hat.com>,
<hare@...e.de>, <chenxiang66@...ilicon.com>,
<linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-ide@...r.kernel.org>, <linux-scsi@...r.kernel.org>,
<dm-devel@...hat.com>, <beanhuo@...ron.com>
Subject: Re: [PATCH 01/11] blk-mq: Add blk_mq_init_queue_ops()
On 22/03/2022 11:18, Christoph Hellwig wrote:
> On Tue, Mar 22, 2022 at 06:39:35PM +0800, John Garry wrote:
>> Add an API to allocate a request queue which accepts a custom set of
>> blk_mq_ops for that request queue.
>>
>> The reason which we may want custom ops is for queuing requests which we
>> don't want to go through the normal queuing path.
>
> Eww. I really do not think we should do separate ops per queue, as that
> is going to get us into a deep mess eventually.
>
Yeah... so far (here) it works out quite nicely, as we don't need to
change the SCSI blk mq ops nor allocate a scsi_device - everything is
just separate.
The other method mentioned previously was to add the request "reserved"
flag and add new paths in scsi_queue_rq() et al to handle this, but that
gets messy.
Any other ideas ...?
Cheers,
John
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