Messages in this thread | | | Subject | Re: [PATCH] scsi: core: use blk_mq_requeue_request in __scsi_queue_insert | From | "jianchao.wang" <> | Date | Tue, 27 Feb 2018 12:00:30 +0800 |
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Hi Bart
Thanks for your kindly response.
On 02/27/2018 11:41 AM, Bart Van Assche wrote: > On Tue, 2018-02-27 at 11:28 +0800, jianchao.wang wrote: >> If that is true, what if aacraid driver uses block legacy instead of blk-mq ? >> w/ blk-mq disabled, __scsi_queue_insert just requeue the request with blk_requeue_request. >> >> __scsi_queue_insert >> ... >> if (q->mq_ops) { >> scsi_mq_requeue_cmd(cmd); >> return; >> } >> spin_lock_irqsave(q->queue_lock, flags); >> blk_requeue_request(q, cmd->request); >> kblockd_schedule_work(&device->requeue_work); >> spin_unlock_irqrestore(q->queue_lock, flags); >> ... >> >> no prep/unprep code there for block legacy code. > > Hello Jianchao, > > For the legacy block layer preparing and unpreparing a request happens from > inside the block layer core. Please have a look at block/blk-core.c and the > code in that file that handles the request flag RQF_DONTPREP. Yes, thanks for your directive.
On the other hand, this patch is to align the actions between blk-mq and block legacy code in __scsi_queue_insert. As we know, __scsi_queue_insert is just to requeue the request back to queue, as the block legacy code segment above: for block legacy, it just blk_requeue_request for the request and kick the queue run. However, for the blk-mq, scsi_mq_requeue_cmd will be invoked, it not only requeue the request, but also unprep request. This is not what __scsi_queue_insert should do, but scsi_io_completion. When the request is not finished completely, and scsi_io_completion finds it need a ACTION_REPREP, at the moment, we need requeue and unprep there.
If I missed something, please feel free to point out. :)
Thanks Jianchao
> > Thanks, > > Bart. > > >
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