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From: Mike Snitzer <snitzer@kernel.org>
To: Uday Shankar <ushankar@purestorage.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Jens Axboe <axboe@kernel.dk>,
	dm-devel@redhat.com, linux-block@vger.kernel.org,
	Alasdair Kergon <agk@redhat.com>
Subject: Re: [dm-devel] blk-mq: enforce op-specific segment limits in blk_insert_cloned_request
Date: Thu, 16 Feb 2023 19:13:51 -0500	[thread overview]
Message-ID: <Y+7Gv84lxIR0OsWc@redhat.com> (raw)
In-Reply-To: <20230216192702.GA801590@dev-ushankar.dev.purestorage.com>

On Thu, Feb 16 2023 at  2:27P -0500,
Uday Shankar <ushankar@purestorage.com> wrote:

> On Wed, Feb 15, 2023 at 10:09:36PM -0800, Christoph Hellwig wrote:
> > I'd just remove the debug check entirely
> 
> Older kernels have these checks in a separate function called
> blk_cloned_rq_check_limits, which carries the following comment:
> 
> /**
>  * blk_cloned_rq_check_limits - Helper function to check a cloned request
>  *                              for the new queue limits
>  * @q:  the queue
>  * @rq: the request being checked
>  *
>  * Description:
>  *    @rq may have been made based on weaker limitations of upper-level queues
>  *    in request stacking drivers, and it may violate the limitation of @q.
>  *    Since the block layer and the underlying device driver trust @rq
>  *    after it is inserted to @q, it should be checked against @q before
>  *    the insertion using this generic function.
>  *
>  *    Request stacking drivers like request-based dm may change the queue
>  *    limits when retrying requests on other queues. Those requests need
>  *    to be checked against the new queue limits again during dispatch.
>  */.
> 
> Is this concern no longer relevant?

Still relevant.

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WARNING: multiple messages have this Message-ID (diff)
From: Mike Snitzer <snitzer@kernel.org>
To: Uday Shankar <ushankar@purestorage.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, dm-devel@redhat.com,
	Alasdair Kergon <agk@redhat.com>
Subject: Re: blk-mq: enforce op-specific segment limits in blk_insert_cloned_request
Date: Thu, 16 Feb 2023 19:13:51 -0500	[thread overview]
Message-ID: <Y+7Gv84lxIR0OsWc@redhat.com> (raw)
In-Reply-To: <20230216192702.GA801590@dev-ushankar.dev.purestorage.com>

On Thu, Feb 16 2023 at  2:27P -0500,
Uday Shankar <ushankar@purestorage.com> wrote:

> On Wed, Feb 15, 2023 at 10:09:36PM -0800, Christoph Hellwig wrote:
> > I'd just remove the debug check entirely
> 
> Older kernels have these checks in a separate function called
> blk_cloned_rq_check_limits, which carries the following comment:
> 
> /**
>  * blk_cloned_rq_check_limits - Helper function to check a cloned request
>  *                              for the new queue limits
>  * @q:  the queue
>  * @rq: the request being checked
>  *
>  * Description:
>  *    @rq may have been made based on weaker limitations of upper-level queues
>  *    in request stacking drivers, and it may violate the limitation of @q.
>  *    Since the block layer and the underlying device driver trust @rq
>  *    after it is inserted to @q, it should be checked against @q before
>  *    the insertion using this generic function.
>  *
>  *    Request stacking drivers like request-based dm may change the queue
>  *    limits when retrying requests on other queues. Those requests need
>  *    to be checked against the new queue limits again during dispatch.
>  */.
> 
> Is this concern no longer relevant?

Still relevant.

  reply	other threads:[~2023-02-17  0:14 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-15 20:15 [dm-devel] [PATCH] blk-mq: enforce op-specific segment limits in blk_insert_cloned_request Uday Shankar
2023-02-15 20:15 ` Uday Shankar
2023-02-16  6:09 ` [dm-devel] " Christoph Hellwig
2023-02-16  6:09   ` Christoph Hellwig
2023-02-16 19:27   ` [dm-devel] " Uday Shankar
2023-02-16 19:27     ` Uday Shankar
2023-02-17  0:13     ` Mike Snitzer [this message]
2023-02-17  0:13       ` Mike Snitzer
2023-02-17 16:16     ` [dm-devel] [PATCH] " Christoph Hellwig
2023-02-17 16:16       ` Christoph Hellwig
2023-02-17 16:43       ` [dm-devel] " Mike Snitzer
2023-02-17 16:43         ` Mike Snitzer
2023-02-17 21:41         ` [dm-devel] " Uday Shankar
2023-02-17 21:41           ` Uday Shankar
2023-02-16 13:06 ` [dm-devel] [PATCH] " kernel test robot
2023-02-16 13:06   ` kernel test robot

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