From: Christoph Hellwig <hch@lst.de>
To: Mike Snitzer <snitzer@redhat.com>
Cc: axboe@kernel.dk, hch@lst.de, keith.busch@intel.com,
emilne@redhat.com, james.smart@broadcom.com, hare@suse.de,
Bart.VanAssche@wdc.com, linux-block@vger.kernel.org,
linux-nvme@lists.infradead.org, dm-devel@redhat.com
Subject: Re: [for-4.16 PATCH v2 1/5] block: establish request failover callback
Date: Fri, 29 Dec 2017 11:10:13 +0100 [thread overview]
Message-ID: <20171229101013.GA25333@lst.de> (raw)
In-Reply-To: <20171227032257.8182-2-snitzer@redhat.com>
On Tue, Dec 26, 2017 at 10:22:53PM -0500, Mike Snitzer wrote:
> All requests allocated from a request_queue with this callback set can
> failover their requests during completion.
>
> This callback is expected to use the blk_steal_bios() interface to
> transfer a request's bios back to an upper-layer bio-based
> request_queue.
>
> This will be used by both NVMe multipath and DM multipath. Without it
> DM multipath cannot get access to NVMe-specific error handling that NVMe
> core provides in nvme_complete_rq().
And the whole point is that it should not get any such access.
The reason why we did nvme multipathing differently is because the
design of dm-multipath inflicts so much pain on users that we absolutely
want to avoid it this time around.
WARNING: multiple messages have this Message-ID (diff)
From: hch@lst.de (Christoph Hellwig)
Subject: [for-4.16 PATCH v2 1/5] block: establish request failover callback
Date: Fri, 29 Dec 2017 11:10:13 +0100 [thread overview]
Message-ID: <20171229101013.GA25333@lst.de> (raw)
In-Reply-To: <20171227032257.8182-2-snitzer@redhat.com>
On Tue, Dec 26, 2017@10:22:53PM -0500, Mike Snitzer wrote:
> All requests allocated from a request_queue with this callback set can
> failover their requests during completion.
>
> This callback is expected to use the blk_steal_bios() interface to
> transfer a request's bios back to an upper-layer bio-based
> request_queue.
>
> This will be used by both NVMe multipath and DM multipath. Without it
> DM multipath cannot get access to NVMe-specific error handling that NVMe
> core provides in nvme_complete_rq().
And the whole point is that it should not get any such access.
The reason why we did nvme multipathing differently is because the
design of dm-multipath inflicts so much pain on users that we absolutely
want to avoid it this time around.
next prev parent reply other threads:[~2017-12-29 10:10 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-27 3:22 [for-4.16 PATCH v2 0/5] block, nvme, dm: allow DM multipath to use NVMe's error handler Mike Snitzer
2017-12-27 3:22 ` Mike Snitzer
2017-12-27 3:22 ` [for-4.16 PATCH v2 1/5] block: establish request failover callback Mike Snitzer
2017-12-27 3:22 ` Mike Snitzer
2017-12-29 10:10 ` Christoph Hellwig [this message]
2017-12-29 10:10 ` Christoph Hellwig
2017-12-29 20:19 ` Mike Snitzer
2017-12-29 20:19 ` Mike Snitzer
2018-01-04 10:28 ` Christoph Hellwig
2018-01-04 10:28 ` Christoph Hellwig
2018-01-04 14:42 ` Mike Snitzer
2018-01-04 14:42 ` Mike Snitzer
2017-12-27 3:22 ` [for-4.16 PATCH v2 2/5] nvme: use request_queue's failover_rq_fn callback for multipath failover Mike Snitzer
2017-12-27 3:22 ` Mike Snitzer
2017-12-29 10:11 ` Christoph Hellwig
2017-12-29 10:11 ` Christoph Hellwig
2017-12-29 20:22 ` Mike Snitzer
2017-12-29 20:22 ` Mike Snitzer
2017-12-27 3:22 ` [for-4.16 PATCH v2 3/5] nvme: move nvme_req_needs_failover() from multipath to core Mike Snitzer
2017-12-27 3:22 ` Mike Snitzer
2017-12-27 3:22 ` [for-4.16 PATCH v2 4/5] dm mpath: use NVMe error handling to know when an error is retryable Mike Snitzer
2017-12-27 3:22 ` Mike Snitzer
2017-12-27 3:22 ` [for-4.16 PATCH v2 5/5] dm mpath: skip calls to end_io_bio if using NVMe bio-based and round-robin Mike Snitzer
2017-12-27 3:22 ` Mike Snitzer
2018-01-02 23:29 ` [for-4.16 PATCH v2 0/5] block, nvme, dm: allow DM multipath to use NVMe's error handler Keith Busch
2018-01-02 23:29 ` Keith Busch
2018-01-03 0:24 ` Mike Snitzer
2018-01-03 0:24 ` Mike Snitzer
2018-01-04 10:26 ` Christoph Hellwig
2018-01-04 10:26 ` Christoph Hellwig
2018-01-04 14:08 ` Mike Snitzer
2018-01-04 14:08 ` Mike Snitzer
2018-01-04 16:26 ` Mike Snitzer
2018-01-04 16:26 ` Mike Snitzer
2018-01-08 6:52 ` Hannes Reinecke
2018-01-08 6:52 ` Hannes Reinecke
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