From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@meta.com>,
linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
axboe@kernel.dk, nilay@linux.ibm.com
Subject: Re: [PATCHv2 2/2] nvme: add support multipath passthrough iostats
Date: Wed, 27 May 2026 07:27:12 -0600 [thread overview]
Message-ID: <ahbxMLlLH1KlrD1P@kbusch-mbp> (raw)
In-Reply-To: <20260527131657.GB10351@lst.de>
On Wed, May 27, 2026 at 03:16:57PM +0200, Christoph Hellwig wrote:
> On Tue, May 26, 2026 at 08:39:21AM -0700, Keith Busch wrote:
> > + struct nvme_ns *ns = q->queuedata;
> > struct request *req;
> >
> > + if (ns && nvme_ns_head_multipath(ns->head))
> > + rq_flags |= REQ_NVME_MPATH;
>
> I just wanted to come with reasons why it this is wrong, but it actually
> seems already - we only have a ns for multipath nodes if multipathing
> is enabled. Maybe throw a little comment in on that?
Yes. An added subtlety here is that we unconditionally set
REQ_FAILFAST_DRIVER for passthrough requests, so it does not get
failover consideration. You can't steal bio's from a REQ_DRV_IN/OUT
request because all the necessary driver info is attached to the
original request, which doesn't follow the bio.
prev parent reply other threads:[~2026-05-27 13:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-26 15:39 [PATCHv2 0/2] block, nvme: enable passthrough iostats Keith Busch
2026-05-26 15:39 ` [PATCHv2 1/2] block: export passthrough stats enabled Keith Busch
2026-05-27 6:15 ` Nilay Shroff
2026-05-27 6:46 ` Nitesh Shetty
2026-05-27 13:14 ` Christoph Hellwig
2026-05-27 13:22 ` Keith Busch
2026-05-27 13:28 ` Christoph Hellwig
2026-05-26 15:39 ` [PATCHv2 2/2] nvme: add support multipath passthrough iostats Keith Busch
2026-05-27 6:15 ` Nilay Shroff
2026-05-27 6:46 ` Nitesh Shetty
2026-05-27 13:16 ` Christoph Hellwig
2026-05-27 13:27 ` Keith Busch [this message]
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