From: sashiko-bot@kernel.org
To: "Mykola Marzhan" <mykola@meshstor.io>
Cc: linux-pci@vger.kernel.org, linux-raid@vger.kernel.org, yukuai@fygo.io
Subject: Re: [PATCH v5 04/10] md/raid1: don't use write-behind for P2PDMA bios
Date: Thu, 23 Jul 2026 21:01:48 +0000 [thread overview]
Message-ID: <20260723210149.583331F000E9@smtp.kernel.org> (raw)
In-Reply-To: <20260723204206.76930-5-mykola@meshstor.io>
> alloc_behind_master_bio() copies the bio's data with bio_copy_data(),
> a CPU copy. P2PDMA pages are peer device (BAR) memory; generic code
> must not assume CPU load/store access to them is safe or fast on
> every architecture, and bouncing peer memory through the CPU defeats
> the point of a peer-to-peer transfer.
>
> Skip write-behind for P2PDMA bios: they are written directly to all
> members, including write-mostly ones. Ordering against write-behind
> I/O in flight to overlapping sectors is preserved: the non-behind
> clone path serializes on CollisionCheck rdevs (see the preceding
> fix), which covers these bios like any other write that bypasses
> write-behind.
>
> Fixes: 02666132403a ("md: propagate BLK_FEAT_PCI_P2PDMA from member devices to RAID device")
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Mykola Marzhan <mykola@meshstor.io>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260723204206.76930-1-mykola@meshstor.io?part=4
next prev parent reply other threads:[~2026-07-23 21:01 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-23 20:41 [PATCH v5 00/10] block,md,nvme: correct handling of unsupported P2PDMA transfers Mykola Marzhan
2026-07-23 20:41 ` [PATCH v5 01/10] block: add BLK_STS_P2PDMA for unsupported peer-to-peer transfers Mykola Marzhan
2026-07-23 20:51 ` sashiko-bot
2026-07-23 20:41 ` [PATCH v5 02/10] md: ensure REQ_NOMERGE is set on P2PDMA bios Mykola Marzhan
2026-07-23 20:51 ` sashiko-bot
2026-07-23 20:41 ` [PATCH v5 03/10] md/raid1: serialize non-write-behind writes on CollisionCheck rdevs Mykola Marzhan
2026-07-23 21:04 ` sashiko-bot
2026-07-23 20:42 ` [PATCH v5 04/10] md/raid1: don't use write-behind for P2PDMA bios Mykola Marzhan
2026-07-23 21:01 ` sashiko-bot [this message]
2026-07-23 20:42 ` [PATCH v5 05/10] md/raid1,raid10: factor out raid1_write_error() helper Mykola Marzhan
2026-07-23 20:54 ` sashiko-bot
2026-07-23 20:42 ` [PATCH v5 06/10] md/raid1,raid10: keep REQ_NOMERGE on narrow_write_error() retry clones Mykola Marzhan
2026-07-23 21:05 ` sashiko-bot
2026-07-23 20:42 ` [PATCH v5 07/10] md/raid1,raid10: skip futile retries on P2PDMA mapping failures Mykola Marzhan
2026-07-23 21:09 ` sashiko-bot
2026-07-23 20:42 ` [PATCH v5 08/10] md/raid1,raid10: set IO_BLOCKED in case of BLK_STS_P2PDMA Mykola Marzhan
2026-07-23 21:13 ` sashiko-bot
2026-07-23 20:42 ` [PATCH v5 09/10] nvme-rdma: use ib_dma_map_sgtable_attrs() Mykola Marzhan
2026-07-23 21:09 ` sashiko-bot
2026-07-23 20:42 ` [PATCH v5 10/10] nvme-rdma: return BLK_STS_P2PDMA for unsupported P2P transfers Mykola Marzhan
2026-07-23 21:19 ` sashiko-bot
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