Re: [PATCH v2 1/7] blk-mq-dma: restore BLK_STS_TARGET for unsupported P2P transfers

> Commit 91fb2b6052f7 ("nvme-pci: convert to using dma_map_sgtable()")
> deliberately mapped unsupported P2PDMA transfers to BLK_STS_TARGET,
> matching dma_map_sgtable()'s -EREMOTEIO: "When this happens, return
> BLK_STS_TARGET so the request isn't retried." The conversion to
> blk_rq_dma_map silently changed the status to BLK_STS_INVAL, which
> regresses two consumers:
> 
>  - md/raid1 and raid10 ignore BLK_STS_INVAL leg failures
>    (commit f7b24c7b41f2 ("md/raid1,raid10: don't fail devices for
>    invalid IO errors"), where it means a request-shaped error that
>    fails identically on every member).  Since commit 02666132403a
>    ("md: propagate BLK_FEAT_PCI_P2PDMA from member devices to RAID device")
>    P2PDMA bios reach md arrays: a peer-memory write to a member the
>    peer cannot reach is counted as written, the master bio reports
>    success, mirrors silently diverge, and on a topology where no
> [ ... ]
> Fixes: 858299dc6160 ("block: add scatterlist-less DMA mapping helpers")
> Fixes: 7ce3c1dd78fc ("nvme-pci: convert the data mapping to blk_rq_dma_map")
> Cc: [email protected] # v6.17
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Mykola Marzhan <[email protected]>

Sashiko has reviewed this patch and found no issues. It looks great!

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