Re: [PATCH v2 6/7] md/raid1,raid10: skip futile retries on P2PDMA mapping failures

[Mykola Marzhan]

Thanks you!

On 2026-07-20 10:49, Logan Gunthorpe wrote:
> My eyes glazed over a bit. But one point is that maybe this could be
> split into multiple patches: one patch introduces R1BIO_P2PDMA, one
> patch for raid1 and another patch for raid10? That might make it a bit
> more manageable.

I have split it in v3 into a raid1 patch and a raid10 patch.
I am not sure about separate "introduce the bit" patches.
R1BIO_P2PDMA and R10BIO_P2PDMA are entries in the two personalities'
with own r*bio state enums.
The commit messages are shorter now.

> Also, I'm not sure if it's possible without digging deeper but, instead
> of adding a !p2pdma_unmappable check to every if() statement in the
> raid*_end_write_request() functions, might it be possible to factor out
> a helper function and return early from it?

An early return doesn't work here: on a mapping failure the
function must still fall through to set R1BIO_WriteError, so the
completion path runs the (single, whole-range) retry and records
the bad range -- only WantReplacement and the FailFast md_error()
are skipped.  v3 folds the two tests into one branch now,
which reads better and keeps the fall-through. Please check v3.

> Maybe the helper could be
> shared between raid10 and raid1 as they look very similar. The
> differences between the two are minimal -- there might be a bug fix that
> was applied to one that should be applied to both?

I compared the two sides after splitting: the P2PDMA handling is
symmetric, and the remaining differences are pre-existing
personality differences rather than missed fixes.
A shared helper would be heavier than the two open-coded branches,
so I kept it per-personality.

Mykola