Re: [RFC PATCH 0/3] xfs: forced extent alignment

John Garry
2024-03-06T11:46:48Z

On 06/03/2024 05:20, Dave Chinner wrote:
> Hi Garry,
>
> I figured that it was simpler just to write the forced extent
> alignment allocator patches that to make you struggle through them
> and require lots of round trips to understand all the weird corner
> cases.

I appreciate that.

>
> The following 3 patches:
>
> - rework the setup and extent allocation logic a bit to make force
> aligned allocation much easier to implement and understand
> - move all the alignment adjustments into the setup logic
> - rework the alignment slop calculations and greatly simplify the
> the exact EOF block allocation case
> - add a XFS_ALLOC_FORCEALIGN flag so that the inode config only
> needs to be checked once at setup. This also allows other
> allocation types (e.g. inode clusters) use forced alignment
> allocation semantics in future.
> - clearly document when we are turning off allocation alignment and
> abort FORCEALIGN allocation at that point rather than doing
> unaligned allocation.
>
> I've run this through fstests once so it doesn't let the smoke out,
> but I haven't actually tested it against a stripe aligned filesystem
> config yet, nor tested the forcealign functionality so it may not be
> exactly right yet.
>
> Is this sufficiently complete for you to take from here into the
> forcealign series?
>

I'll try it out.

What baseline are these against? Mine were against v6.8-rc5, but I guess
that you develop against an XFS integration tree. Maybe they apply and
build cleanly against v6.8-rc5 ...

Cheers,
John