Re: Regression in generic/749 with 8k fsblock size on 6.18-rc1

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Oct 15, 2025 at 08:39:53AM +0100, Kirill A. Shutemov wrote:
> On Tue, Oct 14, 2025, at 18:52, Darrick J. Wong wrote:
> > Did your testing also demonstrate this regression?
> 
> I have not reproduced the issue yet.
> 
> Could you check if this patch makes a difference:
> 
> https://gist.github.com/kiryl/a2c71057bec332240216cc425aca791a

Yes, it does make the test failure go away:

FSTYP         -- xfs (debug)
PLATFORM      -- Linux/x86_64 alder-mtr00 6.18.0-rc1-xfsx #rc1 SMP PREEMPT_DYNAMIC Wed Oct 15 10:34:11 PDT 2025
MKFS_OPTIONS  -- -f -b size=8192, /dev/sdf
MOUNT_OPTIONS -- -o uquota,gquota,pquota, /dev/sdf /opt

generic/749        9s
Ran: generic/749
Passed all 1 tests

Is it valid to i_size_read() in the two places you add them?  I /think/
the folio is locked in the filemap.c hunk.  I'm not as sure about the
finish_fault changes.  If the EOF folio's locked then I think it's the
case that anything trying to change the file size will block until the
folio lock drops.

<shrug> Thanks for your help, in any case :)

--D

> -- 
> Kiryl Shutsemau / Kirill A. Shutemov
>