Re: [PATCH] iomap: use largest_zero_folio() in iomap_dio_zero()

André Almeida
2025-08-18T14:13:27Z

Em 18/08/2025 01:41, Christoph Hellwig escreveu:
> On Fri, Aug 15, 2025 at 04:02:58PM +0200, Christian Brauner wrote:
>> On Thu, 14 Aug 2025 16:21:37 +0200, Pankaj Raghav (Samsung) wrote:
>>> iomap_dio_zero() uses a custom allocated memory of zeroes for padding
>>> zeroes. This was a temporary solution until there was a way to request a
>>> zero folio that was greater than the PAGE_SIZE.
>>>
>>> Use largest_zero_folio() function instead of using the custom allocated
>>> memory of zeroes. There is no guarantee from largest_zero_folio()
>>> function that it will always return a PMD sized folio. Adapt the code so
>>> that it can also work if largest_zero_folio() returns a ZERO_PAGE.
>>>
>>> [...]
>>
>> Applied to the vfs-6.18.iomap branch of the vfs/vfs.git tree.
>> Patches in the vfs-6.18.iomap branch should appear in linux-next soon.
>
> Hmm, AFAIK largest_zero_folio just showed up in mm.git a few days ago.
> Wouldn't it be better to queue up this change there?
>
>

Indeed, compiling vfs/vfs.all as of today fails with:

fs/iomap/direct-io.c:281:36: error: implicit declaration of function
‘largest_zero_folio’; did you mean ‘is_zero_folio’?
[-Wimplicit-function-declaration]

Reverting "iomap: use largest_zero_folio() in iomap_dio_zero()" fixes
the compilation.