Re: [PATCH v7 04/11] readahead: allocate folios with mapping_min_order in readahead

Hannes Reinecke
2024-06-21T13:28:08Z

On 6/21/24 14:19, Pankaj Raghav (Samsung) wrote:
> On Tue, Jun 18, 2024 at 08:56:53AM +0200, Hannes Reinecke wrote:
>> On 6/17/24 18:39, Pankaj Raghav (Samsung) wrote:
>>> On Mon, Jun 17, 2024 at 05:10:15PM +0100, Matthew Wilcox wrote:
>>>> On Mon, Jun 17, 2024 at 04:04:20PM +0000, Pankaj Raghav (Samsung) wrote:
>>>>> On Mon, Jun 17, 2024 at 01:32:42PM +0100, Matthew Wilcox wrote:
>>>>> So the following can still be there from Hannes patch as we have a
>>>>> stable reference:
>>>>>
>>>>> ractl->_workingset |= folio_test_workingset(folio);
>>>>> - ractl->_nr_pages++;
>>>>> + ractl->_nr_pages += folio_nr_pages(folio);
>>>>> + i += folio_nr_pages(folio);
>>>>> }
>>>>
>>>> We _can_, but we just allocated it, so we know what size it is already.
>>> Yes.
>>>
>>>> I'm starting to feel that Hannes' patch should be combined with this
>>>> one.
>>>
>>> Fine by me. @Hannes, is that ok with you?
>>
>> Sure. I was about to re-send my patchset anyway, so feel free to wrap it in.
> Is it ok if I add your Co-developed and Signed-off tag?
> This is what I have combining your patch with mine and making willy's
> changes:
>
> diff --git a/mm/readahead.c b/mm/readahead.c
> index 389cd802da63..f56da953c130 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -247,9 +247,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
> struct folio *folio = xa_load(&mapping->i_pages, index + i);
> int ret;
>
> -
> if (folio && !xa_is_value(folio)) {
> - long nr_pages = folio_nr_pages(folio);
> /*
> * Page already present? Kick off the current batch
> * of contiguous pages before continuing with the
> @@ -259,18 +257,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
> * not worth getting one just for that.
> */
> read_pages(ractl);
> -
> - /*
> - * Move the ractl->_index by at least min_pages
> - * if the folio got truncated to respect the
> - * alignment constraint in the page cache.
> - *
> - */
> - if (mapping != folio->mapping)
> - nr_pages = min_nrpages;
> -
> - VM_BUG_ON_FOLIO(nr_pages < min_nrpages, folio);
> - ractl->_index += nr_pages;
> + ractl->_index += min_nrpages;
> i = ractl->_index + ractl->_nr_pages - index;
> continue;
> }
> @@ -293,8 +280,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
> if (i == mark)
> folio_set_readahead(folio);
> ractl->_workingset |= folio_test_workingset(folio);
> - ractl->_nr_pages += folio_nr_pages(folio);
> - i += folio_nr_pages(folio);
> + ractl->_nr_pages += min_nrpages;
> + i += min_nrpages;
> }
>
> /*
>
Yes, that looks fine.
Go.

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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