linux-kernel - Re: [PATCH v2] mm: alloc_pages_bulk: remove assumption of populating only NULL elements

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Message-ID: <f834a7cd-ca0a-4495-a787-134810aa0e4d@huawei.com>
Date: Thu, 6 Mar 2025 19:43:22 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: NeilBrown <neilb@...e.de>
CC: Qu Wenruo <wqu@...e.com>, Yishai Hadas <yishaih@...dia.com>, Jason
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Subject: Re: [PATCH v2] mm: alloc_pages_bulk: remove assumption of populating
 only NULL elements

On 2025/3/6 7:41, NeilBrown wrote:
> On Wed, 05 Mar 2025, Yunsheng Lin wrote:
>>
>> For the existing btrfs and sunrpc case, I am agreed that there
>> might be valid use cases too, we just need to discuss how to
>> meet the requirements of different use cases using simpler, more
>> unified and effective APIs.
> 
> We don't need "more unified".

What I meant about 'more unified' is how to avoid duplicated code as
much as possible for two different interfaces with similar‌ functionality.

The best way I tried to avoid duplicated code as much as possible is
to defragment the page_array before calling the alloc_pages_bulk()
for the use case of btrfs and sunrpc so that alloc_pages_bulk() can
be removed of the assumption populating only NULL elements, so that
the API is simpler and more efficient.

> 
> If there are genuinely two different use cases with clearly different
> needs - even if only slightly different - then it is acceptable to have
> two different interfaces.  Be sure to choose names which emphasise the
> differences.

The best name I can come up with for the use case of btrfs and sunrpc
is something like alloc_pages_bulk_refill(), any better suggestion about
the naming?

> 
> Thanks,
> NeilBrown