Re: [PATCH 0/5] export __clear_page_buffers to cleanup code

[Guoqing Jiang <guoqing.jiang@cloud.ionos.com>]

On 19.04.20 07:14, Gao Xiang wrote:
> On Sat, Apr 18, 2020 at 08:14:43PM -0700, Matthew Wilcox wrote:
>> On Sun, Apr 19, 2020 at 12:51:18AM +0200, Guoqing Jiang wrote:
>>> When reading md code, I find md-bitmap.c copies __clear_page_buffers from
>>> buffer.c, and after more search, seems there are some places in fs could
>>> use this function directly. So this patchset tries to export the function
>>> and use it to cleanup code.
>> OK, I see why you did this, but there are a couple of problems with it.
>>
>> One is just a sequencing problem; between exporting __clear_page_buffers()
>> and removing it from the md code, the md code won't build.
>>
>> More seriously, most of this code has nothing to do with buffers.  It
>> uses page->private for its own purposes.
>>
>> What I would do instead is add:
>>
>> clear_page_private(struct page *page)
>> {
>> 	ClearPagePrivate(page);
>> 	set_page_private(page, 0);
>> 	put_page(page);
>> }
>>
>> to include/linux/mm.h, then convert all callers of __clear_page_buffers()
>> to call that instead.
> Agreed with the new naming (__clear_page_buffers is confusing), that is not
> only for initial use buffer head, but a generic convention for all unlocked
> PagePrivate pages (such migration & reclaim paths indicate that).
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/mm.h?h=v5.7-rc1#n990

Thanks for the link, and will rename the function to clear_page_private.

Thanks,
Guoqing