Re: [PATCH] fs: buffer: check huge page size instead of single page for invalidatepage

On Wed, Oct 20, 2021 at 4:51 PM Matthew Wilcox [off-list ref] wrote:

On Wed, Oct 20, 2021 at 04:38:49PM -0700, Yang Shi wrote:

quoted

quoted

However, it still doesn't make too much sense to have thp_size passed
to do_invalidatepage(), then have PAGE_SIZE hardcoded in a BUG
assertion IMHO. So it seems this patch is still useful because
block_invalidatepage() is called by a few filesystems as well, for
example, ext4. Or I'm wondering whether we should call
do_invalidatepage() for each subpage of THP in truncate_cleanup_page()
since private is for each subpage IIUC.

Seems no interest?

No.  I have changes in this area as part of the folio patchset (where
we end up converting this to invalidate_folio).  I'm not really
interested in doing anything before that, since this shouldn't be
reachable today.

Understood. But this is definitely reachable unless Hugh's patch
(skipping non-regular file) is applied.

quoted

Anyway the more I was staring at the code the more I thought calling
do_invalidatepage() for each subpage made more sense. So, something
like the below makes sense?

Definitely not.  We want to invalidate the entire folio at once.

I didn't look at the folio patch (on each individual patch level), but
I'm supposed it still needs to invalidate buffer for each subpage,
right?