Re: [PATCH v2 2/2] btrfs: simplify the page uptodate preparation for prepare_pages()

[David Sterba <dsterba@suse.cz>]

On Wed, Oct 02, 2024 at 06:41:58AM +0930, Qu Wenruo wrote:
> 
> 
> 在 2024/10/2 01:00, David Sterba 写道:
> > On Tue, Oct 01, 2024 at 08:17:11AM +0930, Qu Wenruo wrote:
> >> +	if (force_uptodate)
> >> +		goto read;
> >> +
> >> +	/* The dirty range fully cover the page, no need to read it out. */
> >> +	if (IS_ALIGNED(clamp_start, PAGE_SIZE) &&
> >> +	    IS_ALIGNED(clamp_end, PAGE_SIZE))
> >> +		return 0;
> >> +read:
> >
> > I've commented under v1 and will repeat it here so it does not get lost,
> > this if and goto is not necessary here and can be a normal if () { ...  }
> >
> 
> This is not that simple.
> 
> If @force_uptodate we need to read the folio no matter what, meanwhile
> if the range is not aligned, we also need to read the folio.
> 
> And the @force_uptodate check should go before the alignment check, thus
> I'm wondering if there is any better alternative.

if (!force_update) {
	/* The dirty range fully cover the page, no need to read it out. */
	if (IS_ALIGNED(clamp_start, PAGE_SIZE) &&
	    IS_ALIGNED(clamp_end, PAGE_SIZE))
		return 0;
}