Re: [PATCH v5.1] fs: Allow fine-grained control of folio sizes

["Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>]

On Mon, May 27, 2024 at 11:39:47PM +0100, Matthew Wilcox wrote:
> On Mon, May 27, 2024 at 10:09:26PM +0000, Pankaj Raghav (Samsung) wrote:
> > > For this version, I fixed the TODO that the maximum folio size was not
> > > being honoured.  I made some other changes too like adding const, moving
> > > the location of the constants, checking CONFIG_TRANSPARENT_HUGEPAGE, and
> > > dropping some of the functions which aren't needed until later patches.
> > > (They can be added in the commits that need them).  Also rebased against
> > > current Linus tree, so MAX_PAGECACHE_ORDER no longer needs to be moved).
> > 
> > Thanks for this! So I am currently running my xfstests on the new series
> > I am planning to send in a day or two based on next-20240523.
> > 
> > I assume this patch is intended to be folded in to the next LBS series?
> 
> Right, that was why I numbered it as 5.1 so as to not preempt your v6.
> 
> > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> > > index 1ed9274a0deb..c6aaceed0de6 100644
> > > --- a/include/linux/pagemap.h
> > > +++ b/include/linux/pagemap.h
> > > @@ -204,13 +204,18 @@ enum mapping_flags {
> > >  	AS_EXITING	= 4, 	/* final truncate in progress */
> > >  	/* writeback related tags are not used */
> > >  	AS_NO_WRITEBACK_TAGS = 5,
> > > -	AS_LARGE_FOLIO_SUPPORT = 6,
> > > -	AS_RELEASE_ALWAYS,	/* Call ->release_folio(), even if no private data */
> > > -	AS_STABLE_WRITES,	/* must wait for writeback before modifying
> > > +	AS_RELEASE_ALWAYS = 6,	/* Call ->release_folio(), even if no private data */
> > > +	AS_STABLE_WRITES = 7,	/* must wait for writeback before modifying
> > >  				   folio contents */
> > > -	AS_UNMOVABLE,		/* The mapping cannot be moved, ever */
> > > +	AS_UNMOVABLE = 8,	/* The mapping cannot be moved, ever */
> > > +	AS_FOLIO_ORDER_MIN = 16,
> > > +	AS_FOLIO_ORDER_MAX = 21, /* Bits 16-25 are used for FOLIO_ORDER */
> > >  };
> > >  
> > > +#define AS_FOLIO_ORDER_MIN_MASK 0x001f0000
> > > +#define AS_FOLIO_ORDER_MAX_MASK 0x03e00000
> > 
> > As you changed the mapping flag offset, these masks also needs to be
> > changed accordingly.
> 
> That's why I did change them?

Oops, I missed the zeroes at the end.


Btw, I noticed you have removed mapping_align_start_index(). I will add
it back in.

-- 
Pankaj Raghav