linux-kernel - Re: [PATCH v5 05/78] xarray: Replace exceptional entries

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Date:   Wed, 27 Dec 2017 13:24:42 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-kernel@...r.kernel.org,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        David Howells <dhowells@...hat.com>,
        Shaohua Li <shli@...nel.org>, Jens Axboe <axboe@...nel.dk>,
        Rehas Sachdeva <aquannie@...il.com>,
        Marc Zyngier <marc.zyngier@....com>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-nilfs@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-raid@...r.kernel.org
Subject: Re: [PATCH v5 05/78] xarray: Replace exceptional entries

On Tue, Dec 26, 2017 at 07:05:34PM -0800, Matthew Wilcox wrote:
> On Tue, Dec 26, 2017 at 08:15:42PM +0300, Kirill A. Shutemov wrote:
> > >  28 files changed, 249 insertions(+), 240 deletions(-)
> > 
> > Everything looks fine to me after quick scan, but hat's a lot of changes for
> > one patch...
> 
> Yeah.  It's pretty mechanical though.
> 
> > > -			if (radix_tree_exceptional_entry(page)) {
> > > +			if (xa_is_value(page)) {
> > >  				if (!invalidate_exceptional_entry2(mapping,
> > >  								   index, page))
> > >  					ret = -EBUSY;
> > 
> > invalidate_exceptional_entry? Are we going to leave the terminology here as is?
> 
> That is a great question.  If the page cache wants to call its value
> entries exceptional entries, it can continue to do that.  I think there's
> a better name for them, but I'm not sure what it is.  Right now, the
> page cache uses value entries to store:
> 
> 1. Shadow entries (for workingset)
> 2. Swap entries (for shmem)
> 3. DAX entries
> 
> I can't come up with a good name for these three things.  'nonpage' is
> the only thing which hasn't immediately fallen off my ideas list.

Yeah, naming problem...

> But I think renaming exceptional entries in the page cache is a great idea,
> and I don't want to do it as part of this patch set ;-)

Fair enough.

-- 
 Kirill A. Shutemov