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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Qian Cai <cai@lca.pw>
Cc: Matthew Wilcox <willy@infradead.org>,
	Huang Ying <ying.huang@intel.com>,
	linux-mm@kvack.org
Subject: Re: page cache: Store only head pages in i_pages
Date: Fri, 5 Apr 2019 16:37:42 +0300
Message-ID: <20190405133742.goqgpxvbc4jsasz5@kshutemo-mobl1> (raw)
In-Reply-To: <1554413282.26196.40.camel@lca.pw>

On Thu, Apr 04, 2019 at 05:28:02PM -0400, Qian Cai wrote:
> On Thu, 2019-04-04 at 16:45 +0300, Kirill A. Shutemov wrote:
> > What about this:
> > 
> > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> > index f939e004c5d1..2e8438a1216a 100644
> > --- a/include/linux/pagemap.h
> > +++ b/include/linux/pagemap.h
> > @@ -335,12 +335,15 @@ static inline struct page *grab_cache_page_nowait(struct
> > address_space *mapping,
> >  
> >  static inline struct page *find_subpage(struct page *page, pgoff_t offset)
> >  {
> > -	unsigned long index = page_index(page);
> > +	unsigned long mask;
> > +
> > +	if (PageHuge(page))
> > +		return page;
> >  
> >  	VM_BUG_ON_PAGE(PageTail(page), page);
> > -	VM_BUG_ON_PAGE(index > offset, page);
> > -	VM_BUG_ON_PAGE(index + (1 << compound_order(page)) <= offset, page);
> > -	return page - index + offset;
> > +
> > +	mask = (1UL << compound_order(page)) - 1;
> > +	return page + (offset & mask);
> >  }
> >  
> >  struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
> 
> It works fine.

Nice.

Matthew, does it look fine to you?

-- 
 Kirill A. Shutemov


  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1553285568.26196.24.camel@lca.pw>
2019-03-23  3:38 ` Matthew Wilcox
2019-03-23 23:50   ` Qian Cai
2019-03-24  2:06     ` Matthew Wilcox
2019-03-24  2:52       ` Qian Cai
2019-03-24  3:04         ` Matthew Wilcox
2019-03-24 15:42           ` Qian Cai
2019-03-27 10:48           ` William Kucharski
2019-03-27 11:50             ` Matthew Wilcox
2019-03-29  1:43           ` Qian Cai
2019-03-29 19:59             ` Matthew Wilcox
2019-03-29 21:25               ` Qian Cai
2019-03-30  3:04                 ` Matthew Wilcox
2019-03-30 14:10                   ` Matthew Wilcox
2019-03-31  3:23                     ` Matthew Wilcox
2019-04-01  9:18                       ` Kirill A. Shutemov
2019-04-01  9:27                         ` Kirill A. Shutemov
2019-04-04 13:10                           ` Qian Cai
2019-04-04 13:45                             ` Kirill A. Shutemov
2019-04-04 21:28                               ` Qian Cai
2019-04-05 13:37                                 ` Kirill A. Shutemov [this message]
2019-04-05 13:51                                   ` Matthew Wilcox

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