Re: [PATCH 3/3] f2fs: introduce f2fs_cache_node_page() to add page into node_inode cache

[Chao Yu <chao2.yu@samsung.com>]

Hi,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@samsung.com]
> Sent: Friday, December 06, 2013 9:43 AM
> To: Chao Yu
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; 谭姝
> Subject: RE: [f2fs-dev] [PATCH 3/3] f2fs: introduce f2fs_cache_node_page() to add page into node_inode cache
> 
> Hi,
> 
> 2013-12-05 (목), 10:10 +0800, Chao Yu:
> > > -----Original Message-----
> > > From: Chao Yu [mailto:chao2.yu@samsung.com]
> > > Sent: Thursday, December 05, 2013 9:55 AM
> > > To: ???
> > > Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net
> > > Subject: [f2fs-dev] [PATCH 3/3] f2fs: introduce f2fs_cache_node_page() to add page into node_inode cache
> > >
> > > This patch introduces f2fs_cache_node_page(), in this function, page which is
> > > readed ahead will be copy to node_inode's mapping cache.
> > > It will avoid rereading these node pages.
> > >
> > > Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> >
> > Suggested-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> >
> > I miss that, my mistake.
> >
> > > ---
> > >  fs/f2fs/node.c |   30 ++++++++++++++++++++++++++++++
> > >  1 file changed, 30 insertions(+)
> > >
> > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > > index 099f06f..5e2588f 100644
> > > --- a/fs/f2fs/node.c
> > > +++ b/fs/f2fs/node.c
> > > @@ -1600,6 +1600,34 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head *pages,
> > >  	return 0;
> > >  }
> > >
> > > +/*
> > > + * f2fs_cache_node_page() copy updated page data to node_inode cache page.
> > > + */
> > > +void f2fs_cache_node_page(struct f2fs_sb_info *sbi, struct page *page,
> > > +						nid_t nid)
> > > +{
> > > +	struct address_space *mapping = sbi->node_inode->i_mapping;
> > > +	struct page *npage;
> > > +
> > > +	npage = find_get_page(mapping, nid);
> > > +	if (npage && PageUptodate(npage)) {
> > > +		f2fs_put_page(npage, 0);
> > > +		return;
> > > +	}
> > > +	f2fs_put_page(npage, 0);
> > > +
> > > +	npage = grab_cache_page(mapping, nid);
> > > +	if (!npage)
> > > +		return;
> > > +
> 
> I forgot to tell you that we need to check its validity here.
> We should not cache this page all the time.
> So, let's consider this approach a little bit more.
> Thank you, :)

Ah, agreed.

I think we should check whether this page is uptodate or not.
And find_lock_page() will check value of 'mapping',
so we do not check here.

Anyway, I will send patch V2.
Thanks for your review. :)

> 
> > > +	memcpy(page_address(npage), page_address(page), PAGE_CACHE_SIZE);
> > > +
> > > +	SetPageUptodate(npage);
> > > +	f2fs_put_page(npage, 1);
> > > +
> > > +	return;
> > > +}
> > > +
> > >  int restore_node_summary(struct f2fs_sb_info *sbi,
> > >  			unsigned int segno, struct f2fs_summary_block *sum)
> > >  {
> > > @@ -1633,6 +1661,8 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
> > >  				sum_entry->version = 0;
> > >  				sum_entry->ofs_in_node = 0;
> > >  				sum_entry++;
> > > +				f2fs_cache_node_page(sbi, page,
> > > +					le32_to_cpu(rn->footer.nid));
> > >  			} else {
> > >  				err = -EIO;
> > >  			}
> > > --
> > > 1.7.9.5
> > >
> > >
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> --
> Jaegeuk Kim
> Samsung


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