RE: [f2fs-dev] [PATCH 3/3] f2fs: introduce f2fs_cache_node_page() toadd page into node_inode cache

[Jaegeuk Kim]

Hi,

2013-12-05 (ë), 10:10 +0800, Chao Yu:
> > -----Original Message-----
> > From: Chao Yu [mailto:chao2.yu@xxxxxxxxxxx]
> > Sent: Thursday, December 05, 2013 9:55 AM
> > To: ???
> > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> > 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@xxxxxxxxxxx>
> 
> Suggested-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
> 
> 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, :)

> > +	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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