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Date: Tue, 10 Dec 2013 17:43:33 +0800
From: Chao Yu <chao2.yu@...sung.com>
To: jaegeuk.kim@...sung.com
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: RE: [f2fs-dev] [PATCH 3/3 V3] f2fs: introduce f2fs_cache_node_page()
to add page into node_inode cache
> -----Original Message-----
> From: Chao Yu [mailto:chao2.yu@...sung.com]
> Sent: Tuesday, December 10, 2013 9:52 AM
> To: jaegeuk.kim@...sung.com
> Cc: linux-fsdevel@...r.kernel.org; linux-kernel@...r.kernel.org; linux-f2fs-devel@...ts.sourceforge.net
> Subject: Re: [f2fs-dev] [PATCH 3/3 V3] f2fs: introduce f2fs_cache_node_page() to add page into node_inode cache
>
> Hi,
>
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk.kim@...sung.com]
> > Sent: Monday, December 09, 2013 4:01 PM
> > To: Chao Yu
> > Cc: linux-fsdevel@...r.kernel.org; linux-kernel@...r.kernel.org; linux-f2fs-devel@...ts.sourceforge.net
> > Subject: Re: [f2fs-dev] [PATCH 3/3 V3] f2fs: introduce f2fs_cache_node_page() to add page into node_inode cache
> >
> > Hi,
> >
> > Sorry for the noise.
> > Once I tested this patch, I recognized that I made a mistake:
> >
> > f2fs_fill_super()
> > 1. build_segment_manager()
> > -> restore_node_summary()
> > -> NULL pointer exception, due to no NAT cache.
> > 2. build_node_manager()
> >
> > So, we should not call get_node_info() prior to build_node_manager().
> > And, it's not easy to change the order of build_*_manager simply.
> >
> > Let's consider in more details.
>
> Before we call restore_node_summary(), we have read HOT_DATA
> Summary. It means already we got the NAT cache in curseg.
> Although we could not call get_node_info() directly, we still could use
> NAT cache in HOT_DATA curseg.
>
> So how about using this cache to verify validity of page like this?
>
> f2fs_cache_node_page()
> if(!looup_nat_curseg_cache())
> return;
Code of verification is missed here.
if (curseg cache blk_addr != current blkaddr)
return;
> grab_cache_page();
> memcpy();
> SetPageUptodate();
> f2fs_put_page();
>
> > Thanks,
> >
> > 2013-12-09 (월), 13:35 +0800, Chao Yu:
> > > 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.
> > >
> > > change log:
> > > o check validity of page by searching NAT suggested by Jaegeuk Kim.
> > > o add 'unlikely' for compiler optimization suggested by Jaegeuk Kim.
> > >
> > > Suggested-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
> > > Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> > > ---
> > > fs/f2fs/node.c | 39 ++++++++++++++++++++++++++++++++++++++-
> > > 1 file changed, 38 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > > index 099f06f..4c6da98 100644
> > > --- a/fs/f2fs/node.c
> > > +++ b/fs/f2fs/node.c
> > > @@ -1600,13 +1600,46 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head *pages,
> > > return 0;
> > > }
> > >
> > > +/*
> > > + * f2fs_cache_node_page() check validaty of input page by searching NAT.
> > > + * Then, it will copy updated data of vaild page to node_inode cache.
> > > + */
> > > +void f2fs_cache_node_page(struct f2fs_sb_info *sbi, struct page *page,
> > > + nid_t nid, block_t blkaddr)
> > > +{
> > > + struct address_space *mapping = sbi->node_inode->i_mapping;
> > > + struct page *npage;
> > > + struct node_info ni;
> > > +
> > > + get_node_info(sbi, nid, &ni);
> > > +
> > > + if (ni.blk_addr != blkaddr)
> > > + return;
> > > +
> > > + npage = grab_cache_page(mapping, nid);
> > > + if (unlikely(!npage))
> > > + return;
> > > +
> > > + if (PageUptodate(npage)) {
> > > + f2fs_put_page(npage, 1);
> > > + return;
> > > + }
> > > +
> > > + 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)
> > > {
> > > struct f2fs_node *rn;
> > > struct f2fs_summary *sum_entry;
> > > struct page *page, *tmp;
> > > - block_t addr;
> > > + block_t addr, blkaddr;
> > > int bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
> > > int i, last_offset, nrpages, err = 0;
> > > LIST_HEAD(page_list);
> > > @@ -1624,6 +1657,7 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
> > > if (err)
> > > return err;
> > >
> > > + blkaddr = addr;
> > > list_for_each_entry_safe(page, tmp, &page_list, lru) {
> > >
> > > lock_page(page);
> > > @@ -1633,6 +1667,8 @@ 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), blkaddr);
> > > } else {
> > > err = -EIO;
> > > }
> > > @@ -1640,6 +1676,7 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
> > > list_del(&page->lru);
> > > unlock_page(page);
> > > __free_pages(page, 0);
> > > + blkaddr++;
> > > }
> > > }
> > > return err;
> >
> > --
> > Jaegeuk Kim
> > Samsung
>
>
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