Hi,
> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk....@samsung.com]
> Sent: Monday, December 09, 2013 4:01 PM
> To: Chao Yu
> Cc: linux-fsde...@vger.kernel.org; linux-ker...@vger.kernel.org;
> linux-f2fs-devel@lists.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;
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....@samsung.com>
> > Signed-off-by: Chao Yu <chao2...@samsung.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
------------------------------------------------------------------------------
Sponsored by Intel(R) XDK
Develop, test and display web and hybrid apps with a single code base.
Download it for free now!
http://pubads.g.doubleclick.net/gampad/clk?id=111408631&iu=/4140/ostg.clktrk
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
