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Message-id: <000a01cf3c27$cb269c10$6173d430$@samsung.com>
Date: Mon, 10 Mar 2014 14:12:19 +0800
From: Chao Yu <chao2.yu@...sung.com>
To: jaegeuk.kim@...sung.com
Cc: 'Gu Zheng' <guz.fnst@...fujitsu.com>,
'linux-kernel' <linux-kernel@...r.kernel.org>,
'f2fs' <linux-f2fs-devel@...ts.sourceforge.net>
Subject: RE: [f2fs-dev] [PATCH 4/5] f2fs: optimize restore_node_summary slightly
Hi,
> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@...sung.com]
> Sent: Monday, March 10, 2014 1:38 PM
> To: Chao Yu
> Cc: 'Gu Zheng'; 'linux-kernel'; 'f2fs'
> Subject: RE: [f2fs-dev] [PATCH 4/5] f2fs: optimize restore_node_summary slightly
>
> Hi,
>
> 2014-03-10 (월), 13:13 +0800, Chao Yu:
> > Hi Gu, Kim:
> >
> > One more comment.
> >
> > > -----Original Message-----
> > > From: Jaegeuk Kim [mailto:jaegeuk.kim@...sung.com]
> > > Sent: Monday, March 10, 2014 12:46 PM
> > > To: Gu Zheng
> > > Cc: linux-kernel; f2fs
> > > Subject: Re: [f2fs-dev] [PATCH 4/5] f2fs: optimize restore_node_summary slightly
> > >
> > > Hi Gu,
> > >
> > > 2014-03-07 (금), 18:43 +0800, Gu Zheng:
> > > > Previously, we ra_sum_pages to pre-read contiguous pages as more
> > > > as possible, and if we fail to alloc more pages, an ENOMEM error
> > > > will be reported upstream, even though we have alloced some pages
> > > > yet. In fact, we can use the available pages to do the job partly,
> > > > and continue the rest in the following circle. Only reporting ENOMEM
> > > > upstream if we really can not alloc any available page.
> > > >
> > > > And another fix is ignoring dealing with the following pages if an
> > > > EIO occurs when reading page from page_list.
> > > >
> > > > Signed-off-by: Gu Zheng <guz.fnst@...fujitsu.com>
> >
> > Reviewed-by: Chao Yu <chao2.yu@...sung.com>
> >
> > > > ---
> > > > fs/f2fs/node.c | 44 ++++++++++++++++++++------------------------
> > > > fs/f2fs/segment.c | 7 +++++--
> > > > 2 files changed, 25 insertions(+), 26 deletions(-)
> > > >
> > > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > > > index 8787469..4b7861d 100644
> > > > --- a/fs/f2fs/node.c
> > > > +++ b/fs/f2fs/node.c
> > > > @@ -1588,15 +1588,8 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head
> > > *pages,
> > > > for (; page_idx < start + nrpages; page_idx++) {
> > > > /* alloc temporal page for read node summary info*/
> > > > page = alloc_page(GFP_F2FS_ZERO);
> > > > - if (!page) {
> > > > - struct page *tmp;
> > > > - list_for_each_entry_safe(page, tmp, pages, lru) {
> > > > - list_del(&page->lru);
> > > > - unlock_page(page);
> > > > - __free_pages(page, 0);
> > > > - }
> > > > - return -ENOMEM;
> > > > - }
> > > > + if (!page)
> > > > + break;
> > > >
> > > > lock_page(page);
> > > > page->index = page_idx;
> > > > @@ -1607,7 +1600,8 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head
> > > *pages,
> > > > f2fs_submit_page_mbio(sbi, page, page->index, &fio);
> > > >
> > > > f2fs_submit_merged_bio(sbi, META, READ);
> > > > - return 0;
> > > > +
> > > > + return page_idx - start;
> > > > }
> > > >
> > > > int restore_node_summary(struct f2fs_sb_info *sbi,
> > > > @@ -1630,28 +1624,30 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
> > > > nrpages = min(last_offset - i, bio_blocks);
> > > >
> > > > /* read ahead node pages */
> > > > - err = ra_sum_pages(sbi, &page_list, addr, nrpages);
> > > > - if (err)
> > > > - return err;
> > > > + nrpages = ra_sum_pages(sbi, &page_list, addr, nrpages);
> > > > + if (!nrpages)
> > > > + return -ENOMEM;
> > > >
> > > > list_for_each_entry_safe(page, tmp, &page_list, lru) {
> > > > -
> > >
> > > Here we can just add:
> > > if (err)
> > > goto skip;
> > > lock_page();
> > > ...
> > > unlock_page();
> > > skip:
> > > list_del();
> > > __free_pages();
> > >
> > > IMO, it's more neat, so if you have any objection, let me know.
> > > Otherwise, I'll handle this by myself. :)
> > > Thanks,
> > >
> > > > - lock_page(page);
> > > > - if (unlikely(!PageUptodate(page))) {
> > > > - err = -EIO;
> > > > - } else {
> > > > - rn = F2FS_NODE(page);
> > > > - sum_entry->nid = rn->footer.nid;
> > > > - sum_entry->version = 0;
> > > > - sum_entry->ofs_in_node = 0;
> > > > - sum_entry++;
> > > > + if (!err) {
> >
> > If we skip here, next round we will fill these summary page entries with
> > wrong info because we skip the code 'sum_entry++;'.
>
> There is no next round. Once err = -EIO, there's no route to make err =
> 0.
Ah, you're right. Only old code has this problem, this new patch can fix it well.
Thanks for the mention. :)
Thanks.
>
> >
> > > > + lock_page(page);
> > > > + if (unlikely(!PageUptodate(page))) {
> > > > + err = -EIO;
> > > > + } else {
> > > > + rn = F2FS_NODE(page);
> > > > + sum_entry->nid = rn->footer.nid;
> > > > + sum_entry->version = 0;
> > > > + sum_entry->ofs_in_node = 0;
> > > > + sum_entry++;
> > > > + }
> > > > + unlock_page(page);
> > > > }
> > > >
> > > > list_del(&page->lru);
> > > > - unlock_page(page);
> > > > __free_pages(page, 0);
> > > > }
> >
> > Maybe we should add code here.
> > if (err)
> > return err;
>
> This can reduce unnecessary loop executions.
> I'll add this.
> Thanks,
>
> >
> > > > }
> > > > +
> > > > return err;
> > > > }
> > > >
> > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > > > index 199c964..b3f8431 100644
> > > > --- a/fs/f2fs/segment.c
> > > > +++ b/fs/f2fs/segment.c
> > > > @@ -1160,9 +1160,12 @@ static int read_normal_summaries(struct f2fs_sb_info *sbi, int
> type)
> > > > ns->ofs_in_node = 0;
> > > > }
> > > > } else {
> > > > - if (restore_node_summary(sbi, segno, sum)) {
> > > > + int err;
> > > > +
> > > > + err = restore_node_summary(sbi, segno, sum);
> > > > + if (err) {
> > > > f2fs_put_page(new, 1);
> > > > - return -EINVAL;
> > > > + return err;
> > > > }
> > > > }
> > > > }
> > >
> > > --
> > > Jaegeuk Kim
> > > Samsung
> > >
> > >
> > > ------------------------------------------------------------------------------
> > > Learn Graph Databases - Download FREE O'Reilly Book
> > > "Graph Databases" is the definitive new guide to graph databases and their
> > > applications. Written by three acclaimed leaders in the field,
> > > this first edition is now available. Download your free book today!
> > > http://p.sf.net/sfu/13534_NeoTech
> > > _______________________________________________
> > > Linux-f2fs-devel mailing list
> > > Linux-f2fs-devel@...ts.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> >
>
> --
> Jaegeuk Kim
> Samsung
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