From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754231AbbCIKCl (ORCPT ); Mon, 9 Mar 2015 06:02:41 -0400 Received: from mailout2.samsung.com ([203.254.224.25]:22683 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753669AbbCIKCg (ORCPT ); Mon, 9 Mar 2015 06:02:36 -0400 X-AuditID: cbfee61a-f79c06d000004e71-18-54fd6fbad88f From: Chao Yu To: "'Wanpeng Li'" , "'Jaegeuk Kim'" Cc: "'Changman Lee'" , linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <1425870055-27694-1-git-send-email-wanpeng.li@linux.intel.com> <1425870055-27694-2-git-send-email-wanpeng.li@linux.intel.com> <20150309041847.GC4472@jaegeuk-mac02> <20150309042453.GA27895@kernel> In-reply-to: <20150309042453.GA27895@kernel> Subject: RE: [PATCH 2/3] f2fs: fix get stale meta pages when build free nids Date: Mon, 09 Mar 2015 18:01:26 +0800 Message-id: <000801d05a50$2a029440$7e07bcc0$@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit X-Mailer: Microsoft Outlook 14.0 Thread-index: AQKhUotwu/8AOnLPqWY2QDHvMdi7TAHEX3E/A5GfOYkCeXKpSZszeoUw Content-language: zh-cn X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrFLMWRmVeSWpSXmKPExsVy+t9jAd1d+X9DDDaslbK4tq+RyeLJ+lnM FpcWuVvs2XuSxeLyrjlsFveebGN3YPPYtKqTzWPeyUCP3Qs+M3n0bVnF6PF5k1wAaxSXTUpq TmZZapG+XQJXxqWme0wFL2UrenZfYGtg3CbexcjJISFgInHz8U5GCFtM4sK99WxdjFwcQgKL GCX27/vJCuH8YJRoO3KGGaSKTUBFYnnHfyYQW0QgWOLz0Z8sIEXMApMZJWb13WWC6LjMKPFi WwPYXE4BHYnWCW/AOoQFfCQWvPoLtIODg0VAVeJ8tzlImFfAUmJv5xM2CFtQ4sfkeywgNrOA lsT6nceZIGx5ic1r3jJDnKogsePsa0aII9wkjp25xQhRIy6x8cgtlgmMQrOQjJqFZNQsJKNm IWlZwMiyilE0tSC5oDgpPddQrzgxt7g0L10vOT93EyM4Rp5J7WBc2WBxiFGAg1GJh3fHiT8h QqyJZcWVuYcYJTiYlUR43TL+hgjxpiRWVqUW5ccXleakFh9ilOZgURLnVbJvCxESSE8sSc1O TS1ILYLJMnFwSjUwSrE9P2jyI5O5yd1pmYDutWbX028XKagKaV/STvmT9Hzu1km2ex32z7WO mvLeQ4Vveo9ozXF+v+rAJwqfGaLVNmmdcHw8K+z4R/5PVg/Wndl53Cto4ozDe5cLvjTct4m1 ds7Sv3EO+8PPy8pV87eWqZt85Yr9Zu7KeDn/xsFfbBGz0kViKs49VGIpzkg01GIuKk4EAFEU jriNAgAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Wanpeng, > -----Original Message----- > From: Wanpeng Li [mailto:wanpeng.li@linux.intel.com] > Sent: Monday, March 09, 2015 12:25 PM > To: Jaegeuk Kim > Cc: Changman Lee; Chao Yu; linux-f2fs-devel@lists.sourceforge.net; > linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; Wanpeng Li > Subject: Re: [PATCH 2/3] f2fs: fix get stale meta pages when build free nids > > Hi Jaegeuk, > On Sun, Mar 08, 2015 at 09:18:47PM -0700, Jaegeuk Kim wrote: > >Hi Wanpeng, > > > >On Mon, Mar 09, 2015 at 11:00:54AM +0800, Wanpeng Li wrote: > >> The blocks of nat pages to be scanned will be readahead when build free > >> nids. The start blkno will be adjusted to 0 when the intended range over > >> max_nids, then function ra_meta_pages readahead the right blkno, however, > >> function get_current_nat_page which is called in build_free_nids still > >> get the meta pages w/ stale blkno, this patch fix it by adjusting the nid > >> and the blkno which will be readahead in avdance in order to readahead and > >> get the right meta pages. > >> > >> Signed-off-by: Wanpeng Li > >> --- > >> fs/f2fs/checkpoint.c | 3 --- > >> fs/f2fs/node.c | 9 ++++++++- > >> 2 files changed, 8 insertions(+), 4 deletions(-) > >> > >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > >> index 53bc328..aedb441 100644 > >> --- a/fs/f2fs/checkpoint.c > >> +++ b/fs/f2fs/checkpoint.c > >> @@ -129,9 +129,6 @@ int ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages, > int type > >> > >> switch (type) { > >> case META_NAT: > >> - if (unlikely(blkno >= > >> - NAT_BLOCK_OFFSET(NM_I(sbi)->max_nid))) > >> - blkno = 0; > >> /* get nat block addr */ > >> fio.blk_addr = current_nat_addr(sbi, > >> blkno * NAT_ENTRY_PER_BLOCK); > >> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > >> index 1a7e925..8751375 100644 > >> --- a/fs/f2fs/node.c > >> +++ b/fs/f2fs/node.c > >> @@ -1509,13 +1509,20 @@ static void build_free_nids(struct f2fs_sb_info *sbi) > >> struct f2fs_summary_block *sum = curseg->sum_blk; > >> int i = 0; > >> nid_t nid = nm_i->next_scan_nid; > >> + block_t blkno = NAT_BLOCK_OFFSET(nid); > >> > >> /* Enough entries */ > >> if (nm_i->fcnt > NAT_ENTRY_PER_BLOCK) > >> return; > >> > >> + if (unlikely(blkno >= > >> + NAT_BLOCK_OFFSET(NM_I(sbi)->max_nid))) { > >> + blkno = 0; > >> + nid = 0; > >> + } > > > >The assumption here is that the nid does not exceeed max_nid, since the > >previous call already set next_scan_nid to 0, if it exceeds max_nid. > >So, we don't need to do like this. > > So get_current_nat_page in while(1) still get the wrong meta page for > one time, right? The nid will be set to 0 in the second round. When we break while (1), our nid will not exceed max_nid because: while (1) ... if (unlikely(nid >= nm_i->max_nid)) nid = 0; then next_scan_nid is assigned nid, for next round in build_free_nids our nid which is assigned next_scan_nid will also not exceed max_nid. So get_current_nat_page will get the right meta page. Thanks, > > Regards, > Wanpeng Li > > > > >BTW, even if ra_meta_pages doesn't get the below condition, > > if (unlikely(blkno >= > > NAT_BLOCK_OFFSET(NM_I(sbi)->max_nid))) > > blkno = 0; > >IMO, it is still worth to remain that to avoid any bugs due to further code > >changes. It makes sense that unlikely was used for this too. > > > >Thanks, > > > >> + > >> /* readahead nat pages to be scanned */ > >> - ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), FREE_NID_PAGES, META_NAT); > >> + ra_meta_pages(sbi, blkno, FREE_NID_PAGES, META_NAT); > >> > >> while (1) { > >> struct page *page = get_current_nat_page(sbi, nid); > >> -- > >> 1.9.1