From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chao Yu Subject: Re: [PATCH v2] f2fs: get victim segment again after new cp Date: Sun, 24 Jul 2016 06:38:46 +0800 Message-ID: <6fbd66c3-ccfc-0389-dde5-81b901cb4586@kernel.org> References: <1469185711-27932-1-git-send-email-heyunlei@huawei.com> <20160722185922.GA36408@jaegeuk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1bR5ZS-000514-Sq for linux-f2fs-devel@lists.sourceforge.net; Sat, 23 Jul 2016 22:38:58 +0000 Received: from mail.kernel.org ([198.145.29.136]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1bR5ZR-00081e-Nn for linux-f2fs-devel@lists.sourceforge.net; Sat, 23 Jul 2016 22:38:58 +0000 In-Reply-To: <20160722185922.GA36408@jaegeuk> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Jaegeuk Kim , Yunlei He Cc: linux-f2fs-devel@lists.sourceforge.net Hi Jaegeuk, On 2016/7/23 2:59, Jaegeuk Kim wrote: > Hi Yunlei, > > On Fri, Jul 22, 2016 at 07:08:31PM +0800, Yunlei He wrote: >> Previous selected segment may become free after write_checkpoint, >> if we do garbage collect on this segment, and then new_curseg happen >> to reuse it, it may cause f2fs_bug_on as below. >> >> panic+0x154/0x29c >> do_garbage_collect+0x15c/0xaf4 >> f2fs_gc+0x2dc/0x444 >> f2fs_balance_fs.part.22+0xcc/0x14c >> f2fs_balance_fs+0x28/0x34 >> f2fs_map_blocks+0x5ec/0x790 >> f2fs_preallocate_blocks+0xe0/0x100 >> f2fs_file_write_iter+0x64/0x11c >> new_sync_write+0xac/0x11c >> vfs_write+0x144/0x1e4 >> SyS_write+0x60/0xc0 >> >> Here, maybe we check sit and ssa type during reset_curseg. So, we check >> segment is stale or not, and select a new victim to avoid this. >> >> Signed-off-by: Yunlei He >> --- >> fs/f2fs/gc.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >> index de6c41c..ec17096 100644 >> --- a/fs/f2fs/gc.c >> +++ b/fs/f2fs/gc.c >> @@ -908,10 +908,14 @@ gc_more: >> * enough free sections, we should flush dent/node blocks and do >> * garbage collections. >> */ >> - if (__get_victim(sbi, &segno, gc_type) || prefree_segments(sbi)) >> + if (__get_victim(sbi, &segno, gc_type) || prefree_segments(sbi)) { >> write_checkpoint(sbi, &cpc); >> - else if (has_not_enough_free_secs(sbi, 0)) > > If segno is NULL_SEGNO, we get a panic when checking the below conditions. > Anyway, I don't think we need this condition at all. I thinks the condition which trigger our f2fs_bug_on is really a corner case, we'd better not waste the victim we found everytime, especially for these victims from last background gc's victims. What about checking segno first? if(segno != NULL_SEGNO && (!get_valid_blocks(sbi, segno, sbi->segs_per_sec) || IS_CURSEC(sbi, GET_SECNO(sbi, segno))) segno = NULL_SEGNO; Thanks, > Let me remove them and just set NULL_SEGNO only after checkpoint. > Please check the dev-test repo. > > Thanks, > >> + if(!get_valid_blocks(sbi, segno, sbi->segs_per_sec) >> + || IS_CURSEC(sbi, segno / sbi->segs_per_sec)) >> + segno = NULL_SEGNO; >> + } else if (has_not_enough_free_secs(sbi, 0)) { >> write_checkpoint(sbi, &cpc); >> + } >> } >> >> if (segno == NULL_SEGNO && !__get_victim(sbi, &segno, gc_type)) >> -- >> 1.9.1 > > ------------------------------------------------------------------------------ > What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic > patterns at an interface-level. Reveals which users, apps, and protocols are > consuming the most bandwidth. Provides multi-vendor support for NetFlow, > J-Flow, sFlow and other flows. Make informed decisions using capacity planning > reports.http://sdm.link/zohodev2dev > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports.http://sdm.link/zohodev2dev