From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753745AbcITBlo (ORCPT ); Mon, 19 Sep 2016 21:41:44 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:49626 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752458AbcITBlm (ORCPT ); Mon, 19 Sep 2016 21:41:42 -0400 Subject: Re: [PATCH 3/6] f2fs: fix to avoid race condition when updating sbi flag To: Jaegeuk Kim , Chao Yu References: <1474212608-6930-1-git-send-email-chao@kernel.org> <1474212608-6930-3-git-send-email-chao@kernel.org> <20160919214058.GA68913@jaegeuk> CC: , From: Chao Yu Message-ID: <5129623b-f261-3eb4-d82d-3fedee91644f@huawei.com> Date: Tue, 20 Sep 2016 09:41:32 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.0 MIME-Version: 1.0 In-Reply-To: <20160919214058.GA68913@jaegeuk> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.57E093CB.00B2,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: b7b5ba6df7544b20370af2338631499c Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jaegeuk, On 2016/9/20 5:40, Jaegeuk Kim wrote: > Hi Chao, > > On Sun, Sep 18, 2016 at 11:30:05PM +0800, Chao Yu wrote: >> From: Chao Yu >> >> Making updating of sbi flag atomic by using {test,set,clear}_bit, >> otherwise in concurrency scenario, the flag could be updated incorrectly. >> >> Signed-off-by: Chao Yu >> --- >> fs/f2fs/f2fs.h | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >> index 9b4bbf2..c30f744b 100644 >> --- a/fs/f2fs/f2fs.h >> +++ b/fs/f2fs/f2fs.h >> @@ -794,7 +794,7 @@ struct f2fs_sb_info { >> struct proc_dir_entry *s_proc; /* proc entry */ >> struct f2fs_super_block *raw_super; /* raw super block pointer */ >> int valid_super_block; /* valid super block no */ >> - int s_flag; /* flags for sbi */ >> + unsigned long s_flag; /* flags for sbi */ >> >> #ifdef CONFIG_F2FS_FS_ENCRYPTION >> u8 key_prefix[F2FS_KEY_DESC_PREFIX_SIZE]; >> @@ -1063,17 +1063,19 @@ static inline struct address_space *NODE_MAPPING(struct f2fs_sb_info *sbi) >> >> static inline bool is_sbi_flag_set(struct f2fs_sb_info *sbi, unsigned int type) >> { >> - return sbi->s_flag & (0x01 << type); >> + return test_bit(type, &sbi->s_flag); >> } >> >> static inline void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type) >> { >> - sbi->s_flag |= (0x01 << type); >> + if (!test_bit(type, &sbi->s_flag)) >> + set_bit(type, &sbi->s_flag); > > The set_bit() is enough, no? It seems OK to me, let me send v2. Thanks, > >> } >> >> static inline void clear_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type) >> { >> - sbi->s_flag &= ~(0x01 << type); >> + if (test_bit(type, &sbi->s_flag)) >> + clear_bit(type, &sbi->s_flag); > > ditto. > > Thanks, > >> } >> >> static inline unsigned long long cur_cp_version(struct f2fs_checkpoint *cp) >> -- >> 2.7.2 > > . >