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Thu, 01 Jul 2021 17:10:35 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4D70661405; Thu, 1 Jul 2021 17:10:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625159422; bh=xdnAA7baVCohcq+q0n62eDKdetlkpnI4UjNwJ3Ih8CU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M+RhoUajTF1gDgnHS60QrdV574dAeRY/sXEy1jFcWO6rPhV07SByNFM8vKZH/auLT PSINIJLIG8yzSgOA8LTGfMk9heo0H5qbFim6132xUPayb9R7uvBIpgyqLis9Ej4EsF 9FyE4zlnLw8iKeQ1hTPUN+k1IkgUcvtEhesKv3I7Lj8WyHQemeLMz1onksshmlA/jd 0udbOX+Nwau9XcbhVdimeNGmjoeang+5BLX2GU+MHCGhbpYqGsz9dNnrGD+VQGunkF Vasq0rXWNNzqRrXkgsSLuzvyNZA0hlN2fMQ/ZNM331EC2MI+WcJCEAuz86T21tQOwj wD2WPOszA+gKA== Date: Thu, 1 Jul 2021 10:10:20 -0700 From: Jaegeuk Kim To: Chao Yu Message-ID: References: <20210601101024.119356-1-yuchao0@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210601101024.119356-1-yuchao0@huawei.com> X-Headers-End: 1lz0Cp-0007IC-SX Subject: Re: [f2fs-dev] [PATCH v2 RFC] f2fs: fix to force keeping write barrier for strict fsync mode X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 06/01, Chao Yu wrote: > [1] https://www.mail-archive.com/linux-f2fs-devel@lists.sourceforge.net/msg15126.html > > As [1] reported, if lower device doesn't support write barrier, in below > case: > > - write page #0; persist > - overwrite page #0 > - fsync > - write data page #0 OPU into device's cache > - write inode page into device's cache > - issue flush Well, we have preflush for node writes, so I don't think this is the case. fio.op_flags |= REQ_PREFLUSH | REQ_FUA; > > If SPO is triggered during flush command, inode page can be persisted > before data page #0, so that after recovery, inode page can be recovered > with new physical block address of data page #0, however there may > contains dummy data in new physical block address. > > Then what user will see is: after overwrite & fsync + SPO, old data in > file was corrupted, if any user do care about such case, we can suggest > user to use STRICT fsync mode, in this mode, we will force to trigger > preflush command to persist data in device cache in prior to node > writeback, it avoids potential data corruption during fsync(). > > Signed-off-by: Chao Yu > --- > v2: > - fix this by adding additional preflush command rather than using > atomic write flow. > fs/f2fs/file.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index 7d5311d54f63..238ca2a733ac 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -301,6 +301,20 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end, > f2fs_exist_written_data(sbi, ino, UPDATE_INO)) > goto flush_out; > goto out; > + } else { > + /* > + * for OPU case, during fsync(), node can be persisted before > + * data when lower device doesn't support write barrier, result > + * in data corruption after SPO. > + * So for strict fsync mode, force to trigger preflush to keep > + * data/node write order to avoid potential data corruption. > + */ > + if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_STRICT && > + !atomic) { > + ret = f2fs_issue_flush(sbi, inode->i_ino); > + if (ret) > + goto out; > + } > } > go_write: > /* > -- > 2.29.2 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel