From: Markus Trippelsdorf Subject: Re: mounting with lazytime doesn't work on ext4 Date: Tue, 19 Sep 2017 10:35:06 +0200 Message-ID: <20170919083506.GA233@x4> References: <20170918192644.GA232@x4> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andreas Dilger , linux-ext4@vger.kernel.org, Alexander Viro , linux-fsdevel@vger.kernel.org To: Theodore Ts'o Return-path: Received: from ud10.udmedia.de ([194.117.254.50]:44220 "EHLO mail.ud10.udmedia.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750952AbdISIfJ (ORCPT ); Tue, 19 Sep 2017 04:35:09 -0400 Content-Disposition: inline In-Reply-To: <20170918192644.GA232@x4> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2017.09.18 at 21:26 +0200, Markus Trippelsdorf wrote: > I switched back to ext4 yesterday, because my btrfs fs got corrupted. > However mounting with lazytime doesn't work, neither specifying it in > /etc/fstab nor a manual remount. It looks like the option is simply > ignored. > > Strace shows, e.g.: > > # mount -o lazytime /boot > mount("/dev/sdc2", "/boot", "ext4", MS_LAZYTIME, NULL) = 0 > EXT4-fs (sdc2): mounted filesystem with ordered data mode. Opts: (null) > /dev/sdc2 on /boot type ext4 (rw,relatime,data=ordered) > > # mount -o remount,lazytime /var > mount("/dev/sdb2", "/var", 0x12c4460, MS_REMOUNT|MS_NOATIME|MS_LAZYTIME, NULL) = 0 > EXT4-fs (sdb2): re-mounted. Opts: (null) > /dev/sdb2 on /var type ext4 (rw,noatime,data=ordered) > > When I set "sb->s_flags |= MS_LAZYTIME;" unconditionally in > fs/ext4/super.c:5057 (just deleting the if statement), then lazytime > gets used when I remount. > > I'm running the latest git tree (4.14.0-rc1). The following patch seems to fix the issue for remounts: diff --git a/fs/namespace.c b/fs/namespace.c index 54059b142d6b..d0b386706c5b 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2322,6 +2322,9 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags, if (err) return err; + if (mnt_flags & MS_LAZYTIME) + sb_flags |= MS_LAZYTIME; + down_write(&sb->s_umount); if (ms_flags & MS_BIND) err = change_mount_flags(path->mnt, ms_flags); @@ -2809,6 +2812,8 @@ long do_mount(const char *dev_name, const char __user *dir_name, mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); if (flags & SB_RDONLY) mnt_flags |= MNT_READONLY; + if (flags & MS_LAZYTIME) + mnt_flags |= MS_LAZYTIME; /* The default atime for remount is preservation */ if ((flags & MS_REMOUNT) && -- Markus