From: "J. Bruce Fields" Subject: Re: [RFC PATCH v1 00/30] fs: inode->i_version rework and optimization Date: Tue, 4 Apr 2017 13:53:38 -0400 Message-ID: <20170404175338.GB14303@fieldses.org> References: <20170321183006.GD17872@fieldses.org> <1490122013.2593.1.camel@redhat.com> <20170329111507.GA18467@quack2.suse.cz> <1490810071.2678.6.camel@redhat.com> <20170330064724.GA21542@quack2.suse.cz> <1490872308.2694.1.camel@redhat.com> <20170330161231.GA9824@fieldses.org> <20170401230526.GW23007@dastard> <20170403140055.GF15168@quack2.suse.cz> <20170404123414.GA23007@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Jeff Layton , Christoph Hellwig , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-btrfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dave Chinner Return-path: Content-Disposition: inline In-Reply-To: <20170404123414.GA23007@dastard> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Tue, Apr 04, 2017 at 10:34:14PM +1000, Dave Chinner wrote: > On Mon, Apr 03, 2017 at 04:00:55PM +0200, Jan Kara wrote: > > What filesystems can or cannot easily do obviously differs. Ext4 has a > > recovery flag set in superblock on RW mount/remount and cleared on > > umount/RO remount. > > Even this doesn't help. A recent bug that was reported to the XFS > list - turns out that systemd can't remount-ro the root > filesystem sucessfully on shutdown because there are open write fds > on the root filesystem when it attempts the remount. So it just > reboots without a remount-ro. I'd certainly rather not invalidate caches on *every* boot. On the other hand, if the only cases involve the root filesystem, then from the point of view of NFS, we probably don't care much. > > This flag being set on mount would imply incrementing the crash > > counter. It should be pretty easy for each filesystem to implement > > such flag and the counter but I agree it requires an on-disk > > format change. > > Yup, anything we want that is persistent and consistent across > filesystems will need on-disk format changes. Hence we need a solid > specification first, not to mention tests to validate correct > behaviour across all filesystems in xfstests... For xfstests we'll need a way to get i_version (patch it into statx, I guess?). Ideally we'd have a way to test behavior across crashes too, any advice there? --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html