On Sun, Feb 17, 2019 at 9:55 AM Adam Borowski <kilobyte@xxxxxxxxxx> wrote: > > On Sun, Feb 17, 2019 at 06:35:25PM +0200, Boaz Harrosh wrote: > > On 15/02/19 00:06, Dave Chinner wrote: > > > So you're adding an interface that allows users to change the create > > > time of files without needing any privileges? > > > > Inode create time is forensic metadata in XFS - information we use > > > for sequence of event and inode lifetime analysis during examination > > > of broken filesystem images and systems that have been broken into. > > > I think the difference in opinion here is that there are two totally > > different BTIme out in the world. For two somewhat opposite motivations > > and it seems they both try to be crammed into the same on disk space. > > > > One - Author creation time > > Two - Local creation time > > > So it looks like both sides are correct trying to preserve their own guy? > > I'd say that [2] is too easily gameable to be worth the effort. You can > just change it on the disk. That right now it'd take some skill to find the > right place to edit doesn't matter -- a tool to update the btime against > your wishes would need to be written just once. Unlike btrfs, XFS doesn't > even have a chain of checksums all the way to the root. > > On the other hand, [1] has a lot of uses. It can also be preserved in > backups and version control (svnt and git-restore-mtime could be easily > extended). > > I'd thus go with [2] -- any uses for [1] are better delegated to filesystem > specific tools. > I started out in the Windows world, and I found it quite handy to right-click a file and see when it was created. When I started using Linux, I saw things like this: Access: 2019-02-16 22:19:32.024284060 -0800 Modify: 2016-02-02 19:26:47.901766778 -0800 Change: 2016-02-02 19:26:47.907766649 -0800 and my mind boggled a bit. Modify makes sense. Change? What's that? Why do I care? Adding "birth" makes sense, and I think that filesystem-agnostic backup tools *should* be able to write it. So I'm highly in favor of this patch. If XFS wants to disallow writing the birth time, fine, but I think that behavior should be overridable.
