On Sat, Mar 13, 2021 at 11:24:00AM -0500, Neal Gompa wrote: > On Sat, Mar 13, 2021 at 8:09 AM Adam Borowski <kilob...@angband.pl> wrote: > > > > On Wed, Mar 10, 2021 at 02:26:43PM +0000, Matthew Wilcox wrote: > > > On Wed, Mar 10, 2021 at 08:21:59AM -0600, Goldwyn Rodrigues wrote: > > > > DAX on btrfs has been attempted[1]. Of course, we could not > > > > > > But why? A completeness fetish? I don't understand why you decided > > > to do this work. > > > > * xfs can shapshot only single files, btrfs entire subvolumes > > * btrfs-send|receive > > * enumeration of changed parts of a file > > XFS cannot do snapshots since it lacks metadata COW. XFS reflinking is > primarily for space efficiency.
A reflink is a single-file snapshot. My work team really wants this very patchset -- reflinks on DAX allow backups and/or checkpointing, without stopping the world (there's a single file, "pool", here). Besides, you can still get poor-man's whole-subvolume(/directory) snapshots by manually walking the tree and reflinking everything. That's not atomic -- but rsync isn't atomic either. That's enough for eg. dnf/dpkg purposes. Meow! -- ⢀⣴⠾⠻⢶⣦⠀ ⣾⠁⢰⠒⠀⣿⡁ ⢿⡄⠘⠷⠚⠋⠀ NADIE anticipa la inquisición de españa! ⠈⠳⣄⠀⠀⠀⠀
