samba - Jan 2025 - Clarification on Benefits of vfs_ceph_snapshots Over vfs_shadow_copy2

Hi all,
I?m curious about the advantages that the
vfs_ceph_snapshots<https://www.samba.org/samba/docs/4.11/man-html/vfs_ceph_snapshots.8.html>
module offers compared to the older
vfs_shadow_copy2<https://www.samba.org/samba/docs/4.9/man-html/vfs_shadow_copy2.8.html>
module. Does vfs_ceph_snapshots address or handle any Ceph-specific challenges
or issues more effectively?
Looking forward to your insights!

Regards,
Shwetha

Hi Shwetha,

On Mon, 6 Jan 2025 09:17:25 +0000, Shwetha K Acharya wrote:
> Hi all,
> I?m curious about the advantages that the
vfs_ceph_snapshots<https://www.samba.org/samba/docs/4.11/man-html/vfs_ceph_snapshots.8.html>
module offers compared to the older
vfs_shadow_copy2<https://www.samba.org/samba/docs/4.9/man-html/vfs_shadow_copy2.8.html>
module. Does vfs_ceph_snapshots address or handle any Ceph-specific challenges
or issues more effectively?
It's been some time since I worked on vfs_ceph_snapshots, but my main
reason for adding a new module was to explicitly handle CephFS' snapshot
interface, in that snapshots can be created anywhere in the directory
tree and are recursively inherited by child directories. The module
makes use of the ceph.snap.btime xattr for obtaining the snapshot
creation time, so is not dependent on timestamped path names.
At one point I'd also expected to add CephFS .snap_create_fn hooks for
FSRVP, but AFAICT that sub-protocol doesn't appear to get much use.

Cheers, David