Explore convenience and usability of vfs_snapper for Samba shadow copies

[FroggyFlox]

Samba now has a snapper vfs module:
https://www.samba.org/samba/docs/current/man-html/vfs_snapper.8.html

As described there:

The vfs_snapper VFS module exposes snapshots managed by snapper for use by Samba. This provides the ability for remote SMB clients to access shadow-copies via Windows Explorer using the "previous versions" dialog.

A very nice and detailed description and set of instructions are in the Leap 15.4 docs:
https://doc.opensuse.org/documentation/leap/reference/html/book-reference/cha-samba.html#sec-samba-advanced-snapshots-client

We currently support this functionality using the shadow_copy_2 vfs module but it requires a bit of configuration that makes it prone to errors (https://rockstor.com/docs/howtos/windows-shadow-copy.html).

Although we do not have snapper integrated in Rockstor, it is there and running (used by our upstream bits). It would thus be worth looking into the benefits of using vfs_snapper to manage shadow copies in Samba.

Note that this would (most likely) be in combination with #2136.

[FroggyFlox]

A first potential obstacle I see, though: from the manual: https://www.samba.org/samba/docs/current/man-html/vfs_snapper.8.html

Snapper stores snapshots under a .snapshots subdirectory.

From this, I understand we would need to have our snapshots for such volumes stored under a .snapshots dir... In other words, we would need to have snapper create the snapshots for a share exported by Samba.

[phillxnet]

@FroggyFlox Nice find. I think we need to revisit the work done by @sfranzen here:

#1491

which is now very outdated, and in-turn required a backbone jslib update rockstor/rockstor-jslibs#8

[FroggyFlox]

It turns out I (again) did not do enough research before posting this. There have been multiple references to that vfs module here (including by myself):

• [Samba] Enable the btrfs vfs module #2136 (comment)
• Feature: snapper for snapshot management #1432 (comment)