SMB service - ability to use multiple vfs modules concurrently

[Hooverdan96]

Thanks to forum user orangejulio for helping to surface this issue here.
As part of the basic Samba configuration using the WebUI, one can enable the option for shadow copies (essentially file-level snapshots that can be seen e.g. by Windows machines as versions of the current file). This functionality is technically enabled by adding the following option to the share definition in the smb.conf file:

vfs objects = shadow_copy2 

If multiple vfs objects need to be stacked, they should not get each their own entry, but should be added to the option line. As per:

https://www.linuxtopia.org/online_books/network_administration_guides/samba_reference_guide/30_VFS_04.html

it would be formulated like this:

vfs objects = example:example1 example example:test

When a Rockstor user adds manual configuration during the setup (or changes the existing one), the system does not recognize the need to consolidate this into a single line, but it will result in the parameter being duplicated, e.g.:

...
vfs objects = shadow_copy2
vfs objects = btrfs

Also important will be the sequence as outlined in an example on the above page, due to the "stacked" nature of vfs libraries:

"Let's say that you want to both have a virus scanner module and a recycle bin module. It is wise to put the virus scanner module as the first one so that it is the first to get run and may detect a virus immediately, before any action is performed on that file:
vfs objects = vscan-clamav recycle"

It might be as simple as having some more instructions (either in the documentation and/or as part of the more info tag for the manual configuration section) that if a user wants to add more vfs modules in addition to the shadow copy option, that they will have to define all of them in the manual configuration, including the shadow copy vfs and that they need to be mindful of the sequence. Or we remove the shadow copy option entirely and offer the hint to the user to manually add it in the config, or something like a template button that prepopulates the manual config section with the shadow copy option and then the user can modify as they see fit ...

For reference linking to a couple of other issues raised about usage of additional vfs modules, some of them fairly old:
#2557, #2136, #1481, #1467