Due to VFS changes with 4.17 (for example no valid stat in smb_fname when SMB_VFS_OPENAT is called), at the moment the libgfapi gluster backend is broken in Samba. vfs_ceph being the other big library-based VFS module might also be affected.
Upstream Samba has no way of properly fixing this due to the lack of gluster and ceph environments in autobuild or gitlab CI.
Marking this bug as a known regression that needs fixing by people with access to a working gluster setup, likewise ceph.
Assigning to Günther, I had talked to him before I have submitted the merge request breaking the Samba gluster VFS module.
I am yet to figure out(and fix) the issues w.r.t snapshot consumption using vfs_shadow_copy2 module but otherwise things are expected to work() after 767ede0064ce9a9d0576a337b2059f4ba3a6adeb and 0633d8837ce4ddcf7f46c5f320e8d0b3142177fa.
For reference added upstream glusterfs github issue tracking the addition of various 'at' calls to gluster gfapi.