For statfs information , vfs_ceph_disk_free is using the inode based on mount point , this always gives root volume quota information when proxy is enabled because proxy internally mount always root volume. But If quota is set for subvolume share, It doesn't report the correct information for subvolume. Ideally it should look the inode based on connectpath to fetch the correct inode and to report the correct quota information of subvolume/subdir.
This bug was referenced in samba master: f2ccf020046bc4f0465dfa8b5a8737b018fa66ac
Created attachment 18783 [details] patch from master for v4-23-test