smb3: add support for statfs for smb3.1.1 posix extensions

Output now matches expected stat -f output for all fields
except for Namelen and ID which were addressed in a companion
patch (which retrieves them from existing SMB3 mechanisms
and works whether POSIX enabled or not)

Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 6e6a4f2..7019459 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -197,6 +197,9 @@ void smb2_cancelled_close_fid(struct work_struct *work);
 extern int SMB2_QFS_info(const unsigned int xid, struct cifs_tcon *tcon,
 			 u64 persistent_file_id, u64 volatile_file_id,
 			 struct kstatfs *FSData);
+extern int SMB311_posix_qfs_info(const unsigned int xid, struct cifs_tcon *tcon,
+			 u64 persistent_file_id, u64 volatile_file_id,
+			 struct kstatfs *FSData);
 extern int SMB2_QFS_attr(const unsigned int xid, struct cifs_tcon *tcon,
 			 u64 persistent_file_id, u64 volatile_file_id, int lvl);
 extern int SMB2_lock(const unsigned int xid, struct cifs_tcon *tcon,