names.

       uni_xlate={0|1|2}
           For 0 (or 'no' or 'false'), do not use escape sequences for unknown
           Unicode characters. For 1 (or 'yes' or 'true') or 2, use vfat-style
           4-byte escape sequences starting with ":". Here 2 gives a
           little-endian encoding and 1 a byteswapped bigendian encoding.

       posix=[0|1]
           If enabled (posix=1), the filesystem distinguishes between upper and
           lower case. The 8.3 alias names are presented as hard links instead
           of being suppressed. This option is obsolete.

       uid=value, gid=value and umask=value
           Set the file permission on the filesystem. The umask value is given
           in octal. By default, the files are owned by root and not readable
           by somebody else.

   Mount options for overlay
       Since Linux 3.18 the overlay pseudo filesystem implements a union mount
       for other filesystems.

       An overlay filesystem combines two filesystems - an upper filesystem and
       a lower filesystem. When a name exists in both filesystems, the object
       in the upper filesystem is visible while the object in the lower
       filesystem is either hidden or, in the case of directories, merged with
       the upper object.

       The lower filesystem can be any filesystem supported by Linux and does
       not need to be writable. The lower filesystem can even be another
       overlayfs. The upper filesystem will normally be writable and if it is
       it must support the creation of trusted.* extended attributes, and must
       provide a valid d_type in readdir responses, so NFS is not suitable.

       A read-only overlay of two read-only filesystems may use any filesystem
       type. The options lowerdir and upperdir are combined into a merged
       directory by using:

              mount -t overlay  overlay  \
                -olowerdir=/lower,upperdir=/upper,workdir=/work  /merged

       lowerdir=directory
           Any filesystem, does not need to be on a writable filesystem.

       upperdir=directory
           The upperdir is normally on a writable filesystem.

       workdir=directory
           The workdir needs to be an empty directory on the same filesystem as
           upperdir.

       userxattr
           Use the "user.overlay." xattr namespace instead of
           "trusted.overlay.". This is useful for unprivileged mounting of
           overlayfs.

       redirect_dir={on|off|follow|nofollow}
           If the redirect_dir feature is enabled, then the directory will be
           copied up (but not the contents). Then the
           "{trusted|user}.overlay.redirect" extended attribute is set to the
           path of the original location from the root of the overlay. Finally
           the directory is moved to the new location.

           on
               Redirects are enabled.

           off
               Redirects are not created and only followed if
               "redirect_always_follow" feature is enabled in the kernel/module
               config.

           follow
               Redirects are not created, but followed.

           nofollow
               Redirects are not created and not followed (equivalent to
               "redirect_dir=off" if "redirect_always_follow" feature is not
               enabled).

       index={on|off}
           Inode index. If this feature is disabled and a file with multiple
           hard links is copied up, then this will "break" the link. Changes
           will not be propagated to other names referring to the same inode.

       uuid={on|off}
           Can be used to replace UUID of the underlying filesystem in file
           handles with null, and effectively disable UUID checks. This can be
           useful in case the underlying disk is copied and the UUID of this
           copy is changed. This is only applicable if all lower/upper/work
           directories are on the same filesystem, otherwise it will