config OVERLAY_FS tristate "Overlay filesystem support" help 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. For more information see Documentation/filesystems/overlayfs.txt config OVERLAY_FS_V1 bool "Overlayfs filesystem (V1) format support" help Support the older whiteout format overlayfs filesystems via the overlay module. This is needed to support legacy kernels built using the original overlayfs patch set.