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_REDIRECT_DIR bool "Overlayfs: turn on redirect dir feature by default" depends on OVERLAY_FS help If this config option is enabled then overlay filesystems will use redirects when renaming directories by default. In this case it is still possible to turn off redirects globally with the "redirect_dir=off" module option or on a filesystem instance basis with the "redirect_dir=off" mount option. Note, that redirects are not backward compatible. That is, mounting an overlay which has redirects on a kernel that doesn't support this feature will have unexpected results.
