fs/overlayfs/Kconfig

   1 config OVERLAY_FS
   2         tristate "Overlay filesystem support"
   3         select EXPORTFS
   4         help
   5           An overlay filesystem combines two filesystems - an 'upper' filesystem
   6           and a 'lower' filesystem.  When a name exists in both filesystems, the
   7           object in the 'upper' filesystem is visible while the object in the
   8           'lower' filesystem is either hidden or, in the case of directories,
   9           merged with the 'upper' object.
  10
  11           For more information see Documentation/filesystems/overlayfs.txt
  12
  13 config OVERLAY_FS_REDIRECT_DIR
  14         bool "Overlayfs: turn on redirect dir feature by default"
  15         depends on OVERLAY_FS
  16         help
  17           If this config option is enabled then overlay filesystems will use
  18           redirects when renaming directories by default.  In this case it is
  19           still possible to turn off redirects globally with the
  20           "redirect_dir=off" module option or on a filesystem instance basis
  21           with the "redirect_dir=off" mount option.
  22
  23           Note, that redirects are not backward compatible.  That is, mounting
  24           an overlay which has redirects on a kernel that doesn't support this
  25           feature will have unexpected results.
  26
  27 config OVERLAY_FS_INDEX
  28         bool "Overlayfs: turn on inodes index feature by default"
  29         depends on OVERLAY_FS
  30         help
  31           If this config option is enabled then overlay filesystems will use
  32           the inodes index dir to map lower inodes to upper inodes by default.
  33           In this case it is still possible to turn off index globally with the
  34           "index=off" module option or on a filesystem instance basis with the
  35           "index=off" mount option.
  36
  37           The inodes index feature prevents breaking of lower hardlinks on copy
  38           up.
  39
  40           Note, that the inodes index feature is read-only backward compatible.
  41           That is, mounting an overlay which has an index dir on a kernel that
  42           doesn't support this feature read-only, will not have any negative
  43           outcomes.  However, mounting the same overlay with an old kernel
  44           read-write and then mounting it again with a new kernel, will have
  45           unexpected results.