Documentation/filesystems/overlayfs.rst

35 make the overlay mount more compliant with filesystem scanners and
48 The "xino" feature can be enabled with the "-o xino=on" overlay mount option.
51 the lifetime of the filesystem.  The "-o xino=auto" overlay mount option
120 At mount time, the two directories given as mount options "lowerdir" and
123   mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,\
237 Mount options:
299  2) task creating the overlay mount MUST NOT gain additional privileges
325   mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,... /merged
330   mount --bind /upper /merged
342   mount -t overlay overlay -olowerdir=/lower1:/lower2:/lower3 /merged
354   mount -t overlay overlay -olowerdir=/a\:lower\:\:dir /merged
357 be configured as lower layer using the "lowerdir+" mount options and the
358 fsconfig syscall from new mount api.  For example::
382 parameter metacopy=on/off. Lastly, there is also a per mount option
383 metacopy=on/off to enable/disable this feature per mount.
392 Note: redirect_dir={off|nofollow|follow[*]} and nfs_export=on mount options
422   mount -t overlay overlay -olowerdir=/l1:/l2:/l3::/do1::/do2 /merged
433 the "datadir+" mount options and the fsconfig syscall from new mount api.
455 (during a mount, after a remount, etc) such a file in the lower is
470 such file content, and the entire mount can be trusted to match the
473 This feature is controlled by the "verity" mount option, which
494 a very common practice.  An overlay mount may use the same lower layer
495 path as another overlay mount and it may use a lower layer path that is
499 another overlay mount is not allowed and may fail with EBUSY.  Using
510 With the "index" feature, on the first time mount, an NFS file
513 attribute on the upper layer root directory.  On subsequent mount attempts,
516 lower root origin, mount will fail with ESTALE.  An overlayfs mount with
522 mount time. So if same upper is mounted with different set of lower, mount
527 to a different machine.  With the "index" feature, trying to mount
534 mount. For regular files this does not need any special care. However, files
536 interpreted by the underlying overlayfs mount and stripped out. In order to
537 allow the second overlayfs mount to see the attributes they must be escaped.
542 "trusted.overlay.metacopy" xattr in the overlayfs mount. This can be nested by
546 mount, so to support storing an effective whiteout file in an overlayfs mount an
579 Enabled with the mount option or module option: "redirect_dir=on" or with
588 Enabled with the mount option or module option "index=on" or with the
598 Enabled with the mount option "xino=auto" or "xino=on", with the module
711 verified on mount time to check that upper file handles are not stale.
714 Note: the mount options index=off,nfs_export=on are conflicting for a
715 read-write mount and will result in an error.
717 Note: the mount option uuid=off can be used to replace UUID of the underlying
728 controlled by the "uuid" mount option, which supports these values:
742     Upgrade to "uuid=on" on first time mount of new overlay filesystem that
748 Volatile mount
751 This is enabled with the "volatile" mount option.  Volatile mounts are not
762 volatile mount takes place, all sync functions will return an error.  Once this
768 "$workdir/work/incompat/volatile" is created.  During next mount, overlay
769 checks for this directory and refuses to mount if present. This is a strong
779 The "-o userxattr" mount option forces overlayfs to use the