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:
298 In the old mount api the credentials of the task calling mount(2) are
299 stashed. In the new mount api the credentials of the task creating the
304 mount option which will cause the credentials of the calling task to be
306 the new mount api as the old mount api combines setting options and
307 superblock creation in a single mount(2) syscall.
313  2) task creating the overlay mount MUST NOT gain additional privileges
339   mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,... /merged
344   mount --bind /upper /merged
356   mount -t overlay overlay -olowerdir=/lower1:/lower2:/lower3 /merged
368   mount -t overlay overlay -olowerdir=/a\:lower\:\:dir /merged
371 be configured as lower layer using the "lowerdir+" mount options and the
372 fsconfig syscall from new mount api.  For example::
396 parameter metacopy=on/off. Lastly, there is also a per mount option
397 metacopy=on/off to enable/disable this feature per mount.
406 Note: redirect_dir={off|nofollow|follow[*]} and nfs_export=on mount options
436   mount -t overlay overlay -olowerdir=/l1:/l2:/l3::/do1::/do2 /merged
447 the "datadir+" mount options and the fsconfig syscall from new mount api.
462 "datadir+", "lowerdir+", "upperdir", and "workdir+" mount options with the
463 fsconfig syscall from the new mount api::
486 (during a mount, after a remount, etc) such a file in the lower is
501 such file content, and the entire mount can be trusted to match the
504 This feature is controlled by the "verity" mount option, which
525 a very common practice.  An overlay mount may use the same lower layer
526 path as another overlay mount and it may use a lower layer path that is
530 another overlay mount is not allowed and may fail with EBUSY.  Using
541 With the "index" feature, on the first time mount, an NFS file
544 attribute on the upper layer root directory.  On subsequent mount attempts,
547 lower root origin, mount will fail with ESTALE.  An overlayfs mount with
553 mount time. So if same upper is mounted with different set of lower, mount
558 to a different machine.  With the "index" feature, trying to mount
565 mount. For regular files this does not need any special care. However, files
567 be interpreted by the underlying overlayfs mount and stripped out. In order to
568 allow the second overlayfs mount to see the attributes they must be escaped.
573 "trusted.overlay.metacopy" xattr in the overlayfs mount. This can be nested by
577 mount, so to support storing an effective whiteout file in an overlayfs mount an
610 Enabled with the mount option or module option: "redirect_dir=on" or with
619 Enabled with the mount option or module option "index=on" or with the
629 Enabled with the mount option "xino=auto" or "xino=on", with the module
742 verified on mount time to check that upper file handles are not stale.
745 Note: the mount options index=off,nfs_export=on are conflicting for a
746 read-write mount and will result in an error.
748 Note: the mount option uuid=off can be used to replace UUID of the underlying
759 controlled by the "uuid" mount option, which supports these values:
773     Upgrade to "uuid=on" on first time mount of new overlay filesystem that
779 Volatile mount
782 This is enabled with the "volatile" mount option.  Volatile mounts are not
793 volatile mount takes place, all sync functions will return an error.  Once this
799 "$workdir/work/incompat/volatile" is created.  During next mount, overlay
800 checks for this directory and refuses to mount if present. This is a strong
810 The "-o userxattr" mount option forces overlayfs to use the