Package: mount Version: 2.27.1-1 Severity: wishlist Tags: patch The Debian mount package which packages the util-linux source. It's mount.8 is missing description on overlay.
Here is a wishlist bug to add documentation with a proposed patch (to the head of upstream git repo.) Osamu PS: I could not locate the upstream bug tracker.
>From 12aa515bb8f1c33344aaf7206329bac7edf655da Mon Sep 17 00:00:00 2001 From: Osamu Aoki <os...@debian.org> Date: Sat, 26 Dec 2015 12:57:08 +0900 Subject: [PATCH] mount.8: Add documentation of overlay mount options --- sys-utils/mount.8 | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/sys-utils/mount.8 b/sys-utils/mount.8 index 004a513..5d838c8 100644 --- a/sys-utils/mount.8 +++ b/sys-utils/mount.8 @@ -2389,6 +2389,37 @@ Set the file permission on the filesystem. The umask value is given in octal. By default, the files are owned by root and not readable by somebody else. +.SH "Mount options for overlay" +The overlay filesystem is a pseudo filesystem which implements a union mount +for other file systems. The details are documented in +.IR /usr/src/linux/Documentation/filesystems/overlayfs.txt . +.\" present since 3.18 + +Overlaying mainly involves directories. The two directories given as mount +options \fBlowerdir\fR and \fBupperdir\fR are combined into a merged directory +by using: +.RS +.br +\fBmount \-t overlay overlay \-olowerdir=\fP\,\fI/lower\fP\fB,upperdir=\fP\,\fI/upper\fP\fB,\\ +.br +\fBworkdir=\fP\,\fI/work\fP\fB \fI/merged\fR +.RE +.TP +\fBlowerdir=\fP\,\fI/lower\fP + +The \fBlowerdir\fR does not need to be on a writable filesystem. + +.TP +\fBupperdir=\fP\,\fI/upper\fP + +The \fBupperdir\fR is normally on a writable filesystem. + +.TP +\fBworkdir=\fP\,\fI/work\fP + +The \fBworkdir\fR needs to be an empty directory on the same filesystem +as \fBupperdir\fR. + .SH "Mount options for proc" .TP \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP -- 2.6.4
