.TH MOUNT.LOCKFS 8 2020\-02\-02 bilibop "System Administration"

.SH NAME
mount.lockfs \- helper script for the mount command

.SH SYNOPSIS
.B mount.lockfs
.I FILESYSTEM
.I MOUNTPOINT
.RB [ MOUNTFLAGS ]
.B \-o
.I MOUNTOPTIONS

.SH DESCRIPTION
.B /usr/sbin/mount.lockfs
is a symlink to
.IR /usr/libexec/bilibop/lockfs_mount_helper .
It is used as an helper program by the
.BR mount (8)
command for the
.RB \(aq lockfs \(aq
filesystem type entries in
.IR /etc/fstab .
This script cannot be run manually, and fails if the root filesystem is not
already managed by
.BR bilibop-lockfs .
The expected way to run it and how it does its job are the followings:
.IP 1. 3
Enable
.BR bilibop\-lockfs :
set the BILIBOP_LOCKFS variable to
.I true
in
.BR bilibop.conf (5)
and reboot the computer; or reboot the computer and append the
.RB \(aq lockfs \(aq
kernel parameter to the boot commandline.
.IP 2.
One time the future \(aq/\(aq is set as an union filesystem
mountpoint from into the initramfs environment, the temporary and writable
.BR fstab (5)
on it is modified to replace filesystem types of some entries by
.RB \(aq lockfs \(aq.
Options are also modified to remember the original fstype.
.IP 3.
One time the union mount is the new root filesystem, initscripts are
executed:
.BR fstab (5)
is parsed by
.RB \(aq mount
.BR \-a \(aq,
and then
.BR mount (8)
calls
.I mount.lockfs
with the proper arguments when a
.RB \(aq lockfs \(aq
fstype is encountered.
.IP 4.
.B mount.lockfs
parses arguments and checks if the filesystem has been whitelisted in
.BR bilibop.conf (5),
or not. If it is the case, the filesystem is mounted normally and the
fstab entry is modified to reflect the actual mount call. If neither
the filesystem nor the mountpoint have been whitelisted, then the
filesystem is mounted elsewhere and readonly, a temporary filesystem
is mounted with proper options, size, permissions and ownership, and an
aufs or overlay filesystem (depending on the version of your kernel) is
mounted on the
.I MOUNTPOINT
given as argument with the lower/readonly and upper/writable branches
previously set. The fstab entry is replaced by three lines reflecting
the actual mount calls. If something fails,
.B mount.lockfs
acts as if the filesystem was whitelisted. See
.I /usr/share/doc/bilibop\-lockfs/README.Debian
for details.

.SH OPTIONS
.B lockfs_mount_helper
uses options and arguments as they are given by
.BR mount (8)
after it has parsed the corresponding
.BR fstab (5)
entry. So, options and arguments are mandatory, mount flags are optional,
and all come in the following order:
.TP
.I FILESYSTEM
Corresponding to the first field in fstab. This must be a block device,
or a symlink to a block device. If this field is given with one of the
.B UUID=*
or
.B LABEL=*
formats, then the mount command translates it to the corresponding device
name before to call the helper program.
.TP
.I MOUNTPOINT
Corresponding to the second field in fstab.
.TP
.RI [ MOUNTFLAGS ]
Generic flags passed to the mount commandline (the most usual being
.B \-v
and
.BR \-n ).
.TP
.I \-o MOUNTOPTIONS
Corresponding to the fourth field in fstab. The mount options are parsed
by the helper script: if
.B fstype=*
is encountered, it is removed from the options and used to mount the
readonly branch with this filesystem type. If
.BR ro ,
.BR noexec ,
.B nosuid
or
.B nodev
options are encountered, they are added to the list of mount options of
the writable branch.

.SH FILES
/etc/fstab
.br
/usr/libexec/bilibop/lockfs_mount_helper
.br
/usr/share/doc/bilibop\-lockfs/README.Debian

.SH SEE ALSO
.BR aufs (5),
.BR bilibop (7),
.BR bilibop.conf (5),
.BR fstab (5),
.BR mount (8)

.SH AUTHOR
This manual page has been written by Bilibop Project <quidame@poivron.org>.