Re: systemd-fstab-generator overwrites sysroot.mount created by dmsquash-generator.

[Harald Hoyer <harald-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 18.07.2015 15:27, Ali H. Caliskan wrote:
> dracut-dmsquash-generator creates $GENERATOR_DIR/sysroot.mount and
> dracut-rootfs-generator doesn't touch it but systemd-fstab-generator
> does overwrite the sysroot.mount file which causes error like "Timed
> out waiting for device dev-mapper-live\x2drw.device." I don't know if
> it can be resolved by dracut or if systemd should skip writing
> sysroot.mount if it already exists.
> 
> I'm able to boot with rd.live.image by letting
> dracut-dmsquash-generator create sysroot.mount.new and then tell
> dracut-rootfs-generator to sysmlink sysroot.mount.new to
> initrd-root-fs.target.requires/sysroot.mount. Also I had to remove "if
> [ -z "$DRACUT_SYSTEMD" ]; then" condition from the
> dmsquash-live-root.sh in order to mount LiveOS/rootfs.img into
> /sysroot directory.


Hmm,

according to the man page systemd.generator:

SYNOPSIS
       /path/to/generator normal-dir early-dir late-dir


        1. normal-dir

           argv[1] may be used to override unit files in /usr, but not those in
/etc. This means that unit files placed in this directory take precedence
           over vendor unit configuration but not over native
user/administrator unit configuration.

        2. early-dir

           argv[2] may be used to override unit files in /usr and in /etc. This
means that unit files placed in this directory take precedence over all
           configuration, both vendor and user/administrator.

        3. late-dir

           argv[3] may be used to extend the unit file tree without overriding
any other unit files. Any native configuration files supplied by the
           vendor or user/administrator take precedence over the generated ones
placed in this directory.


systemd-fstab-generator uses argv[1], so this is normal-dir
<https://github.com/systemd/systemd/blob/master/src/fstab-generator/fstab-generator.c#L653>

dmsquash-generator.sh uses argv[2], so this is early-dir
<https://github.com/haraldh/dracut/blob/master/modules.d/90dmsquash-live/dmsquash-generator.sh#L53>


If I run test/TEST-16-DMSQUASH and rd.break before switch-root, I can see

switch_root:/run/systemd# find generator.early/
generator.early/
generator.early/dev-mapper-live\x2drw.device.d
generator.early/dev-mapper-live\x2drw.device.d/timeout.conf
generator.early/sysroot.mount
switch_root:/run/systemd# find generator
generator
generator/initrd-root-fs.target.requires
generator/initrd-root-fs.target.requires/sysroot.mount
generator/sysroot.mount


# systemctl show sysroot.mount |grep Path
FragmentPath=/run/systemd/generator.early/sysroot.mount

# cat generator.early/sysroot.mount
[Unit]
Before=initrd-root-fs.target
[Mount]
Where=/sysroot
What=/dev/mapper/live-rw

# cat generator/sysroot.mount
# Automatically generated by systemd-fstab-generator

[Unit]
SourcePath=/proc/cmdline
Documentation=man:fstab(5) man:systemd-fstab-generator(8)
Before=initrd-root-fs.target

[Mount]
What=live:CDLABEL=LiveCD
Where=/sysroot
Options=rw


So, works as expected. The question is, why is your system different?