[systemd-devel] mount failed during system start but after "systemctl daemon-reload" everything works

[Andrey Borzenkov]

В Tue, 22 Apr 2014 18:49:49 +0200
Oliver <oliver at business-security.de> пишет:

> 
> Am 22.04.2014 07:04, schrieb Lennart Poettering:
> > On Fri, 18.04.14 10:32, Oliver (oliver at business-security.de) wrote:
> >
> >> Hello.
> >> Could anyone tell me a reason why a mount (regardless of via fstab
> >> or "mountpoint.mount" unit file) during system boot leads to a
> >> timeout because of device timeout and after i do a "systemctl
> >> daemon-reload" the mount is successful?
> >>
> >> Detailed information:
> >> My system is a Linuxfromscratch 7.5 (so no "real" distribution -
> >> everything is self-compiled) and it runs as a paravirtualized Xen
> >> DomU. Therefore the block devices are /dev/xvda1 and /dev/xvdb1.
> >> The first is the root fs and mount and remount are okay. Then the
> >> second block device should mount and it timed out with "Dependency
> >> failed" and "dev-xvdb1.device/start timed out"
> >> When I run "udevadm info /dev/xvdb1" everything seems to be okay,
> >> but any try of mount this via systemd failes. When I mount manually
> >> via "mount /dev/xvdb1 /mountpoint" it's fine. Then "systemctl status
> >> mountpoint.mount" says "active".
> >> Manually unmount is okay and after this a mount via systemd failes again.
> >> If I do, and only if I do "systemctl daemon-reload" and then
> >> "systemctl start mountpoint.mount" it works.
> >>
> >> I'm a beginner with a systemd based system and do not know much
> >> about the internals. What could lead to this behaviour? Is it
> >> possible that I do anything wrong?
> >> Please help. I'm very frustrated. If you need more Input, please tell me.
> > systemd's .device units rely on the "systemd" tag to be on the udev
> > device, as well as DEVICE_READY=1 being absent of it. I have no idea how
> > xen sets up block device nodes, but what is essential that this used to
> > inform systemd when the devices are ready to be mounted.
> >
> > Lennart
> >
> This is the output of "udevadm info /dev/xvdb1":
> 
> P: /devices/vbd-51729/block/xvdb1
> N: xvdb1
> S: disk/by-uuid/d2b62043-e504-4005-b1f4-212e87360284
> E: DEVLINKS=/dev/disk/by-uuid/d2b62043-e504-4005-b1f4-212e87360284
> E: DEVNAME=/dev/xvdb1
> E: DEVPATH=/devices/vbd-51729/block/xvdb1
> E: DEVTYPE=disk
> E: ID_FS_TYPE=ext4
> E: ID_FS_USAGE=filesystem
> E: ID_FS_UUID=d2b62043-e504-4005-b1f4-212e87360284
> E: ID_FS_UUID_ENC=d2b62043-e504-4005-b1f4-212e87360284
> E: ID_FS_VERSION=1.0
> E: MAJOR=202
> E: MINOR=17
> E: SUBSYSTEM=block
> E: TAGS=:systemd:
> E: USEC_INITIALIZED=70616
> 
> Doesn't this mean, that the device is ready for a mount?
> 
> Here one can see the difference before and after "systemctl daemon-reload":
> 
> domU [ ~ ]# systemctl status dev-xvdb1.device
> * dev-xvdb1.device
>     Loaded: loaded
>     Active: inactive (dead)
> domU [ ~ ]# systemctl status dev-hvc0.device
> * dev-hvc0.device
>     Loaded: loaded
>     Active: inactive (dead)
> domU [ ~ ]# systemctl daemon-reload
> domU [ ~ ]# systemctl status dev-xvdb1.device
> * dev-xvdb1.device - /dev/xvdb1
>     Follow: unit currently follows state of 
> sys-devices-vbd\x2d51729-block-xvdb1.device
>     Loaded: loaded
>     Active: active (plugged)
>     Device: /sys/devices/vbd-51729/block/xvdb1
> domU [ ~ ]# systemctl status dev-hvc0.device
> * dev-hvc0.device - /dev/hvc0
>     Follow: unit currently follows state of 
> sys-devices-virtual-tty-hvc0.device
>     Loaded: loaded
>     Active: active (plugged)
>     Device: /sys/devices/virtual/tty/hvc0
> 
> I added the device /dev/hvc0 (console inside Xen domU) because it's the 
> same behaviour.
> What's going on at "systemctl daemon-reload"?

It runs coldplug for units including devices. So it sets PLUGGED state
for existing devices. It actually looks like your system is missing
udev coldplug on boot.

>                                              I thought it only looks 
> for new updates in "/etc/systemd/system" "/var/run/systemd/system" and 
> "[/usr]/lib/systemd/system".
> What I realized was, that it updates files in /var/run/systemd/generator/
> But everything there is the same.
> 
> Any ideas?
> 
> Best regard
> Oliver
> 
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