libvirt users - Jun 2021 - unaccessible directory in lxcContainerResolveSymlinks

Hi Michal,

This is how snippets from my XML looks like. Full XML at the end of the
mail..
    <emulator>/usr/sbin/libvirt_lxc</emulator>
    <filesystem type='mount' accessmode='passthrough'>
      <source dir='/vol/usb1/iox/repo-lxc/utd/rootfs_mnt'/>
      <target dir='/'/>
    </filesystem>
    <filesystem type='mount' accessmode='passthrough'>
      <source dir='/flash/dir'/>
      <target dir='/flash/dir'/>
    </filesystem>

The issue I am facing is, my container doesnt start. Fails at mounting this
/flash/dir  with below message.

2021-06-09 06:52:55.548+0000: 1: error : lxcContainerMountFSBind:1223 :
Failed to bind mount directory /.oldroot/flash/dir to /flash/dir: No such
file or directory

I see that .oldroot is added to this path and figured out
that lxcContainerPivotRoot is creating and mounting all folders under
rootfs to rootfs/.oldroot
But durig pivot root, this path /flash/dir is unaccessible and hence we
don't seem to create this .oldroot/flash/dir.
Later on, during lxcContainerMountFSBind(), /.oldroot/flash/dir bind mount
fails.

Any thoughts?

Thanks
Priyanka

===Full XML
===
<domain type='lxc'>
  <name>try</name>
  <memory>1048576</memory>
  <currentMemory>1048576</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <os>
    <type arch='x86_64'>exe</type>
    <init>/sbin/init</init>
  </os>
  <devices>
    <emulator>/usr/sbin/libvirt_lxc</emulator>
    <filesystem type='mount' accessmode='passthrough'>
      <source dir='/vol/usb1/iox/repo-lxc/utd/rootfs_mnt'/>
      <target dir='/'/>
    </filesystem>
    <filesystem type='mount' accessmode='passthrough'>
      <source dir='/flash/dir'/>
      <target dir='/flash/dir'/>
    </filesystem>
    <console type='pty'>
      <target type='lxc' port='2'/>
    </console>
  </devices>
</domain>

On Wed, Jun 23, 2021 at 1:46 PM Michal Pr?vozn?k <mprivozn at redhat.com>
wrote:
> On 6/22/21 6:17 PM, Priyanka Gupta wrote:
> > Hi,
> >
> > Could someone pls let me know when this condition could possibly
arise?
> > lxcContainerResolveSymlinks:621 : Skipped unaccessible
'/flash/dir'
> >
> > The code seems to call access('/flash/dir', F_OK) which shall
only check
> > for existence of this directory '/flash/dir'. I have this
directory
> > created on my host. Is there anything that I am missing?
> >
>
> Hey, looking into the code the function is ran from a mount namespace
> thus the path may not exist. But is there a problem you are seeing? If
> so, can you share your LXC XML and describe the problem? I mean, the
> message you mention is just a debug printing, harmless.
>
> Michal
>
>
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On 6/23/21 11:08 AM, Priyanka Gupta wrote:
> Hi Michal,
> 
> This is how snippets from my XML looks like. Full XML at the end of the
> mail..?
> ? ? <emulator>/usr/sbin/libvirt_lxc</emulator>
> ? ? <filesystem type='mount'
accessmode='passthrough'>
> ? ? ? <source dir='/vol/usb1/iox/repo-lxc/utd/rootfs_mnt'/>
> ? ? ? <target dir='/'/>
> ? ? </filesystem>
> ? ? <filesystem type='mount'
accessmode='passthrough'>
> ? ? ? <source dir='/flash/dir'/>
> ? ? ? <target dir='/flash/dir'/>
> ? ? </filesystem>
> 
> The issue I am facing is, my container doesnt start. Fails at mounting
> this /flash/dir? with below message.
> 
> 2021-06-09 06:52:55.548+0000: 1: error : lxcContainerMountFSBind:1223 :
> Failed to bind mount directory /.oldroot/flash/dir to /flash/dir: No
> such file or directory
Yeah, the lxc driver thinks that /flash/dir doesn't exist.
Unfortunately, I am unable to reproduce - when I mkdir -p /flash/dir
and add corresponding <filesystem/> to one of my containers it boots up
just fine. What's your libvirt version?

Michal