libvirt users - Aug 2011 - Reg: Workaround to use pivot_root while using "rootfs" for "/" ?

Hi All,

   I am trying to start a lxc container using libvirt and I am facing an
issue due to pivot_root.

  The return code from the system call ?pivot_root? is EINVAL (Invalid
arguments).
  I isolated the issue to this specific condition check within the system
call.

This is an code snippet from fs/namespace.c::pivot_root

*    error = -EINVAL;
    if (root.mnt->mnt_root != root.dentry)
        goto out2; /* not a mountpoint */
    if (root.mnt->mnt_parent == root.mnt)  << this represents a
circular
mount reference
            goto out2; /* not attached */
    if (new.mnt->mnt_root != new.dentry)
        goto out2; /* not a mountpoint */
    if (new.mnt->mnt_parent == new.mnt)
        goto out2; /* not attached */
*
This issue occurs for me, since I am using fstype "rootfs" as
"/" and all
binaries are mounted ISO's for execution within "/".
Based on information from the below links, I have realized, that pivot_root
is not possible for the above case.*
**https://lkml.org/lkml/2005/10/8/17
https://bugzilla.kernel.org/show_bug.cgi?id=4857
*
I would like to know , if my observations are correct and is there any
workaround to overcome this issue?

Any help in this regard would be useful.

-Alphonse
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Hi All,

   I am trying to start a lxc container using libvirt and I am facing an
issue due to pivot_root.

  The return code from the system call ?pivot_root? is EINVAL (Invalid
arguments).
  I isolated the issue to this specific condition check within the system
call.

This is an code snippet from fs/namespace.c::pivot_root

*    error = -EINVAL;
    if (root.mnt->mnt_root != root.dentry)
        goto out2; /* not a mountpoint */
    if (root.mnt->mnt_parent == root.mnt)  << this represents a
circular
mount reference
            goto out2; /* not attached */
    if (new.mnt->mnt_root != new.dentry)
        goto out2; /* not a mountpoint */
    if (new.mnt->mnt_parent == new.mnt)
        goto out2; /* not attached */
*
This issue occurs for me, since I am using fstype "rootfs" as
"/" and all
binaries are mounted ISO's for execution within "/".
Based on information from the below links, I have realized, that pivot_root
is not possible for the above case.*
**https://lkml.org/lkml/2005/10/8/17
https://bugzilla.kernel.org/show_bug.cgi?id=4857
*
I would like to know , if my observations are correct and is there any
workaround to overcome this issue?

Any help in this regard would be useful.

-Alphonse
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