Comment 65 for bug 1476662

Stephen Gaito (3-stephen) wrote :

I have a similar problem (but not with /proc).

***Roman Fielder's link (above) suggests the correct work around.***

My lxc configuration file has the following line:

> lxc.mount.entry = /data/references /var/lib/lxc/noteServer/rootfs/data/references none ro,bind 0 0

(Note that the mount directory is an **absolute** path)

My resulting error message (in /var/log/lxc/noteServer.log) is:

> lxc-start 1443599663.225 ERROR lxc_utils - utils.c:ensure_not_symlink:1384 - Mount onto /usr/lib/x86_64-linux-gnu/lxc//data/references resulted in /usr/lib/x86_64-linux-gnu/lxc/data/references

Tracing through the apt-get source lxc code I think the offending code (in the mount_entry_on_absolute_rootfs function in the lxc-1.0.7/src/lxc/conf.c file) is:

> aux = strstr(mntent->mnt_dir, path);
> if (aux) {
> offset = strlen(path);
> goto skipabs;
> }
> aux = strstr(mntent->mnt_dir, rootfs->path);
> if (!aux) {
> WARN("ignoring mount point '%s'", mntent->mnt_dir);
> goto out;
> }
> offset = strlen(rootfs->path);
> r = snprintf(path, MAXPATHLEN, "%s/%s", rootfs->mount,
> aux + offset);

Note that the last line should (probably -- I have not compiled any code to test this) be:

> r = snprintf(path, MAXPATHLEN, "%s/%s", rootfs->mount,
> aux + offset + 1);

The "+1" then skips over the "/" in the mntent->mnt_dir so there will only be *one* "/" in the resulting path.

Note that the work around in Roman Fiedler's link ensures that the mount entry uses the mount_entry_on_relative_rootfs function (which works) rather than the (currently broken?) mount_entry_on_absolute_rootfs function.

I can confirm that the following configuration line:

> lxc.mount.entry = /data/references data/references none ro,bind 0 0

now in fact works, since it specifies a **relative** mount directory and so invokes the mount_entry_on_relative_rootfs function.

Many thanks for excellent **open source** tools!