[libvirt] PATCH: 4/4: Add pivot_root support to container

[Dan Smith]

DB> +static int lxcContainerMountNewFS(virDomainDefPtr vmDef)
DB> +{
DB> +    virDomainFSDefPtr tmp;
DB> +
DB> +    /* Pull in rest of container's mounts */
DB> +    for (tmp = vmDef->fss; tmp; tmp = tmp->next) {
DB> +        char *src;
DB> +        if (STREQ(tmp->dst, "/"))
DB> +            continue;
DB> +        // XXX fix
DB> +        if (tmp->type != VIR_DOMAIN_FS_TYPE_MOUNT)
DB> +            continue;
DB> +
DB> +        if (asprintf(&src, "/.oldroot/%s", tmp->src) < 0)
DB> +            return -1;
DB> +
DB> +        if (virFileMakePath(tmp->dst) < 0 ||
DB> +            mount(src, tmp->dst, NULL, MS_BIND, NULL) < 0) {
DB> +            VIR_FREE(src);
DB> +            lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
DB> +                     _("failed to mount %s at %s for container: %s"),
DB> +                     tmp->src, tmp->dst, strerror(errno));
DB> +            return -1;
DB> +        }
DB> +        VIR_FREE(src);
DB> +    }
DB> +    return -1;

Shouldn't this be "return 0"?  AFAICT, this means this function will
always fail and thus any domain with a root target will fail to start.
If I change this to "return 0" I'm able to start such guests, with
properly pivoted roots.

On a more general note, it seems like there are a lot of places where
failures trigger a "return -1" that rolls completely up the stack with
no error information getting logged.  Since you have the excellent
per-container logging functionality, can we increase the verbosity a
little so that there is some way to diagnose where things are failing?
Thus far, I've just started sprinkling fprintf()'s into the code until I
start to narrow things down.  I'd be glad to help with that after this
goes in.

Thanks!

-- 
Dan Smith
IBM Linux Technology Center
Open Hypervisor Team
email: danms at us.ibm.com
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