Re: [libvirt] [PATCH 5/5] lxc: don't unmount subtree if it contains the source of the mount
On Tue, 2014-11-25 at 08:48 +0100, Martin Kletzander wrote:
On Mon, Nov 24, 2014 at 09:54:46PM +0100, Cédric Bosdonnat wrote:
>The typical case where we had a problem is with such a filesystem
>definition as created by virt-sandbox-service:
>
> <filesystem type='bind' accessmode='passthrough'>
> <source dir='/var/lib/libvirt/filesystems/mysshd/var'/>
> <target dir='/var'/>
> </filesystem>
>
>In this case, we don't want to unmount the /var subtree or we may
>loose the access to the source folder.
I probably didn't quite get this. This is only true when host root is
the root of the container, isn't it? And in that case it doesn't make
much sense to do this.
Indeed that happens when the host root is mounted as the container
root... and that's what virt-sandbox-service does. We have this
situation when the libvirt-sandbox service has a disk image:
* The disk image is mounted to /var/lib/libvirt/filesystems/<name>
* Quite a few items from /var/lib/libvirt/filesystems/<name> are
bind mounted to their equivalent in the container root, and /var is
one of them.
--
Cedric
>---
> src/lxc/lxc_container.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
>diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
>index 12f3a41..334a1df 100644
>--- a/src/lxc/lxc_container.c
>+++ b/src/lxc/lxc_container.c
>@@ -1597,11 +1597,15 @@ static int lxcContainerMountAllFS(virDomainDefPtr vmDef,
> if (STREQ(vmDef->fss[i]->dst, "/"))
> continue;
>
>+ VIR_DEBUG("Mounting '%s' -> '%s'",
vmDef->fss[i]->src, vmDef->fss[i]->dst);
>+
> if (lxcContainerResolveSymlinks(vmDef->fss[i], false) < 0)
> return -1;
>
>- if (lxcContainerUnmountSubtree(vmDef->fss[i]->dst,
>- false) < 0)
>+
>+ if (!(vmDef->fss[i]->src &&
>+ STRPREFIX(vmDef->fss[i]->src, vmDef->fss[i]->dst))
&&
>+ lxcContainerUnmountSubtree(vmDef->fss[i]->dst, false) < 0)
> return -1;
>
> if (lxcContainerMountFS(vmDef->fss[i], sec_mount_options) < 0)
>--
>2.1.2
>
>--
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