Changes

= The solution =

= The solution =

When we see all these variation of commands to build a mount tree, we can understand that the final picture may be very complicated to be repeated, so we suggest to add a new flag to the mount() syscall, which allows us to add a mount into an existing group.

When we see all variation of commands to build a mount tree, we can understand that the final picture may be very complicated to be repeated, so we suggest to add [https://patchwork.kernel.org/patch/9703885/ a new flag] to the mount() syscall, which allows us to add a mount into an existing group.

In this case the restore algorithm will be very simple.

In this case the restore algorithm will be very simple.

Create a temporary mount which is called “root yard”

* Create a temporary mount which is called “root yard”

Create all namespaces (in specified user namespaces)

* Create all namespaces (in specified user namespaces)

Add root yards from all namespaces into one shared group, so a mount is created in one mntns, will be propagated into others.

* Add root yards from all namespaces into one shared group, so a mount is created in one mntns, will be propagated into others.

Create all mounts in separate directories in the root yards.

* Create all mounts in separate directories in the root yards.

Restore opened files (nothing is over-mounted at this point)

* Restore opened files (nothing is over-mounted at this point)

Build mount trees in namespaces by moving mounts to right places

* Build mount trees in namespaces by moving mounts to right places

Do pivot_root() in all namespaces

* Do pivot_root() in all namespaces

Let’s look at the next example:

Let’s look at the next example:

[[File:mntns-2.0-tree-3.svg]]

[[File:mntns-2.0-tree-3.svg]]

= Restore of unix sockets =

= Restore of unix sockets =