mount: execute collect shared for all mounts
mount: execute collect shared for all mounts

Currently collect_shared is executed for each mount namespace separately,
so we miss the dependencies between namespaces.

For example, we have two namespaces, the first one contains a tmpfs mount
and the second one contains a non-root bind-mount of this tmpfs. Without
this patch this example can't be dumped.

On restore mnt_build_tree() is called for all namespaces at once, thus
this bug doesn't exist there.

Signed-off-by: Andrey Vagin <74c05afa918858348d6db8037d82fa8124870113@openvz.org>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

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