[PATCH v4 2/6] mounts: keep list of mounts in an rbtree

[Miklos Szeredi]

On Mon, Oct 30, 2023 at 6:45 AM Ian Kent <raven at themaw.net> wrote:

> Is fs/namespace.c:iterate_mounts() a problem?
>
> It's called from:
>
> 1) ./kernel/audit_tree.c:709: if (iterate_mounts(compare_root,
> 2) ./kernel/audit_tree.c:839:    err = iterate_mounts(tag_mount, tree, mnt);
> 3) ./kernel/audit_tree.c:917:        failed = iterate_mounts(tag_mount,
> tree, tagged);
>
>
>  From functions 1) audit_trim_trees(), 2) audit_add_tree_rule() and
>
> 3) audit_tag_tree().

So that interface works like this:

 - collect_mounts() creates a temporary copy of a mount tree, mounts
are chained on mnt_list.

 - iterate_mounts() is used to do some work on the temporary tree

 - drop_collected_mounts() frees the temporary tree

These mounts are never installed in a namespace.  My guess is that a
private copy is used instead of the original mount tree to prevent
races.

Thanks,
Miklos