[rhel8]: Switch to BindReadOnlyPaths for /var/lib/containers
#3941
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This fixes https://bugzilla.redhat.com/show_bug.cgi?id=2111817 The way systemd implements `InaccessiblePaths` involves recursively traversing all mounted paths in the target root, and unmounting them; this takes about a tenth of a second in the kernel. Further, after each unmount, it also re-parses `/proc/self/mountinfo`. The combination of these two things makes handling mounts there `O(N²)` in userspace CPU time. The implementation of `BindReadOnlyPaths` seems better; it just effectively overmounts, which avoids any `O(N²)` behavior. (cherry picked from commit 21c82ff)
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This fixes https://bugzilla.redhat.com/show_bug.cgi?id=2111817
The way systemd implements
InaccessiblePathsinvolvesrecursively traversing all mounted paths in the target root, and
unmounting them; this takes about a tenth of a second in the kernel.
Further, after each unmount, it also re-parses
/proc/self/mountinfo. The combination of these two thingsmakes handling mounts there
O(N²)in userspace CPU time.The implementation of
BindReadOnlyPathsseems better; it justeffectively overmounts, which avoids any
O(N²)behavior.(cherry picked from commit 21c82ff)