What is the problem you're trying to solve

A WithTransaction convenience method was introduced in #7781 to make the boilerplate portions of snapshotters a little toned down. Migration to this started in the same PR with devmapper and overlay being ported over, and was continued in #7529 with btrfs.

Describe the solution you'd like

Same treatment as devmapper, overlay and btrfs for the remaining in-tree snapshotters.