It turns out permanent root bookmark creates some rather interesting
constraints on our mtree:
1. We can never delete all mids, since at least one mid needs to exist
to represent the root's bookmark.
2. We can never revert to an inlined mdir after uninlining, since our
root bookmark always exists to stop this. This is an unfortunate
downside as it would be nice to be able to reinline mdirs, but not
the end of the world.
This restricts what operations are possible, and transitively, what we
can test.
This commit drops the removal of root bookmarks in test_mtree, which was
a workaround to keep tests from early implementation running. This was
preventing some minor optimizations. This required dropping some tests,
but these tests tested operations that aren't really possible in
practice.
Dropping the removal of root bookmarks allowed for a minor optimization
in lfsr_mdir_drop, and may lead to more in the future (or maybe just
stricter asserts):
code stack
before: 31280 2648
after: 31208 (-0.2%) 2648 (+0.0%)
Christopher Haster
a9772d785a