This was introduced with the simplified traversal clobbering logic.
Previously, traversal clobbering was a bit more aggressive, relying on
the explicit tstate state machine. This was replaced by implicit
mid-related state, which looks like it may have introduced some holes.
In this case, lfs3_mdir_commit was failing to clobber non-active mroot
chain mdirs. Non-active mroots are particularly tricky because we
(1) don't track these in-RAM, (2) only reach them during traversals,
and (3) require heavy wear-leveling writes for them to even appear in
in system.
---
The solution here is an extra check in lfs3_mdir_commit_'s post-commit
state updates to update any mid<=-1 mroots to the new active mroot.
This clobbers mroot chain traversals by skipping non-active mroots, but
this is unavoidable since lfs3_mdir_commit_ could always introduce
new/relocate mroot chain mroots. Note this should match the previous
state-machine dependent behavior.
Code changes:
code stack ctx
before: 35144 2136 660
after: 35152 (+0.0%) 2136 (+0.0%) 660 (+0.0%)
code stack ctx
gbmap before: 38380 2144 776
gbmap after: 38392 (+0.0%) 2144 (+0.0%) 776 (+0.0%)
code stack ctx
preerase before: 38920 2168 796
preerase after: 38928 (+0.0%) 2168 (+0.0%) 796 (+0.0%)
Christopher Haster
dbc457bde1