It turned out by implicitly handling root allocation in
lfsr_btree_commit_, we were never allowing lfsr_bshrub_commit to
intercept new roots as new bshrubs. Fixing this required moving the
root allocation logic up into lfsr_btree_commit.
This resulted in quite a bit of small bug fixing because it turns out if
you can never create non-inlined bshrubs you never test non-inlined
bshrubs:
- Our previous rbyd.weight == btree.weight check for if we've reached
the root no longer works, changed to an explicit check that the blocks
match. Fortunately, now that new roots set trunk=0 new roots are no
longer a problematic case.
- We need to only evict when we calculate an accurate estimate, the
previous code had a bug where eviction occurred early based only on the
progged-since-last-estimate.
- We need to manually set bshrub.block=mdir.block on new bshrubs,
otherwise the lfsr_bshrub_isbshrub check fails in mdir commit staging.
Also updated btree/bshrub following code in the dbg scripts, which
mostly meant making them accept both BRANCH and SHRUBBRANCH tags as
btree/bshrub branches. Conveniently very little code needs to change
to extend btree read operations to support bshrubs.
Note this is intentionally different from how lfsr_rbyd_fetch behaves
in lfs.c. We only call lfsr_rbyd_fetch when we need validated checksums,
otherwise we just don't fetch.
The dbg scripts, on the other hand, always go through fetch, but it is
useful to be able to inspect the state of incomplete trunks when
debugging.
This use to be how the dbg scripts behaved, but they broke because of
some recent script work.
dbgbmap.py parses littlefs's mtree/btrees and displays that status of
every block in use:
$ ./scripts/dbgbmap.py disk -B4096x256 -Z -H8 -W64
bd 4096x256, 7.8% mdir, 10.2% btree, 78.1% data
mmddbbddddddmmddddmmdd--bbbbddddddddddddddbbdddd--ddddddmmdddddd
mmddddbbddbbddddddddddddddddbbddddbbddddddmmddbbdddddddddddddddd
bbdddddddddddd--ddddddddddddddddbbddddmmmmddddddddddddmmmmdddddd
ddddddddddbbdddddddddd--ddddddddddddddmmddddddddddddddddddddmmdd
ddddddbbddddddddbb--ddddddddddddddddddddbb--mmmmddbbdddddddddddd
ddddddddddddddddddddbbddbbdddddddddddddddddddddddddddddddddddddd
dddddddddd--ddddbbddddddddmmbbdd--ddddddddddddddbbmmddddbbdddddd
ddmmddddddddddmmddddddddmmddddbbbbdddddddd--ddbbddddddmmdd--ddbb
(ok, it looks a bit better with colors)
dbgbmap.py matches the layout and has the same options as tracebd.py,
allowing the combination of both to provide valuable insight into what
exactly littlefs is doing.
This required a bit of tweaking of tracebd.py to get right, mostly
around conflicting order-based arguments. This also reworks the internal
Bmap class to be more resilient to out-of-window ops, and adds an
optional informative header.
