btree: Resurrected btree leaf caching

This is an indulgence to simplify the upcoming auxiliary btree work.

Brings back the previously-reverted per-btree leaf caches, where each
lfs3_btree_t keeps track of two rbyds: The root and the most recently
accessed leaf.

At the surface level, this optimizes repeated access to the same btree
leaf. A common pattern for a number of littlefs's operations that has
proven tricky to manually optimize:

- Btree iteration
- Pokes for our crystalization heuristic
- Checksum collision resolution for dids and (FUTURE) ddkeys
- Related rattrs attached to a single bid

But the real motivation is to drop lfs3_btree_*lookupleaf and simplify
the internal APIs. If repeated lfs3_btree_lookup*s are already
efficient, there's no reason for extra leaf-level APIs, and in theory
any logic that interacts with btrees will be simpler.

---

This comes at a cost (humorously about the same amount as the
tag-returning refactor, if you ignore the extra 28 bytes of ctx).
Unsurprisingly, increasing the size of lfs3_btree_t has the biggest
impact on stack and ctx:

           code          stack          ctx
  before: 36084           2336          656
  after:  36784 (+1.9%)   2400 (+2.7%)  684 (+4.3%)

Also note from the previous commit messages: Btree leaf caching has
resulted in surprisingly little performance improvement for our current
benchmarks + implementation. It turns out if you're dominated by write
cost, optimizing btree lookups -- which already skip rbyd fetches, has
barely noticeable impact.

---

A note on reverting!

Eventually (after the auxiliary btree work) it will probably make sense
to revert this -- or at least provide a non-leaf-caching build for
code/RAM sensitive users.

I don't think this should be reverted as-is. Instead, I think we should
allow the option to just disable the leaf cache, while keeping the
simpler internal API. This would give us the best of all three worlds:

- A small code/RAM option
- Optimal btree iteration/nearby-lookup performance
- Simpler internal APIs

The only reason this isn't already implemented is because I want to
avoid fragmenting the codebase further while we're still in development
mode.

lfs3.h

@@ -681,8 +681,19 @@ typedef struct lfs3_rbyd {
     uint32_t cksum;
 } lfs3_rbyd_t;
 
-// a btree is represented by the root rbyd
-typedef lfs3_rbyd_t lfs3_btree_t;
+// littlefs's btree representation
+//
+// technically all we need for btrees is the root rbyd, but tracking the
+// most recent leaf helps speed up iteration/subattrs/etc without
+// local rbyd allocations -- less code and stack for the same
+// performance
+typedef struct lfs3_btree {
+    lfs3_rbyd_t r;
+    struct {
+        lfs3_bid_t bid;
+        lfs3_rbyd_t rbyd;
+    } leaf;
+} lfs3_btree_t;
 
 // littlefs's atomic metadata log type
 typedef struct lfs3_mdir {
@@ -712,7 +723,7 @@ typedef struct lfs3_bshrub {
     // trunk=0       => no bshrub/btree
     // sign(trunk)=1 => bshrub
     // sign(trunk)=0 => btree
-    lfs3_shrub_t shrub;
+    lfs3_btree_t shrub;
     #ifndef LFS3_RDONLY
     lfs3_shrub_t shrub_;
     #endif

tests/test_badblocks.toml

@@ -98,10 +98,10 @@ code = '''
         }
         printf("]\n");
         printf("btree: w%d 0x%x.%x\n",
-                btree.weight,
-                btree.blocks[0],
-                btree.trunk);
-        assert(btree.weight == sim_size);
+                btree.r.weight,
+                btree.r.blocks[0],
+                btree.r.trunk);
+        assert(btree.r.weight == sim_size);
 
         uint8_t buffer[4];
         lfs3_bid_t bid_;
@@ -2053,10 +2053,10 @@ code = '''
     }
     printf("]\n");
     printf("btree: w%d 0x%x.%x\n",
-            btree.weight,
-            btree.blocks[0],
-            btree.trunk);
-    assert(btree.weight == sim_size);
+            btree.r.weight,
+            btree.r.blocks[0],
+            btree.r.trunk);
+    assert(btree.r.weight == sim_size);
 
     uint8_t buffer[4];
     lfs3_bid_t bid_;
@@ -4010,10 +4010,10 @@ code = '''
     }
     printf("]\n");
     printf("btree: w%d 0x%x.%x\n",
-            btree.weight,
-            btree.blocks[0],
-            btree.trunk);
-    assert(btree.weight == sim_size);
+            btree.r.weight,
+            btree.r.blocks[0],
+            btree.r.trunk);
+    assert(btree.r.weight == sim_size);
 
     uint8_t buffer[4];
     lfs3_bid_t bid_;

tests/test_files.toml

@@ -1227,10 +1227,10 @@ code = '''
 
     // create an empty btree
     lfs3_alloc_ckpoint(&lfs3);
-    lfs3_rbyd_alloc(&lfs3, &file.b.shrub) => 0;
-    lfs3_rbyd_commit(&lfs3, &file.b.shrub, 0, LFS3_RATTRS(
+    lfs3_rbyd_alloc(&lfs3, &file.b.shrub.r) => 0;
+    lfs3_rbyd_commit(&lfs3, &file.b.shrub.r, 0, LFS3_RATTRS(
             LFS3_RATTR_BUF(LFS3_TAG_DATA, +1, "?", 1))) => 0;
-    lfs3_rbyd_commit(&lfs3, &file.b.shrub, 0, LFS3_RATTRS(
+    lfs3_rbyd_commit(&lfs3, &file.b.shrub.r, 0, LFS3_RATTRS(
             LFS3_RATTR(LFS3_TAG_RM, -1))) => 0;
     lfs3_mdir_commit(&lfs3, &file.b.h.mdir, LFS3_RATTRS(
             LFS3_RATTR_BTREE(

tests/test_mtree.toml

@@ -205,7 +205,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(3), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -232,7 +232,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -296,7 +296,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -325,7 +325,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -391,7 +391,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -411,7 +411,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(2), 0, "e", 1))) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -452,7 +452,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -728,7 +728,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -741,7 +741,7 @@ code = '''
     assert(mdir.r.weight == 0);
 
     // assert mdir was dropped
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -763,7 +763,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdir was dropped
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -822,7 +822,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -837,7 +837,7 @@ code = '''
     assert(mdir.r.weight == 0);
 
     // assert mdir was dropped
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -859,7 +859,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdir was dropped
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -924,7 +924,7 @@ code = '''
     assert(mdir.r.weight == 2);
 
     // assert split/drop worked out
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -941,7 +941,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdir was dropped
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -995,7 +995,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1020,7 +1020,7 @@ code = '''
     assert(mdir.r.weight == 1);
 
     // assert split/drop worked out
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1049,7 +1049,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert split/drop worked out
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1115,7 +1115,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1140,7 +1140,7 @@ code = '''
     assert(mdir.r.weight == 1);
 
     // assert split/drop worked out
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1169,7 +1169,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert split/drop worked out
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1366,7 +1366,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(3), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1383,7 +1383,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mdir, &mdir) != 0);
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1422,7 +1422,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1500,7 +1500,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1519,7 +1519,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mdir, &mdir) != 0);
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1560,7 +1560,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1640,7 +1640,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1659,7 +1659,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mdir, &mdir) != 0);
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -1700,7 +1700,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2112,7 +2112,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2136,7 +2136,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mroot, &lfs3.mroot) != 0);
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2177,7 +2177,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2257,7 +2257,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2288,7 +2288,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mroot, &lfs3.mroot) != 0);
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2334,7 +2334,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2419,7 +2419,7 @@ code = '''
             LFS3_RATTR_BUF(LFS3_TAG_ATTR(1), 0, "c", 1))) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2443,7 +2443,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mroot, &lfs3.mroot) != 0);
 
     // assert mdir was dropped
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2465,7 +2465,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdir was dropped
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2526,7 +2526,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mroot, &lfs3.mroot) != 0);
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2553,7 +2553,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2627,7 +2627,7 @@ code = '''
     assert(lfs3_mdir_cmp(&old_mroot, &lfs3.mroot) != 0);
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -2656,7 +2656,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3065,7 +3065,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &lfs3.mroot, NULL, 0) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3156,7 +3156,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &mdir, NULL, 0) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3291,7 +3291,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &lfs3.mroot, NULL, 0) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3388,7 +3388,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &lfs3.mroot, NULL, 0) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3497,7 +3497,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &mdir, NULL, 0) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3516,7 +3516,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &mdir, NULL, 0) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (4 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (4 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3607,7 +3607,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &mdir, NULL, 0) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3617,7 +3617,7 @@ code = '''
     assert(mdir.r.weight == 0);
 
     // assert mdir was dropped correctly
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3779,7 +3779,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &lfs3.mroot, NULL, 0) => 0;
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3846,7 +3846,7 @@ code = '''
     // and the tree should still work
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3868,7 +3868,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined
-    assert(lfs3.mtree.weight == (1 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (1 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3927,7 +3927,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &lfs3.mroot, NULL, 0) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -3994,7 +3994,7 @@ code = '''
     // and the tree should still work
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -4018,7 +4018,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -4079,7 +4079,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &lfs3.mroot, NULL, 0) => 0;
 
     // assert mdirs were unininlined and split
-    assert(lfs3.mtree.weight == (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (2 << lfs3.mbits));
     // assert mroot now has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -4098,7 +4098,7 @@ code = '''
     lfs3_mdir_commit(&lfs3, &mdir, NULL, 0) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -4165,7 +4165,7 @@ code = '''
     // and the tree should still work
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 
@@ -4196,7 +4196,7 @@ code = '''
     lfs3_mount(&lfs3, LFS3_M_RDWR | M_FLAGS, CFG) => 0;
 
     // assert mdir was split correctly
-    assert(lfs3.mtree.weight == (3 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight == (3 << lfs3.mbits));
     // assert mroot still has no entries
     assert(lfs3.mroot.r.weight == 0);
 

tests/test_trvs.toml

@@ -3446,7 +3446,7 @@ code = '''
 
     // create enough files for mroot to split
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "uloborus%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -3566,7 +3566,7 @@ code = '''
 
     // create enough files for mroot to split
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "uloborus%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -3694,7 +3694,7 @@ code = '''
 
     // create enough files for mroot to split
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "uloborus%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4222,7 +4222,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "tarantula%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4232,8 +4232,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "xnotata%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4258,8 +4258,8 @@ code = '''
 
     // create enough files for mdir to split again
     i = 0;
-    orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "vulsor%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4398,7 +4398,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "tarantula%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4408,8 +4408,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "xnotata%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4458,8 +4458,8 @@ code = '''
 
     // create enough files for mdir to split again
     i = 0;
-    orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "vulsor%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4581,7 +4581,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "tarantula%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4591,8 +4591,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "xnotata%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4646,8 +4646,8 @@ code = '''
 
     // create enough files for mdir to split again
     i = 0;
-    orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "vulsor%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4758,7 +4758,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "tarantula%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4768,8 +4768,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "xnotata%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4932,7 +4932,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "tarantula%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -4942,8 +4942,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "xnotata%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -5124,7 +5124,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "tarantula%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -5134,8 +5134,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "xnotata%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -5304,7 +5304,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "tarantula%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -5314,8 +5314,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "xnotata%03x", i);
         lfs3_file_open(&lfs3, &file, name,
@@ -5841,7 +5841,7 @@ code = '''
     lfs3_size_t i = 0;
     while (true) {
         // we should not have split yet
-        assert(lfs3.mtree.weight == 0);
+        assert(lfs3.mtree.r.weight == 0);
         // we need internals to check this
         lfs3_ssize_t estimate = lfs3_mdir_estimate__(&lfs3,
                 &file1.b.h.mdir, -1, -1,
@@ -6011,7 +6011,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "hydroid%03x", i);
         lfs3_file_t file;
@@ -6022,8 +6022,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "medusa%03x", i);
         lfs3_file_t file;
@@ -6246,7 +6246,7 @@ code = '''
 
     // create enough files for mroot to split twice
     lfs3_size_t i = 0;
-    while (lfs3.mtree.weight == 0) {
+    while (lfs3.mtree.r.weight == 0) {
         char name[256];
         sprintf(name, "hydroid%03x", i);
         lfs3_file_t file;
@@ -6257,8 +6257,8 @@ code = '''
     }
 
     i = 0;
-    lfs3_size_t orig = lfs3.mtree.weight;
-    while (lfs3.mtree.weight == orig) {
+    lfs3_size_t orig = lfs3.mtree.r.weight;
+    while (lfs3.mtree.r.weight == orig) {
         char name[256];
         sprintf(name, "polyp%03x", i);
         lfs3_file_t file;
@@ -6270,10 +6270,10 @@ code = '''
 
     // create enough files to both compact and split
     i = 0;
-    orig = lfs3.mtree.weight;
+    orig = lfs3.mtree.r.weight;
     while (true) {
         // we should not have split yet
-        assert(lfs3.mtree.weight == orig);
+        assert(lfs3.mtree.r.weight == orig);
         // we need internals to check this
         lfs3_ssize_t estimate = lfs3_mdir_estimate__(&lfs3,
                 &file2.b.h.mdir, -1, -1,
@@ -6535,7 +6535,7 @@ code = '''
     assert(!(lfs3.flags & LFS3_I_MKCONSISTENT));
 
     // which means there shouldn't be that many files left
-    assert(lfs3.mtree.weight <= (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight <= (2 << lfs3.mbits));
     assert(file1.b.h.mdir.r.weight <= 3);
     assert(file2.b.h.mdir.r.weight <= 3);
 
@@ -6844,7 +6844,7 @@ code = '''
     assert(!(lfs3.flags & LFS3_I_MKCONSISTENT));
 
     // which means there shouldn't be that many files left
-    assert(lfs3.mtree.weight <= (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight <= (2 << lfs3.mbits));
     assert(file1.b.h.mdir.r.weight <= 3);
     assert(file2.b.h.mdir.r.weight <= 3);
 
@@ -7008,7 +7008,7 @@ code = '''
     assert(!(lfs3.flags & LFS3_I_MKCONSISTENT));
 
     // which means there shouldn't be that many files left
-    assert(lfs3.mtree.weight <= (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight <= (2 << lfs3.mbits));
     assert(file1.b.h.mdir.r.weight <= 3);
     assert(file2.b.h.mdir.r.weight <= 3);
 
@@ -7181,7 +7181,7 @@ code = '''
     assert(!(lfs3.flags & LFS3_I_MKCONSISTENT));
 
     // which means there shouldn't be that many files left
-    assert(lfs3.mtree.weight <= (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight <= (2 << lfs3.mbits));
     assert(file1.b.h.mdir.r.weight <= 3);
     assert(file2.b.h.mdir.r.weight <= 3);
 
@@ -7354,7 +7354,7 @@ code = '''
     assert(!(lfs3.flags & LFS3_I_MKCONSISTENT));
 
     // which means there shouldn't be that many files left
-    assert(lfs3.mtree.weight <= (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight <= (2 << lfs3.mbits));
     assert(file1.b.h.mdir.r.weight <= 3);
     assert(file2.b.h.mdir.r.weight <= 3);
 
@@ -7523,7 +7523,7 @@ code = '''
     assert(!(lfs3.flags & LFS3_I_MKCONSISTENT));
 
     // which means there shouldn't be that many files left
-    assert(lfs3.mtree.weight <= (2 << lfs3.mbits));
+    assert(lfs3.mtree.r.weight <= (2 << lfs3.mbits));
     assert(file1.b.h.mdir.r.weight <= 3);
     assert(file2.b.h.mdir.r.weight <= 3);