preerase: Added test_mount_t_preerase, fixed several more bugs

- Fixed lfs3_alloc_cansyncgbmap ignoring known window changes.

  Being able to just call lfs3_btree_cmp(b, b_p) would be nice, but this
  ignores known window changes!

  Fixed by comparing the on-disk encoding, which is heavy-handed, but
  probably the safest approach.

  lfs3_alloc_cansyncgbmap will probably never be on the stack hot-path,
  and the added code is roughly one function call. The main cost is
  CPU-cycles, but fortunately(?) that's not something we really care
  about?

- Fixed lfs3_allocclaim accidentally returning lfs3_mdir_commit's return
  value instead of the allocated block!

  Probably caused by a copy-paste, resulted in lfs3_allocclaim returning
  block 0, which is really not good!

- Fixed assert typo in lfs3_trv_open where we assert REVPERTURB in flags
  instead of lfs3->flags.

Code changes:

                    code          stack          ctx
  before:          35260           2136          660
  after:           35260 (+0.0%)   2136 (+0.0%)  660 (+0.0%)

                    code          stack          ctx
  gbmap before:    38560           2144          776
  gbmap after:     38616 (+0.1%)   2144 (+0.0%)  776 (+0.0%)

                    code          stack          ctx
  preerase before: 39168           2168          796
  preerase after:  39232 (+0.2%)   2168 (+0.0%)  796 (+0.0%)

lfs3.c

@@ -10868,7 +10868,15 @@ static inline bool lfs3_alloc_canpreerase(const lfs3_t *lfs3) {
 // is gbmap out-of-sync with disk?
 #if !defined(LFS3_RDONLY) && defined(LFS3_GBMAP)
 static inline bool lfs3_alloc_cansyncgbmap(const lfs3_t *lfs3) {
-    return lfs3_btree_cmp(&lfs3->gbmap.b, &lfs3->gbmap.b_p) != 0;
+    // do we even have a gbmap?
+    if (!lfs3_f_isgbmap(lfs3->flags)) {
+        return false;
+    }
+
+    // just compare the on-disk encoding
+    uint8_t gbmap_[LFS3_GBMAP_DSIZE];
+    lfs3_data_fromgbmap(&lfs3->gbmap, gbmap_);
+    return memcmp(gbmap_, lfs3->gbmap_p, LFS3_GBMAP_DSIZE) != 0;
 }
 #endif
 
@@ -11311,7 +11319,10 @@ static lfs3_sblock_t lfs3_allocclaim(lfs3_t *lfs3, lfs3_mdir_t *mdir,
     if (lfs3_ecksum_isecksum(&ecksum_)) {
         LFS3_ASSERT(lfs3_alloc_cansyncgbmap(lfs3));
         // lfs3_mdir_commit implicitly commits any pending gbmap state
-        return lfs3_mdir_commit(lfs3, mdir, LFS3_RATTRS(LFS3_RATTR_NULL));
+        int err = lfs3_mdir_commit(lfs3, mdir, LFS3_RATTRS(LFS3_RATTR_NULL));
+        if (err) {
+            return err;
+        }
     }
     #endif
 
@@ -17091,7 +17102,8 @@ int lfs3_trv_open(lfs3_t *lfs3, lfs3_trv_t *trv, uint32_t flags) {
     // we can't use preerased blocks without revperturb, so this is
     // likely a mistake
     #if !defined(LFS3_RDONLY) && defined(LFS3_PREERASE)
-    LFS3_ASSERT(lfs3_m_isrevperturb(flags) || !lfs3_t_ispreerase(flags));
+    LFS3_ASSERT(lfs3_m_isrevperturb(lfs3->flags)
+            || !lfs3_t_ispreerase(flags));
     #endif
 
     // setup traversal state

tests/test_gc.toml

@@ -1853,9 +1853,19 @@ code = '''
     lfs3_t lfs3;
     lfs3_format(&lfs3,
             LFS3_F_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_F_REVPERTURB, -1)
+                    : 0)
                 | ((GBMAP) ? LFS3_IFDEF_GBMAP(LFS3_F_GBMAP, -1) : 0),
             CFG) => 0;
-    lfs3_mount(&lfs3, LFS3_M_RDWR, CFG) => 0;
+    lfs3_mount(&lfs3,
+            LFS3_M_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                    : 0),
+            CFG) => 0;
 
     // create an interesting filesystem
     uint32_t prng = 42;
@@ -1877,13 +1887,22 @@ code = '''
 
     // remount to reset flags
     lfs3_unmount(&lfs3) => 0;
-    lfs3_mount(&lfs3, LFS3_M_RDWR, CFG) => 0;
+    lfs3_mount(&lfs3,
+            LFS3_M_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                    : 0),
+            CFG) => 0;
 
     // check that flags were reset
     struct lfs3_fsinfo fsinfo;
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | LFS3_I_MKCONSISTENT
                 | ((!GBMAP || (fsinfo.flags & LFS3_I_LOOKAHEAD))
@@ -1982,7 +2001,14 @@ code = '''
     // remount with gc flags
     } else if (AFTER == 3) {
         lfs3_unmount(&lfs3) => 0;
-        lfs3_mount(&lfs3, LFS3_M_RDWR | GC_FLAGS, CFG) => 0;
+        lfs3_mount(&lfs3,
+                LFS3_M_RDWR
+                    // note preerasing needs revperturb
+                    | ((PREERASE)
+                        ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                        : 0)
+                    | GC_FLAGS,
+                CFG) => 0;
 
     } else {
         assert(false);
@@ -1991,7 +2017,10 @@ code = '''
     // did these clear the right flags?
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                 | ((!LOOKAHEAD
@@ -2054,9 +2083,19 @@ code = '''
     lfs3_t lfs3;
     lfs3_format(&lfs3,
             LFS3_F_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_F_REVPERTURB, -1)
+                    : 0)
                 | ((GBMAP) ? LFS3_IFDEF_GBMAP(LFS3_F_GBMAP, -1) : 0),
             CFG) => 0;
-    lfs3_mount(&lfs3, LFS3_M_RDWR, CFG) => 0;
+    lfs3_mount(&lfs3,
+            LFS3_M_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                    : 0),
+            CFG) => 0;
 
     // create an interesting filesystem
     uint32_t prng = 42;
@@ -2078,13 +2117,22 @@ code = '''
 
     // remount to reset flags
     lfs3_unmount(&lfs3) => 0;
-    lfs3_mount(&lfs3, LFS3_M_RDWR, CFG) => 0;
+    lfs3_mount(&lfs3,
+            LFS3_M_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                    : 0),
+            CFG) => 0;
 
     // check that flags were reset
     struct lfs3_fsinfo fsinfo;
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | LFS3_I_MKCONSISTENT
                 | ((!GBMAP || (fsinfo.flags & LFS3_I_LOOKAHEAD))
@@ -2183,7 +2231,14 @@ code = '''
     // remount with gc flags
     } else if (AFTER == 3) {
         lfs3_unmount(&lfs3) => 0;
-        lfs3_mount(&lfs3, LFS3_M_RDWR | GC_FLAGS, CFG) => 0;
+        lfs3_mount(&lfs3,
+                LFS3_M_RDWR
+                    // note preerasing needs revperturb
+                    | ((PREERASE)
+                        ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                        : 0)
+                    | GC_FLAGS,
+                CFG) => 0;
 
     } else {
         assert(false);
@@ -2192,7 +2247,10 @@ code = '''
     // did these clear the right flags?
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                 | ((!LOOKAHEAD
@@ -2214,7 +2272,10 @@ code = '''
     // check that flags were reset
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | LFS3_I_MKCONSISTENT
                 | ((!GBMAP || (fsinfo.flags & LFS3_I_LOOKAHEAD))
@@ -2317,7 +2378,14 @@ code = '''
     // remount with gc flags
     } else if (AFTER == 3) {
         lfs3_unmount(&lfs3) => 0;
-        lfs3_mount(&lfs3, LFS3_M_RDWR | GC_FLAGS, CFG) => 0;
+        lfs3_mount(&lfs3,
+                LFS3_M_RDWR
+                    // note preerasing needs revperturb
+                    | ((PREERASE)
+                        ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                        : 0)
+                    | GC_FLAGS,
+                CFG) => 0;
 
     } else {
         assert(false);
@@ -2326,7 +2394,10 @@ code = '''
     // did these clear the right flags?
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                 | ((!LOOKAHEAD

tests/test_mount.toml

@@ -47,6 +47,7 @@ if = [
     '!RDONLY || !LOOKAHEAD',
     'LFS3_IFDEF_PREERASE(true, !PREERASE)',
     'GBMAP || !PREERASE',
+    'REVPERTURB || !PREERASE',
     '!RDONLY || !PREERASE',
     '!RDONLY || !COMPACT',
 ]
@@ -140,6 +141,7 @@ if = [
     'LFS3_IFDEF_CKDATACKSUMS(true, !CKDATACKSUMS)',
     'LFS3_IFDEF_PREERASE(true, !PREERASE)',
     'GBMAP || !PREERASE',
+    'REVPERTURB || !PREERASE',
 ]
 code = '''
     lfs3_t lfs3;
@@ -259,7 +261,7 @@ code = '''
 
     uint32_t prng = 42;
 
-    // gbmap is persistant, so by default we _don't_ need a gbmap scan
+    // gbmap is persistent, so by default we _don't_ need a gbmap scan
     lfs3_mount(&lfs3, LFS3_M_RDWR, CFG) => 0;
     struct lfs3_fsinfo fsinfo;
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
@@ -320,6 +322,112 @@ code = '''
     lfs3_unmount(&lfs3) => 0;
 '''
 
+[cases.test_mount_t_preerase]
+defines.LOOKAHEAD = [false, true]
+defines.CKMETA = [false, true]
+defines.CKDATA = [false, true]
+defines.SIZE = [
+    'BLOCK_SIZE/2',
+    'BLOCK_SIZE',
+    '2*BLOCK_SIZE',
+    '8*BLOCK_SIZE',
+]
+# REMOUNT=0 => don't remount
+# REMOUNT=1 => remount with preerase
+# REMOUNT=2 => remount without preerase
+defines.REMOUNT = [0, 1, 2]
+ifdef = 'LFS3_GBMAP && LFS3_REVPERTURB && LFS3_PREERASE'
+if = 'GBMAP'
+code = '''
+    lfs3_t lfs3;
+    lfs3_format(&lfs3,
+            LFS3_F_RDWR
+                // note preerasing needs revperturb
+                | LFS3_F_REVPERTURB
+                | ((GBMAP) ? LFS3_IFDEF_GBMAP(LFS3_F_GBMAP, -1) : 0),
+            CFG) => 0;
+
+    uint32_t prng = 42;
+
+    // by default, we don't preerase
+    lfs3_mount(&lfs3,
+            LFS3_M_RDWR
+                // note preerasing needs revperturb
+                | LFS3_M_REVPERTURB,
+            CFG) => 0;
+    struct lfs3_fsinfo fsinfo;
+    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
+    assert(fsinfo.flags == (
+            LFS3_I_REVPERTURB
+                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
+                | LFS3_I_MKCONSISTENT
+                | LFS3_I_PREERASE
+                | LFS3_I_COMPACT
+                | LFS3_I_CKMETA
+                | LFS3_I_CKDATA
+                | ((GBMAP) ? LFS3_IFDEF_GBMAP(LFS3_I_GBMAP, -1) : 0)));
+    lfs3_unmount(&lfs3) => 0;
+
+    // with LFS3_M_PREERASE, mount preerases a configurable number of
+    // blocks
+    lfs3_mount(&lfs3,
+            LFS3_M_RDWR
+                // note preerasing needs revperturb
+                | LFS3_M_REVPERTURB
+                | ((LOOKAHEAD) ? LFS3_M_LOOKAHEAD : 0)
+                | LFS3_M_PREERASE,
+            CFG) => 0;
+    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
+    assert(fsinfo.flags == (
+            LFS3_I_REVPERTURB
+                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
+                | LFS3_I_MKCONSISTENT
+                | ((!LOOKAHEAD) ? LFS3_I_LOOKAHEAD : 0)
+                | LFS3_I_COMPACT
+                | LFS3_I_CKMETA
+                | LFS3_I_CKDATA
+                | ((GBMAP) ? LFS3_IFDEF_GBMAP(LFS3_I_GBMAP, -1) : 0)));
+
+    // remount?
+    //
+    // preerasing is persistent, but our preeraser doesn't know the
+    // gbmap state until triggered at least once
+    if (REMOUNT) {
+        lfs3_unmount(&lfs3) => 0;
+        lfs3_mount(&lfs3,
+                LFS3_M_RDWR
+                    // note preerasing needs revperturb
+                    | LFS3_M_REVPERTURB
+                    | ((REMOUNT == 1 && LOOKAHEAD) ? LFS3_M_LOOKAHEAD : 0)
+                    | ((REMOUNT == 1) ? LFS3_M_PREERASE : 0),
+                CFG) => 0;
+        lfs3_fs_stat(&lfs3, &fsinfo) => 0;
+        assert(fsinfo.flags == (
+                LFS3_I_REVPERTURB
+                    | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
+                    | LFS3_I_MKCONSISTENT
+                    | ((!LOOKAHEAD) ? LFS3_I_LOOKAHEAD : 0)
+                    | ((REMOUNT != 1) ? LFS3_I_PREERASE : 0)
+                    | LFS3_I_COMPACT
+                    | LFS3_I_CKMETA
+                    | LFS3_I_CKDATA
+                    | ((GBMAP) ? LFS3_IFDEF_GBMAP(LFS3_I_GBMAP, -1) : 0)));
+    }
+
+    // write to a file to try to make sure nothing obvious is broken
+    lfs3_file_t file;
+    lfs3_file_open(&lfs3, &file, "jellyfish",
+            LFS3_O_WRONLY | LFS3_O_CREAT | LFS3_O_EXCL) => 0;
+    uint8_t wbuf[SIZE];
+    for (lfs3_size_t j = 0; j < SIZE; j++) {
+        wbuf[j] = 'a' + (TEST_PRNG(&prng) % 26);
+    }
+    lfs3_file_write(&lfs3, &file, wbuf, SIZE) => SIZE;
+    lfs3_file_close(&lfs3, &file) => 0;
+
+    lfs3_unmount(&lfs3) => 0;
+'''
+
 [cases.test_mount_t_compact]
 defines.LOOKAHEAD = [false, true]
 defines.CKMETA = [false, true]

tests/test_trvs.toml

@@ -1772,15 +1772,28 @@ code = '''
     lfs3_t lfs3;
     lfs3_format(&lfs3,
             LFS3_F_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_F_REVPERTURB, -1)
+                    : 0)
                 | ((GBMAP) ? LFS3_IFDEF_GBMAP(LFS3_F_GBMAP, -1) : 0),
             CFG) => 0;
-    lfs3_mount(&lfs3, LFS3_M_RDWR, CFG) => 0;
+    lfs3_mount(&lfs3,
+            LFS3_M_RDWR
+                // note preerasing needs revperturb
+                | ((PREERASE)
+                    ? LFS3_IFDEF_PREERASE(LFS3_M_REVPERTURB, -1)
+                    : 0),
+            CFG) => 0;
 
     // check flags before
     struct lfs3_fsinfo fsinfo;
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | LFS3_I_MKCONSISTENT
                 | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
@@ -1821,7 +1834,10 @@ code = '''
     // check flags after
     lfs3_fs_stat(&lfs3, &fsinfo) => 0;
     assert(fsinfo.flags == (
-            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
+            LFS3_IFYES_REVPERTURB(
+                    LFS3_I_REVPERTURB,
+                    (PREERASE) ? LFS3_I_REVPERTURB : 0,
+                    0)
                 | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                 | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                 | ((!LOOKAHEAD && !GBMAP) ? LFS3_I_LOOKAHEAD : 0)