Added REVPERTURB, reworked how we handle revision counts

The main change is adding LFS3_M_REVPERTURB, which will be necessary for preerase allocations, but I got distracted and ended up giving the revision count subsystem a bit of a refactor. Main changes: - Added LFS3_M_REVPERTURB, which ensures the leading bit in the revision count changes after each allocation/relocation/compaction. This is generally optional, but will be required for preerase allocations. Our ecksum system is only reliable if we ensure at least one bit changes, otherwise the chance of ecksum collision is very high. The downside of LFS3_M_REVPERTURB is that we need to read the contents of the new block to figure out what the bit should change to. Probably a minimal cost in the system, but still a good reason to make the behavior optional. Does LFS3_M_REVPERTURB have any use outside of preerased allocation? I'm not sure. Maybe it has some niche use reducing the chance of bd ECC collisions? - Dropped LFS3_M_REVDBG, but adding low-effort debug bits that are always enabled. Making LFS3_M_REVDBG conditional was probably overkill. The flag checks probably cost more than the actual debug bits when enabled. Instead, replaced with a simpler, low-effort debug bit system, where we only set the debug bits during mdir allocation/relocation. These bits shouldn't change during normal compaction, but we _don't_ introduce debug bits if mounting a filesystem from a driver without these debug bits. - Restricted recycle counter to at most 20-bits to make space for things. This ensures perturb/debug bits don't get overwritten (though we really only care about perturb bits). 2^20 (~1M) recycles is probably enough for any device littlefs will run on, especially considering the recycle_count should probably be several orders of magnitude smaller than the device's expected erase cycles. Worst case this can always be increased in the future without backwards incompatible changes. The only hard requirement for revision counts is that the full 32-bits are comparable. - Simplified lfs3_rev_inc and friends, and moved most of the disk-dependent revision count stuff down into lfs3_rbyd appendrev. This deduplicates the messy revision count handling in lfs3_btree_commit_. Though note the implicit lfs3_rbyd_appendrev now defaults to writing the btree debug bits ('b'). A bit of a hack, but works for littlefs. Here's the resulting encoding: vvvv---- -------- -------- -ddddddd vvvvrrrr rrrrrr-- -------- -ddddddd vvvvrrrr rrrrrrnn nnnnnnnn pddddddd '-.''----.----''----.----' ^'--.--' '------|----------|------|---|---- 4-bit relocation revision '----------|------|---|---- recycle-bits recycle counter '------|---|---- pseudorandom noise (if revnoise) '---|---- perturb bit (if revperturb) '---- low-effort debug bits 11-1--- - h = mroot anchor 11-11-1 - m = mdir 11---1- - b = btree node Note we store revision counts as le32s, so the perturb bit should end up as the leading bit in the first byte. Costs a bit more code (mostly because the debug bits are now unconditional, even if low-effort), but simplifies the codebase: code stack ctx before: 35124 2136 660 after: 35144 (+0.1%) 2136 (+0.0%) 660 (+0.0%) after+yesrevperturb: 35192 (+0.2%) 2136 (+0.0%) 660 (+0.0%) code stack ctx gbmap+np before: 38252 2144 776 gbmap+np after: 38272 (+0.1%) 2144 (+0.0%) 776 (+0.0%) gbmap+np after+yrp: 38328 (+0.2%) 2144 (+0.0%) 776 (+0.0%) code stack ctx gbmap+yp before: 38832 2168 796 gbmap+yp after: 38852 (+0.1%) 2168 (+0.0%) 796 (+0.0%) gbmap+yp after+yrp: 38908 (+0.2%) 2168 (+0.0%) 796 (+0.0%)
2025-12-29 16:50:04 -06:00
parent 2b1f2e3ca9
commit b3ab83d5b5
8 changed files with 220 additions and 320 deletions
@@ -3241,15 +3241,55 @@ static lfs3_stag_t lfs3_rbyd_lookup(lfs3_t *lfs3, const lfs3_rbyd_t *rbyd,
 // rbyd append operations


+// needed in lfs3_rbyd_appendrev
+static inline bool lfs3_m_isrevperturb(uint32_t flags);
+static inline bool lfs3_m_isrevnoise(uint32_t flags);
+
 // append a revision count
 //
-// this is optional, if not called revision count defaults to 0 (for btrees)
+// this is optional, if not called revision count defaults
+// to ~0 (+noise/perturb/debug, for btrees)
 #ifndef LFS3_RDONLY
-static int lfs3_rbyd_appendrev(lfs3_t *lfs3, lfs3_rbyd_t *rbyd, uint32_t rev) {
+static int lfs3_rbyd_appendrev(lfs3_t *lfs3, lfs3_rbyd_t *rbyd,
+        uint32_t rev) {
    // should only be called before any tags are written
    LFS3_ASSERT(rbyd->eoff == 0);
    LFS3_ASSERT(rbyd->cksum == 0);

+    // perturb first bit?
+    //
+    // this ensures at least one big changes in the new rbyd, and is
+    // necessary to invalidate any ecksums
+    #ifdef LFS3_REVPERTURB
+    if (lfs3_m_isrevperturb(lfs3->flags)) {
+        uint8_t e = 0;
+        int err = lfs3_bd_read(lfs3,
+                rbyd->blocks[0], 0, 0,
+                &e, 1);
+        if (err && err != LFS3_ERR_CORRUPT) {
+            return err;
+        }
+
+        // perturb!
+        rev = (rev & ~0x80) | (~e & 0x80);
+    }
+    #endif
+
+    // xor in pseudorandom noise?
+    //
+    // this reduces chance of checksum collisions due to filesystem
+    // bugs, but is otherwise unnecessary, note we really don't want
+    // this enabled during testing!
+    #ifdef LFS3_REVNOISE
+    if (lfs3_m_isrevnoise(lfs3->flags)) {
+        rev ^= ~(~((1 << (28-lfs3_smax(lfs3->recycle_bits, 0)))-1)
+                    | 0xff)
+                // we need to use gcksum_p because we have be in the
+                // middle of updating the gcksum
+                & lfs3->gcksum_p;
+    }
+    #endif
+
    // revision count stored as le32, we don't use a leb128 encoding as we
    // intentionally allow the revision count to overflow
    uint8_t rev_buf[sizeof(uint32_t)];
@@ -3578,7 +3618,9 @@ static int lfs3_rbyd_appendinit(lfs3_t *lfs3, lfs3_rbyd_t *rbyd) {

    // make sure every rbyd starts with a revision count
    if (rbyd->eoff == 0) {
-        int err = lfs3_rbyd_appendrev(lfs3, rbyd, 0);
+        // we only fallback to this when updating btrees, so default to
+        // btree debug bits, they're called low-effort after all
+        int err = lfs3_rbyd_appendrev(lfs3, rbyd, 'b');
        if (err) {
            return err;
        }
@@ -5814,18 +5856,6 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
            return err;
        }

-        #if defined(LFS3_REVDBG) || defined(LFS3_REVNOISE)
-        // append a revision count?
-        err = lfs3_rbyd_appendrev(lfs3, child_, lfs3_rev_btree(lfs3));
-        if (err) {
-            // bad prog? try another block
-            if (err == LFS3_ERR_CORRUPT) {
-                goto relocate;
-            }
-            return err;
-        }
-        #endif
-
        // try to compact
        err = lfs3_rbyd_compact(lfs3, child_, &child, -1, -1);
        if (err) {
@@ -5864,18 +5894,6 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
            return err;
        }

-        #if defined(LFS3_REVDBG) || defined(LFS3_REVNOISE)
-        // append a revision count?
-        err = lfs3_rbyd_appendrev(lfs3, child_, lfs3_rev_btree(lfs3));
-        if (err) {
-            // bad prog? try another block
-            if (err == LFS3_ERR_CORRUPT) {
-                goto split_relocate_l;
-            }
-            return err;
-        }
-        #endif
-
        // copy over tags < split_rid
        err = lfs3_rbyd_compact(lfs3, child_, &child, -1, split_rid);
        if (err) {
@@ -5920,18 +5938,6 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
            return err;
        }

-        #if defined(LFS3_REVDBG) || defined(LFS3_REVNOISE)
-        // append a revision count?
-        err = lfs3_rbyd_appendrev(lfs3, &sibling, lfs3_rev_btree(lfs3));
-        if (err) {
-            // bad prog? try another block
-            if (err == LFS3_ERR_CORRUPT) {
-                goto split_relocate_r;
-            }
-            return err;
-        }
-        #endif
-
        // copy over tags >= split_rid
        err = lfs3_rbyd_compact(lfs3, &sibling, &child, split_rid, -1);
        if (err) {
@@ -6048,18 +6054,6 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
            return err;
        }

-        #if defined(LFS3_REVDBG) || defined(LFS3_REVNOISE)
-        // append a revision count?
-        err = lfs3_rbyd_appendrev(lfs3, child_, lfs3_rev_btree(lfs3));
-        if (err) {
-            // bad prog? try another block
-            if (err == LFS3_ERR_CORRUPT) {
-                goto merge_relocate;
-            }
-            return err;
-        }
-        #endif
-
        // merge the siblings together
        err = lfs3_rbyd_appendcompactrbyd(lfs3, child_, &child, -1, -1);
        if (err) {
@@ -6154,18 +6148,6 @@ relocate:;
        return err;
    }

-    #if defined(LFS3_REVDBG) || defined(LFS3_REVNOISE)
-    // append a revision count?
-    err = lfs3_rbyd_appendrev(lfs3, btree_, lfs3_rev_btree(lfs3));
-    if (err) {
-        // bad prog? try another block
-        if (err == LFS3_ERR_CORRUPT) {
-            goto relocate;
-        }
-        return err;
-    }
-    #endif
-
    // bshrubs may call this just to migrate rattrs to a btree
    if (lfs3_rbyd_isshrub(&btree->r)) {
        err = lfs3_rbyd_compact(lfs3, btree_, &btree->r, -1, -1);
@@ -7294,13 +7276,13 @@ static inline bool lfs3_m_isrdonly(uint32_t flags) {
    #endif
 }

-#ifdef LFS3_REVDBG
-static inline bool lfs3_m_isrevdbg(uint32_t flags) {
+#ifdef LFS3_REVPERTURB
+static inline bool lfs3_m_isrevperturb(uint32_t flags) {
    (void)flags;
-    #ifdef LFS3_YES_REVDBG
+    #ifdef LFS3_YES_REVPERTURB
    return true;
    #else
-    return flags & LFS3_M_REVDBG;
+    return flags & LFS3_M_REVPERTURB;
    #endif
 }
 #endif
@@ -7773,89 +7755,32 @@ static int lfs3_fs_consumegdelta(lfs3_t *lfs3, const lfs3_mdir_t *mdir) {

 /// Revision count things ///

-// in mdirs, our revision count is broken down into 1-4 parts:
+// note! the only strict requirement for revision counts is that the
+// most recent block has the most recent revision count, all drivers
+// must be ok with _simple_ 32-bit counters!
 //
-//   vvvv---- -------- -------- --------
-//   vvvvrrrr rrrrrr-- -------- --------
-//   vvvvrrrr rrrrrrnn nnnnnnnn nnnnnnnn
-//   vvvvrrrr rrrrrrnn nnnnnnnn dddddddd
-//   '-.''----.----''----.- - - '---.--'
-//     '------|----------|----------|---- 4-bit relocation revision
-//            '----------|----------|---- recycle-bits recycle counter
-//                       '----------|---- pseudorandom noise (if revnoise)
-//                                  '---- h, i, m, or b (if revdbg)
-//                              -11-1---  - h = mroot anchor
-//                              -11-1--1  - i = mroot
-//                              -11-11-1  - m = mdir
-//                              -11---1-  - b = btree node
+// with that said, this driver crams a few more _optional_ features
+// into those 32-bits:
+//
+//   vvvv---- -------- -------- -ddddddd
+//   vvvvrrrr rrrrrr-- -------- -ddddddd
+//   vvvvrrrr rrrrrrnn nnnnnnnn pddddddd
+//   '-.''----.----''----.----' ^'--.--'
+//     '------|----------|------|---|---- 4-bit relocation revision
+//            '----------|------|---|---- recycle-bits recycle counter
+//                       '------|---|---- pseudorandom noise (if revnoise)
+//                              '---|---- perturb bit (if revperturb)
+//                                  '---- low-effort debug bits
+//                               11-1---  - h = mroot anchor
+//                               11-11-1  - m = mdir
+//                               11---1-  - b = btree node
 //

-// needed in lfs3_rev_init
-static inline bool lfs3_mdir_ismrootanchor(const lfs3_mdir_t *mdir);
-static inline int lfs3_mdir_cmp(const lfs3_mdir_t *a, const lfs3_mdir_t *b);
-
 #ifndef LFS3_RDONLY
-static inline uint32_t lfs3_rev_init(lfs3_t *lfs3, const lfs3_mdir_t *mdir,
-        uint32_t rev) {
+static inline uint32_t lfs3_rev_init(lfs3_t *lfs3, uint32_t rev) {
    (void)lfs3;
-    (void)mdir;
-    // we really only care about the top revision bits here
-    rev &= ~((1 << 28)-1);
-    // increment revision
-    rev += 1 << 28;
-    // xor in pseudorandom noise?
-    #ifdef LFS3_REVNOISE
-    if (lfs3_m_isrevnoise(lfs3->flags)) {
-        rev ^= ((1 << (28-lfs3_smax(lfs3->recycle_bits, 0)))-1)
-                // we need to use gcksum_p because we have be in the
-                // middle of updating the gcksum
-                & lfs3->gcksum_p;
-    }
-    #endif
-    // include debug bits?
-    #ifdef LFS3_REVDBG
-    if (lfs3_m_isrevdbg(lfs3->flags)) {
-        uint32_t mask = (1 << (28-lfs3_smax(lfs3->recycle_bits, 0)))-1;
-        // mroot anchor?
-        if (lfs3_mdir_ismrootanchor(mdir)) {
-            rev = (rev & ~(mask & 0xff)) | (mask & 0x68);
-        // mroot?
-        } else if (mdir->mid <= -1
-                || lfs3_mdir_cmp(mdir, &lfs3->mroot) == 0) {
-            rev = (rev & ~(mask & 0xff)) | (mask & 0x69);
-        // mdir?
-        } else {
-            rev = (rev & ~(mask & 0xff)) | (mask & 0x6d);
-        }
-    }
-    #endif
-    return rev;
-}
-#endif
-
-// btrees don't normally need revision counts, but we make use of them
-// if revdbg or revnoise is enabled
-#ifndef LFS3_RDONLY
-static inline uint32_t lfs3_rev_btree(lfs3_t *lfs3) {
-    (void)lfs3;
-    uint32_t rev = 0;
-    // xor in pseudorandom noise?
-    #ifdef LFS3_REVNOISE
-    if (lfs3_m_isrevnoise(lfs3->flags)) {
-        // keep the top nibble zero
-        rev ^= 0x0fffffff
-                // we need to use gcksum_p because we have be in the
-                // middle of updating the gcksum
-                & lfs3->gcksum_p;
-    }
-    #endif
-    // include debug bits?
-    #ifdef LFS3_REVDBG
-    if (lfs3_m_isrevdbg(lfs3->flags)) {
-        rev = (rev & ~0xff) | 0x62;
-    }
-    #endif
-    return rev;
+    // we really only care about the top revision bits here, increment
+    return (rev & ~((1 << 28)-1)) + (1 << 28);
 }
 #endif

@@ -7872,38 +7797,9 @@ static inline bool lfs3_rev_needsrelocation(lfs3_t *lfs3, uint32_t rev) {
 #endif

 #ifndef LFS3_RDONLY
-static inline uint32_t lfs3_rev_inc(lfs3_t *lfs3, const lfs3_mdir_t *mdir,
-        uint32_t rev) {
-    (void)mdir;
+static inline uint32_t lfs3_rev_inc(lfs3_t *lfs3, uint32_t rev) {
    // increment recycle counter/revision
-    rev += 1 << (28-lfs3_smax(lfs3->recycle_bits, 0));
-    // xor in pseudorandom noise?
-    #ifdef LFS3_REVNOISE
-    if (lfs3_m_isrevnoise(lfs3->flags)) {
-        rev ^= ((1 << (28-lfs3_smax(lfs3->recycle_bits, 0)))-1)
-                // we need to use gcksum_p because we have be in the
-                // middle of updating the gcksum
-                & lfs3->gcksum_p;
-    }
-    #endif
-    // include debug bits?
-    #ifdef LFS3_REVDBG
-    if (lfs3_m_isrevdbg(lfs3->flags)) {
-        uint32_t mask = (1 << (28-lfs3_smax(lfs3->recycle_bits, 0)))-1;
-        // mroot anchor?
-        if (lfs3_mdir_ismrootanchor(mdir)) {
-            rev = (rev & ~(mask & 0xff)) | (mask & 0x68);
-        // mroot?
-        } else if (mdir->mid <= -1
-                || lfs3_mdir_cmp(mdir, &lfs3->mroot) == 0) {
-            rev = (rev & ~(mask & 0xff)) | (mask & 0x69);
-        // mdir?
-        } else {
-            rev = (rev & ~(mask & 0xff)) | (mask & 0x6d);
-        }
-    }
-    #endif
-    return rev;
+    return rev + (1 << (28-lfs3_smax(lfs3->recycle_bits, 0)));
 }
 #endif

@@ -8190,8 +8086,8 @@ static int lfs3_mdir_alloc___(lfs3_t *lfs3, lfs3_mdir_t *mdir,
    }
    // note we allow corrupt errors here, as long as they are consistent
    rev = (err != LFS3_ERR_CORRUPT) ? lfs3_fromle32(&rev) : 0;
-    // reset recycle bits in revision count and increment
-    rev = lfs3_rev_init(lfs3, mdir, rev);
+    // reset recycle bits in revision count, add low-effort debug bits
+    rev = lfs3_rev_init(lfs3, rev) | 'm';

 relocate:;
    // allocate another block with an erase
@@ -8236,8 +8132,6 @@ static int lfs3_mdir_swap___(lfs3_t *lfs3, lfs3_mdir_t *mdir_,
    }
    // note we allow corrupt errors here, as long as they are consistent
    rev = (err != LFS3_ERR_CORRUPT) ? lfs3_fromle32(&rev) : 0;
-    // increment our revision count
-    rev = lfs3_rev_inc(lfs3, mdir_, rev);

    // decide if we need to relocate
    if (!force && lfs3_rev_needsrelocation(lfs3, rev)) {
@@ -8259,7 +8153,8 @@ static int lfs3_mdir_swap___(lfs3_t *lfs3, lfs3_mdir_t *mdir_,
    }

    // increment our revision count and write it to our rbyd
-    err = lfs3_rbyd_appendrev(lfs3, &mdir_->r, rev);
+    err = lfs3_rbyd_appendrev(lfs3, &mdir_->r,
+            lfs3_rev_inc(lfs3, rev));
    if (err) {
        return err;
    }
@@ -15098,7 +14993,7 @@ static int lfs3_init(lfs3_t *lfs3, uint32_t flags,
                | LFS3_M_RDONLY
                | LFS3_M_FLUSH
                | LFS3_M_SYNC
-                | LFS3_IFDEF_REVDBG(LFS3_M_REVDBG, 0)
+                | LFS3_IFDEF_REVPERTURB(LFS3_M_REVPERTURB, 0)
                | LFS3_IFDEF_REVNOISE(LFS3_M_REVNOISE, 0)
                | LFS3_IFDEF_CKPROGS(LFS3_M_CKPROGS, 0)
                | LFS3_IFDEF_CKFETCHES(LFS3_M_CKFETCHES, 0)
@@ -15266,6 +15161,10 @@ static int lfs3_init(lfs3_t *lfs3, uint32_t flags,
        lfs3->recycle_bits = lfs3_min(
                lfs3_nlog2(2*(lfs3->cfg->block_recycles+1)+1)-1,
                28);
+        // we're currently limited to 20-bits to keep space for
+        // perturb/low-effort debug bits, though this could be relaxed
+        // in the future
+        LFS3_ASSERT(lfs3->recycle_bits <= 20);
    } else {
        lfs3->recycle_bits = -1;
    }
@@ -15997,8 +15896,8 @@ int lfs3_mount(lfs3_t *lfs3, uint32_t flags,
    #ifdef LFS3_YES_SYNC
    flags |= LFS3_M_SYNC;
    #endif
-    #ifdef LFS3_YES_REVDBG
-    flags |= LFS3_M_REVDBG;
+    #ifdef LFS3_YES_REVPERTURB
+    flags |= LFS3_M_REVPERTURB;
    #endif
    #ifdef LFS3_YES_REVNOISE
    flags |= LFS3_M_REVNOISE;
@@ -16040,7 +15939,7 @@ int lfs3_mount(lfs3_t *lfs3, uint32_t flags,
                | LFS3_M_RDONLY
                | LFS3_M_FLUSH
                | LFS3_M_SYNC
-                | LFS3_IFDEF_REVDBG(LFS3_M_REVDBG, 0)
+                | LFS3_IFDEF_REVPERTURB(LFS3_M_REVPERTURB, 0)
                | LFS3_IFDEF_REVNOISE(LFS3_M_REVNOISE, 0)
                | LFS3_IFDEF_CKPROGS(LFS3_M_CKPROGS, 0)
                | LFS3_IFDEF_CKFETCHES(LFS3_M_CKFETCHES, 0)
@@ -16072,7 +15971,7 @@ int lfs3_mount(lfs3_t *lfs3, uint32_t flags,
                    | LFS3_M_RDONLY
                    | LFS3_M_FLUSH
                    | LFS3_M_SYNC
-                    | LFS3_IFDEF_REVDBG(LFS3_M_REVDBG, 0)
+                    | LFS3_IFDEF_REVPERTURB(LFS3_M_REVPERTURB, 0)
                    | LFS3_IFDEF_REVNOISE(LFS3_M_REVNOISE, 0)
                    | LFS3_IFDEF_CKPROGS(LFS3_M_CKPROGS, 0)
                    | LFS3_IFDEF_CKFETCHES(LFS3_M_CKFETCHES, 0)
@@ -16172,14 +16071,6 @@ static int lfs3_formatgbmap(lfs3_t *lfs3) {
        return err;
    }

-    #if defined(LFS3_REVDBG) || defined(LFS3_REVNOISE)
-    // append a revision count?
-    err = lfs3_rbyd_appendrev(lfs3, &lfs3->gbmap.b.r, lfs3_rev_btree(lfs3));
-    if (err) {
-        return err;
-    }
-    #endif
-
    err = lfs3_rbyd_commit(lfs3, &lfs3->gbmap.b.r, 0, LFS3_RATTRS(
            // blocks 0..3 - in-use
            LFS3_RATTR(2, LFS3_TAG_BMINUSE, -2),
@@ -16228,7 +16119,7 @@ static int lfs3_formatinited(lfs3_t *lfs3) {

        // the initial revision count is arbitrary, but it's nice to have
        // something here to tell the initial mroot apart from btree nodes
-        // (rev=0), it's also useful for start with -1 and 0 in the upper
+        // (rev=0), it's also useful to start with -1 and 0 in the upper
        // bits to help test overflow/sequence comparison
        uint32_t rev = (((uint32_t)i-1) << 28)
                | (((1 << (28-lfs3_smax(lfs3->recycle_bits, 0)))-1)
@@ -16324,8 +16215,8 @@ int lfs3_format(lfs3_t *lfs3, uint32_t flags,
    #ifdef LFS3_YES_GBMAP
    flags |= LFS3_F_GBMAP;
    #endif
-    #ifdef LFS3_YES_REVDBG
-    flags |= LFS3_F_REVDBG;
+    #ifdef LFS3_YES_REVPERTURB
+    flags |= LFS3_F_REVPERTURB;
    #endif
    #ifdef LFS3_YES_REVNOISE
    flags |= LFS3_F_REVNOISE;
@@ -16365,7 +16256,7 @@ int lfs3_format(lfs3_t *lfs3, uint32_t flags,
    LFS3_ASSERT((flags & ~(
            LFS3_F_RDWR
                | LFS3_IFDEF_GBMAP(LFS3_F_GBMAP, 0)
-                | LFS3_IFDEF_REVDBG(LFS3_F_REVDBG, 0)
+                | LFS3_IFDEF_REVPERTURB(LFS3_F_REVPERTURB, 0)
                | LFS3_IFDEF_REVNOISE(LFS3_F_REVNOISE, 0)
                | LFS3_IFDEF_CKPROGS(LFS3_F_CKPROGS, 0)
                | LFS3_IFDEF_CKFETCHES(LFS3_F_CKFETCHES, 0)
@@ -16384,7 +16275,7 @@ int lfs3_format(lfs3_t *lfs3, uint32_t flags,
            flags & (
                LFS3_F_RDWR
                    | LFS3_IFDEF_GBMAP(LFS3_F_GBMAP, 0)
-                    | LFS3_IFDEF_REVDBG(LFS3_F_REVDBG, 0)
+                    | LFS3_IFDEF_REVPERTURB(LFS3_F_REVPERTURB, 0)
                    | LFS3_IFDEF_REVNOISE(LFS3_F_REVNOISE, 0)
                    | LFS3_IFDEF_CKPROGS(LFS3_F_CKPROGS, 0)
                    | LFS3_IFDEF_CKFETCHES(LFS3_F_CKFETCHES, 0)
@@ -16456,7 +16347,7 @@ int lfs3_fs_stat(lfs3_t *lfs3, struct lfs3_fsinfo *fsinfo) {
                LFS3_I_RDONLY
                    | LFS3_I_FLUSH
                    | LFS3_I_SYNC
-                    | LFS3_IFDEF_REVDBG(LFS3_I_REVDBG, 0)
+                    | LFS3_IFDEF_REVPERTURB(LFS3_I_REVPERTURB, 0)
                    | LFS3_IFDEF_REVNOISE(LFS3_I_REVNOISE, 0)
                    | LFS3_IFDEF_CKPROGS(LFS3_I_CKPROGS, 0)
                    | LFS3_IFDEF_CKFETCHES(LFS3_I_CKFETCHES, 0)
@@ -182,8 +182,9 @@ enum lfs3_type {
 #if !defined(LFS3_RDONLY) && defined(LFS3_GBMAP)
 #define LFS3_F_GBMAP    0x02000000  // Use the global on-disk block-map
 #endif
-#if !defined(LFS3_RDONLY) && defined(LFS3_REVDBG)
-#define LFS3_F_REVDBG   0x00000010  // Add debug info to revision counts
+#if !defined(LFS3_RDONLY) && defined(LFS3_REVPERTURB)
+#define LFS3_F_REVPERTURB \
+                        0x00000010  // Perturb first bit in revision count
 #endif
 #if !defined(LFS3_RDONLY) && defined(LFS3_REVNOISE)
 #define LFS3_F_REVNOISE 0x00000020  // Add noise to revision counts
@@ -246,8 +247,9 @@ enum lfs3_type {
 #define LFS3_M_RDONLY            1  // Mount the filesystem as read only
 #define LFS3_M_FLUSH    0x00000040  // Open all files with LFS3_O_FLUSH
 #define LFS3_M_SYNC     0x00000080  // Open all files with LFS3_O_SYNC
-#if !defined(LFS3_RDONLY) && defined(LFS3_REVDBG)
-#define LFS3_M_REVDBG   0x00000010  // Add debug info to revision counts
+#if !defined(LFS3_RDONLY) && defined(LFS3_REVPERTURB)
+#define LFS3_M_REVPERTURB \
+                        0x00000010  // Add debug info to revision counts
 #endif
 #if !defined(LFS3_RDONLY) && defined(LFS3_REVNOISE)
 #define LFS3_M_REVNOISE 0x00000020  // Add noise to revision counts
@@ -305,8 +307,9 @@ enum lfs3_type {
 #endif
 #define LFS3_I_FLUSH    0x00000040  // Mounted with LFS3_M_FLUSH
 #define LFS3_I_SYNC     0x00000080  // Mounted with LFS3_M_SYNC
-#if !defined(LFS3_RDONLY) && defined(LFS3_REVDBG)
-#define LFS3_I_REVDBG   0x00000010  // Mounted with LFS3_M_REVDBG
+#if !defined(LFS3_RDONLY) && defined(LFS3_REVPERTURB)
+#define LFS3_I_REVPERTURB \
+                        0x00000010  // Mounted with LFS3_M_REVPERTURB
 #endif
 #if !defined(LFS3_RDONLY) && defined(LFS3_REVNOISE)
 #define LFS3_I_REVNOISE 0x00000020  // Mounted with LFS3_M_REVNOISE
@@ -26,8 +26,8 @@

 // LFS3_BIGGEST enables all opt-in features
 #ifdef LFS3_BIGGEST
-#ifndef LFS3_REVDBG
-#define LFS3_REVDBG
+#ifndef LFS3_REVPERTURB
+#define LFS3_REVPERTURB
 #endif
 #ifndef LFS3_REVNOISE
 #define LFS3_REVNOISE
@@ -59,8 +59,8 @@
 #ifdef LFS3_YES_RDONLY
 #define LFS3_RDONLY
 #endif
-#ifdef LFS3_YES_REVDBG
-#define LFS3_REVDBG
+#ifdef LFS3_YES_REVPERTURB
+#define LFS3_REVPERTURB
 #endif
 #ifdef LFS3_YES_REVNOISE
 #define LFS3_REVNOISE
@@ -209,18 +209,18 @@
 #define LFS3_IFDEF_RDONLY(a, b) (b)
 #endif

-#ifdef LFS3_REVDBG
-#define LFS3_IFDEF_REVDBG(a, b) (a)
+#ifdef LFS3_REVPERTURB
+#define LFS3_IFDEF_REVPERTURB(a, b) (a)
 #else
-#define LFS3_IFDEF_REVDBG(a, b) (b)
+#define LFS3_IFDEF_REVPERTURB(a, b) (b)
 #endif

-#if defined(LFS3_REVDBG) && defined(LFS3_YES_REVDBG)
-#define LFS3_IFYES_REVDBG(a, b, c) (a)
-#elif defined(LFS3_REVDBG)
-#define LFS3_IFYES_REVDBG(a, b, c) (b)
+#if defined(LFS3_REVPERTURB) && defined(LFS3_YES_REVPERTURB)
+#define LFS3_IFYES_REVPERTURB(a, b, c) (a)
+#elif defined(LFS3_REVPERTURB)
+#define LFS3_IFYES_REVPERTURB(a, b, c) (b)
 #else
-#define LFS3_IFYES_REVDBG(a, b, c) (c)
+#define LFS3_IFYES_REVPERTURB(a, b, c) (c)
 #endif

 #ifdef LFS3_REVNOISE
@@ -75,7 +75,7 @@ F_MODE          =          1  # -m  Format's access mode
 F_RDWR          =          0  # -^  Format the filesystem as read and write
 F_GBMAP         = 0x02000000  # y-  Use the global on-disk block-map

-F_REVDBG        = 0x00000010  # y-  Add debug info to revision counts
+F_REVPERTURB    = 0x00000010  # y-  Perturb first bit in revision count
 F_REVNOISE      = 0x00000020  # y-  Add noise to revision counts
 F_CKPROGS       = 0x00100000  # y-  Check progs by reading back progged data
 F_CKFETCHES     = 0x00200000  # y-  Check block checksums before first use
@@ -97,7 +97,7 @@ M_RDWR          =          0  # -^  Mount the filesystem as read and write
 M_RDONLY        =          1  # -^  Mount the filesystem as read only
 M_FLUSH         = 0x00000040  # y-  Open all files with LFS3_O_FLUSH
 M_SYNC          = 0x00000080  # y-  Open all files with LFS3_O_SYNC
-M_REVDBG        = 0x00000010  # y-  Add debug info to revision counts
+M_REVPERTURB    = 0x00000010  # y-  Perturb first bit in revision count
 M_REVNOISE      = 0x00000020  # y-  Add noise to revision counts
 M_CKPROGS       = 0x00100000  # y-  Check progs by reading back progged data
 M_CKFETCHES     = 0x00200000  # y-  Check block checksums before first use
@@ -139,7 +139,7 @@ I_GBMAP         = 0x02000000  # --  Global on-disk block-map in use

 I_FLUSH         = 0x00000040  # --  Mounted with LFS3_M_FLUSH
 I_SYNC          = 0x00000080  # --  Mounted with LFS3_M_SYNC
-I_REVDBG        = 0x00000010  # --  Mounted with LFS3_M_REVDBG
+I_REVPERTURB    = 0x00000010  # --  Mounted with LFS3_M_REVPERTURB
 I_REVNOISE      = 0x00000020  # --  Mounted with LFS3_M_REVNOISE
 I_CKPROGS       = 0x00100000  # --  Mounted with LFS3_M_CKPROGS
 I_CKFETCHES     = 0x00200000  # --  Mounted with LFS3_M_CKFETCHES
@@ -1877,7 +1877,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP || (fsinfo.flags & LFS3_I_LOOKAHEAD))
@@ -1996,7 +1996,7 @@ code = '''
    // did these clear the right flags?
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                | ((!LOOKAHEAD
@@ -2080,7 +2080,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP || (fsinfo.flags & LFS3_I_LOOKAHEAD))
@@ -2199,7 +2199,7 @@ code = '''
    // did these clear the right flags?
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                | ((!LOOKAHEAD
@@ -2218,7 +2218,7 @@ code = '''
    // check that flags were reset
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP || (fsinfo.flags & LFS3_I_LOOKAHEAD))
@@ -2339,7 +2339,7 @@ code = '''
    // did these clear the right flags?
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                | ((!LOOKAHEAD
@@ -24,7 +24,7 @@ code = '''
 defines.RDONLY = [false, true]
 defines.FLUSH = [false, true]
 defines.SYNC = [false, true]
-defines.REVDBG = [false, true]
+defines.REVPERTURB = [false, true]
 defines.REVNOISE = [false, true]
 defines.CKPROGS = [false, true]
 defines.CKFETCHES = [false, true]
@@ -36,7 +36,7 @@ defines.COMPACT = [false, true]
 defines.CKMETA = [false, true]
 defines.CKDATA = [false, true]
 if = [
-    'LFS3_IFYES_REVDBG(REVDBG, true, !REVDBG)',
+    'LFS3_IFYES_REVPERTURB(REVPERTURB, true, !REVPERTURB)',
    'LFS3_IFYES_REVNOISE(REVNOISE, true, !REVNOISE)',
    'LFS3_IFDEF_CKPROGS(true, !CKPROGS)',
    'LFS3_IFDEF_CKFETCHES(true, !CKFETCHES)',
@@ -56,7 +56,9 @@ code = '''
            ((RDONLY) ? LFS3_M_RDONLY : LFS3_M_RDWR)
                | ((FLUSH) ? LFS3_M_FLUSH : 0)
                | ((SYNC) ? LFS3_M_SYNC : 0)
-                | ((REVDBG) ? LFS3_IFDEF_REVDBG(LFS3_M_REVDBG, -1) : 0)
+                | ((REVPERTURB)
+                    ? LFS3_IFDEF_REVPERTURB(LFS3_M_REVPERTURB, -1)
+                    : 0)
                | ((REVNOISE) ? LFS3_IFDEF_REVNOISE(LFS3_M_REVNOISE, -1) : 0)
                | ((CKPROGS) ? LFS3_IFDEF_CKPROGS(LFS3_M_CKPROGS, -1) : 0)
                | ((CKFETCHES) ? LFS3_IFDEF_CKFETCHES(LFS3_M_CKFETCHES, -1) : 0)
@@ -80,7 +82,9 @@ code = '''
            ((RDONLY) ? LFS3_I_RDONLY : 0)
                | ((FLUSH) ? LFS3_I_FLUSH : 0)
                | ((SYNC) ? LFS3_I_SYNC : 0)
-                | ((REVDBG) ? LFS3_IFDEF_REVDBG(LFS3_I_REVDBG, -1) : 0)
+                | ((REVPERTURB)
+                    ? LFS3_IFDEF_REVPERTURB(LFS3_I_REVPERTURB, -1)
+                    : 0)
                | ((REVNOISE) ? LFS3_IFDEF_REVNOISE(LFS3_I_REVNOISE, -1) : 0)
                | ((CKPROGS) ? LFS3_IFDEF_CKPROGS(LFS3_I_CKPROGS, -1) : 0)
                | ((CKFETCHES) ? LFS3_IFDEF_CKFETCHES(LFS3_I_CKFETCHES, -1) : 0)
@@ -105,7 +109,7 @@ code = '''
 # 
 # these end up passed to mount internally
 [cases.test_mount_format_flags]
-defines.REVDBG = [false, true]
+defines.REVPERTURB = [false, true]
 defines.REVNOISE = [false, true]
 defines.CKPROGS = [false, true]
 defines.CKFETCHES = [false, true]
@@ -117,7 +121,7 @@ defines.COMPACT = [false, true]
 defines.CKMETA = [false, true]
 defines.CKDATA = [false, true]
 if = [
-    'LFS3_IFYES_REVDBG(REVDBG, true, !REVDBG)',
+    'LFS3_IFYES_REVPERTURB(REVPERTURB, true, !REVPERTURB)',
    'LFS3_IFYES_REVNOISE(REVNOISE, true, !REVNOISE)',
    'LFS3_IFDEF_CKPROGS(true, !CKPROGS)',
    'LFS3_IFDEF_CKFETCHES(true, !CKFETCHES)',
@@ -128,7 +132,9 @@ code = '''
    lfs3_t lfs3;
    lfs3_format(&lfs3,
            LFS3_F_RDWR
-                | ((REVDBG) ? LFS3_IFDEF_REVDBG(LFS3_F_REVDBG, -1) : 0)
+                | ((REVPERTURB)
+                    ? LFS3_IFDEF_REVPERTURB(LFS3_F_REVPERTURB, -1)
+                    : 0)
                | ((REVNOISE) ? LFS3_IFDEF_REVNOISE(LFS3_F_REVNOISE, -1) : 0)
                | ((CKPROGS) ? LFS3_IFDEF_CKPROGS(LFS3_F_CKPROGS, -1) : 0)
                | ((CKFETCHES) ? LFS3_IFDEF_CKFETCHES(LFS3_F_CKFETCHES, -1) : 0)
@@ -151,7 +157,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
@@ -184,7 +190,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
@@ -203,7 +209,7 @@ code = '''
            CFG) => 0;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | LFS3_I_COMPACT
@@ -239,7 +245,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | LFS3_I_COMPACT
@@ -262,7 +268,7 @@ code = '''
    lfs3_mount(&lfs3, LFS3_M_RDWR, CFG) => 0;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | LFS3_I_LOOKAHEAD
@@ -281,7 +287,7 @@ code = '''
            CFG) => 0;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | LFS3_I_COMPACT
@@ -342,7 +348,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP || SIZE >= BLOCK_SIZE/4)
@@ -364,7 +370,7 @@ code = '''
            CFG) => 0;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!LOOKAHEAD && (!GBMAP || SIZE >= BLOCK_SIZE/4))
@@ -457,7 +463,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP || ORPHANS >= 100)
@@ -480,7 +486,7 @@ code = '''
            CFG) => 0;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD && (!GBMAP || ORPHANS >= 100))
                    ? LFS3_I_LOOKAHEAD
@@ -7,20 +7,20 @@ defines.LOOKAHEAD_SIZE = '(BLOCK_COUNT+8-1) / 8'

 # test with normal revision counts, debug revision counts, and noisy
 # revision counts
-defines.REVDBG = [false, true]
+defines.REVPERTURB = [false, true]
 defines.REVNOISE = [false, true]
 defines.F_FLAGS = '''
-    ((REVDBG) ? LFS3_IFDEF_REVDBG(LFS3_F_REVDBG, -1) : 0)
+    ((REVPERTURB) ? LFS3_IFDEF_REVPERTURB(LFS3_F_REVPERTURB, -1) : 0)
        | ((REVNOISE) ? LFS3_IFDEF_REVNOISE(LFS3_F_REVNOISE, -1) : 0)
 '''
 defines.M_FLAGS = '''
-    ((REVDBG) ? LFS3_IFDEF_REVDBG(LFS3_M_REVDBG, -1) : 0)
+    ((REVPERTURB) ? LFS3_IFDEF_REVPERTURB(LFS3_M_REVPERTURB, -1) : 0)
        | ((REVNOISE) ? LFS3_IFDEF_REVNOISE(LFS3_M_REVNOISE, -1) : 0)
 '''
 if = [
-    'LFS3_IFDEF_REVDBG(true, !REVDBG)',
+    'LFS3_IFDEF_REVPERTURB(true, !REVPERTURB)',
    'LFS3_IFDEF_REVNOISE(true, !REVNOISE)',
-    '!REVDBG || !REVNOISE',
+    '!REVPERTURB || !REVNOISE',
 ]


@@ -1775,7 +1775,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_MKCONSISTENT
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
@@ -1812,7 +1812,7 @@ code = '''
    // check flags after
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!MKCONSISTENT) ? LFS3_I_MKCONSISTENT : 0)
                | ((!LOOKAHEAD && !GBMAP) ? LFS3_I_LOOKAHEAD : 0)
@@ -1913,7 +1913,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -1988,7 +1988,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -2021,7 +2021,7 @@ code = '''
    // we should _not_ update lookahead/compact/ckmeta/ckdata
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -2112,7 +2112,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -2207,7 +2207,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -2310,7 +2310,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -2394,7 +2394,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP || SIZE >= BLOCK_SIZE/4)
                    ? LFS3_I_LOOKAHEAD
@@ -2491,7 +2491,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                // ok we might've updated lookahead if write stayed in
                // cache
@@ -2616,7 +2616,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -2748,7 +2748,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -2870,7 +2870,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -2977,7 +2977,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -3111,7 +3111,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -3235,7 +3235,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -3354,7 +3354,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((DESYNC) ? LFS3_I_MKCONSISTENT : 0)
                | ((!(LOOKAHEAD && DESYNC) && !GBMAP) ? LFS3_I_LOOKAHEAD : 0)
@@ -3499,7 +3499,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((DESYNC) ? LFS3_I_MKCONSISTENT : 0)
                | ((!(LOOKAHEAD && DESYNC)) ? LFS3_I_LOOKAHEAD : 0)
@@ -3634,7 +3634,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((DESYNC) ? LFS3_I_MKCONSISTENT : 0)
                | ((!(LOOKAHEAD && DESYNC)) ? LFS3_I_LOOKAHEAD : 0)
@@ -3755,7 +3755,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((DESYNC) ? LFS3_I_MKCONSISTENT : 0)
                | ((!(LOOKAHEAD && DESYNC)) ? LFS3_I_LOOKAHEAD : 0)
@@ -3879,7 +3879,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4004,7 +4004,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4132,7 +4132,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4273,7 +4273,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4414,7 +4414,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4535,7 +4535,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4657,7 +4657,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4792,7 +4792,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -4928,7 +4928,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -5118,7 +5118,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -5324,7 +5324,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -5525,7 +5525,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -5723,7 +5723,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -5927,7 +5927,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -6136,7 +6136,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -6350,7 +6350,7 @@ done:;
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -6423,7 +6423,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -6461,7 +6461,7 @@ code = '''
    // but because we mutated, we're still marked as uncompacted
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -6486,7 +6486,7 @@ code = '''
    // uncompacted flag should have been cleared
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD && !GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                // note ckdata implies ckmeta
@@ -6572,7 +6572,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -6618,7 +6618,7 @@ code = '''
    // but because we mutated, we're still marked as uncompacted
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -6645,7 +6645,7 @@ code = '''
    // uncompacted flag should have been cleared
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD) ? LFS3_I_LOOKAHEAD : 0)
                // note ckdata implies ckmeta
@@ -6713,7 +6713,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -6753,7 +6753,7 @@ code = '''
    // but because we mutated, we're still marked as uncompacted
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -6778,7 +6778,7 @@ code = '''
    // uncompacted flag should have been cleared
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD) ? LFS3_I_LOOKAHEAD : 0)
                // note ckdata implies ckmeta
@@ -6873,7 +6873,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -6925,7 +6925,7 @@ code = '''
    // but because we mutated, we're still marked as uncompacted
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -6951,7 +6951,7 @@ code = '''
    // uncompacted flag should have been cleared
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD) ? LFS3_I_LOOKAHEAD : 0)
                // note ckdata implies ckmeta
@@ -7100,7 +7100,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -7159,7 +7159,7 @@ code = '''
        // but because we mutated, we're still marked as uncompacted
        lfs3_fs_stat(&lfs3, &fsinfo) => 0;
        assert(fsinfo.flags == (
-                LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+                LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                    | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                    | LFS3_I_LOOKAHEAD
                    | LFS3_I_COMPACT
@@ -7187,7 +7187,7 @@ code = '''
    // uncompacted flag should have been cleared
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD) ? LFS3_I_LOOKAHEAD : 0)
                // note ckdata implies ckmeta
@@ -7341,7 +7341,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -7405,7 +7405,7 @@ code = '''
    // but because we mutated, we're still marked as uncompacted
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | LFS3_I_LOOKAHEAD
                | LFS3_I_COMPACT
@@ -7433,7 +7433,7 @@ code = '''
    // uncompacted flag should have been cleared
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD) ? LFS3_I_LOOKAHEAD : 0)
                // note ckdata implies ckmeta
@@ -7552,7 +7552,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS > 0) ? LFS3_I_MKCONSISTENT : 0)
                | ((!GBMAP || ORPHANS >= 100) ? LFS3_I_LOOKAHEAD : 0)
@@ -7620,7 +7620,7 @@ code = '''
    // and we should be marked as consistent
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | (((!LOOKAHEAD || ORPHANS > 0)
                        && (!GBMAP || ORPHANS >= 100))
@@ -7702,7 +7702,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -7790,7 +7790,7 @@ code = '''
    // if we introduced actual orphans, we _must_ be marked as inconsistent
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS >= 3) ? LFS3_I_MKCONSISTENT : 0)
                | (((!LOOKAHEAD || ORPHANS > 0)
@@ -7898,7 +7898,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS > 0) ? LFS3_I_MKCONSISTENT : 0)
                | LFS3_I_LOOKAHEAD
@@ -7979,7 +7979,7 @@ code = '''
    // and we should be marked as consistent
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD || ORPHANS > 0) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -8083,7 +8083,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS > 0) ? LFS3_I_MKCONSISTENT : 0)
                | LFS3_I_LOOKAHEAD
@@ -8164,7 +8164,7 @@ code = '''
    // and we should be marked as consistent
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD || ORPHANS > 0) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -8269,7 +8269,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS > 0) ? LFS3_I_MKCONSISTENT : 0)
                | LFS3_I_LOOKAHEAD
@@ -8358,7 +8358,7 @@ code = '''
    // and we should be marked as consistent
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD || ORPHANS > 0) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -8463,7 +8463,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS > 0) ? LFS3_I_MKCONSISTENT : 0)
                | LFS3_I_LOOKAHEAD
@@ -8552,7 +8552,7 @@ code = '''
    // and we should be marked as consistent
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD || ORPHANS > 0) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -8675,7 +8675,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS > 0) ? LFS3_I_MKCONSISTENT : 0)
                | ((!GBMAP || ORPHANS >= 100)
@@ -8750,7 +8750,7 @@ code = '''
    // still marked as uncompacted
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP || ORPHANS >= 100)
                    ? LFS3_I_LOOKAHEAD
@@ -8778,7 +8778,7 @@ code = '''
    // uncompacted flag should have been cleared
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!LOOKAHEAD && (!GBMAP || ORPHANS >= 100))
                    ? LFS3_I_LOOKAHEAD
@@ -8881,7 +8881,7 @@ code = '''
    struct lfs3_fsinfo fsinfo;
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((!GBMAP) ? LFS3_I_LOOKAHEAD : 0)
                | LFS3_I_COMPACT
@@ -8974,7 +8974,7 @@ code = '''
    // if we introduced actual orphans, we _must_ be marked as inconsistent
    lfs3_fs_stat(&lfs3, &fsinfo) => 0;
    assert(fsinfo.flags == (
-            LFS3_IFYES_REVDBG(LFS3_I_REVDBG, 0, 0)
+            LFS3_IFYES_REVPERTURB(LFS3_I_REVPERTURB, 0, 0)
                | LFS3_IFYES_REVNOISE(LFS3_I_REVNOISE, 0, 0)
                | ((ORPHANS >= 3) ? LFS3_I_MKCONSISTENT : 0)
                | ((!GBMAP || ORPHANS >= 100)