Revisited xored-globals and related logic

Added separate bit for "hasmove", which means we don't need to check
the move id, and allows us to add more sync-related global states in
the future, as long as they never happen simultaneously (such as
orphans and moves).

Also refactored some of the logic and removed the union in the global
structure, which didn't really add anything of value.

2 files changed, 295 insertions, 306 deletions

diff --git a/lfs.c b/lfs.c
index 592f980..8607946 100644
--- a/lfs.c
+++ b/lfs.c
@@ -315,52 +315,55 @@ struct lfs_diskoff {
 };
 
 // operations on set of globals
-static inline void lfs_global_xor(lfs_global_t *a, const lfs_global_t *b) {
-    for (int i = 0; i < sizeof(lfs_global_t)/4; i++) {
-        a->u32[i] ^= b->u32[i];
+static inline void lfs_global_xor(struct lfs_globals *a,
+        const struct lfs_globals *b) {
+    uint32_t *a32 = (uint32_t *)a;
+    const uint32_t *b32 = (const uint32_t *)b;
+    for (int i = 0; i < sizeof(struct lfs_globals)/4; i++) {
+        a32[i] ^= b32[i];
     }
 }
 
-static inline bool lfs_global_iszero(const lfs_global_t *a) {
-    for (int i = 0; i < sizeof(lfs_global_t)/4; i++) {
-        if (a->u32[i] != 0) {
+static inline bool lfs_global_iszero(const struct lfs_globals *a) {
+    const uint32_t *a32 = (const uint32_t *)a;
+    for (int i = 0; i < sizeof(struct lfs_globals)/4; i++) {
+        if (a32[i] != 0) {
             return false;
         }
     }
     return true;
 }
 
-static inline void lfs_global_zero(lfs_global_t *a) {
-    memset(a, 0, sizeof(lfs_global_t));
+static inline void lfs_global_zero(struct lfs_globals *a) {
+    lfs_global_xor(a, a);
 }
 
-static inline void lfs_global_fromle32(lfs_global_t *a) {
-    lfs_pair_fromle32(a->l.movepair);
-    a->l.moveid = lfs_fromle16(a->l.moveid);
+static inline void lfs_global_fromle32(struct lfs_globals *a) {
+    lfs_pair_fromle32(a->pair);
+    a->id = lfs_fromle16(a->id);
 }
 
-static inline void lfs_global_tole32(lfs_global_t *a) {
-    lfs_pair_tole32(a->l.movepair);
-    a->l.moveid = lfs_tole16(a->l.moveid);
+static inline void lfs_global_tole32(struct lfs_globals *a) {
+    lfs_pair_tole32(a->pair);
+    a->id = lfs_tole16(a->id);
 }
 
 static inline void lfs_global_move(lfs_t *lfs,
-        const lfs_block_t pair[2], uint16_t id) {
-    lfs_global_t diff;
-    lfs_global_zero(&diff);
-    diff.l.movepair[0] ^= lfs->globals.g.movepair[0] ^ pair[0];
-    diff.l.movepair[1] ^= lfs->globals.g.movepair[1] ^ pair[1];
-    diff.l.moveid      ^= lfs->globals.g.moveid      ^ id;
+        bool hasmove, const lfs_block_t pair[2], uint16_t id) {
     lfs_global_fromle32(&lfs->locals);
-    lfs_global_xor(&lfs->locals, &diff);
+    lfs_global_xor(&lfs->locals, &lfs->globals);
+    lfs->globals.hasmove = hasmove;
+    lfs->globals.pair[0] = pair[0];
+    lfs->globals.pair[1] = pair[1];
+    lfs->globals.id      = id;
+    lfs_global_xor(&lfs->locals, &lfs->globals);
     lfs_global_tole32(&lfs->locals);
-    lfs_global_xor(&lfs->globals, &diff);
 }
 
 static inline void lfs_global_orphans(lfs_t *lfs, int8_t orphans) {
-    lfs->locals.l.deorphaned ^= (lfs->globals.g.orphans == 0);
-    lfs->locals.l.deorphaned ^= (lfs->globals.g.orphans + orphans == 0);
-    lfs->globals.g.orphans += orphans;
+    lfs->locals.orphans ^= (lfs->globals.orphans == 0);
+    lfs->globals.orphans += orphans;
+    lfs->locals.orphans ^= (lfs->globals.orphans == 0);
 }
 
 // other endianness operations
@@ -730,11 +733,12 @@ static lfs_stag_t lfs_dir_fetchmatch(lfs_t *lfs,
         // consider what we have good enough
         if (dir->off > 0) {
             // synthetic move
-            if (lfs_pair_cmp(dir->pair, lfs->globals.g.movepair) == 0) {
-                if (lfs->globals.g.moveid == lfs_tag_id(foundtag)) {
+            if (lfs->globals.hasmove &&
+                    lfs_pair_cmp(dir->pair, lfs->globals.pair) == 0) {
+                if (lfs->globals.id == lfs_tag_id(foundtag)) {
                     foundtag = 0;
                 } else if (foundtag &&
-                        lfs->globals.g.moveid < lfs_tag_id(foundtag)) {
+                        lfs->globals.id < lfs_tag_id(foundtag)) {
                     foundtag -= LFS_MKTAG(0, 1, 0);
                 }
             }
@@ -758,24 +762,6 @@ static int lfs_dir_fetch(lfs_t *lfs,
             0xffffffff, 0x00000000, NULL, NULL);
 }
 
-static lfs_stag_t lfs_dir_findmatch(lfs_t *lfs,
-        lfs_mdir_t *dir, const lfs_block_t pair[2], bool fs,
-        lfs_tag_t findmask, lfs_tag_t findtag,
-        int (*cb)(void *data, lfs_tag_t tag, const void *buffer), void *data) {
-    dir->split = true;
-    dir->tail[0] = pair[0];
-    dir->tail[1] = pair[1];
-    while ((dir->split || fs) && !lfs_pair_isnull(dir->tail)) {
-        lfs_stag_t tag = lfs_dir_fetchmatch(lfs, dir, dir->tail,
-                findmask, findtag, cb, data);
-        if (tag) {
-            return tag;
-        }
-    }
-
-    return LFS_ERR_NOENT;
-}
-
 struct lfs_dir_get_match {
     lfs_t *lfs;
     void *buffer;
@@ -811,8 +797,9 @@ static int lfs_dir_get_match(void *data,
 static lfs_stag_t lfs_dir_get(lfs_t *lfs, const lfs_mdir_t *dir,
         lfs_tag_t getmask, lfs_tag_t gettag, void *buffer) {
     lfs_stag_t getdiff = 0;
-    if (lfs_pair_cmp(dir->pair, lfs->globals.g.movepair) == 0 &&
-            lfs_tag_id(gettag) <= lfs->globals.g.moveid) {
+    if (lfs->globals.hasmove &&
+            lfs_pair_cmp(dir->pair, lfs->globals.pair) == 0 &&
+            lfs_tag_id(gettag) <= lfs->globals.id) {
         // synthetic moves
         gettag += LFS_MKTAG(0, 1, 0);
         getdiff -= LFS_MKTAG(0, 1, 0);
@@ -829,6 +816,181 @@ static lfs_stag_t lfs_dir_get(lfs_t *lfs, const lfs_mdir_t *dir,
     return res ? res : LFS_ERR_NOENT;
 }
 
+static int lfs_dir_getglobals(lfs_t *lfs, const lfs_mdir_t *dir,
+        struct lfs_globals *globals) {
+    struct lfs_globals locals;
+    lfs_stag_t res = lfs_dir_get(lfs, dir, 0x7c000000,
+            LFS_MKTAG(LFS_TYPE_GLOBALS, 0, 10), &locals);
+    if (res < 0 && res != LFS_ERR_NOENT) {
+        return res;
+    }
+
+    if (res != LFS_ERR_NOENT) {
+        locals.hasmove = (lfs_tag_type(res) & 2);
+        locals.orphans = (lfs_tag_type(res) & 1);
+        // xor together to find resulting globals
+        lfs_global_xor(globals, &locals);
+    }
+
+    return 0;
+}
+
+static int lfs_dir_getinfo(lfs_t *lfs, lfs_mdir_t *dir,
+        uint16_t id, struct lfs_info *info) {
+    if (id == 0x3ff) {
+        // special case for root
+        strcpy(info->name, "/");
+        info->type = LFS_TYPE_DIR;
+        return 0;
+    }
+
+    lfs_stag_t tag = lfs_dir_get(lfs, dir, 0x7c3ff000,
+            LFS_MKTAG(LFS_TYPE_NAME, id, lfs->name_max+1), info->name);
+    if (tag < 0) {
+        return tag;
+    }
+
+    info->type = lfs_tag_type(tag);
+
+    struct lfs_ctz ctz;
+    tag = lfs_dir_get(lfs, dir, 0x7c3ff000,
+            LFS_MKTAG(LFS_TYPE_STRUCT, id, sizeof(ctz)), &ctz);
+    if (tag < 0) {
+        return tag;
+    }
+    lfs_ctz_fromle32(&ctz);
+
+    if (lfs_tag_type(tag) == LFS_TYPE_CTZSTRUCT) {
+        info->size = ctz.size;
+    } else if (lfs_tag_type(tag) == LFS_TYPE_INLINESTRUCT) {
+        info->size = lfs_tag_size(tag);
+    }
+
+    return 0;
+}
+
+static lfs_stag_t lfs_dir_findmatch(lfs_t *lfs,
+        lfs_mdir_t *dir, const lfs_block_t pair[2], bool fs,
+        lfs_tag_t findmask, lfs_tag_t findtag,
+        int (*cb)(void *data, lfs_tag_t tag, const void *buffer), void *data) {
+    dir->split = true;
+    dir->tail[0] = pair[0];
+    dir->tail[1] = pair[1];
+    while ((dir->split || fs) && !lfs_pair_isnull(dir->tail)) {
+        lfs_stag_t tag = lfs_dir_fetchmatch(lfs, dir, dir->tail,
+                findmask, findtag, cb, data);
+        if (tag) {
+            return tag;
+        }
+    }
+
+    return LFS_ERR_NOENT;
+}
+
+struct lfs_dir_find_match {
+    lfs_t *lfs;
+    const void *name;
+    lfs_size_t size;
+};
+
+static int lfs_dir_find_match(void *data,
+        lfs_tag_t tag, const void *buffer) {
+    struct lfs_dir_find_match *name = data;
+    lfs_t *lfs = name->lfs;
+    const struct lfs_diskoff *disk = buffer;
+    (void)tag;
+
+    return lfs_bd_cmp(lfs,
+            NULL, &lfs->rcache, name->size,
+            disk->block, disk->off, name->name, name->size);
+}
+
+static lfs_stag_t lfs_dir_find(lfs_t *lfs,
+        lfs_mdir_t *dir, const char **path) {
+    // we reduce path to a single name if we can find it
+    const char *name = *path;
+    *path = NULL;
+
+    // default to root dir
+    lfs_stag_t tag = LFS_MKTAG(LFS_TYPE_DIR, 0x3ff, 0);
+    lfs_block_t pair[2] = {lfs->root[0], lfs->root[1]};
+
+    while (true) {
+nextname:
+        // skip slashes
+        name += strspn(name, "/");
+        lfs_size_t namelen = strcspn(name, "/");
+
+        // skip '.' and root '..'
+        if ((namelen == 1 && memcmp(name, ".", 1) == 0) ||
+            (namelen == 2 && memcmp(name, "..", 2) == 0)) {
+            name += namelen;
+            goto nextname;
+        }
+
+        // skip if matched by '..' in name
+        const char *suffix = name + namelen;
+        lfs_size_t sufflen;
+        int depth = 1;
+        while (true) {
+            suffix += strspn(suffix, "/");
+            sufflen = strcspn(suffix, "/");
+            if (sufflen == 0) {
+                break;
+            }
+
+            if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
+                depth -= 1;
+                if (depth == 0) {
+                    name = suffix + sufflen;
+                    goto nextname;
+                }
+            } else {
+                depth += 1;
+            }
+
+            suffix += sufflen;
+        }
+
+        // found path
+        if (name[0] == '\0') {
+            return tag;
+        }
+
+        // update what we've found if path is only a name
+        if (strchr(name, '/') == NULL) {
+            *path = name;
+        }
+
+        // only continue if we hit a directory
+        if (lfs_tag_type(tag) != LFS_TYPE_DIR) {
+            return LFS_ERR_NOTDIR;
+        }
+
+        // grab the entry data
+        if (lfs_tag_id(tag) != 0x3ff) {
+            lfs_stag_t res = lfs_dir_get(lfs, dir, 0x7c3ff000,
+                    LFS_MKTAG(LFS_TYPE_STRUCT, lfs_tag_id(tag), 8), pair);
+            if (res < 0) {
+                return res;
+            }
+            lfs_pair_fromle32(pair);
+        }
+
+        // find entry matching name
+        tag = lfs_dir_findmatch(lfs, dir, pair, false, 0x7c000fff,
+                LFS_MKTAG(LFS_TYPE_NAME, 0, namelen),
+                lfs_dir_find_match, &(struct lfs_dir_find_match){
+                    lfs, name, namelen});
+        if (tag < 0) {
+            return tag;
+        }
+
+        // to next name
+        name += namelen;
+    }
+}
+
 // commit logic
 struct lfs_commit {
     lfs_block_t block;
@@ -980,6 +1142,13 @@ static int lfs_commit_attr(lfs_t *lfs, struct lfs_commit *commit,
     return 0;
 }
 
+static int lfs_commit_globals(lfs_t *lfs, struct lfs_commit *commit,
+        struct lfs_globals *globals) {
+    return lfs_commit_attr(lfs, commit,
+            LFS_MKTAG(LFS_TYPE_GLOBALS + 2*globals->hasmove + globals->orphans,
+                0x3ff, 10), globals);
+}
+
 static int lfs_commit_crc(lfs_t *lfs, struct lfs_commit *commit,
         bool compacting) {
     // align to program units
@@ -1090,18 +1259,12 @@ static int lfs_dir_drop(lfs_t *lfs, lfs_mdir_t *dir, const lfs_mdir_t *tail) {
     dir->split = tail->split;
 
     // steal state
-    lfs_global_t locals;
-    lfs_stag_t res = lfs_dir_get(lfs, tail, 0x7c000000,
-            LFS_MKTAG(LFS_TYPE_GLOBALS, 0, 10), &locals);
-    if (res < 0 && res != LFS_ERR_NOENT) {
-        return res;
-    }
-
-    if (res != LFS_ERR_NOENT) {
-        locals.l.deorphaned = (lfs_tag_type(res) & 1);
-        lfs_global_xor(&lfs->locals, &locals);
+    int err = lfs_dir_getglobals(lfs, tail, &lfs->locals);
+    if (err) {
+        return err;
     }
 
+    // update pred's tail
     return lfs_dir_commit(lfs, dir,
             LFS_MKATTR(LFS_TYPE_TAIL + dir->split,
                 0x3ff, dir->tail, sizeof(dir->tail),
@@ -1117,16 +1280,9 @@ static int lfs_dir_compact(lfs_t *lfs,
 
     // There's nothing special about our global delta, so feed it back
     // into the global global delta
-    lfs_global_t locals;
-    lfs_stag_t res = lfs_dir_get(lfs, dir, 0x7c000000,
-            LFS_MKTAG(LFS_TYPE_GLOBALS, 0, 10), &locals);
-    if (res < 0 && res != LFS_ERR_NOENT) {
-        return res;
-    }
-
-    if (res != LFS_ERR_NOENT) {
-        locals.l.deorphaned = (lfs_tag_type(res) & 1);
-        lfs_global_xor(&lfs->locals, &locals);
+    int err = lfs_dir_getglobals(lfs, dir, &lfs->locals);
+    if (err) {
+        return err;
     }
 
     // begin loop to commit compaction to blocks until a compact sticks
@@ -1167,7 +1323,7 @@ commit:
                         (const lfs_block_t[2]){0, 1}) == 0) {
                     // we're writing too much to the superblock,
                     // should we expand?
-                    res = lfs_fs_size(lfs);
+                    lfs_stag_t res = lfs_fs_size(lfs);
                     if (res < 0) {
                         return res;
                     }
@@ -1187,7 +1343,7 @@ commit:
             }
 
             // erase block to write to
-            int err = lfs_bd_erase(lfs, dir->pair[1]);
+            err = lfs_bd_erase(lfs, dir->pair[1]);
             if (err) {
                 if (err == LFS_ERR_CORRUPT) {
                     goto relocate;
@@ -1198,7 +1354,7 @@ commit:
 
         // write out header
         uint32_t rev = lfs_tole32(dir->rev);
-        int err = lfs_commit_prog(lfs, &commit, &rev, sizeof(rev));
+        err = lfs_commit_prog(lfs, &commit, &rev, sizeof(rev));
         if (err) {
             if (err == LFS_ERR_CORRUPT) {
                 goto relocate;
@@ -1245,9 +1401,7 @@ commit:
         if (!relocated && !lfs_global_iszero(&lfs->locals)) {
             // commit any globals, unless we're relocating,
             // in which case our parent will steal our globals
-            err = lfs_commit_attr(lfs, &commit,
-                    LFS_MKTAG(LFS_TYPE_GLOBALS + lfs->locals.l.deorphaned,
-                        0x3ff, 10), &lfs->locals);
+            err = lfs_commit_globals(lfs, &commit, &lfs->locals);
             if (err) {
                 if (err == LFS_ERR_CORRUPT) {
                     goto relocate;
@@ -1357,7 +1511,7 @@ relocate:
         // update references if we relocated
         LFS_DEBUG("Relocating %"PRIu32" %"PRIu32" to %"PRIu32" %"PRIu32,
                 oldpair[0], oldpair[1], dir->pair[0], dir->pair[1]);
-        int err = lfs_fs_relocate(lfs, oldpair, dir->pair);
+        err = lfs_fs_relocate(lfs, oldpair, dir->pair);
         if (err) {
             return err;
         }
@@ -1369,21 +1523,23 @@ relocate:
 static int lfs_dir_commit(lfs_t *lfs, lfs_mdir_t *dir,
         const struct lfs_mattr *attrs) {
     struct lfs_mattr cancelattr;
-    lfs_global_t canceldiff;
-    lfs_global_zero(&canceldiff);
-    if (lfs_pair_cmp(dir->pair, lfs->globals.g.movepair) == 0) {
+    struct lfs_globals cancels;
+    lfs_global_zero(&cancels);
+    if (lfs->globals.hasmove &&
+            lfs_pair_cmp(dir->pair, lfs->globals.pair) == 0) {
         // Wait, we have the move? Just cancel this out here
         // We need to, or else the move can become outdated
-        canceldiff.l.movepair[0] ^= lfs->globals.g.movepair[0] ^ 0xffffffff;
-        canceldiff.l.movepair[1] ^= lfs->globals.g.movepair[1] ^ 0xffffffff;
-        canceldiff.l.moveid      ^= lfs->globals.g.moveid      ^ 0x3ff;
-        lfs_global_fromle32(&lfs->locals);
-        lfs_global_xor(&lfs->locals, &canceldiff);
-        lfs_global_tole32(&lfs->locals);
-
-        cancelattr.tag = LFS_MKTAG(LFS_TYPE_DELETE, lfs->globals.l.moveid, 0);
+        cancelattr.tag = LFS_MKTAG(LFS_TYPE_DELETE, lfs->globals.id, 0);
         cancelattr.next = attrs;
         attrs = &cancelattr;
+
+        cancels.hasmove = lfs->globals.hasmove;
+        cancels.pair[0] = lfs->globals.pair[0];
+        cancels.pair[1] = lfs->globals.pair[1];
+        cancels.id      = lfs->globals.id;
+        lfs_global_fromle32(&lfs->locals);
+        lfs_global_xor(&lfs->locals, &cancels);
+        lfs_global_tole32(&lfs->locals);
     }
 
     // calculate new directory size
@@ -1451,22 +1607,13 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_mdir_t *dir,
 
         // commit any global diffs if we have any
         if (!lfs_global_iszero(&lfs->locals)) {
-            lfs_global_t locals;
-            lfs_global_zero(&locals);
-            lfs_stag_t res = lfs_dir_get(lfs, dir, 0x7c000000,
-                    LFS_MKTAG(LFS_TYPE_GLOBALS, 0, 10), &locals);
-            if (res < 0 && res != LFS_ERR_NOENT) {
-                return res;
-            }
-
-            if (res != LFS_ERR_NOENT) {
-                locals.l.deorphaned = (lfs_tag_type(res) & 1);
+            struct lfs_globals locals = lfs->locals;
+            int err = lfs_dir_getglobals(lfs, dir, &locals);
+            if (err) {
+                return err;
             }
 
-            lfs_global_xor(&locals, &lfs->locals);
-            int err = lfs_commit_attr(lfs, &commit,
-                    LFS_MKTAG(LFS_TYPE_GLOBALS + locals.l.deorphaned,
-                        0x3ff, 10), &locals);
+            err = lfs_commit_globals(lfs, &commit, &locals);
             if (err) {
                 if (err == LFS_ERR_NOSPC || err == LFS_ERR_CORRUPT) {
                     goto compact;
@@ -1504,7 +1651,7 @@ compact:
     }
 
     // update globals that are affected
-    lfs_global_xor(&lfs->globals, &canceldiff);
+    lfs_global_xor(&lfs->globals, &cancels);
 
     // update any directories that are affected
     lfs_mdir_t copy = *dir;
@@ -1538,143 +1685,6 @@ compact:
     return 0;
 }
 
-struct lfs_dir_find_match {
-    lfs_t *lfs;
-    const void *name;
-    lfs_size_t size;
-};
-
-static int lfs_dir_find_match(void *data,
-        lfs_tag_t tag, const void *buffer) {
-    struct lfs_dir_find_match *name = data;
-    lfs_t *lfs = name->lfs;
-    const struct lfs_diskoff *disk = buffer;
-    (void)tag;
-
-    return lfs_bd_cmp(lfs,
-            NULL, &lfs->rcache, name->size,
-            disk->block, disk->off, name->name, name->size);
-}
-
-static lfs_stag_t lfs_dir_find(lfs_t *lfs,
-        lfs_mdir_t *dir, const char **path) {
-    // we reduce path to a single name if we can find it
-    const char *name = *path;
-    *path = NULL;
-
-    // default to root dir
-    lfs_stag_t tag = LFS_MKTAG(LFS_TYPE_DIR, 0x3ff, 0);
-    lfs_block_t pair[2] = {lfs->root[0], lfs->root[1]};
-
-    while (true) {
-nextname:
-        // skip slashes
-        name += strspn(name, "/");
-        lfs_size_t namelen = strcspn(name, "/");
-
-        // skip '.' and root '..'
-        if ((namelen == 1 && memcmp(name, ".", 1) == 0) ||
-            (namelen == 2 && memcmp(name, "..", 2) == 0)) {
-            name += namelen;
-            goto nextname;
-        }
-
-        // skip if matched by '..' in name
-        const char *suffix = name + namelen;
-        lfs_size_t sufflen;
-        int depth = 1;
-        while (true) {
-            suffix += strspn(suffix, "/");
-            sufflen = strcspn(suffix, "/");
-            if (sufflen == 0) {
-                break;
-            }
-
-            if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
-                depth -= 1;
-                if (depth == 0) {
-                    name = suffix + sufflen;
-                    goto nextname;
-                }
-            } else {
-                depth += 1;
-            }
-
-            suffix += sufflen;
-        }
-
-        // found path
-        if (name[0] == '\0') {
-            return tag;
-        }
-
-        // update what we've found if path is only a name
-        if (strchr(name, '/') == NULL) {
-            *path = name;
-        }
-
-        // only continue if we hit a directory
-        if (lfs_tag_type(tag) != LFS_TYPE_DIR) {
-            return LFS_ERR_NOTDIR;
-        }
-
-        // grab the entry data
-        if (lfs_tag_id(tag) != 0x3ff) {
-            lfs_stag_t res = lfs_dir_get(lfs, dir, 0x7c3ff000,
-                    LFS_MKTAG(LFS_TYPE_STRUCT, lfs_tag_id(tag), 8), pair);
-            if (res < 0) {
-                return res;
-            }
-            lfs_pair_fromle32(pair);
-        }
-
-        // find entry matching name
-        tag = lfs_dir_findmatch(lfs, dir, pair, false, 0x7c000fff,
-                LFS_MKTAG(LFS_TYPE_NAME, 0, namelen),
-                lfs_dir_find_match, &(struct lfs_dir_find_match){
-                    lfs, name, namelen});
-        if (tag < 0) {
-            return tag;
-        }
-
-        // to next name
-        name += namelen;
-    }
-}
-
-static int lfs_dir_getinfo(lfs_t *lfs, lfs_mdir_t *dir,
-        uint16_t id, struct lfs_info *info) {
-    if (id == 0x3ff) {
-        // special case for root
-        strcpy(info->name, "/");
-        info->type = LFS_TYPE_DIR;
-        return 0;
-    }
-
-    lfs_stag_t tag = lfs_dir_get(lfs, dir, 0x7c3ff000,
-            LFS_MKTAG(LFS_TYPE_NAME, id, lfs->name_max+1), info->name);
-    if (tag < 0) {
-        return tag;
-    }
-
-    info->type = lfs_tag_type(tag);
-
-    struct lfs_ctz ctz;
-    tag = lfs_dir_get(lfs, dir, 0x7c3ff000,
-            LFS_MKTAG(LFS_TYPE_STRUCT, id, sizeof(ctz)), &ctz);
-    if (tag < 0) {
-        return tag;
-    }
-    lfs_ctz_fromle32(&ctz);
-
-    if (lfs_tag_type(tag) == LFS_TYPE_CTZSTRUCT) {
-        info->size = ctz.size;
-    } else if (lfs_tag_type(tag) == LFS_TYPE_INLINESTRUCT) {
-        info->size = lfs_tag_size(tag);
-    }
-
-    return 0;
-}
 
 /// Top level directory operations ///
 int lfs_mkdir(lfs_t *lfs, const char *path) {
@@ -2865,7 +2875,7 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
     }
 
     // create move to fix later
-    lfs_global_move(lfs, oldcwd.pair, lfs_tag_id(oldtag));
+    lfs_global_move(lfs, true, oldcwd.pair, lfs_tag_id(oldtag));
 
     // move over all attributes
     err = lfs_dir_commit(lfs, &newcwd,
@@ -3052,10 +3062,7 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
     lfs->root[1] = 0xffffffff;
     lfs->mlist = NULL;
     lfs->seed = 0;
-    lfs->globals.g.movepair[0] = 0xffffffff;
-    lfs->globals.g.movepair[1] = 0xffffffff;
-    lfs->globals.g.moveid = 0x3ff;
-    lfs->globals.g.orphans = 0;
+    lfs_global_zero(&lfs->globals);
     lfs_global_zero(&lfs->locals);
 
     return 0;
@@ -3216,18 +3223,9 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
         }
 
         // has globals?
-        lfs_global_t locals;
-        res = lfs_dir_get(lfs, &dir, 0x7c000000,
-                LFS_MKTAG(LFS_TYPE_GLOBALS, 0, 10), &locals);
-        if (res < 0 && res != LFS_ERR_NOENT) {
-            err = res;
-            goto cleanup;
-        }
-
-        if (res != LFS_ERR_NOENT) {
-            locals.l.deorphaned = (lfs_tag_type(res) & 1);
-            // xor together to find resulting globals
-            lfs_global_xor(&lfs->locals, &locals);
+        err = lfs_dir_getglobals(lfs, &dir, &lfs->locals);
+        if (err) {
+            return err;
         }
     }
 
@@ -3235,11 +3233,9 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
     lfs_global_fromle32(&lfs->locals);
     lfs_global_xor(&lfs->globals, &lfs->locals);
     lfs_global_zero(&lfs->locals);
-    if (!lfs_pair_isnull(lfs->globals.g.movepair)) {
+    if (lfs->globals.hasmove) {
         LFS_DEBUG("Found move %"PRIu32" %"PRIu32" %"PRIu32,
-                lfs->globals.g.movepair[0],
-                lfs->globals.g.movepair[1],
-                lfs->globals.g.moveid);
+                lfs->globals.pair[0], lfs->globals.pair[1], lfs->globals.id);
     }
 
     // setup free lookahead
@@ -3463,7 +3459,36 @@ static int lfs_fs_relocate(lfs_t *lfs,
     return 0;
 }
 
+static int lfs_fs_demove(lfs_t *lfs) {
+    if (!lfs->globals.hasmove) {
+        return 0;
+    }
+
+    // Fix bad moves
+    LFS_DEBUG("Fixing move %"PRIu32" %"PRIu32" %"PRIu32,
+            lfs->globals.pair[0], lfs->globals.pair[1], lfs->globals.id);
+
+    // fetch and delete the moved entry
+    lfs_mdir_t movedir;
+    int err = lfs_dir_fetch(lfs, &movedir, lfs->globals.pair);
+    if (err) {
+        return err;
+    }
+
+    // rely on cancel logic inside commit
+    err = lfs_dir_commit(lfs, &movedir, NULL);
+    if (err) {
+        return err;
+    }
+
+    return 0;
+}
+
 static int lfs_fs_deorphan(lfs_t *lfs) {
+    if (!lfs->globals.orphans) {
+        return 0;
+    }
+
     // Fix any orphans
     lfs_mdir_t pdir = {.split = true};
     lfs_mdir_t dir = {.tail = {0, 1}};
@@ -3527,26 +3552,17 @@ static int lfs_fs_deorphan(lfs_t *lfs) {
     }
 
     // mark orphans as fixed
-    lfs_global_orphans(lfs, -lfs->globals.g.orphans);
+    lfs_global_orphans(lfs, -lfs->globals.orphans);
     return 0;
 }
 
-static int lfs_fs_demove(lfs_t *lfs) {
-    // Fix bad moves
-    LFS_DEBUG("Fixing move %"PRIu32" %"PRIu32" %"PRIu32,
-            lfs->globals.g.movepair[0],
-            lfs->globals.g.movepair[1],
-            lfs->globals.g.moveid);
-
-    // fetch and delete the moved entry
-    lfs_mdir_t movedir;
-    int err = lfs_dir_fetch(lfs, &movedir, lfs->globals.g.movepair);
+static int lfs_fs_forceconsistency(lfs_t *lfs) {
+    int err = lfs_fs_demove(lfs);
     if (err) {
         return err;
     }
 
-    // rely on cancel logic inside commit
-    err = lfs_dir_commit(lfs, &movedir, NULL);
+    err = lfs_fs_deorphan(lfs);
     if (err) {
         return err;
     }
@@ -3554,24 +3570,6 @@ static int lfs_fs_demove(lfs_t *lfs) {
     return 0;
 }
 
-static int lfs_fs_forceconsistency(lfs_t *lfs) {
-    if (lfs->globals.g.orphans) {
-        int err = lfs_fs_deorphan(lfs);
-        if (err) {
-            return err;
-        }
-    }
-
-    if (lfs->globals.g.moveid != 0x3ff) {
-        int err = lfs_fs_demove(lfs);
-        if (err) {
-            return err;
-        }
-    }
-
-    return 0;
-}
-
 static int lfs_fs_size_count(void *p, lfs_block_t block) {
     (void)block;
     lfs_size_t *size = p;
diff --git a/lfs.h b/lfs.h
index 5acb484..23b0bc6 100644
--- a/lfs.h
+++ b/lfs.h
@@ -290,20 +290,6 @@ typedef struct lfs_cache {
     uint8_t *buffer;
 } lfs_cache_t;
 
-typedef union lfs_global {
-    uint32_t u32[3];
-    struct {
-        lfs_block_t movepair[2];
-        uint16_t moveid;
-        uint8_t deorphaned;
-    } l;
-    struct {
-        lfs_block_t movepair[2];
-        uint16_t moveid;
-        uint8_t orphans;
-    } g;
-} lfs_global_t;
-
 typedef struct lfs_mdir {
     lfs_block_t pair[2];
     uint32_t rev;
@@ -373,8 +359,13 @@ typedef struct lfs {
     } *mlist;
     uint32_t seed;
 
-    lfs_global_t globals;
-    lfs_global_t locals;
+    struct lfs_globals {
+        lfs_block_t pair[2];
+        uint16_t id;
+        bool hasmove;
+        uint8_t orphans;
+    } globals, locals;
+
     struct lfs_free {
         lfs_block_t off;
         lfs_block_t size;