]> git.ozlabs.org Git - ccan/blobdiff - ccan/tdb2/check.c
tdb2: fix tdb_check() return when free table entries missing.
[ccan] / ccan / tdb2 / check.c
index 5500883ff2b04cad383953877f4c8f415b06b0b2..c5450cccb0cd17d9e8ba248db18fb272b152023c 100644 (file)
@@ -30,66 +30,78 @@ static bool append(tdb_off_t **arr, size_t *num, tdb_off_t off)
        return true;
 }
 
-static bool check_header(struct tdb_context *tdb)
+static bool check_header(struct tdb_context *tdb, tdb_off_t *recovery)
 {
        uint64_t hash_test;
+       struct tdb_header hdr;
+
+       if (tdb_read_convert(tdb, 0, &hdr, sizeof(hdr)) == -1)
+               return false;
+       /* magic food should not be converted, so convert back. */
+       tdb_convert(tdb, hdr.magic_food, sizeof(hdr.magic_food));
 
        hash_test = TDB_HASH_MAGIC;
        hash_test = tdb_hash(tdb, &hash_test, sizeof(hash_test));
-       if (tdb->header.hash_test != hash_test) {
+       if (hdr.hash_test != hash_test) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                         "check: hash test %llu should be %llu\n",
-                        tdb->header.hash_test, hash_test);
+                        (long long)hdr.hash_test,
+                        (long long)hash_test);
                return false;
        }
-       if (strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
+
+       if (strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                         "check: bad magic '%.*s'\n",
-                        sizeof(tdb->header.magic_food),
-                        tdb->header.magic_food);
-               return false;
-       }
-       if (tdb->header.v.hash_bits < INITIAL_HASH_BITS) {
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "check: bad hash bits %llu\n",
-                        (long long)tdb->header.v.hash_bits);
+                        (unsigned)sizeof(hdr.magic_food), hdr.magic_food);
                return false;
        }
 
-       /* We check hash_off later. */
+       *recovery = hdr.recovery;
+       if (*recovery) {
+               if (*recovery < sizeof(hdr) || *recovery > tdb->map_size) {
+                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                                "tdb_check: invalid recovery offset %zu\n",
+                                (size_t)*recovery);
+                       return false;
+               }
+       }
 
        /* Don't check reserved: they *can* be used later. */
        return true;
 }
 
-static int off_cmp(const tdb_off_t *a, const tdb_off_t *b)
-{
-       /* Can overflow an int. */
-       return *a > *b ? 1
-               : *a < *b ? -1
-               : 0;
-}
-
-static bool check_hash_list(struct tdb_context *tdb,
+static bool check_hash_tree(struct tdb_context *tdb,
+                           tdb_off_t off, unsigned int group_bits,
+                           uint64_t hprefix,
+                           unsigned hprefix_bits,
                            tdb_off_t used[],
-                           size_t num_used)
+                           size_t num_used,
+                           size_t *num_found,
+                           int (*check)(TDB_DATA, TDB_DATA, void *),
+                           void *private_data);
+
+static bool check_hash_record(struct tdb_context *tdb,
+                             tdb_off_t off,
+                             uint64_t hprefix,
+                             unsigned hprefix_bits,
+                             tdb_off_t used[],
+                             size_t num_used,
+                             size_t *num_found,
+                             int (*check)(TDB_DATA, TDB_DATA, void *),
+                             void *private_data)
 {
        struct tdb_used_record rec;
-       tdb_len_t hashlen, i, num_nonzero;
-       tdb_off_t h;
-       size_t num_found;
-
-       hashlen = sizeof(tdb_off_t) << tdb->header.v.hash_bits;
 
-       if (tdb_read_convert(tdb, tdb->header.v.hash_off - sizeof(rec),
-                            &rec, sizeof(rec)) == -1)
+       if (tdb_read_convert(tdb, off, &rec, sizeof(rec)) == -1)
                return false;
 
-       if (rec_data_length(&rec) != hashlen) {
+       if (rec_data_length(&rec)
+           != sizeof(tdb_off_t) << TDB_SUBLEVEL_HASH_BITS) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                         "tdb_check: Bad hash table length %llu vs %llu\n",
                         (long long)rec_data_length(&rec),
-                        (long long)hashlen);
+                        (long long)sizeof(tdb_off_t)<<TDB_SUBLEVEL_HASH_BITS);
                return false;
        }
        if (rec_key_length(&rec) != 0) {
@@ -105,69 +117,194 @@ static bool check_hash_list(struct tdb_context *tdb,
                return false;
        }
 
-       num_found = 0;
-       num_nonzero = 0;
-       for (i = 0, h = tdb->header.v.hash_off;
-            i < (1ULL << tdb->header.v.hash_bits);
-            i++, h += sizeof(tdb_off_t)) {
-               tdb_off_t off, *p, pos;
-               struct tdb_used_record rec;
-               uint64_t hash;
-
-               off = tdb_read_off(tdb, h);
-               if (off == TDB_OFF_ERR)
-                       return false;
-               if (!off) {
-                       num_nonzero = 0;
-                       continue;
-               }
-               /* FIXME: Check hash bits */
-               p = asearch(&off, used, num_used, off_cmp);
-               if (!p) {
-                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                "tdb_check: Invalid offset %llu in hash\n",
-                                (long long)off);
-                       return false;
-               }
-               /* Mark it invalid. */
-               *p ^= 1;
-               num_found++;
+       off += sizeof(rec);
+       return check_hash_tree(tdb, off,
+                              TDB_SUBLEVEL_HASH_BITS-TDB_HASH_GROUP_BITS,
+                              hprefix, hprefix_bits,
+                              used, num_used, num_found, check, private_data);
+}
 
-               if (tdb_read_convert(tdb, off, &rec, sizeof(rec)) == -1)
-                       return false;
+static int off_cmp(const tdb_off_t *a, const tdb_off_t *b)
+{
+       /* Can overflow an int. */
+       return *a > *b ? 1
+               : *a < *b ? -1
+               : 0;
+}
 
-               /* Check it is hashed correctly. */
-               hash = hash_record(tdb, off);
+static uint64_t get_bits(uint64_t h, unsigned num, unsigned *used)
+{
+       *used += num;
 
-               /* Top bits must match header. */
-               if (hash >> (64 - 5) != rec_hash(&rec)) {
-                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                "tdb_check: Bad hash magic at offset %llu"
-                                " (0x%llx vs 0x%llx)\n",
-                                (long long)off,
-                                (long long)hash, (long long)rec_hash(&rec));
-                       return false;
-               }
+       return (h >> (64 - *used)) & ((1U << num) - 1);
+}
+
+static bool check_hash_tree(struct tdb_context *tdb,
+                           tdb_off_t off, unsigned int group_bits,
+                           uint64_t hprefix,
+                           unsigned hprefix_bits,
+                           tdb_off_t used[],
+                           size_t num_used,
+                           size_t *num_found,
+                           int (*check)(TDB_DATA, TDB_DATA, void *),
+                           void *private_data)
+{
+       unsigned int g, b;
+       const tdb_off_t *hash;
+       struct tdb_used_record rec;
+
+       hash = tdb_access_read(tdb, off,
+                              sizeof(tdb_off_t)
+                              << (group_bits + TDB_HASH_GROUP_BITS),
+                              true);
+       if (!hash)
+               return false;
 
-               /* It must be in the right place in hash array. */
-               pos = hash & ((1ULL << tdb->header.v.hash_bits)-1);
-               if (pos < i - num_nonzero || pos > i) {
-                       /* Could be wrap from end of array?  FIXME: check? */
-                       if (i != num_nonzero) {
+       for (g = 0; g < (1 << group_bits); g++) {
+               const tdb_off_t *group = hash + (g << TDB_HASH_GROUP_BITS);
+               for (b = 0; b < (1 << TDB_HASH_GROUP_BITS); b++) {
+                       unsigned int bucket, i, used_bits;
+                       uint64_t h;
+                       tdb_off_t *p;
+                       if (group[b] == 0)
+                               continue;
+
+                       off = group[b] & TDB_OFF_MASK;
+                       p = asearch(&off, used, num_used, off_cmp);
+                       if (!p) {
                                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                        "tdb_check: Bad hash position %llu at"
-                                        " offset %llu hash 0x%llx\n",
-                                        (long long)i,
+                                        "tdb_check: Invalid offset %llu "
+                                        "in hash\n",
+                                        (long long)off);
+                               goto fail;
+                       }
+                       /* Mark it invalid. */
+                       *p ^= 1;
+                       (*num_found)++;
+
+                       if (is_subhash(group[b])) {
+                               uint64_t subprefix;
+                               subprefix = (hprefix 
+                                    << (group_bits + TDB_HASH_GROUP_BITS))
+                                       + g * (1 << TDB_HASH_GROUP_BITS) + b;
+
+                               if (!check_hash_record(tdb,
+                                              group[b] & TDB_OFF_MASK,
+                                              subprefix,
+                                              hprefix_bits
+                                                      + group_bits
+                                                      + TDB_HASH_GROUP_BITS,
+                                              used, num_used, num_found,
+                                              check, private_data))
+                                       goto fail;
+                               continue;
+                       }
+                       /* A normal entry */
+
+                       /* Does it belong here at all? */
+                       h = hash_record(tdb, off);
+                       used_bits = 0;
+                       if (get_bits(h, hprefix_bits, &used_bits) != hprefix
+                           && hprefix_bits) {
+                               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                                        "check: bad hash placement"
+                                        " 0x%llx vs 0x%llx\n",
+                                        (long long)h, (long long)hprefix);
+                               goto fail;
+                       }
+
+                       /* Does it belong in this group? */
+                       if (get_bits(h, group_bits, &used_bits) != g) {
+                               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                                        "check: bad group %llu vs %u\n",
+                                        (long long)h, g);
+                               goto fail;
+                       }
+
+                       /* Are bucket bits correct? */
+                       bucket = group[b] & TDB_OFF_HASH_GROUP_MASK;
+                       if (get_bits(h, TDB_HASH_GROUP_BITS, &used_bits)
+                           != bucket) {
+                               used_bits -= TDB_HASH_GROUP_BITS;
+                               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                                        "check: bad bucket %u vs %u\n",
+                                        (unsigned)get_bits(h,
+                                                           TDB_HASH_GROUP_BITS,
+                                                           &used_bits),
+                                        bucket);
+                               goto fail;
+                       }
+
+                       /* There must not be any zero entries between
+                        * the bucket it belongs in and this one! */
+                       for (i = bucket;
+                            i != b;
+                            i = (i + 1) % (1 << TDB_HASH_GROUP_BITS)) {
+                               if (group[i] == 0) {
+                                       tdb->log(tdb, TDB_DEBUG_ERROR,
+                                                tdb->log_priv,
+                                                "check: bad group placement"
+                                                " %u vs %u\n",
+                                                b, bucket);
+                                       goto fail;
+                               }
+                       }
+
+                       if (tdb_read_convert(tdb, off, &rec, sizeof(rec)) == -1)
+                               goto fail;
+
+                       /* Bottom bits must match header. */
+                       if ((h & ((1 << 11)-1)) != rec_hash(&rec)) {
+                               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                                        "tdb_check: Bad hash magic at"
+                                        " offset %llu (0x%llx vs 0x%llx)\n",
                                         (long long)off,
-                                        (long long)hash);
-                               return false;
+                                        (long long)h,
+                                        (long long)rec_hash(&rec));
+                               goto fail;
+                       }
+
+                       if (check) {
+                               TDB_DATA key, data;
+                               key.dsize = rec_key_length(&rec);
+                               data.dsize = rec_data_length(&rec);
+                               key.dptr = (void *)tdb_access_read(tdb,
+                                                  off + sizeof(rec),
+                                                  key.dsize + data.dsize,
+                                                  false);
+                               if (!key.dptr)
+                                       goto fail;
+                               data.dptr = key.dptr + key.dsize;
+                               if (check(key, data, private_data) != 0)
+                                       goto fail;
+                               tdb_access_release(tdb, key.dptr);
                        }
                }
-               num_nonzero++;
        }
+       tdb_access_release(tdb, hash);
+       return true;
 
-       /* hash table is one of the used blocks. */
-       if (num_found != num_used - 1) {
+fail:
+       tdb_access_release(tdb, hash);
+       return false;
+}
+
+static bool check_hash(struct tdb_context *tdb,
+                      tdb_off_t used[],
+                      size_t num_used, size_t num_flists,
+                      int (*check)(TDB_DATA, TDB_DATA, void *),
+                      void *private_data)
+{
+       /* Free lists also show up as used. */
+       size_t num_found = num_flists;
+
+       if (!check_hash_tree(tdb, offsetof(struct tdb_header, hashtable),
+                            TDB_TOPLEVEL_HASH_BITS-TDB_HASH_GROUP_BITS,
+                            0, 0, used, num_used, &num_found,
+                            check, private_data))
+               return false;
+
+       if (num_found != num_used) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                         "tdb_check: Not all entries are in hash\n");
                return false;
@@ -178,8 +315,7 @@ static bool check_hash_list(struct tdb_context *tdb,
 static bool check_free(struct tdb_context *tdb,
                       tdb_off_t off,
                       const struct tdb_free_record *frec,
-                      tdb_off_t prev,
-                      tdb_off_t zone_off, unsigned int bucket)
+                      tdb_off_t prev, tdb_off_t flist_off, unsigned int bucket)
 {
        if (frec_magic(frec) != TDB_FREE_MAGIC) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
@@ -187,24 +323,22 @@ static bool check_free(struct tdb_context *tdb,
                         (long long)off, (long long)frec->magic_and_meta);
                return false;
        }
-       if (tdb->methods->oob(tdb, off
-                             + frec->data_len-sizeof(struct tdb_used_record),
-                             true))
-               return false;
-       if (off < zone_off || off >= zone_off + (1ULL<<frec_zone_bits(frec))) {
+       if (frec_flist(frec) != flist_off) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "tdb_check: offset %llu outside zone %llu-%llu\n",
-                        (long long)off,
-                        (long long)zone_off,
-                        (long long)zone_off + (1ULL<<frec_zone_bits(frec)));
+                        "tdb_check: offset %llu bad freelist 0x%llx\n",
+                        (long long)off, (long long)frec_flist(frec));
                return false;
        }
-       if (size_to_bucket(frec_zone_bits(frec), frec->data_len) != bucket) {
+
+       if (tdb->methods->oob(tdb, off
+                             + frec->data_len+sizeof(struct tdb_used_record),
+                             false))
+               return false;
+       if (size_to_bucket(frec->data_len) != bucket) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                         "tdb_check: offset %llu in wrong bucket %u vs %u\n",
                         (long long)off,
-                        bucket,
-                        size_to_bucket(frec_zone_bits(frec), frec->data_len));
+                        bucket, size_to_bucket(frec->data_len));
                return false;
        }
        if (prev != frec->prev) {
@@ -217,30 +351,40 @@ static bool check_free(struct tdb_context *tdb,
        return true;
 }
                       
-static tdb_len_t check_free_list(struct tdb_context *tdb,
-                                tdb_off_t zone_off,
-                                tdb_off_t free[],
-                                size_t num_free,
-                                size_t *num_found)
+static bool check_free_list(struct tdb_context *tdb,
+                           tdb_off_t flist_off,
+                           tdb_off_t free[],
+                           size_t num_free,
+                           size_t *num_found)
 {
-       struct free_zone_header zhdr;
+       struct tdb_freelist flist;
        tdb_off_t h;
        unsigned int i;
 
-       if (tdb_read_convert(tdb, zone_off, &zhdr, sizeof(zhdr)) == -1)
-               return TDB_OFF_ERR;
+       if (tdb_read_convert(tdb, flist_off, &flist, sizeof(flist)) == -1)
+               return false;
 
-       for (i = 0; i <= BUCKETS_FOR_ZONE(zhdr.zone_bits); i++) {
+       if (rec_magic(&flist.hdr) != TDB_MAGIC
+           || rec_key_length(&flist.hdr) != 0
+           || rec_data_length(&flist.hdr) != sizeof(flist) - sizeof(flist.hdr)
+           || rec_hash(&flist.hdr) != 1) {
+               tdb->log(tdb, TDB_DEBUG_ERROR,
+                        tdb->log_priv,
+                        "tdb_check: Invalid header on free list\n");
+               return false;
+       }
+
+       for (i = 0; i < TDB_FREE_BUCKETS; i++) {
                tdb_off_t off, prev = 0, *p;
                struct tdb_free_record f;
 
-               h = bucket_off(zone_off, i);
+               h = bucket_off(flist_off, i);
                for (off = tdb_read_off(tdb, h); off; off = f.next) {
                        if (off == TDB_OFF_ERR)
                                return false;
                        if (tdb_read_convert(tdb, off, &f, sizeof(f)))
                                return false;
-                       if (!check_free(tdb, off, &f, prev, zone_off, i))
+                       if (!check_free(tdb, off, &f, prev, flist_off, i))
                                return false;
 
                        /* FIXME: Check hash bits */
@@ -259,74 +403,88 @@ static tdb_len_t check_free_list(struct tdb_context *tdb,
                        prev = off;
                }
        }
-       return 1ULL << zhdr.zone_bits;
+       return true;
 }
 
-static tdb_off_t check_zone(struct tdb_context *tdb, tdb_off_t zone_off,
-                           tdb_off_t **used, size_t *num_used,
-                           tdb_off_t **free, size_t *num_free,
-                           bool *hash_found, unsigned int *max_zone_bits)
+/* Slow, but should be very rare. */
+size_t dead_space(struct tdb_context *tdb, tdb_off_t off)
 {
-       struct free_zone_header zhdr;
-       tdb_off_t off, hdrlen;
-       tdb_len_t len;
-
-       if (tdb_read_convert(tdb, zone_off, &zhdr, sizeof(zhdr)) == -1)
-               return TDB_OFF_ERR;
-
-       if (zhdr.zone_bits < INITIAL_ZONE_BITS) {
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "check: bad zone_bits %llu at zone %llu\n",
-                        (long long)zhdr.zone_bits, (long long)zone_off);
-               return TDB_OFF_ERR;
-       }
-
-       /* Zone bits can only increase... */
-       if (zhdr.zone_bits > *max_zone_bits)
-               *max_zone_bits = zhdr.zone_bits;
-       else if (zhdr.zone_bits < *max_zone_bits) {
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "check: small zone_bits %llu at zone %llu\n",
-                        (long long)zhdr.zone_bits, (long long)zone_off);
-               return TDB_OFF_ERR;
+       size_t len;
+
+       for (len = 0; off + len < tdb->map_size; len++) {
+               char c;
+               if (tdb->methods->read(tdb, off, &c, 1))
+                       return 0;
+               if (c != 0 && c != 0x43)
+                       break;
        }
+       return len;
+}
 
-       /* Zone must be within file! */
-       if (tdb->methods->oob(tdb, zone_off + (1ULL << zhdr.zone_bits), false))
-               return TDB_OFF_ERR;
+static bool check_linear(struct tdb_context *tdb,
+                        tdb_off_t **used, size_t *num_used,
+                        tdb_off_t **free, size_t *num_free,
+                        tdb_off_t recovery)
+{
+       tdb_off_t off;
+       tdb_len_t len;
+       bool found_recovery = false;
 
-       hdrlen = sizeof(zhdr)
-               + (BUCKETS_FOR_ZONE(zhdr.zone_bits) + 1) * sizeof(tdb_off_t);
-       for (off = zone_off + hdrlen;
-            off < zone_off + (1ULL << zhdr.zone_bits);
-            off += len) {
+       for (off = sizeof(struct tdb_header); off < tdb->map_size; off += len) {
                union {
                        struct tdb_used_record u;
                        struct tdb_free_record f;
+                       struct tdb_recovery_record r;
                } pad, *p;
                p = tdb_get(tdb, off, &pad, sizeof(pad));
                if (!p)
-                       return TDB_OFF_ERR;
-               if (frec_magic(&p->f) == TDB_FREE_MAGIC) {
-                       if (frec_zone_bits(&p->f) != zhdr.zone_bits) {
+                       return false;
+
+               /* If we crash after ftruncate, we can get zeroes or fill. */
+               if (p->r.magic == TDB_RECOVERY_INVALID_MAGIC
+                   || p->r.magic ==  0x4343434343434343ULL) {
+                       if (recovery == off) {
+                               found_recovery = true;
+                               len = sizeof(p->r) + p->r.max_len;
+                       } else {
+                               len = dead_space(tdb, off);
+                               if (len < sizeof(p->r)) {
+                                       tdb->log(tdb, TDB_DEBUG_ERROR,
+                                                tdb->log_priv,
+                                                "tdb_check: invalid dead space"
+                                                " at %zu\n", (size_t)off);
+                                       return false;
+                               }
+
+                               tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
+                                        "Dead space at %zu-%zu (of %zu)\n",
+                                        (size_t)off, (size_t)(off + len),
+                                        (size_t)tdb->map_size);
+                       }
+               } else if (p->r.magic == TDB_RECOVERY_MAGIC) {
+                       if (recovery != off) {
                                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                        "tdb_check: Bad free zone bits %u"
-                                        " at offset %llu\n",
-                                        frec_zone_bits(&p->f),
-                                        (long long)off);
-                               return TDB_OFF_ERR;
+                                        "tdb_check: unexpected recovery"
+                                        " record at offset %zu\n",
+                                        (size_t)off);
+                               return false;
                        }
-                       /* This record is free! */
-                       if (!append(free, num_free, off))
-                               return TDB_OFF_ERR;
+                       found_recovery = true;
+                       len = sizeof(p->r) + p->r.max_len;
+               } else if (frec_magic(&p->f) == TDB_FREE_MAGIC
+                          || frec_magic(&p->f) == TDB_COALESCING_MAGIC) {
                        len = sizeof(p->u) + p->f.data_len;
-                       if (off + len > zone_off + (1ULL << zhdr.zone_bits)) {
+                       if (off + len > tdb->map_size) {
                                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                                         "tdb_check: free overlength %llu"
                                         " at offset %llu\n",
                                         (long long)len, (long long)off);
-                               return TDB_OFF_ERR;
+                               return false;
                        }
+                       /* This record is free! */
+                       if (frec_magic(&p->f) == TDB_FREE_MAGIC
+                           && !append(free, num_free, off))
+                               return false;
                } else {
                        uint64_t klen, dlen, extra;
 
@@ -337,32 +495,23 @@ static tdb_off_t check_zone(struct tdb_context *tdb, tdb_off_t zone_off,
                                         " at offset %llu\n",
                                         (long long)rec_magic(&p->u),
                                         (long long)off);
-                               return TDB_OFF_ERR;
+                               return false;
                        }
 
-                       if (rec_zone_bits(&p->u) != zhdr.zone_bits) {
-                               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                        "tdb_check: Bad zone bits %u"
-                                        " at offset %llu\n",
-                                        rec_zone_bits(&p->u),
-                                        (long long)off);
-                               return TDB_OFF_ERR;
-                       }
-                       
                        if (!append(used, num_used, off))
-                               return TDB_OFF_ERR;
+                               return false;
 
                        klen = rec_key_length(&p->u);
                        dlen = rec_data_length(&p->u);
                        extra = rec_extra_padding(&p->u);
 
                        len = sizeof(p->u) + klen + dlen + extra;
-                       if (off + len > zone_off + (1ULL << zhdr.zone_bits)) {
+                       if (off + len > tdb->map_size) {
                                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                                         "tdb_check: used overlength %llu"
                                         " at offset %llu\n",
                                         (long long)len, (long long)off);
-                               return TDB_OFF_ERR;
+                               return false;
                        }
 
                        if (len < sizeof(p->f)) {
@@ -370,85 +519,68 @@ static tdb_off_t check_zone(struct tdb_context *tdb, tdb_off_t zone_off,
                                         "tdb_check: too short record %llu at"
                                         " %llu\n",
                                         (long long)len, (long long)off);
-                               return TDB_OFF_ERR;
+                               return false;
                        }
-
-                       if (off + sizeof(p->u) == tdb->header.v.hash_off)
-                               *hash_found = true;
                }
        }
-       return 1ULL << zhdr.zone_bits;
+
+       /* We must have found recovery area if there was one. */
+       if (recovery != 0 && !found_recovery) {
+               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                        "tdb_check: expected a recovery area at %zu\n",
+                        (size_t)recovery);
+               return false;
+       }
+
+       return true;
 }
 
-/* FIXME: call check() function. */
 int tdb_check(struct tdb_context *tdb,
              int (*check)(TDB_DATA key, TDB_DATA data, void *private_data),
              void *private_data)
 {
-       tdb_off_t *free = NULL, *used = NULL, off;
-       tdb_len_t len;
-       size_t num_free = 0, num_used = 0, num_found = 0;
-       bool hash_found = false;
-       unsigned max_zone_bits = INITIAL_ZONE_BITS;
-       uint8_t tailer;
+       tdb_off_t *free = NULL, *used = NULL, flist, recovery;
+       size_t num_free = 0, num_used = 0, num_found = 0, num_flists = 0;
 
-       /* FIXME: need more locking? against expansion? */
-       /* This always ensures the header is uptodate. */
        if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false) != 0)
                return -1;
 
-       if (!check_header(tdb))
-               goto fail;
-
-       /* First we do a linear scan, checking all records. */
-       for (off = sizeof(struct tdb_header);
-            off < tdb->map_size - 1;
-            off += len) {
-               len = check_zone(tdb, off, &used, &num_used, &free, &num_free,
-                                &hash_found, &max_zone_bits);
-               if (len == TDB_OFF_ERR)
-                       goto fail;
+       if (tdb_lock_expand(tdb, F_RDLCK) != 0) {
+               tdb_allrecord_unlock(tdb, F_RDLCK);
+               return -1;
        }
 
-       /* Check tailer. */
-       if (tdb->methods->read(tdb, tdb->map_size - 1, &tailer, 1) == -1)
+       if (!check_header(tdb, &recovery))
                goto fail;
-       if (tailer != max_zone_bits) {
-               tdb->ecode = TDB_ERR_CORRUPT;
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "tdb_check: Bad tailer value %u vs %u\n", tailer,
-                        max_zone_bits);
-               goto fail;
-       }
 
-       if (!hash_found) {
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "tdb_check: hash table not found at %llu\n",
-                        (long long)tdb->header.v.hash_off);
+       /* First we do a linear scan, checking all records. */
+       if (!check_linear(tdb, &used, &num_used, &free, &num_free, recovery))
                goto fail;
+
+       for (flist = first_flist(tdb); flist; flist = next_flist(tdb, flist)) {
+               if (flist == TDB_OFF_ERR)
+                       goto fail;
+               if (!check_free_list(tdb, flist, free, num_free, &num_found))
+                       goto fail;
+               num_flists++;
        }
 
        /* FIXME: Check key uniqueness? */
-       if (!check_hash_list(tdb, used, num_used))
+       if (!check_hash(tdb, used, num_used, num_flists, check, private_data))
                goto fail;
 
-       for (off = sizeof(struct tdb_header);
-            off < tdb->map_size - 1;
-            off += len) {
-               len = check_free_list(tdb, off, free, num_free, &num_found);
-               if (len == TDB_OFF_ERR)
-                       goto fail;
-       }
        if (num_found != num_free) {
                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                         "tdb_check: Not all entries are in free table\n");
-               return false;
+               return -1;
        }
 
        tdb_allrecord_unlock(tdb, F_RDLCK);
+       tdb_unlock_expand(tdb, F_RDLCK);
        return 0;
 
 fail:
        tdb_allrecord_unlock(tdb, F_RDLCK);
+       tdb_unlock_expand(tdb, F_RDLCK);
        return -1;
 }