1 files changed, 395 insertions, 655 deletions

diff --git a/lib/ntdb/hash.c b/lib/ntdb/hash.c
index e87705b123..69192a119b 100644
--- a/lib/ntdb/hash.c
+++ b/lib/ntdb/hash.c
@@ -17,68 +17,23 @@
 */
 #include "private.h"
 #include <ccan/hash/hash.h>
-#include <assert.h>
 
 /* Default hash function. */
-uint64_t ntdb_jenkins_hash(const void *key, size_t length, uint64_t seed,
+uint32_t ntdb_jenkins_hash(const void *key, size_t length, uint32_t seed,
 			  void *unused)
 {
-	uint64_t ret;
-	/* hash64_stable assumes lower bits are more important; they are a
-	 * slightly better hash.  We use the upper bits first, so swap them. */
-	ret = hash64_stable((const unsigned char *)key, length, seed);
-	return (ret >> 32) | (ret << 32);
+	return hash_stable((const unsigned char *)key, length, seed);
 }
 
-uint64_t ntdb_hash(struct ntdb_context *ntdb, const void *ptr, size_t len)
+uint32_t ntdb_hash(struct ntdb_context *ntdb, const void *ptr, size_t len)
 {
 	return ntdb->hash_fn(ptr, len, ntdb->hash_seed, ntdb->hash_data);
 }
 
-uint64_t hash_record(struct ntdb_context *ntdb, ntdb_off_t off)
-{
-	const struct ntdb_used_record *r;
-	const void *key;
-	uint64_t klen, hash;
-
-	r = ntdb_access_read(ntdb, off, sizeof(*r), true);
-	if (NTDB_PTR_IS_ERR(r)) {
-		/* FIXME */
-		return 0;
-	}
-
-	klen = rec_key_length(r);
-	ntdb_access_release(ntdb, r);
-
-	key = ntdb_access_read(ntdb, off + sizeof(*r), klen, false);
-	if (NTDB_PTR_IS_ERR(key)) {
-		return 0;
-	}
-
-	hash = ntdb_hash(ntdb, key, klen);
-	ntdb_access_release(ntdb, key);
-	return hash;
-}
-
-/* Get bits from a value. */
-static uint32_t bits_from(uint64_t val, unsigned start, unsigned num)
-{
-	assert(num <= 32);
-	return (val >> start) & ((1U << num) - 1);
-}
-
-/* We take bits from the top: that way we can lock whole sections of the hash
- * by using lock ranges. */
-static uint32_t use_bits(struct hash_info *h, unsigned num)
-{
-	h->hash_used += num;
-	return bits_from(h->h, 64 - h->hash_used, num);
-}
-
 static ntdb_bool_err key_matches(struct ntdb_context *ntdb,
-				const struct ntdb_used_record *rec,
-				ntdb_off_t off,
-				const NTDB_DATA *key)
+				 const struct ntdb_used_record *rec,
+				 ntdb_off_t off,
+				 const NTDB_DATA *key)
 {
 	ntdb_bool_err ret = false;
 	const char *rkey;
@@ -102,792 +57,577 @@ static ntdb_bool_err key_matches(struct ntdb_context *ntdb,
 
 /* Does entry match? */
 static ntdb_bool_err match(struct ntdb_context *ntdb,
-			  struct hash_info *h,
-			  const NTDB_DATA *key,
-			  ntdb_off_t val,
-			  struct ntdb_used_record *rec)
+			   uint32_t hash,
+			   const NTDB_DATA *key,
+			   ntdb_off_t val,
+			   struct ntdb_used_record *rec,
+			   const ntdb_off_t **mapped)
 {
 	ntdb_off_t off;
 	enum NTDB_ERROR ecode;
 
 	ntdb->stats.compares++;
-	/* Desired bucket must match. */
-	if (h->home_bucket != (val & NTDB_OFF_HASH_GROUP_MASK)) {
-		ntdb->stats.compare_wrong_bucket++;
-		return false;
-	}
 
 	/* Top bits of offset == next bits of hash. */
-	if (bits_from(val, NTDB_OFF_HASH_EXTRA_BIT, NTDB_OFF_UPPER_STEAL_EXTRA)
-	    != bits_from(h->h, 64 - h->hash_used - NTDB_OFF_UPPER_STEAL_EXTRA,
-		    NTDB_OFF_UPPER_STEAL_EXTRA)) {
+	if (bits_from(hash, ntdb->hash_bits, NTDB_OFF_UPPER_STEAL)
+	    != bits_from(val, 64-NTDB_OFF_UPPER_STEAL, NTDB_OFF_UPPER_STEAL)) {
 		ntdb->stats.compare_wrong_offsetbits++;
 		return false;
 	}
 
+	/* Unmap before we try to read actual record, which may cause expand */
+	if (mapped) {
+		ntdb_access_release(ntdb, *mapped);
+		*mapped = NULL;
+	}
+
 	off = val & NTDB_OFF_MASK;
 	ecode = ntdb_read_convert(ntdb, off, rec, sizeof(*rec));
 	if (ecode != NTDB_SUCCESS) {
 		return (ntdb_bool_err)ecode;
 	}
 
-	if ((h->h & ((1 << 11)-1)) != rec_hash(rec)) {
-		ntdb->stats.compare_wrong_rechash++;
-		return false;
-	}
-
 	return key_matches(ntdb, rec, off, key);
 }
 
-static ntdb_off_t hbucket_off(ntdb_off_t group_start, unsigned bucket)
-{
-	return group_start
-		+ (bucket % (1 << NTDB_HASH_GROUP_BITS)) * sizeof(ntdb_off_t);
-}
-
-bool is_subhash(ntdb_off_t val)
+static bool is_chain(ntdb_off_t val)
 {
-	return (val >> NTDB_OFF_UPPER_STEAL_SUBHASH_BIT) & 1;
+	return val & (1ULL << NTDB_OFF_CHAIN_BIT);
 }
 
-/* FIXME: Guess the depth, don't over-lock! */
-static ntdb_off_t hlock_range(ntdb_off_t group, ntdb_off_t *size)
+static ntdb_off_t hbucket_off(ntdb_off_t base, ntdb_len_t idx)
 {
-	*size = 1ULL << (64 - (NTDB_TOPLEVEL_HASH_BITS - NTDB_HASH_GROUP_BITS));
-	return group << (64 - (NTDB_TOPLEVEL_HASH_BITS - NTDB_HASH_GROUP_BITS));
-}
-
-static ntdb_off_t COLD find_in_chain(struct ntdb_context *ntdb,
-				    NTDB_DATA key,
-				    ntdb_off_t chain,
-				    struct hash_info *h,
-				    struct ntdb_used_record *rec,
-				    struct traverse_info *tinfo)
-{
-	ntdb_off_t off, next;
-	enum NTDB_ERROR ecode;
-
-	/* In case nothing is free, we set these to zero. */
-	h->home_bucket = h->found_bucket = 0;
-
-	for (off = chain; off; off = next) {
-		unsigned int i;
-
-		h->group_start = off;
-		ecode = ntdb_read_convert(ntdb, off, h->group, sizeof(h->group));
-		if (ecode != NTDB_SUCCESS) {
-			return NTDB_ERR_TO_OFF(ecode);
-		}
-
-		for (i = 0; i < (1 << NTDB_HASH_GROUP_BITS); i++) {
-			ntdb_off_t recoff;
-			if (!h->group[i]) {
-				/* Remember this empty bucket. */
-				h->home_bucket = h->found_bucket = i;
-				continue;
-			}
-
-			/* We can insert extra bits via add_to_hash
-			 * empty bucket logic. */
-			recoff = h->group[i] & NTDB_OFF_MASK;
-			ecode = ntdb_read_convert(ntdb, recoff, rec,
-						 sizeof(*rec));
-			if (ecode != NTDB_SUCCESS) {
-				return NTDB_ERR_TO_OFF(ecode);
-			}
-
-			ecode = NTDB_OFF_TO_ERR(key_matches(ntdb, rec, recoff,
-							   &key));
-			if (ecode < 0) {
-				return NTDB_ERR_TO_OFF(ecode);
-			}
-			if (ecode == (enum NTDB_ERROR)1) {
-				h->home_bucket = h->found_bucket = i;
-
-				if (tinfo) {
-					tinfo->levels[tinfo->num_levels]
-						.hashtable = off;
-					tinfo->levels[tinfo->num_levels]
-						.total_buckets
-						= 1 << NTDB_HASH_GROUP_BITS;
-					tinfo->levels[tinfo->num_levels].entry
-						= i;
-					tinfo->num_levels++;
-				}
-				return recoff;
-			}
-		}
-		next = ntdb_read_off(ntdb, off
-				    + offsetof(struct ntdb_chain, next));
-		if (NTDB_OFF_IS_ERR(next)) {
-			return next;
-		}
-		if (next)
-			next += sizeof(struct ntdb_used_record);
-	}
-	return 0;
+	return base + sizeof(struct ntdb_used_record)
+		+ idx * sizeof(ntdb_off_t);
 }
 
 /* This is the core routine which searches the hashtable for an entry.
  * On error, no locks are held and -ve is returned.
- * Otherwise, hinfo is filled in (and the optional tinfo).
+ * Otherwise, hinfo is filled in.
  * If not found, the return value is 0.
  * If found, the return value is the offset, and *rec is the record. */
 ntdb_off_t find_and_lock(struct ntdb_context *ntdb,
 			NTDB_DATA key,
 			int ltype,
 			struct hash_info *h,
-			struct ntdb_used_record *rec,
-			struct traverse_info *tinfo)
+			struct ntdb_used_record *rec)
 {
-	uint32_t i, group;
-	ntdb_off_t hashtable;
+	ntdb_off_t off, val;
+	const ntdb_off_t *arr = NULL;
+	ntdb_len_t i;
+	bool found_empty;
 	enum NTDB_ERROR ecode;
+	struct ntdb_used_record chdr;
+	ntdb_bool_err berr;
 
 	h->h = ntdb_hash(ntdb, key.dptr, key.dsize);
-	h->hash_used = 0;
-	group = use_bits(h, NTDB_TOPLEVEL_HASH_BITS - NTDB_HASH_GROUP_BITS);
-	h->home_bucket = use_bits(h, NTDB_HASH_GROUP_BITS);
 
-	h->hlock_start = hlock_range(group, &h->hlock_range);
-	ecode = ntdb_lock_hashes(ntdb, h->hlock_start, h->hlock_range, ltype,
-				NTDB_LOCK_WAIT);
+	h->table = NTDB_HASH_OFFSET;
+	h->table_size = 1 << ntdb->hash_bits;
+	h->bucket = bits_from(h->h, 0, ntdb->hash_bits);
+	h->old_val = 0;
+
+	ecode = ntdb_lock_hash(ntdb, h->bucket, ltype);
 	if (ecode != NTDB_SUCCESS) {
 		return NTDB_ERR_TO_OFF(ecode);
 	}
 
-	hashtable = offsetof(struct ntdb_header, hashtable);
-	if (tinfo) {
-		tinfo->toplevel_group = group;
-		tinfo->num_levels = 1;
-		tinfo->levels[0].entry = 0;
-		tinfo->levels[0].hashtable = hashtable
-			+ (group << NTDB_HASH_GROUP_BITS) * sizeof(ntdb_off_t);
-		tinfo->levels[0].total_buckets = 1 << NTDB_HASH_GROUP_BITS;
+	off = hbucket_off(h->table, h->bucket);
+	val = ntdb_read_off(ntdb, off);
+	if (NTDB_OFF_IS_ERR(val)) {
+		ecode = NTDB_OFF_TO_ERR(val);
+		goto fail;
 	}
 
-	while (h->hash_used <= 64) {
-		/* Read in the hash group. */
-		h->group_start = hashtable
-			+ group * (sizeof(ntdb_off_t) << NTDB_HASH_GROUP_BITS);
-
-		ecode = ntdb_read_convert(ntdb, h->group_start, &h->group,
-					 sizeof(h->group));
-		if (ecode != NTDB_SUCCESS) {
-			goto fail;
-		}
-
-		/* Pointer to another hash table?  Go down... */
-		if (is_subhash(h->group[h->home_bucket])) {
-			hashtable = (h->group[h->home_bucket] & NTDB_OFF_MASK)
-				+ sizeof(struct ntdb_used_record);
-			if (tinfo) {
-				/* When we come back, use *next* bucket */
-				tinfo->levels[tinfo->num_levels-1].entry
-					+= h->home_bucket + 1;
+	/* Directly in hash table? */
+	if (!is_chain(val)) {
+		if (val) {
+			berr = match(ntdb, h->h, &key, val, rec, NULL);
+			if (berr < 0) {
+				ecode = NTDB_OFF_TO_ERR(berr);
+				goto fail;
 			}
-			group = use_bits(h, NTDB_SUBLEVEL_HASH_BITS
-					 - NTDB_HASH_GROUP_BITS);
-			h->home_bucket = use_bits(h, NTDB_HASH_GROUP_BITS);
-			if (tinfo) {
-				tinfo->levels[tinfo->num_levels].hashtable
-					= hashtable;
-				tinfo->levels[tinfo->num_levels].total_buckets
-					= 1 << NTDB_SUBLEVEL_HASH_BITS;
-				tinfo->levels[tinfo->num_levels].entry
-					= group << NTDB_HASH_GROUP_BITS;
-				tinfo->num_levels++;
+			if (berr) {
+				return val & NTDB_OFF_MASK;
 			}
-			continue;
+			/* If you want to insert here, make a chain. */
+			h->old_val = val;
 		}
+		return 0;
+	}
 
-		/* It's in this group: search (until 0 or all searched) */
-		for (i = 0, h->found_bucket = h->home_bucket;
-		     i < (1 << NTDB_HASH_GROUP_BITS);
-		     i++, h->found_bucket = ((h->found_bucket+1)
-					     % (1 << NTDB_HASH_GROUP_BITS))) {
-			ntdb_bool_err berr;
-			if (is_subhash(h->group[h->found_bucket]))
-				continue;
+	/* Nope?  Iterate through chain. */
+	h->table = val & NTDB_OFF_MASK;
 
-			if (!h->group[h->found_bucket])
-				break;
+	ecode = ntdb_read_convert(ntdb, h->table, &chdr, sizeof(chdr));
+	if (ecode != NTDB_SUCCESS) {
+		goto fail;
+	}
+
+	if (rec_magic(&chdr) != NTDB_CHAIN_MAGIC) {
+		ecode = ntdb_logerr(ntdb, NTDB_ERR_CORRUPT,
+				    NTDB_LOG_ERROR,
+				    "find_and_lock:"
+				    " corrupt record %#x at %llu",
+				    rec_magic(&chdr), (long long)off);
+		goto fail;
+	}
 
-			berr = match(ntdb, h, &key, h->group[h->found_bucket],
-				     rec);
+	h->table_size = rec_data_length(&chdr) / sizeof(ntdb_off_t);
+
+	found_empty = false;
+	for (i = 0; i < h->table_size; i++) {
+		/* Careful!  match has to unmap this if we access a
+		 * record (may cause mmap of database to move. */
+		if (!arr) {
+			arr = ntdb_access_read(ntdb, hbucket_off(h->table, 0),
+					       rec_data_length(&chdr), true);
+			if (NTDB_PTR_IS_ERR(arr)) {
+				ecode = NTDB_PTR_ERR(arr);
+				goto fail;
+			}
+		}
+
+		val = arr[i];
+		if (val == 0) {
+			if (!found_empty) {
+				h->bucket = i;
+				found_empty = true;
+			}
+		} else {
+			berr = match(ntdb, h->h, &key, val, rec, &arr);
 			if (berr < 0) {
 				ecode = NTDB_OFF_TO_ERR(berr);
+				if (arr) {
+					ntdb_access_release(ntdb, arr);
+				}
 				goto fail;
 			}
 			if (berr) {
-				if (tinfo) {
-					tinfo->levels[tinfo->num_levels-1].entry
-						+= h->found_bucket;
+				/* We found it! */
+				h->bucket = i;
+				off = val & NTDB_OFF_MASK;
+				if (arr) {
+					ntdb_access_release(ntdb, arr);
 				}
-				return h->group[h->found_bucket] & NTDB_OFF_MASK;
+				return off;
 			}
 		}
-		/* Didn't find it: h indicates where it would go. */
-		return 0;
+	}
+	if (!found_empty) {
+		/* Set to any non-zero value */
+		h->old_val = 1;
+		h->bucket = i;
 	}
 
-	return find_in_chain(ntdb, key, hashtable, h, rec, tinfo);
+	if (arr) {
+		ntdb_access_release(ntdb, arr);
+	}
+	return 0;
 
 fail:
-	ntdb_unlock_hashes(ntdb, h->hlock_start, h->hlock_range, ltype);
+	ntdb_unlock_hash(ntdb, h->bucket, ltype);
 	return NTDB_ERR_TO_OFF(ecode);
 }
 
-/* I wrote a simple test, expanding a hash to 2GB, for the following
- * cases:
- * 1) Expanding all the buckets at once,
- * 2) Expanding the bucket we wanted to place the new entry into.
- * 3) Expanding the most-populated bucket,
- *
- * I measured the worst/average/best density during this process.
- * 1) 3%/16%/30%
- * 2) 4%/20%/38%
- * 3) 6%/22%/41%
- *
- * So we figure out the busiest bucket for the moment.
- */
-static unsigned fullest_bucket(struct ntdb_context *ntdb,
-			       const ntdb_off_t *group,
-			       unsigned new_bucket)
-{
-	unsigned counts[1 << NTDB_HASH_GROUP_BITS] = { 0 };
-	unsigned int i, best_bucket;
-
-	/* Count the new entry. */
-	counts[new_bucket]++;
-	best_bucket = new_bucket;
-
-	for (i = 0; i < (1 << NTDB_HASH_GROUP_BITS); i++) {
-		unsigned this_bucket;
-
-		if (is_subhash(group[i]))
-			continue;
-		this_bucket = group[i] & NTDB_OFF_HASH_GROUP_MASK;
-		if (++counts[this_bucket] > counts[best_bucket])
-			best_bucket = this_bucket;
-	}
-
-	return best_bucket;
-}
-
-static bool put_into_group(ntdb_off_t *group,
-			   unsigned bucket, ntdb_off_t encoded)
+static ntdb_off_t encode_offset(const struct ntdb_context *ntdb,
+				ntdb_off_t new_off, uint32_t hash)
 {
-	unsigned int i;
+	ntdb_off_t extra;
 
-	for (i = 0; i < (1 << NTDB_HASH_GROUP_BITS); i++) {
-		unsigned b = (bucket + i) % (1 << NTDB_HASH_GROUP_BITS);
+	assert((new_off & (1ULL << NTDB_OFF_CHAIN_BIT)) == 0);
+	assert((new_off >> (64 - NTDB_OFF_UPPER_STEAL)) == 0);
+	/* We pack extra hash bits into the upper bits of the offset. */
+	extra = bits_from(hash, ntdb->hash_bits, NTDB_OFF_UPPER_STEAL);
+	extra <<= (64 - NTDB_OFF_UPPER_STEAL);
 
-		if (group[b] == 0) {
-			group[b] = encoded;
-			return true;
-		}
-	}
-	return false;
+	return new_off | extra;
 }
 
-static void force_into_group(ntdb_off_t *group,
-			     unsigned bucket, ntdb_off_t encoded)
+/* Simply overwrite the hash entry we found before. */
+enum NTDB_ERROR replace_in_hash(struct ntdb_context *ntdb,
+				const struct hash_info *h,
+				ntdb_off_t new_off)
 {
-	if (!put_into_group(group, bucket, encoded))
-		abort();
+	return ntdb_write_off(ntdb, hbucket_off(h->table, h->bucket),
+			      encode_offset(ntdb, new_off, h->h));
 }
 
-static ntdb_off_t encode_offset(ntdb_off_t new_off, struct hash_info *h)
+enum NTDB_ERROR delete_from_hash(struct ntdb_context *ntdb,
+				 const struct hash_info *h)
 {
-	return h->home_bucket
-		| new_off
-		| ((uint64_t)bits_from(h->h,
-				  64 - h->hash_used - NTDB_OFF_UPPER_STEAL_EXTRA,
-				  NTDB_OFF_UPPER_STEAL_EXTRA)
-		   << NTDB_OFF_HASH_EXTRA_BIT);
+	return ntdb_write_off(ntdb, hbucket_off(h->table, h->bucket), 0);
 }
 
-/* Simply overwrite the hash entry we found before. */
-enum NTDB_ERROR replace_in_hash(struct ntdb_context *ntdb,
-			       struct hash_info *h,
-			       ntdb_off_t new_off)
-{
-	return ntdb_write_off(ntdb, hbucket_off(h->group_start, h->found_bucket),
-			     encode_offset(new_off, h));
-}
 
-/* We slot in anywhere that's empty in the chain. */
-static enum NTDB_ERROR COLD add_to_chain(struct ntdb_context *ntdb,
-					ntdb_off_t subhash,
-					ntdb_off_t new_off)
+enum NTDB_ERROR add_to_hash(struct ntdb_context *ntdb,
+			    const struct hash_info *h,
+			    ntdb_off_t new_off)
 {
-	ntdb_off_t entry;
 	enum NTDB_ERROR ecode;
+	ntdb_off_t chain;
+	struct ntdb_used_record chdr;
+	const ntdb_off_t *old;
+	ntdb_off_t *new;
 
-	entry = ntdb_find_zero_off(ntdb, subhash, 1<<NTDB_HASH_GROUP_BITS);
-	if (NTDB_OFF_IS_ERR(entry)) {
-		return NTDB_OFF_TO_ERR(entry);
+	/* We hit an empty bucket during search?  That's where it goes. */
+	if (!h->old_val) {
+		return replace_in_hash(ntdb, h, new_off);
 	}
 
-	if (entry == 1 << NTDB_HASH_GROUP_BITS) {
-		ntdb_off_t next;
+	/* Full at top-level?  Create a 2-element chain. */
+	if (h->table == NTDB_HASH_OFFSET) {
+		ntdb_off_t pair[2];
 
-		next = ntdb_read_off(ntdb, subhash
-				    + offsetof(struct ntdb_chain, next));
-		if (NTDB_OFF_IS_ERR(next)) {
-			return NTDB_OFF_TO_ERR(next);
-		}
+		/* One element is old value, the other is the new value. */
+		pair[0] = h->old_val;
+		pair[1] = encode_offset(ntdb, new_off, h->h);
 
-		if (!next) {
-			next = alloc(ntdb, 0, sizeof(struct ntdb_chain), 0,
-				     NTDB_CHAIN_MAGIC, false);
-			if (NTDB_OFF_IS_ERR(next))
-				return NTDB_OFF_TO_ERR(next);
-			ecode = zero_out(ntdb,
-					 next+sizeof(struct ntdb_used_record),
-					 sizeof(struct ntdb_chain));
-			if (ecode != NTDB_SUCCESS) {
-				return ecode;
-			}
-			ecode = ntdb_write_off(ntdb, subhash
-					      + offsetof(struct ntdb_chain,
-							 next),
-					      next);
-			if (ecode != NTDB_SUCCESS) {
-				return ecode;
-			}
+		chain = alloc(ntdb, 0, sizeof(pair), NTDB_CHAIN_MAGIC, true);
+		if (NTDB_OFF_IS_ERR(chain)) {
+			return NTDB_OFF_TO_ERR(chain);
 		}
-		return add_to_chain(ntdb, next, new_off);
+		ecode = ntdb_write_convert(ntdb,
+					   chain
+					   + sizeof(struct ntdb_used_record),
+					   pair, sizeof(pair));
+		if (ecode == NTDB_SUCCESS) {
+			ecode = ntdb_write_off(ntdb,
+					       hbucket_off(h->table, h->bucket),
+					       chain
+					       | (1ULL << NTDB_OFF_CHAIN_BIT));
+		}
+		return ecode;
 	}
 
-	return ntdb_write_off(ntdb, subhash + entry * sizeof(ntdb_off_t),
-			     new_off);
-}
-
-/* Add into a newly created subhash. */
-static enum NTDB_ERROR add_to_subhash(struct ntdb_context *ntdb, ntdb_off_t subhash,
-				     unsigned hash_used, ntdb_off_t val)
-{
-	ntdb_off_t off = (val & NTDB_OFF_MASK), *group;
-	struct hash_info h;
-	unsigned int gnum;
-
-	h.hash_used = hash_used;
-
-	if (hash_used + NTDB_SUBLEVEL_HASH_BITS > 64)
-		return add_to_chain(ntdb, subhash, off);
-
-	h.h = hash_record(ntdb, off);
-	gnum = use_bits(&h, NTDB_SUBLEVEL_HASH_BITS-NTDB_HASH_GROUP_BITS);
-	h.group_start = subhash
-		+ gnum * (sizeof(ntdb_off_t) << NTDB_HASH_GROUP_BITS);
-	h.home_bucket = use_bits(&h, NTDB_HASH_GROUP_BITS);
-
-	group = ntdb_access_write(ntdb, h.group_start,
-				 sizeof(*group) << NTDB_HASH_GROUP_BITS, true);
-	if (NTDB_PTR_IS_ERR(group)) {
-		return NTDB_PTR_ERR(group);
+	/* Full bucket.  Expand. */
+	ecode = ntdb_read_convert(ntdb, h->table, &chdr, sizeof(chdr));
+	if (ecode != NTDB_SUCCESS) {
+		return ecode;
 	}
-	force_into_group(group, h.home_bucket, encode_offset(off, &h));
-	return ntdb_access_commit(ntdb, group);
-}
 
-static enum NTDB_ERROR expand_group(struct ntdb_context *ntdb, struct hash_info *h)
-{
-	unsigned bucket, num_vals, i, magic;
-	size_t subsize;
-	ntdb_off_t subhash;
-	ntdb_off_t vals[1 << NTDB_HASH_GROUP_BITS];
-	enum NTDB_ERROR ecode;
+	if (rec_extra_padding(&chdr) >= sizeof(new_off)) {
+		/* Expand in place. */
+		uint64_t dlen = rec_data_length(&chdr);
 
-	/* Attach new empty subhash under fullest bucket. */
-	bucket = fullest_bucket(ntdb, h->group, h->home_bucket);
+		ecode = set_header(ntdb, &chdr, NTDB_CHAIN_MAGIC, 0,
+				   dlen + sizeof(new_off),
+				   dlen + rec_extra_padding(&chdr));
 
-	if (h->hash_used == 64) {
-		ntdb->stats.alloc_chain++;
-		subsize = sizeof(struct ntdb_chain);
-		magic = NTDB_CHAIN_MAGIC;
-	} else {
-		ntdb->stats.alloc_subhash++;
-		subsize = (sizeof(ntdb_off_t) << NTDB_SUBLEVEL_HASH_BITS);
-		magic = NTDB_HTABLE_MAGIC;
+		if (ecode != NTDB_SUCCESS) {
+			return ecode;
+		}
+		/* find_and_lock set up h to point to last bucket. */
+		ecode = replace_in_hash(ntdb, h, new_off);
+		if (ecode != NTDB_SUCCESS) {
+			return ecode;
+		}
+		ecode = ntdb_write_convert(ntdb, h->table, &chdr, sizeof(chdr));
+		if (ecode != NTDB_SUCCESS) {
+			return ecode;
+		}
+		/* For futureproofing, we always make the first byte of padding
+		 * a zero. */
+		if (rec_extra_padding(&chdr)) {
+			ecode = ntdb->io->twrite(ntdb, h->table + sizeof(chdr)
+						 + dlen + sizeof(new_off),
+						 "", 1);
+		}
+		return ecode;
 	}
 
-	subhash = alloc(ntdb, 0, subsize, 0, magic, false);
-	if (NTDB_OFF_IS_ERR(subhash)) {
-		return NTDB_OFF_TO_ERR(subhash);
+	/* We need to reallocate the chain. */
+	chain = alloc(ntdb, 0, (h->table_size + 1) * sizeof(ntdb_off_t),
+		      NTDB_CHAIN_MAGIC, true);
+	if (NTDB_OFF_IS_ERR(chain)) {
+		return NTDB_OFF_TO_ERR(chain);
 	}
 
-	ecode = zero_out(ntdb, subhash + sizeof(struct ntdb_used_record),
-			 subsize);
-	if (ecode != NTDB_SUCCESS) {
-		return ecode;
+	/* Map both and copy across old buckets. */
+	old = ntdb_access_read(ntdb, hbucket_off(h->table, 0),
+			       h->table_size*sizeof(ntdb_off_t), true);
+	if (NTDB_PTR_IS_ERR(old)) {
+		return NTDB_PTR_ERR(old);
 	}
-
-	/* Remove any which are destined for bucket or are in wrong place. */
-	num_vals = 0;
-	for (i = 0; i < (1 << NTDB_HASH_GROUP_BITS); i++) {
-		unsigned home_bucket = h->group[i] & NTDB_OFF_HASH_GROUP_MASK;
-		if (!h->group[i] || is_subhash(h->group[i]))
-			continue;
-		if (home_bucket == bucket || home_bucket != i) {
-			vals[num_vals++] = h->group[i];
-			h->group[i] = 0;
-		}
+	new = ntdb_access_write(ntdb, hbucket_off(chain, 0),
+				(h->table_size + 1)*sizeof(ntdb_off_t), true);
+	if (NTDB_PTR_IS_ERR(new)) {
+		ntdb_access_release(ntdb, old);
+		return NTDB_PTR_ERR(new);
 	}
-	/* FIXME: This assert is valid, but we do this during unit test :( */
-	/* assert(num_vals); */
-
-	/* Overwrite expanded bucket with subhash pointer. */
-	h->group[bucket] = subhash | (1ULL << NTDB_OFF_UPPER_STEAL_SUBHASH_BIT);
 
-	/* Point to actual contents of record. */
-	subhash += sizeof(struct ntdb_used_record);
+	memcpy(new, old, h->bucket * sizeof(ntdb_off_t));
+	new[h->bucket] = encode_offset(ntdb, new_off, h->h);
+	ntdb_access_release(ntdb, old);
 
-	/* Put values back. */
-	for (i = 0; i < num_vals; i++) {
-		unsigned this_bucket = vals[i] & NTDB_OFF_HASH_GROUP_MASK;
-
-		if (this_bucket == bucket) {
-			ecode = add_to_subhash(ntdb, subhash, h->hash_used,
-					       vals[i]);
-			if (ecode != NTDB_SUCCESS)
-				return ecode;
-		} else {
-			/* There should be room to put this back. */
-			force_into_group(h->group, this_bucket, vals[i]);
-		}
+	ecode = ntdb_access_commit(ntdb, new);
+	if (ecode != NTDB_SUCCESS) {
+		return ecode;
 	}
-	return NTDB_SUCCESS;
+
+	/* Free the old chain. */
+	ecode = add_free_record(ntdb, h->table,
+				sizeof(struct ntdb_used_record)
+				+ rec_data_length(&chdr)
+				+ rec_extra_padding(&chdr),
+				NTDB_LOCK_WAIT, true);
+
+	/* Replace top-level to point to new chain */
+	return ntdb_write_off(ntdb,
+			      hbucket_off(NTDB_HASH_OFFSET,
+					  bits_from(h->h, 0, ntdb->hash_bits)),
+			      chain | (1ULL << NTDB_OFF_CHAIN_BIT));
 }
 
-enum NTDB_ERROR delete_from_hash(struct ntdb_context *ntdb, struct hash_info *h)
+/* Traverse support: returns offset of record, or 0 or -ve error. */
+static ntdb_off_t iterate_chain(struct ntdb_context *ntdb,
+				ntdb_off_t val,
+				struct hash_info *h)
 {
-	unsigned int i, num_movers = 0;
-	ntdb_off_t movers[1 << NTDB_HASH_GROUP_BITS];
+	ntdb_off_t i;
+	enum NTDB_ERROR ecode;
+	struct ntdb_used_record chdr;
 
-	h->group[h->found_bucket] = 0;
-	for (i = 1; i < (1 << NTDB_HASH_GROUP_BITS); i++) {
-		unsigned this_bucket;
+	/* First load up chain header. */
+	h->table = val & NTDB_OFF_MASK;
+	ecode = ntdb_read_convert(ntdb, h->table, &chdr, sizeof(chdr));
+	if (ecode != NTDB_SUCCESS) {
+		return ecode;
+	}
 
-		this_bucket = (h->found_bucket+i) % (1 << NTDB_HASH_GROUP_BITS);
-		/* Empty bucket?  We're done. */
-		if (!h->group[this_bucket])
-			break;
+	if (rec_magic(&chdr) != NTDB_CHAIN_MAGIC) {
+		return ntdb_logerr(ntdb, NTDB_ERR_CORRUPT,
+				   NTDB_LOG_ERROR,
+				   "get_table:"
+				   " corrupt record %#x at %llu",
+				   rec_magic(&chdr),
+				   (long long)h->table);
+	}
 
-		/* Ignore subhashes. */
-		if (is_subhash(h->group[this_bucket]))
-			continue;
+	/* Chain length is implied by data length. */
+	h->table_size = rec_data_length(&chdr) / sizeof(ntdb_off_t);
 
-		/* If this one is not happy where it is, we'll move it. */
-		if ((h->group[this_bucket] & NTDB_OFF_HASH_GROUP_MASK)
-		    != this_bucket) {
-			movers[num_movers++] = h->group[this_bucket];
-			h->group[this_bucket] = 0;
-		}
+	i = ntdb_find_nonzero_off(ntdb, hbucket_off(h->table, 0), h->bucket,
+				  h->table_size);
+	if (NTDB_OFF_IS_ERR(i)) {
+		return i;
 	}
 
-	/* Put back the ones we erased. */
-	for (i = 0; i < num_movers; i++) {
-		force_into_group(h->group, movers[i] & NTDB_OFF_HASH_GROUP_MASK,
-				 movers[i]);
+	if (i != h->table_size) {
+		/* Return to next bucket. */
+		h->bucket = i + 1;
+		val = ntdb_read_off(ntdb, hbucket_off(h->table, i));
+		if (NTDB_OFF_IS_ERR(val)) {
+			return val;
+		}
+		return val & NTDB_OFF_MASK;
 	}
 
-	/* Now we write back the hash group */
-	return ntdb_write_convert(ntdb, h->group_start,
-				 h->group, sizeof(h->group));
+	/* Go back up to hash table. */
+	h->table = NTDB_HASH_OFFSET;
+	h->table_size = 1 << ntdb->hash_bits;
+	h->bucket = bits_from(h->h, 0, ntdb->hash_bits) + 1;
+	return 0;
 }
 
-enum NTDB_ERROR add_to_hash(struct ntdb_context *ntdb, struct hash_info *h,
-			   ntdb_off_t new_off)
+/* Keeps hash locked unless returns 0 or error. */
+static ntdb_off_t lock_and_iterate_hash(struct ntdb_context *ntdb,
+					struct hash_info *h)
 {
+	ntdb_off_t val, i;
 	enum NTDB_ERROR ecode;
 
-	/* We hit an empty bucket during search?  That's where it goes. */
-	if (!h->group[h->found_bucket]) {
-		h->group[h->found_bucket] = encode_offset(new_off, h);
-		/* Write back the modified group. */
-		return ntdb_write_convert(ntdb, h->group_start,
-					 h->group, sizeof(h->group));
-	}
-
-	if (h->hash_used > 64)
-		return add_to_chain(ntdb, h->group_start, new_off);
-
-	/* We're full.  Expand. */
-	ecode = expand_group(ntdb, h);
-	if (ecode != NTDB_SUCCESS) {
-		return ecode;
-	}
+	if (h->table != NTDB_HASH_OFFSET) {
+		/* We're in a chain. */
+		i = bits_from(h->h, 0, ntdb->hash_bits);
+		ecode = ntdb_lock_hash(ntdb, i, F_RDLCK);
+		if (ecode != NTDB_SUCCESS) {
+			return NTDB_ERR_TO_OFF(ecode);
+		}
 
-	if (is_subhash(h->group[h->home_bucket])) {
-		/* We were expanded! */
-		ntdb_off_t hashtable;
-		unsigned int gnum;
+		/* We dropped lock, bucket might have moved! */
+		val = ntdb_read_off(ntdb, hbucket_off(NTDB_HASH_OFFSET, i));
+		if (NTDB_OFF_IS_ERR(val)) {
+			goto unlock;
+		}
 
-		/* Write back the modified group. */
-		ecode = ntdb_write_convert(ntdb, h->group_start, h->group,
-					  sizeof(h->group));
-		if (ecode != NTDB_SUCCESS) {
-			return ecode;
+		/* We don't remove chains: there should still be one there! */
+		if (!val || !is_chain(val)) {
+			ecode = ntdb_logerr(ntdb, NTDB_ERR_CORRUPT,
+					    NTDB_LOG_ERROR,
+					    "iterate_hash:"
+					    " vanished hchain %llu at %llu",
+					    (long long)val,
+					    (long long)i);
+			val = NTDB_ERR_TO_OFF(ecode);
+			goto unlock;
 		}
 
-		/* Move hashinfo down a level. */
-		hashtable = (h->group[h->home_bucket] & NTDB_OFF_MASK)
-			+ sizeof(struct ntdb_used_record);
-		gnum = use_bits(h,NTDB_SUBLEVEL_HASH_BITS - NTDB_HASH_GROUP_BITS);
-		h->home_bucket = use_bits(h, NTDB_HASH_GROUP_BITS);
-		h->group_start = hashtable
-			+ gnum * (sizeof(ntdb_off_t) << NTDB_HASH_GROUP_BITS);
-		ecode = ntdb_read_convert(ntdb, h->group_start, &h->group,
-					 sizeof(h->group));
-		if (ecode != NTDB_SUCCESS) {
-			return ecode;
+		/* Find next bucket in the chain. */
+		val = iterate_chain(ntdb, val, h);
+		if (NTDB_OFF_IS_ERR(val)) {
+			goto unlock;
 		}
-	}
+		if (val != 0) {
+			return val;
+		}
+		ntdb_unlock_hash(ntdb, i, F_RDLCK);
 
-	/* Expanding the group must have made room if it didn't choose this
-	 * bucket. */
-	if (put_into_group(h->group, h->home_bucket, encode_offset(new_off,h))){
-		return ntdb_write_convert(ntdb, h->group_start,
-					 h->group, sizeof(h->group));
+		/* OK, we've reset h back to top level. */
 	}
 
-	/* This can happen if all hashes in group (and us) dropped into same
-	 * group in subhash. */
-	return add_to_hash(ntdb, h, new_off);
-}
-
-/* Traverse support: returns offset of record, or 0 or -ve error. */
-static ntdb_off_t iterate_hash(struct ntdb_context *ntdb,
-			      struct traverse_info *tinfo)
-{
-	ntdb_off_t off, val, i;
-	struct traverse_level *tlevel;
-
-	tlevel = &tinfo->levels[tinfo->num_levels-1];
-
-again:
-	for (i = ntdb_find_nonzero_off(ntdb, tlevel->hashtable,
-				      tlevel->entry, tlevel->total_buckets);
-	     i != tlevel->total_buckets;
-	     i = ntdb_find_nonzero_off(ntdb, tlevel->hashtable,
-				      i+1, tlevel->total_buckets)) {
-		if (NTDB_OFF_IS_ERR(i)) {
-			return i;
+	/* We do this unlocked, then re-check. */
+	for (i = ntdb_find_nonzero_off(ntdb, hbucket_off(h->table, 0),
+				       h->bucket, h->table_size);
+	     i != h->table_size;
+	     i = ntdb_find_nonzero_off(ntdb, hbucket_off(h->table, 0),
+				       i+1, h->table_size)) {
+		ecode = ntdb_lock_hash(ntdb, i, F_RDLCK);
+		if (ecode != NTDB_SUCCESS) {
+			return NTDB_ERR_TO_OFF(ecode);
 		}
 
-		val = ntdb_read_off(ntdb, tlevel->hashtable+sizeof(ntdb_off_t)*i);
+		val = ntdb_read_off(ntdb, hbucket_off(h->table, i));
 		if (NTDB_OFF_IS_ERR(val)) {
-			return val;
+			goto unlock;
 		}
 
-		off = val & NTDB_OFF_MASK;
-
-		/* This makes the delete-all-in-traverse case work
-		 * (and simplifies our logic a little). */
-		if (off == tinfo->prev)
+		/* Lost race, and it's empty? */
+		if (!val) {
+			ntdb->stats.traverse_val_vanished++;
+			ntdb_unlock_hash(ntdb, i, F_RDLCK);
 			continue;
+		}
 
-		tlevel->entry = i;
-
-		if (!is_subhash(val)) {
-			/* Found one. */
-			tinfo->prev = off;
-			return off;
+		if (!is_chain(val)) {
+			/* So caller knows what lock to free. */
+			h->h = i;
+			/* Return to next bucket. */
+			h->bucket = i + 1;
+			val &= NTDB_OFF_MASK;
+			return val;
 		}
 
-		/* When we come back, we want the next one */
-		tlevel->entry++;
-		tinfo->num_levels++;
-		tlevel++;
-		tlevel->hashtable = off + sizeof(struct ntdb_used_record);
-		tlevel->entry = 0;
-		/* Next level is a chain? */
-		if (unlikely(tinfo->num_levels == NTDB_MAX_LEVELS + 1))
-			tlevel->total_buckets = (1 << NTDB_HASH_GROUP_BITS);
-		else
-			tlevel->total_buckets = (1 << NTDB_SUBLEVEL_HASH_BITS);
-		goto again;
-	}
-
-	/* Nothing there? */
-	if (tinfo->num_levels == 1)
-		return 0;
+		/* Start at beginning of chain */
+		h->bucket = 0;
+		h->h = i;
 
-	/* Handle chained entries. */
-	if (unlikely(tinfo->num_levels == NTDB_MAX_LEVELS + 1)) {
-		tlevel->hashtable = ntdb_read_off(ntdb, tlevel->hashtable
-						 + offsetof(struct ntdb_chain,
-							    next));
-		if (NTDB_OFF_IS_ERR(tlevel->hashtable)) {
-			return tlevel->hashtable;
+		val = iterate_chain(ntdb, val, h);
+		if (NTDB_OFF_IS_ERR(val)) {
+			goto unlock;
 		}
-		if (tlevel->hashtable) {
-			tlevel->hashtable += sizeof(struct ntdb_used_record);
-			tlevel->entry = 0;
-			goto again;
+		if (val != 0) {
+			return val;
 		}
+
+		/* Otherwise, bucket has been set to i+1 */
+		ntdb_unlock_hash(ntdb, i, F_RDLCK);
 	}
+	return 0;
 
-	/* Go back up and keep searching. */
-	tinfo->num_levels--;
-	tlevel--;
-	goto again;
+unlock:
+	ntdb_unlock_hash(ntdb, i, F_RDLCK);
+	return val;
 }
 
 /* Return success if we find something, NTDB_ERR_NOEXIST if none. */
 enum NTDB_ERROR next_in_hash(struct ntdb_context *ntdb,
-			    struct traverse_info *tinfo,
-			    NTDB_DATA *kbuf, size_t *dlen)
+			     struct hash_info *h,
+			     NTDB_DATA *kbuf, size_t *dlen)
 {
-	const unsigned group_bits = NTDB_TOPLEVEL_HASH_BITS-NTDB_HASH_GROUP_BITS;
-	ntdb_off_t hl_start, hl_range, off;
+	ntdb_off_t off;
+	struct ntdb_used_record rec;
 	enum NTDB_ERROR ecode;
 
-	while (tinfo->toplevel_group < (1 << group_bits)) {
-		hl_start = (ntdb_off_t)tinfo->toplevel_group
-			<< (64 - group_bits);
-		hl_range = 1ULL << group_bits;
-		ecode = ntdb_lock_hashes(ntdb, hl_start, hl_range, F_RDLCK,
-					NTDB_LOCK_WAIT);
-		if (ecode != NTDB_SUCCESS) {
-			return ecode;
-		}
-
-		off = iterate_hash(ntdb, tinfo);
-		if (off) {
-			struct ntdb_used_record rec;
+	off = lock_and_iterate_hash(ntdb, h);
 
-			if (NTDB_OFF_IS_ERR(off)) {
-				ecode = NTDB_OFF_TO_ERR(off);
-				goto fail;
-			}
-
-			ecode = ntdb_read_convert(ntdb, off, &rec, sizeof(rec));
-			if (ecode != NTDB_SUCCESS) {
-				goto fail;
-			}
-			if (rec_magic(&rec) != NTDB_USED_MAGIC) {
-				ecode = ntdb_logerr(ntdb, NTDB_ERR_CORRUPT,
-						   NTDB_LOG_ERROR,
-						   "next_in_hash:"
-						   " corrupt record at %llu",
-						   (long long)off);
-				goto fail;
-			}
+	if (NTDB_OFF_IS_ERR(off)) {
+		return NTDB_OFF_TO_ERR(off);
+	} else if (off == 0) {
+		return NTDB_ERR_NOEXIST;
+	}
 
-			kbuf->dsize = rec_key_length(&rec);
-
-			/* They want data as well? */
-			if (dlen) {
-				*dlen = rec_data_length(&rec);
-				kbuf->dptr = ntdb_alloc_read(ntdb,
-							    off + sizeof(rec),
-							    kbuf->dsize
-							    + *dlen);
-			} else {
-				kbuf->dptr = ntdb_alloc_read(ntdb,
-							    off + sizeof(rec),
-							    kbuf->dsize);
-			}
-			ntdb_unlock_hashes(ntdb, hl_start, hl_range, F_RDLCK);
-			if (NTDB_PTR_IS_ERR(kbuf->dptr)) {
-				return NTDB_PTR_ERR(kbuf->dptr);
-			}
-			return NTDB_SUCCESS;
-		}
+	/* The hash for this key is still locked. */
+	ecode = ntdb_read_convert(ntdb, off, &rec, sizeof(rec));
+	if (ecode != NTDB_SUCCESS) {
+		goto unlock;
+	}
+	if (rec_magic(&rec) != NTDB_USED_MAGIC) {
+		ecode = ntdb_logerr(ntdb, NTDB_ERR_CORRUPT,
+				    NTDB_LOG_ERROR,
+				    "next_in_hash:"
+				    " corrupt record at %llu",
+				    (long long)off);
+		goto unlock;
+	}
 
-		ntdb_unlock_hashes(ntdb, hl_start, hl_range, F_RDLCK);
+	kbuf->dsize = rec_key_length(&rec);
 
-		tinfo->toplevel_group++;
-		tinfo->levels[0].hashtable
-			+= (sizeof(ntdb_off_t) << NTDB_HASH_GROUP_BITS);
-		tinfo->levels[0].entry = 0;
+	/* They want data as well? */
+	if (dlen) {
+		*dlen = rec_data_length(&rec);
+		kbuf->dptr = ntdb_alloc_read(ntdb, off + sizeof(rec),
+					     kbuf->dsize + *dlen);
+	} else {
+		kbuf->dptr = ntdb_alloc_read(ntdb, off + sizeof(rec),
+					     kbuf->dsize);
 	}
-	return NTDB_ERR_NOEXIST;
+	if (NTDB_PTR_IS_ERR(kbuf->dptr)) {
+		ecode = NTDB_PTR_ERR(kbuf->dptr);
+		goto unlock;
+	}
+	ecode = NTDB_SUCCESS;
 
-fail:
-	ntdb_unlock_hashes(ntdb, hl_start, hl_range, F_RDLCK);
+unlock:
+	ntdb_unlock_hash(ntdb, bits_from(h->h, 0, ntdb->hash_bits), F_RDLCK);
 	return ecode;
 
 }
 
 enum NTDB_ERROR first_in_hash(struct ntdb_context *ntdb,
-			     struct traverse_info *tinfo,
+			     struct hash_info *h,
 			     NTDB_DATA *kbuf, size_t *dlen)
 {
-	tinfo->prev = 0;
-	tinfo->toplevel_group = 0;
-	tinfo->num_levels = 1;
-	tinfo->levels[0].hashtable = offsetof(struct ntdb_header, hashtable);
-	tinfo->levels[0].entry = 0;
-	tinfo->levels[0].total_buckets = (1 << NTDB_HASH_GROUP_BITS);
-
-	return next_in_hash(ntdb, tinfo, kbuf, dlen);
+	h->table = NTDB_HASH_OFFSET;
+	h->table_size = 1 << ntdb->hash_bits;
+	h->bucket = 0;
+
+	return next_in_hash(ntdb, h, kbuf, dlen);
 }
 
 /* Even if the entry isn't in this hash bucket, you'd have to lock this
  * bucket to find it. */
-static enum NTDB_ERROR chainlock(struct ntdb_context *ntdb, const NTDB_DATA *key,
-				int ltype, enum ntdb_lock_flags waitflag,
-				const char *func)
+static enum NTDB_ERROR chainlock(struct ntdb_context *ntdb,
+				 const NTDB_DATA *key, int ltype)
 {
-	enum NTDB_ERROR ecode;
-	uint64_t h = ntdb_hash(ntdb, key->dptr, key->dsize);
-	ntdb_off_t lockstart, locksize;
-	unsigned int group, gbits;
-
-	gbits = NTDB_TOPLEVEL_HASH_BITS - NTDB_HASH_GROUP_BITS;
-	group = bits_from(h, 64 - gbits, gbits);
+	uint32_t h = ntdb_hash(ntdb, key->dptr, key->dsize);
 
-	lockstart = hlock_range(group, &locksize);
-
-	ecode = ntdb_lock_hashes(ntdb, lockstart, locksize, ltype, waitflag);
-	ntdb_trace_1rec(ntdb, func, *key);
-	return ecode;
+	return ntdb_lock_hash(ntdb, bits_from(h, 0, ntdb->hash_bits), ltype);
 }
 
 /* lock/unlock one hash chain. This is meant to be used to reduce
    contention - it cannot guarantee how many records will be locked */
 _PUBLIC_ enum NTDB_ERROR ntdb_chainlock(struct ntdb_context *ntdb, NTDB_DATA key)
 {
-	return chainlock(ntdb, &key, F_WRLCK, NTDB_LOCK_WAIT, "ntdb_chainlock");
+	return chainlock(ntdb, &key, F_WRLCK);
 }
 
 _PUBLIC_ void ntdb_chainunlock(struct ntdb_context *ntdb, NTDB_DATA key)
 {
-	uint64_t h = ntdb_hash(ntdb, key.dptr, key.dsize);
-	ntdb_off_t lockstart, locksize;
-	unsigned int group, gbits;
-
-	gbits = NTDB_TOPLEVEL_HASH_BITS - NTDB_HASH_GROUP_BITS;
-	group = bits_from(h, 64 - gbits, gbits);
+	uint32_t h = ntdb_hash(ntdb, key.dptr, key.dsize);
 
-	lockstart = hlock_range(group, &locksize);
-
-	ntdb_trace_1rec(ntdb, "ntdb_chainunlock", key);
-	ntdb_unlock_hashes(ntdb, lockstart, locksize, F_WRLCK);
+	ntdb_unlock_hash(ntdb, bits_from(h, 0, ntdb->hash_bits), F_WRLCK);
 }
 
-_PUBLIC_ enum NTDB_ERROR ntdb_chainlock_read(struct ntdb_context *ntdb, NTDB_DATA key)
+_PUBLIC_ enum NTDB_ERROR ntdb_chainlock_read(struct ntdb_context *ntdb,
+					     NTDB_DATA key)
 {
-	return chainlock(ntdb, &key, F_RDLCK, NTDB_LOCK_WAIT,
-			 "ntdb_chainlock_read");
+	return chainlock(ntdb, &key, F_RDLCK);
 }
 
 _PUBLIC_ void ntdb_chainunlock_read(struct ntdb_context *ntdb, NTDB_DATA key)
 {
-	uint64_t h = ntdb_hash(ntdb, key.dptr, key.dsize);
-	ntdb_off_t lockstart, locksize;
-	unsigned int group, gbits;
-
-	gbits = NTDB_TOPLEVEL_HASH_BITS - NTDB_HASH_GROUP_BITS;
-	group = bits_from(h, 64 - gbits, gbits);
-
-	lockstart = hlock_range(group, &locksize);
+	uint32_t h = ntdb_hash(ntdb, key.dptr, key.dsize);
 
-	ntdb_trace_1rec(ntdb, "ntdb_chainunlock_read", key);
-	ntdb_unlock_hashes(ntdb, lockstart, locksize, F_RDLCK);
+	ntdb_unlock_hash(ntdb, bits_from(h, 0, ntdb->hash_bits), F_RDLCK);
 }