xref: /freebsd/sys/contrib/openzfs/module/zfs/zap_leaf.c (revision 61145dc2b94f12f6a47344fb9aac702321880e43)

// SPDX-License-Identifier: CDDL-1.0
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or https://opensource.org/licenses/CDDL-1.0.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
 * Copyright 2017 Nexenta Systems, Inc.
 */

/*
 * The 512-byte leaf is broken into 32 16-byte chunks.
 * chunk number n means l_chunk[n], even though the header precedes it.
 * the names are stored null-terminated.
 */

#include <sys/zio.h>
#include <sys/spa.h>
#include <sys/dmu.h>
#include <sys/zfs_context.h>
#include <sys/fs/zfs.h>
#include <sys/zap.h>
#include <sys/zap_impl.h>
#include <sys/zap_leaf.h>
#include <sys/arc.h>

static uint16_t *zap_leaf_rehash_entry(zap_leaf_t *l, struct zap_leaf_entry *le,
    uint16_t entry);

#define	CHAIN_END 0xffff /* end of the chunk chain */

#define	LEAF_HASH(l, h) \
	((ZAP_LEAF_HASH_NUMENTRIES(l)-1) & \
	((h) >> \
	(64 - ZAP_LEAF_HASH_SHIFT(l) - zap_leaf_phys(l)->l_hdr.lh_prefix_len)))

#define	LEAF_HASH_ENTPTR(l, h)	(&zap_leaf_phys(l)->l_hash[LEAF_HASH(l, h)])

static void
stv(int len, void *addr, uint64_t value)
{
	switch (len) {
	case 1:
		*(uint8_t *)addr = value;
		return;
	case 2:
		*(uint16_t *)addr = value;
		return;
	case 4:
		*(uint32_t *)addr = value;
		return;
	case 8:
		*(uint64_t *)addr = value;
		return;
	default:
		PANIC("bad int len %d", len);
	}
}

static uint64_t
ldv(int len, const void *addr)
{
	switch (len) {
	case 1:
		return (*(uint8_t *)addr);
	case 2:
		return (*(uint16_t *)addr);
	case 4:
		return (*(uint32_t *)addr);
	case 8:
		return (*(uint64_t *)addr);
	default:
		PANIC("bad int len %d", len);
	}
	return (0xFEEDFACEDEADBEEFULL);
}

void
zap_leaf_byteswap(zap_leaf_phys_t *buf, size_t size)
{
	zap_leaf_t l;
	dmu_buf_t l_dbuf;

	l_dbuf.db_data = buf;
	l.l_bs = highbit64(size) - 1;
	l.l_dbuf = &l_dbuf;

	buf->l_hdr.lh_block_type =	BSWAP_64(buf->l_hdr.lh_block_type);
	buf->l_hdr.lh_prefix =		BSWAP_64(buf->l_hdr.lh_prefix);
	buf->l_hdr.lh_magic =		BSWAP_32(buf->l_hdr.lh_magic);
	buf->l_hdr.lh_nfree =		BSWAP_16(buf->l_hdr.lh_nfree);
	buf->l_hdr.lh_nentries =	BSWAP_16(buf->l_hdr.lh_nentries);
	buf->l_hdr.lh_prefix_len =	BSWAP_16(buf->l_hdr.lh_prefix_len);
	buf->l_hdr.lh_freelist =	BSWAP_16(buf->l_hdr.lh_freelist);

	for (uint_t i = 0; i < ZAP_LEAF_HASH_NUMENTRIES(&l); i++)
		buf->l_hash[i] = BSWAP_16(buf->l_hash[i]);

	for (uint_t i = 0; i < ZAP_LEAF_NUMCHUNKS(&l); i++) {
		zap_leaf_chunk_t *lc = &ZAP_LEAF_CHUNK(&l, i);
		struct zap_leaf_entry *le;

		switch (lc->l_free.lf_type) {
		case ZAP_CHUNK_ENTRY:
			le = &lc->l_entry;

			le->le_type =		BSWAP_8(le->le_type);
			le->le_value_intlen =	BSWAP_8(le->le_value_intlen);
			le->le_next =		BSWAP_16(le->le_next);
			le->le_name_chunk =	BSWAP_16(le->le_name_chunk);
			le->le_name_numints =	BSWAP_16(le->le_name_numints);
			le->le_value_chunk =	BSWAP_16(le->le_value_chunk);
			le->le_value_numints =	BSWAP_16(le->le_value_numints);
			le->le_cd =		BSWAP_32(le->le_cd);
			le->le_hash =		BSWAP_64(le->le_hash);
			break;
		case ZAP_CHUNK_FREE:
			lc->l_free.lf_type =	BSWAP_8(lc->l_free.lf_type);
			lc->l_free.lf_next =	BSWAP_16(lc->l_free.lf_next);
			break;
		case ZAP_CHUNK_ARRAY:
			lc->l_array.la_type =	BSWAP_8(lc->l_array.la_type);
			lc->l_array.la_next =	BSWAP_16(lc->l_array.la_next);
			/* la_array doesn't need swapping */
			break;
		default:
			cmn_err(CE_PANIC, "bad leaf type %d",
			    lc->l_free.lf_type);
		}
	}
}

void
zap_leaf_init(zap_leaf_t *l, boolean_t sort)
{
	l->l_bs = highbit64(l->l_dbuf->db_size) - 1;
	memset(&zap_leaf_phys(l)->l_hdr, 0,
	    sizeof (struct zap_leaf_header));
	memset(zap_leaf_phys(l)->l_hash, CHAIN_END,
	    2*ZAP_LEAF_HASH_NUMENTRIES(l));
	for (uint_t i = 0; i < ZAP_LEAF_NUMCHUNKS(l); i++) {
		ZAP_LEAF_CHUNK(l, i).l_free.lf_type = ZAP_CHUNK_FREE;
		ZAP_LEAF_CHUNK(l, i).l_free.lf_next = i+1;
	}
	ZAP_LEAF_CHUNK(l, ZAP_LEAF_NUMCHUNKS(l)-1).l_free.lf_next = CHAIN_END;
	zap_leaf_phys(l)->l_hdr.lh_block_type = ZBT_LEAF;
	zap_leaf_phys(l)->l_hdr.lh_magic = ZAP_LEAF_MAGIC;
	zap_leaf_phys(l)->l_hdr.lh_nfree = ZAP_LEAF_NUMCHUNKS(l);
	if (sort)
		zap_leaf_phys(l)->l_hdr.lh_flags |= ZLF_ENTRIES_CDSORTED;
}

/*
 * Routines which manipulate leaf chunks (l_chunk[]).
 */

static uint16_t
zap_leaf_chunk_alloc(zap_leaf_t *l)
{
	ASSERT(zap_leaf_phys(l)->l_hdr.lh_nfree > 0);

	uint_t chunk = zap_leaf_phys(l)->l_hdr.lh_freelist;
	ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
	ASSERT3U(ZAP_LEAF_CHUNK(l, chunk).l_free.lf_type, ==, ZAP_CHUNK_FREE);

	zap_leaf_phys(l)->l_hdr.lh_freelist =
	    ZAP_LEAF_CHUNK(l, chunk).l_free.lf_next;

	zap_leaf_phys(l)->l_hdr.lh_nfree--;

	return (chunk);
}

static void
zap_leaf_chunk_free(zap_leaf_t *l, uint16_t chunk)
{
	struct zap_leaf_free *zlf = &ZAP_LEAF_CHUNK(l, chunk).l_free;
	ASSERT3U(zap_leaf_phys(l)->l_hdr.lh_nfree, <, ZAP_LEAF_NUMCHUNKS(l));
	ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
	ASSERT(zlf->lf_type != ZAP_CHUNK_FREE);

	zlf->lf_type = ZAP_CHUNK_FREE;
	zlf->lf_next = zap_leaf_phys(l)->l_hdr.lh_freelist;
	memset(zlf->lf_pad, 0, sizeof (zlf->lf_pad)); /* help it to compress */
	zap_leaf_phys(l)->l_hdr.lh_freelist = chunk;

	zap_leaf_phys(l)->l_hdr.lh_nfree++;
}

/*
 * Routines which manipulate leaf arrays (zap_leaf_array type chunks).
 */

static uint16_t
zap_leaf_array_create(zap_leaf_t *l, const char *buf,
    int integer_size, int num_integers)
{
	uint16_t chunk_head;
	uint16_t *chunkp = &chunk_head;
	int byten = integer_size;
	uint64_t value = 0;
	int shift = (integer_size - 1) * 8;
	int len = num_integers;

	ASSERT3U(num_integers * integer_size, <=, ZAP_MAXVALUELEN);

	if (len > 0)
		value = ldv(integer_size, buf);
	while (len > 0) {
		uint16_t chunk = zap_leaf_chunk_alloc(l);
		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, chunk).l_array;

		la->la_type = ZAP_CHUNK_ARRAY;
		for (int i = 0; i < ZAP_LEAF_ARRAY_BYTES; i++) {
			la->la_array[i] = value >> shift;
			value <<= 8;
			if (--byten == 0) {
				if (--len == 0)
					break;
				byten = integer_size;
				buf += integer_size;
				value = ldv(integer_size, buf);
			}
		}

		*chunkp = chunk;
		chunkp = &la->la_next;
	}
	*chunkp = CHAIN_END;

	return (chunk_head);
}

/*
 * Non-destructively copy array between leaves.
 */
static uint16_t
zap_leaf_array_copy(zap_leaf_t *l, uint16_t chunk, zap_leaf_t *nl)
{
	uint16_t new_chunk;
	uint16_t *nchunkp = &new_chunk;

	while (chunk != CHAIN_END) {
		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
		uint16_t nchunk = zap_leaf_chunk_alloc(nl);

		struct zap_leaf_array *la =
		    &ZAP_LEAF_CHUNK(l, chunk).l_array;
		struct zap_leaf_array *nla =
		    &ZAP_LEAF_CHUNK(nl, nchunk).l_array;
		ASSERT3U(la->la_type, ==, ZAP_CHUNK_ARRAY);

		*nla = *la; /* structure assignment */

		chunk = la->la_next;
		*nchunkp = nchunk;
		nchunkp = &nla->la_next;
	}
	*nchunkp = CHAIN_END;
	return (new_chunk);
}

/*
 * Free array.  Unlike trivial loop of zap_leaf_chunk_free() this does
 * not reverse order of chunks in the free list, reducing fragmentation.
 */
static void
zap_leaf_array_free(zap_leaf_t *l, uint16_t chunk)
{
	struct zap_leaf_header *hdr = &zap_leaf_phys(l)->l_hdr;
	uint16_t *tailp = &hdr->lh_freelist;
	uint16_t oldfree = *tailp;

	while (chunk != CHAIN_END) {
		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
		zap_leaf_chunk_t *c = &ZAP_LEAF_CHUNK(l, chunk);
		ASSERT3U(c->l_array.la_type, ==, ZAP_CHUNK_ARRAY);

		*tailp = chunk;
		chunk = c->l_array.la_next;

		c->l_free.lf_type = ZAP_CHUNK_FREE;
		memset(c->l_free.lf_pad, 0, sizeof (c->l_free.lf_pad));
		tailp = &c->l_free.lf_next;

		ASSERT3U(hdr->lh_nfree, <, ZAP_LEAF_NUMCHUNKS(l));
		hdr->lh_nfree++;
	}

	*tailp = oldfree;
}

/* array_len and buf_len are in integers, not bytes */
static void
zap_leaf_array_read(zap_leaf_t *l, uint16_t chunk,
    int array_int_len, int array_len, int buf_int_len, uint64_t buf_len,
    void *buf)
{
	int len = MIN(array_len, buf_len);
	int byten = 0;
	uint64_t value = 0;
	char *p = buf;

	ASSERT3U(array_int_len, <=, buf_int_len);

	/* Fast path for one 8-byte integer */
	if (array_int_len == 8 && buf_int_len == 8 && len == 1) {
		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, chunk).l_array;
		uint8_t *ip = la->la_array;
		uint64_t *buf64 = buf;

		*buf64 = (uint64_t)ip[0] << 56 | (uint64_t)ip[1] << 48 |
		    (uint64_t)ip[2] << 40 | (uint64_t)ip[3] << 32 |
		    (uint64_t)ip[4] << 24 | (uint64_t)ip[5] << 16 |
		    (uint64_t)ip[6] << 8 | (uint64_t)ip[7];
		return;
	}

	/* Fast path for an array of 1-byte integers (eg. the entry name) */
	if (array_int_len == 1 && buf_int_len == 1 &&
	    buf_len > array_len + ZAP_LEAF_ARRAY_BYTES) {
		while (chunk != CHAIN_END) {
			struct zap_leaf_array *la =
			    &ZAP_LEAF_CHUNK(l, chunk).l_array;
			memcpy(p, la->la_array, ZAP_LEAF_ARRAY_BYTES);
			p += ZAP_LEAF_ARRAY_BYTES;
			chunk = la->la_next;
		}
		return;
	}

	while (len > 0) {
		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, chunk).l_array;

		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
		for (int i = 0; i < ZAP_LEAF_ARRAY_BYTES; i++) {
			value = (value << 8) | la->la_array[i];
			byten++;
			if (byten == array_int_len) {
				stv(buf_int_len, p, value);
				byten = 0;
				len--;
				if (len == 0)
					return;
				p += buf_int_len;
			}
		}
		chunk = la->la_next;
	}
}

static boolean_t
zap_leaf_array_match(zap_leaf_t *l, zap_name_t *zn,
    uint_t chunk, int array_numints)
{
	int bseen = 0;

	if (zap_getflags(zn->zn_zap) & ZAP_FLAG_UINT64_KEY) {
		uint64_t *thiskey =
		    kmem_alloc(array_numints * sizeof (*thiskey), KM_SLEEP);
		ASSERT(zn->zn_key_intlen == sizeof (*thiskey));

		zap_leaf_array_read(l, chunk, sizeof (*thiskey), array_numints,
		    sizeof (*thiskey), array_numints, thiskey);
		boolean_t match = memcmp(thiskey, zn->zn_key_orig,
		    array_numints * sizeof (*thiskey)) == 0;
		kmem_free(thiskey, array_numints * sizeof (*thiskey));
		return (match);
	}

	ASSERT(zn->zn_key_intlen == 1);
	if (zn->zn_matchtype & MT_NORMALIZE) {
		char *thisname = kmem_alloc(array_numints, KM_SLEEP);

		zap_leaf_array_read(l, chunk, sizeof (char), array_numints,
		    sizeof (char), array_numints, thisname);
		boolean_t match = zap_match(zn, thisname);
		kmem_free(thisname, array_numints);
		return (match);
	}

	/*
	 * Fast path for exact matching.
	 * First check that the lengths match, so that we don't read
	 * past the end of the zn_key_orig array.
	 */
	if (array_numints != zn->zn_key_orig_numints)
		return (B_FALSE);
	while (bseen < array_numints) {
		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, chunk).l_array;
		int toread = MIN(array_numints - bseen, ZAP_LEAF_ARRAY_BYTES);
		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
		if (memcmp(la->la_array, (char *)zn->zn_key_orig + bseen,
		    toread))
			break;
		chunk = la->la_next;
		bseen += toread;
	}
	return (bseen == array_numints);
}

/*
 * Routines which manipulate leaf entries.
 */

int
zap_leaf_lookup(zap_leaf_t *l, zap_name_t *zn, zap_entry_handle_t *zeh)
{
	struct zap_leaf_entry *le;

	ASSERT3U(zap_leaf_phys(l)->l_hdr.lh_magic, ==, ZAP_LEAF_MAGIC);

	for (uint16_t *chunkp = LEAF_HASH_ENTPTR(l, zn->zn_hash);
	    *chunkp != CHAIN_END; chunkp = &le->le_next) {
		uint16_t chunk = *chunkp;
		le = ZAP_LEAF_ENTRY(l, chunk);

		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
		ASSERT3U(le->le_type, ==, ZAP_CHUNK_ENTRY);

		if (le->le_hash != zn->zn_hash)
			continue;

		/*
		 * NB: the entry chain is always sorted by cd on
		 * normalized zap objects, so this will find the
		 * lowest-cd match for MT_NORMALIZE.
		 */
		ASSERT((zn->zn_matchtype == 0) ||
		    (zap_leaf_phys(l)->l_hdr.lh_flags & ZLF_ENTRIES_CDSORTED));
		if (zap_leaf_array_match(l, zn, le->le_name_chunk,
		    le->le_name_numints)) {
			zeh->zeh_num_integers = le->le_value_numints;
			zeh->zeh_integer_size = le->le_value_intlen;
			zeh->zeh_cd = le->le_cd;
			zeh->zeh_hash = le->le_hash;
			zeh->zeh_chunkp = chunkp;
			zeh->zeh_leaf = l;
			return (0);
		}
	}

	return (SET_ERROR(ENOENT));
}

/* Return (h1,cd1 >= h2,cd2) */
#define	HCD_GTEQ(h1, cd1, h2, cd2) \
	((h1 > h2) ? TRUE : ((h1 == h2 && cd1 >= cd2) ? TRUE : FALSE))

int
zap_leaf_lookup_closest(zap_leaf_t *l,
    uint64_t h, uint32_t cd, zap_entry_handle_t *zeh)
{
	uint64_t besth = -1ULL;
	uint32_t bestcd = -1U;
	uint16_t bestlh = ZAP_LEAF_HASH_NUMENTRIES(l)-1;
	struct zap_leaf_entry *le;

	ASSERT3U(zap_leaf_phys(l)->l_hdr.lh_magic, ==, ZAP_LEAF_MAGIC);

	for (uint16_t lh = LEAF_HASH(l, h); lh <= bestlh; lh++) {
		for (uint16_t chunk = zap_leaf_phys(l)->l_hash[lh];
		    chunk != CHAIN_END; chunk = le->le_next) {
			le = ZAP_LEAF_ENTRY(l, chunk);

			ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
			ASSERT3U(le->le_type, ==, ZAP_CHUNK_ENTRY);

			if (HCD_GTEQ(le->le_hash, le->le_cd, h, cd) &&
			    HCD_GTEQ(besth, bestcd, le->le_hash, le->le_cd)) {
				ASSERT3U(bestlh, >=, lh);
				bestlh = lh;
				besth = le->le_hash;
				bestcd = le->le_cd;

				zeh->zeh_num_integers = le->le_value_numints;
				zeh->zeh_integer_size = le->le_value_intlen;
				zeh->zeh_cd = le->le_cd;
				zeh->zeh_hash = le->le_hash;
				zeh->zeh_fakechunk = chunk;
				zeh->zeh_chunkp = &zeh->zeh_fakechunk;
				zeh->zeh_leaf = l;
			}
		}
	}

	return (bestcd == -1U ? SET_ERROR(ENOENT) : 0);
}

int
zap_entry_read(const zap_entry_handle_t *zeh,
    uint8_t integer_size, uint64_t num_integers, void *buf)
{
	struct zap_leaf_entry *le =
	    ZAP_LEAF_ENTRY(zeh->zeh_leaf, *zeh->zeh_chunkp);
	ASSERT3U(le->le_type, ==, ZAP_CHUNK_ENTRY);

	if (le->le_value_intlen > integer_size)
		return (SET_ERROR(EINVAL));

	zap_leaf_array_read(zeh->zeh_leaf, le->le_value_chunk,
	    le->le_value_intlen, le->le_value_numints,
	    integer_size, num_integers, buf);

	if (zeh->zeh_num_integers > num_integers)
		return (SET_ERROR(EOVERFLOW));
	return (0);

}

int
zap_entry_read_name(zap_t *zap, const zap_entry_handle_t *zeh, uint16_t buflen,
    char *buf)
{
	struct zap_leaf_entry *le =
	    ZAP_LEAF_ENTRY(zeh->zeh_leaf, *zeh->zeh_chunkp);
	ASSERT3U(le->le_type, ==, ZAP_CHUNK_ENTRY);

	if (zap_getflags(zap) & ZAP_FLAG_UINT64_KEY) {
		zap_leaf_array_read(zeh->zeh_leaf, le->le_name_chunk, 8,
		    le->le_name_numints, 8, buflen / 8, buf);
	} else {
		zap_leaf_array_read(zeh->zeh_leaf, le->le_name_chunk, 1,
		    le->le_name_numints, 1, buflen, buf);
	}
	if (le->le_name_numints > buflen)
		return (SET_ERROR(EOVERFLOW));
	return (0);
}

int
zap_entry_update(zap_entry_handle_t *zeh,
    uint8_t integer_size, uint64_t num_integers, const void *buf)
{
	zap_leaf_t *l = zeh->zeh_leaf;
	struct zap_leaf_entry *le = ZAP_LEAF_ENTRY(l, *zeh->zeh_chunkp);

	int delta_chunks = ZAP_LEAF_ARRAY_NCHUNKS(num_integers * integer_size) -
	    ZAP_LEAF_ARRAY_NCHUNKS(le->le_value_numints * le->le_value_intlen);

	if ((int)zap_leaf_phys(l)->l_hdr.lh_nfree < delta_chunks)
		return (SET_ERROR(EAGAIN));

	zap_leaf_array_free(l, le->le_value_chunk);
	le->le_value_chunk =
	    zap_leaf_array_create(l, buf, integer_size, num_integers);
	le->le_value_numints = num_integers;
	le->le_value_intlen = integer_size;
	return (0);
}

void
zap_entry_remove(zap_entry_handle_t *zeh)
{
	zap_leaf_t *l = zeh->zeh_leaf;

	ASSERT3P(zeh->zeh_chunkp, !=, &zeh->zeh_fakechunk);

	uint16_t entry_chunk = *zeh->zeh_chunkp;
	struct zap_leaf_entry *le = ZAP_LEAF_ENTRY(l, entry_chunk);
	ASSERT3U(le->le_type, ==, ZAP_CHUNK_ENTRY);

	*zeh->zeh_chunkp = le->le_next;

	/* Free in opposite order to reduce fragmentation. */
	zap_leaf_array_free(l, le->le_value_chunk);
	zap_leaf_array_free(l, le->le_name_chunk);
	zap_leaf_chunk_free(l, entry_chunk);

	zap_leaf_phys(l)->l_hdr.lh_nentries--;
}

int
zap_entry_create(zap_leaf_t *l, zap_name_t *zn, uint32_t cd,
    uint8_t integer_size, uint64_t num_integers, const void *buf,
    zap_entry_handle_t *zeh)
{
	uint16_t chunk;
	struct zap_leaf_entry *le;
	uint64_t h = zn->zn_hash;

	uint64_t valuelen = integer_size * num_integers;

	uint_t numchunks = 1 + ZAP_LEAF_ARRAY_NCHUNKS(zn->zn_key_orig_numints *
	    zn->zn_key_intlen) + ZAP_LEAF_ARRAY_NCHUNKS(valuelen);
	if (numchunks > ZAP_LEAF_NUMCHUNKS(l))
		return (SET_ERROR(E2BIG));

	if (cd == ZAP_NEED_CD) {
		/* find the lowest unused cd */
		if (zap_leaf_phys(l)->l_hdr.lh_flags & ZLF_ENTRIES_CDSORTED) {
			cd = 0;

			for (chunk = *LEAF_HASH_ENTPTR(l, h);
			    chunk != CHAIN_END; chunk = le->le_next) {
				le = ZAP_LEAF_ENTRY(l, chunk);
				if (le->le_cd > cd)
					break;
				if (le->le_hash == h) {
					ASSERT3U(cd, ==, le->le_cd);
					cd++;
				}
			}
		} else {
			/* old unsorted format; do it the O(n^2) way */
			for (cd = 0; ; cd++) {
				for (chunk = *LEAF_HASH_ENTPTR(l, h);
				    chunk != CHAIN_END; chunk = le->le_next) {
					le = ZAP_LEAF_ENTRY(l, chunk);
					if (le->le_hash == h &&
					    le->le_cd == cd) {
						break;
					}
				}
				/* If this cd is not in use, we are good. */
				if (chunk == CHAIN_END)
					break;
			}
		}
		/*
		 * We would run out of space in a block before we could
		 * store enough entries to run out of CD values.
		 */
		ASSERT3U(cd, <, zap_maxcd(zn->zn_zap));
	}

	if (zap_leaf_phys(l)->l_hdr.lh_nfree < numchunks)
		return (SET_ERROR(EAGAIN));

	/* make the entry */
	chunk = zap_leaf_chunk_alloc(l);
	le = ZAP_LEAF_ENTRY(l, chunk);
	le->le_type = ZAP_CHUNK_ENTRY;
	le->le_name_chunk = zap_leaf_array_create(l, zn->zn_key_orig,
	    zn->zn_key_intlen, zn->zn_key_orig_numints);
	le->le_name_numints = zn->zn_key_orig_numints;
	le->le_value_chunk =
	    zap_leaf_array_create(l, buf, integer_size, num_integers);
	le->le_value_numints = num_integers;
	le->le_value_intlen = integer_size;
	le->le_hash = h;
	le->le_cd = cd;

	/* link it into the hash chain */
	/* XXX if we did the search above, we could just use that */
	uint16_t *chunkp = zap_leaf_rehash_entry(l, le, chunk);

	zap_leaf_phys(l)->l_hdr.lh_nentries++;

	zeh->zeh_leaf = l;
	zeh->zeh_num_integers = num_integers;
	zeh->zeh_integer_size = le->le_value_intlen;
	zeh->zeh_cd = le->le_cd;
	zeh->zeh_hash = le->le_hash;
	zeh->zeh_chunkp = chunkp;

	return (0);
}

/*
 * Determine if there is another entry with the same normalized form.
 * For performance purposes, either zn or name must be provided (the
 * other can be NULL).  Note, there usually won't be any hash
 * conflicts, in which case we don't need the concatenated/normalized
 * form of the name.  But all callers have one of these on hand anyway,
 * so might as well take advantage.  A cleaner but slower interface
 * would accept neither argument, and compute the normalized name as
 * needed (using zap_name_alloc_str(zap_entry_read_name(zeh))).
 */
boolean_t
zap_entry_normalization_conflict(zap_entry_handle_t *zeh, zap_name_t *zn,
    const char *name, zap_t *zap)
{
	struct zap_leaf_entry *le;
	boolean_t allocdzn = B_FALSE;

	if (zap->zap_normflags == 0)
		return (B_FALSE);

	for (uint16_t chunk = *LEAF_HASH_ENTPTR(zeh->zeh_leaf, zeh->zeh_hash);
	    chunk != CHAIN_END; chunk = le->le_next) {
		le = ZAP_LEAF_ENTRY(zeh->zeh_leaf, chunk);
		if (le->le_hash != zeh->zeh_hash)
			continue;
		if (le->le_cd == zeh->zeh_cd)
			continue;

		if (zn == NULL) {
			zn = zap_name_alloc_str(zap, name, MT_NORMALIZE);
			allocdzn = B_TRUE;
		}
		if (zap_leaf_array_match(zeh->zeh_leaf, zn,
		    le->le_name_chunk, le->le_name_numints)) {
			if (allocdzn)
				zap_name_free(zn);
			return (B_TRUE);
		}
	}
	if (allocdzn)
		zap_name_free(zn);
	return (B_FALSE);
}

/*
 * Routines for transferring entries between leafs.
 */

static uint16_t *
zap_leaf_rehash_entry(zap_leaf_t *l, struct zap_leaf_entry *le, uint16_t entry)
{
	struct zap_leaf_entry *le2;
	uint16_t *chunkp;

	/*
	 * keep the entry chain sorted by cd
	 * NB: this will not cause problems for unsorted leafs, though
	 * it is unnecessary there.
	 */
	for (chunkp = LEAF_HASH_ENTPTR(l, le->le_hash);
	    *chunkp != CHAIN_END; chunkp = &le2->le_next) {
		le2 = ZAP_LEAF_ENTRY(l, *chunkp);
		if (le2->le_cd > le->le_cd)
			break;
	}

	le->le_next = *chunkp;
	*chunkp = entry;
	return (chunkp);
}

static void
zap_leaf_transfer_entry(zap_leaf_t *l, uint_t entry, zap_leaf_t *nl)
{
	struct zap_leaf_entry *le = ZAP_LEAF_ENTRY(l, entry);
	ASSERT3U(le->le_type, ==, ZAP_CHUNK_ENTRY);

	uint16_t chunk = zap_leaf_chunk_alloc(nl);
	struct zap_leaf_entry *nle = ZAP_LEAF_ENTRY(nl, chunk);
	*nle = *le; /* structure assignment */

	(void) zap_leaf_rehash_entry(nl, nle, chunk);

	nle->le_name_chunk = zap_leaf_array_copy(l, le->le_name_chunk, nl);
	nle->le_value_chunk = zap_leaf_array_copy(l, le->le_value_chunk, nl);

	/* Free in opposite order to reduce fragmentation. */
	zap_leaf_array_free(l, le->le_value_chunk);
	zap_leaf_array_free(l, le->le_name_chunk);
	zap_leaf_chunk_free(l, entry);

	zap_leaf_phys(l)->l_hdr.lh_nentries--;
	zap_leaf_phys(nl)->l_hdr.lh_nentries++;
}

/*
 * Transfer the entries whose hash prefix ends in 1 to the new leaf.
 */
void
zap_leaf_split(zap_leaf_t *l, zap_leaf_t *nl, boolean_t sort)
{
	uint_t bit = 64 - 1 - zap_leaf_phys(l)->l_hdr.lh_prefix_len;

	/* set new prefix and prefix_len */
	zap_leaf_phys(l)->l_hdr.lh_prefix <<= 1;
	zap_leaf_phys(l)->l_hdr.lh_prefix_len++;
	zap_leaf_phys(nl)->l_hdr.lh_prefix =
	    zap_leaf_phys(l)->l_hdr.lh_prefix | 1;
	zap_leaf_phys(nl)->l_hdr.lh_prefix_len =
	    zap_leaf_phys(l)->l_hdr.lh_prefix_len;

	/* break existing hash chains */
	memset(zap_leaf_phys(l)->l_hash, CHAIN_END,
	    2*ZAP_LEAF_HASH_NUMENTRIES(l));

	if (sort)
		zap_leaf_phys(l)->l_hdr.lh_flags |= ZLF_ENTRIES_CDSORTED;

	/*
	 * Transfer entries whose hash bit 'bit' is set to nl; rehash
	 * the remaining entries
	 *
	 * NB: We could find entries via the hashtable instead. That
	 * would be O(hashents+numents) rather than O(numblks+numents),
	 * but this accesses memory more sequentially, and when we're
	 * called, the block is usually pretty full.
	 */
	for (uint_t i = 0; i < ZAP_LEAF_NUMCHUNKS(l); i++) {
		struct zap_leaf_entry *le = ZAP_LEAF_ENTRY(l, i);
		if (le->le_type != ZAP_CHUNK_ENTRY)
			continue;

		if (le->le_hash & (1ULL << bit))
			zap_leaf_transfer_entry(l, i, nl);
		else
			(void) zap_leaf_rehash_entry(l, le, i);
	}
}

void
zap_leaf_stats(zap_t *zap, zap_leaf_t *l, zap_stats_t *zs)
{
	uint_t n = zap_f_phys(zap)->zap_ptrtbl.zt_shift -
	    zap_leaf_phys(l)->l_hdr.lh_prefix_len;
	n = MIN(n, ZAP_HISTOGRAM_SIZE-1);
	zs->zs_leafs_with_2n_pointers[n]++;


	n = zap_leaf_phys(l)->l_hdr.lh_nentries/5;
	n = MIN(n, ZAP_HISTOGRAM_SIZE-1);
	zs->zs_blocks_with_n5_entries[n]++;

	n = ((1<<FZAP_BLOCK_SHIFT(zap)) -
	    zap_leaf_phys(l)->l_hdr.lh_nfree * (ZAP_LEAF_ARRAY_BYTES+1))*10 /
	    (1<<FZAP_BLOCK_SHIFT(zap));
	n = MIN(n, ZAP_HISTOGRAM_SIZE-1);
	zs->zs_blocks_n_tenths_full[n]++;

	for (uint_t i = 0; i < ZAP_LEAF_HASH_NUMENTRIES(l); i++) {
		uint_t nentries = 0;
		uint_t chunk = zap_leaf_phys(l)->l_hash[i];

		while (chunk != CHAIN_END) {
			struct zap_leaf_entry *le =
			    ZAP_LEAF_ENTRY(l, chunk);

			n = 1 + ZAP_LEAF_ARRAY_NCHUNKS(le->le_name_numints) +
			    ZAP_LEAF_ARRAY_NCHUNKS(le->le_value_numints *
			    le->le_value_intlen);
			n = MIN(n, ZAP_HISTOGRAM_SIZE-1);
			zs->zs_entries_using_n_chunks[n]++;

			chunk = le->le_next;
			nentries++;
		}

		n = nentries;
		n = MIN(n, ZAP_HISTOGRAM_SIZE-1);
		zs->zs_buckets_with_n_entries[n]++;
	}
}