--- servers/slapd/overlays/syncprov.c	2005/09/02 08:08:44	1.103
+++ servers/slapd/overlays/syncprov.c	2007/09/15 15:38:54	1.196
@@ -1,8 +1,8 @@
-/* $OpenLDAP: pkg/ldap/servers/slapd/overlays/syncprov.c,v 1.102 2005/08/26 19:42:48 hallvard Exp $ */
+/* $OpenLDAP: pkg/ldap/servers/slapd/overlays/syncprov.c,v 1.195 2007/08/28 22:27:47 ando Exp $ */
 /* syncprov.c - syncrepl provider */
 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
  *
- * Copyright 2004-2005 The OpenLDAP Foundation.
+ * Copyright 2004-2007 The OpenLDAP Foundation.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,6 +26,7 @@
 #include "lutil.h"
 #include "slap.h"
 #include "config.h"
+#include "ldap_rq.h"
 
 /* A modify request on a particular entry */
 typedef struct modinst {
@@ -58,11 +59,20 @@ typedef struct syncops {
 	ID		s_eid;		/* entryID of search base */
 	Operation	*s_op;		/* search op */
 	int		s_rid;
+	int		s_sid;
 	struct berval s_filterstr;
 	int		s_flags;	/* search status */
+#define	PS_IS_REFRESHING	0x01
+#define	PS_IS_DETACHED		0x02
+#define	PS_WROTE_BASE		0x04
+#define	PS_FIND_BASE		0x08
+#define	PS_FIX_FILTER		0x10
+
 	int		s_inuse;	/* reference count */
 	struct syncres *s_res;
 	struct syncres *s_restail;
+	struct re_s	*s_qtask;	/* task for playing psearch responses */
+#define	RUNQ_INTERVAL	36000	/* a long time */
 	ldap_pvt_thread_mutex_t	s_mutex;
 } syncops;
 
@@ -83,9 +93,6 @@ typedef struct sync_control {
 #define SLAP_SYNC_PERSIST				(LDAP_SYNC_RESERVED<<SLAP_CONTROL_SHIFT)
 #define SLAP_SYNC_REFRESH_AND_PERSIST	(LDAP_SYNC_REFRESH_AND_PERSIST<<SLAP_CONTROL_SHIFT)
 
-#define	PS_IS_REFRESHING	0x01
-#define	PS_IS_DETACHED		0x02
-
 /* Record of which searches matched at premodify step */
 typedef struct syncmatches {
 	struct syncmatches *sm_next;
@@ -97,6 +104,7 @@ typedef struct slog_entry {
 	struct slog_entry *se_next;
 	struct berval se_uuid;
 	struct berval se_csn;
+	int	se_sid;
 	ber_tag_t	se_tag;
 } slog_entry;
 
@@ -112,17 +120,20 @@ typedef struct sessionlog {
 /* The main state for this overlay */
 typedef struct syncprov_info_t {
 	syncops		*si_ops;
-	struct berval	si_ctxcsn;	/* ldapsync context */
+	BerVarray	si_ctxcsn;	/* ldapsync context */
+	int		*si_sids;
+	int		si_numcsns;
 	int		si_chkops;	/* checkpointing info */
 	int		si_chktime;
 	int		si_numops;	/* number of ops since last checkpoint */
+	int		si_nopres;	/* Skip present phase */
+	int		si_usehint;	/* use reload hint */
 	time_t	si_chklast;	/* time of last checkpoint */
 	Avlnode	*si_mods;	/* entries being modified */
 	sessionlog	*si_logs;
-	ldap_pvt_thread_mutex_t	si_csn_mutex;
+	ldap_pvt_thread_rdwr_t	si_csn_rwlock;
 	ldap_pvt_thread_mutex_t	si_ops_mutex;
 	ldap_pvt_thread_mutex_t	si_mods_mutex;
-	char		si_ctxcsnbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
 } syncprov_info_t;
 
 typedef struct opcookie {
@@ -359,36 +370,15 @@ findbase_cb( Operation *op, SlapReply *r
 		 * Just store whatever we got.
 		 */
 		if ( fc->fss->s_eid == NOID ) {
-			fc->fbase = 1;
+			fc->fbase = 2;
 			fc->fss->s_eid = rs->sr_entry->e_id;
 			ber_dupbv( &fc->fss->s_base, &rs->sr_entry->e_nname );
 
 		} else if ( rs->sr_entry->e_id == fc->fss->s_eid &&
 			dn_match( &rs->sr_entry->e_nname, &fc->fss->s_base )) {
 
-		/* OK, the DN is the same and the entryID is the same. Now
-		 * see if the fdn resides in the scope.
-		 */
+		/* OK, the DN is the same and the entryID is the same. */
 			fc->fbase = 1;
-			switch ( fc->fss->s_op->ors_scope ) {
-			case LDAP_SCOPE_BASE:
-				fc->fscope = dn_match( fc->fdn, &rs->sr_entry->e_nname );
-				break;
-			case LDAP_SCOPE_ONELEVEL: {
-				struct berval pdn;
-				dnParent( fc->fdn, &pdn );
-				fc->fscope = dn_match( &pdn, &rs->sr_entry->e_nname );
-				break; }
-			case LDAP_SCOPE_SUBTREE:
-				fc->fscope = dnIsSuffix( fc->fdn, &rs->sr_entry->e_nname );
-				break;
-#ifdef LDAP_SCOPE_SUBORDINATE
-			case LDAP_SCOPE_SUBORDINATE:
-				fc->fscope = dnIsSuffix( fc->fdn, &rs->sr_entry->e_nname ) &&
-					!dn_match( fc->fdn, &rs->sr_entry->e_nname );
-				break;
-#endif
-			}
 		}
 	}
 	if ( rs->sr_err != LDAP_SUCCESS ) {
@@ -397,45 +387,83 @@ findbase_cb( Operation *op, SlapReply *r
 	return LDAP_SUCCESS;
 }
 
+static Filter generic_filter = { LDAP_FILTER_PRESENT, { 0 }, NULL };
+static struct berval generic_filterstr = BER_BVC("(objectclass=*)");
+
 static int
 syncprov_findbase( Operation *op, fbase_cookie *fc )
 {
 	opcookie *opc = op->o_callback->sc_private;
 	slap_overinst *on = opc->son;
 
-	slap_callback cb = {0};
-	Operation fop;
-	SlapReply frs = { REP_RESULT };
-	int rc;
+	/* Use basic parameters from syncrepl search, but use
+	 * current op's threadctx / tmpmemctx
+	 */
+	ldap_pvt_thread_mutex_lock( &fc->fss->s_mutex );
+	if ( fc->fss->s_flags & PS_FIND_BASE ) {
+		slap_callback cb = {0};
+		Operation fop;
+		SlapReply frs = { REP_RESULT };
+		BackendInfo *bi;
+		int rc;
 
-	fop = *op;
+		fc->fss->s_flags ^= PS_FIND_BASE;
+		ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
 
-	cb.sc_response = findbase_cb;
-	cb.sc_private = fc;
+		fop = *fc->fss->s_op;
 
-	fop.o_sync_mode &= SLAP_CONTROL_MASK;	/* turn off sync mode */
-	fop.o_managedsait = SLAP_CONTROL_CRITICAL;
-	fop.o_callback = &cb;
-	fop.o_tag = LDAP_REQ_SEARCH;
-	fop.ors_scope = LDAP_SCOPE_BASE;
-	fop.ors_deref = fc->fss->s_op->ors_deref;
-	fop.ors_limit = NULL;
-	fop.ors_slimit = 1;
-	fop.ors_tlimit = SLAP_NO_LIMIT;
-	fop.ors_attrs = slap_anlist_no_attrs;
-	fop.ors_attrsonly = 1;
-	fop.ors_filter = fc->fss->s_op->ors_filter;
-	fop.ors_filterstr = fc->fss->s_op->ors_filterstr;
-
-	fop.o_req_dn = fc->fss->s_op->o_req_dn;
-	fop.o_req_ndn = fc->fss->s_op->o_req_ndn;
-	fop.o_authz = fc->fss->s_op->o_authz;
+		fop.o_hdr = op->o_hdr;
+		fop.o_bd = op->o_bd;
+		fop.o_time = op->o_time;
+		fop.o_tincr = op->o_tincr;
+		bi = op->o_bd->bd_info;
 
-	fop.o_bd->bd_info = on->on_info->oi_orig;
-	rc = fop.o_bd->be_search( &fop, &frs );
-	fop.o_bd->bd_info = (BackendInfo *)on;
+		cb.sc_response = findbase_cb;
+		cb.sc_private = fc;
 
-	if ( fc->fbase ) return LDAP_SUCCESS;
+		fop.o_sync_mode = 0;	/* turn off sync mode */
+		fop.o_managedsait = SLAP_CONTROL_CRITICAL;
+		fop.o_callback = &cb;
+		fop.o_tag = LDAP_REQ_SEARCH;
+		fop.ors_scope = LDAP_SCOPE_BASE;
+		fop.ors_limit = NULL;
+		fop.ors_slimit = 1;
+		fop.ors_tlimit = SLAP_NO_LIMIT;
+		fop.ors_attrs = slap_anlist_no_attrs;
+		fop.ors_attrsonly = 1;
+		fop.ors_filter = &generic_filter;
+		fop.ors_filterstr = generic_filterstr;
+
+		rc = overlay_op_walk( &fop, &frs, op_search, on->on_info, on );
+		op->o_bd->bd_info = bi;
+	} else {
+		ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
+		fc->fbase = 1;
+	}
+
+	/* After the first call, see if the fdn resides in the scope */
+	if ( fc->fbase == 1 ) {
+		switch ( fc->fss->s_op->ors_scope ) {
+		case LDAP_SCOPE_BASE:
+			fc->fscope = dn_match( fc->fdn, &fc->fss->s_base );
+			break;
+		case LDAP_SCOPE_ONELEVEL: {
+			struct berval pdn;
+			dnParent( fc->fdn, &pdn );
+			fc->fscope = dn_match( &pdn, &fc->fss->s_base );
+			break; }
+		case LDAP_SCOPE_SUBTREE:
+			fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base );
+			break;
+		case LDAP_SCOPE_SUBORDINATE:
+			fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base ) &&
+				!dn_match( fc->fdn, &fc->fss->s_base );
+			break;
+		}
+	}
+
+	if ( fc->fbase )
+		return LDAP_SUCCESS;
 
 	/* If entryID has changed, then the base of this search has
 	 * changed. Invalidate the psearch.
@@ -458,9 +486,11 @@ syncprov_findbase( Operation *op, fbase_
  * CSN, and generate Present records for them. We always collect this result
  * in SyncID sets, even if there's only one match.
  */
-#define	FIND_MAXCSN	1
-#define	FIND_CSN	2
-#define	FIND_PRESENT	3
+typedef enum find_csn_t {
+	FIND_MAXCSN	= 1,
+	FIND_CSN	= 2,
+	FIND_PRESENT	= 3
+} find_csn_t;
 
 static int
 findmax_cb( Operation *op, SlapReply *rs )
@@ -483,7 +513,11 @@ findcsn_cb( Operation *op, SlapReply *rs
 {
 	slap_callback *sc = op->o_callback;
 
-	if ( rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS ) {
+	/* We just want to know that at least one exists, so it's OK if
+	 * we exceed the unchecked limit.
+	 */
+	if ( rs->sr_err == LDAP_ADMINLIMIT_EXCEEDED ||
+		(rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS )) {
 		sc->sc_private = (void *)1;
 	}
 	return LDAP_SUCCESS;
@@ -539,7 +573,7 @@ findpres_cb( Operation *op, SlapReply *r
 }
 
 static int
-syncprov_findcsn( Operation *op, int mode )
+syncprov_findcsn( Operation *op, find_csn_t mode )
 {
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = on->on_bi.bi_private;
@@ -550,23 +584,16 @@ syncprov_findcsn( Operation *op, int mod
 	char buf[LDAP_LUTIL_CSNSTR_BUFSIZE + STRLENOF("(entryCSN<=)")];
 	char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
 	struct berval maxcsn;
-	Filter cf, af;
-#ifdef LDAP_COMP_MATCH
-	AttributeAssertion eq = { NULL, BER_BVNULL, NULL };
-#else
-	AttributeAssertion eq = { NULL, BER_BVNULL };
-#endif
-	int i, rc = LDAP_SUCCESS;
+	Filter cf;
+	AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
 	fpres_cookie pcookie;
 	sync_control *srs = NULL;
-	int findcsn_retry = 1;
+	struct slap_limits_set fc_limits;
+	int i, rc = LDAP_SUCCESS, findcsn_retry = 1;
+	int maxid = 0;
 
 	if ( mode != FIND_MAXCSN ) {
 		srs = op->o_controls[slap_cids.sc_LDAPsync];
-
-		if ( srs->sr_state.ctxcsn.bv_len >= LDAP_LUTIL_CSNSTR_BUFSIZE ) {
-			return LDAP_OTHER;
-		}
 	}
 
 	fop = *op;
@@ -576,6 +603,7 @@ syncprov_findcsn( Operation *op, int mod
 
 	cf.f_ava = &eq;
 	cf.f_av_desc = slap_schema.si_ad_entryCSN;
+	BER_BVZERO( &cf.f_av_value );
 	cf.f_next = NULL;
 
 	fop.o_callback = &cb;
@@ -588,7 +616,14 @@ again:
 	switch( mode ) {
 	case FIND_MAXCSN:
 		cf.f_choice = LDAP_FILTER_GE;
-		cf.f_av_value = si->si_ctxcsn;
+		cf.f_av_value = si->si_ctxcsn[0];
+		/* If there are multiple CSNs, use the largest */
+		for ( i=1; i<si->si_numcsns; i++) {
+			if ( ber_bvcmp( &cf.f_av_value, &si->si_ctxcsn[i] ) < 0 ) {
+				cf.f_av_value = si->si_ctxcsn[i];
+				maxid = i;
+			}
+		}
 		fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN>=%s)",
 			cf.f_av_value.bv_val );
 		fop.ors_attrsonly = 0;
@@ -596,12 +631,21 @@ again:
 		fop.ors_slimit = SLAP_NO_LIMIT;
 		cb.sc_private = &maxcsn;
 		cb.sc_response = findmax_cb;
-		strcpy( cbuf, si->si_ctxcsn.bv_val );
+		strcpy( cbuf, cf.f_av_value.bv_val );
 		maxcsn.bv_val = cbuf;
-		maxcsn.bv_len = si->si_ctxcsn.bv_len;
+		maxcsn.bv_len = cf.f_av_value.bv_len;
 		break;
 	case FIND_CSN:
-		cf.f_av_value = srs->sr_state.ctxcsn;
+		if ( BER_BVISEMPTY( &cf.f_av_value )) {
+			cf.f_av_value = srs->sr_state.ctxcsn[0];
+			/* If there are multiple CSNs, use the smallest */
+			for ( i=1; i<srs->sr_state.numcsns; i++ ) {
+				if ( ber_bvcmp( &cf.f_av_value, &srs->sr_state.ctxcsn[i] )
+					> 0 ) {
+					cf.f_av_value = srs->sr_state.ctxcsn[i];
+				}
+			}
+		}
 		/* Look for exact match the first time */
 		if ( findcsn_retry ) {
 			cf.f_choice = LDAP_FILTER_EQUALITY;
@@ -610,6 +654,9 @@ again:
 		/* On retry, look for <= */
 		} else {
 			cf.f_choice = LDAP_FILTER_LE;
+			fop.ors_limit = &fc_limits;
+			memset( &fc_limits, 0, sizeof( fc_limits ));
+			fc_limits.lms_s_unchecked = 1;
 			fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN<=%s)",
 				cf.f_av_value.bv_val );
 		}
@@ -620,14 +667,8 @@ again:
 		cb.sc_response = findcsn_cb;
 		break;
 	case FIND_PRESENT:
-		af.f_choice = LDAP_FILTER_AND;
-		af.f_next = NULL;
-		af.f_and = &cf;
-		cf.f_choice = LDAP_FILTER_LE;
-		cf.f_av_value = srs->sr_state.ctxcsn;
-		cf.f_next = op->ors_filter;
-		fop.ors_filter = &af;
-		filter2bv_x( &fop, fop.ors_filter, &fop.ors_filterstr );
+		fop.ors_filter = op->ors_filter;
+		fop.ors_filterstr = op->ors_filterstr;
 		fop.ors_attrsonly = 0;
 		fop.ors_attrs = uuid_anlist;
 		fop.ors_slimit = SLAP_NO_LIMIT;
@@ -655,8 +696,10 @@ again:
 
 	switch( mode ) {
 	case FIND_MAXCSN:
-		strcpy( si->si_ctxcsnbuf, maxcsn.bv_val );
-		si->si_ctxcsn.bv_len = maxcsn.bv_len;
+		if ( ber_bvcmp( &si->si_ctxcsn[maxid], &maxcsn )) {
+			ber_bvreplace( &si->si_ctxcsn[maxid], &maxcsn );
+			si->si_numops++;	/* ensure a checkpoint */
+		}
 		break;
 	case FIND_CSN:
 		/* If matching CSN was not found, invalidate the context. */
@@ -671,155 +714,68 @@ again:
 		break;
 	case FIND_PRESENT:
 		op->o_tmpfree( pcookie.uuids, op->o_tmpmemctx );
-		op->o_tmpfree( fop.ors_filterstr.bv_val, op->o_tmpmemctx );
 		break;
 	}
 
 	return rc;
 }
 
-/* Queue a persistent search response */
-static int
-syncprov_qresp( opcookie *opc, syncops *so, int mode )
+static void
+syncprov_free_syncop( syncops *so )
 {
-	syncres *sr;
-
-	sr = ch_malloc(sizeof(syncres) + opc->suuid.bv_len + 1 +
-		opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1 + opc->sctxcsn.bv_len + 1 );
-	sr->s_next = NULL;
-	sr->s_dn.bv_val = (char *)(sr + 1);
-	sr->s_dn.bv_len = opc->sdn.bv_len;
-	sr->s_mode = mode;
-	sr->s_isreference = opc->sreference;
-	sr->s_ndn.bv_val = lutil_strcopy( sr->s_dn.bv_val, opc->sdn.bv_val );
-	sr->s_ndn.bv_len = opc->sndn.bv_len;
-	*(sr->s_ndn.bv_val++) = '\0';
-	sr->s_uuid.bv_val = lutil_strcopy( sr->s_ndn.bv_val, opc->sndn.bv_val );
-	sr->s_uuid.bv_len = opc->suuid.bv_len;
-	*(sr->s_uuid.bv_val++) = '\0';
-	sr->s_csn.bv_val = lutil_strcopy( sr->s_uuid.bv_val, opc->suuid.bv_val );
-	sr->s_csn.bv_len = opc->sctxcsn.bv_len;
-	strcpy( sr->s_csn.bv_val, opc->sctxcsn.bv_val );
+	syncres *sr, *srnext;
+	GroupAssertion *ga, *gnext;
 
-	if ( !so->s_res ) {
-		so->s_res = sr;
-	} else {
-		so->s_restail->s_next = sr;
+	ldap_pvt_thread_mutex_lock( &so->s_mutex );
+	if ( --so->s_inuse > 0 ) {
+		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
+		return;
 	}
-	so->s_restail = sr;
 	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-	return LDAP_SUCCESS;
-}
-
-/* Play back queued responses */
-static int
-syncprov_sendresp( Operation *op, opcookie *opc, syncops *so, Entry **e, int mode, int queue );
-
-static int
-syncprov_qplay( Operation *op, slap_overinst *on, syncops *so )
-{
-	syncres *sr, *srnext;
-	Entry *e;
-	opcookie opc;
-	int rc;
-
-	opc.son = on;
-	op->o_bd->bd_info = (BackendInfo *)on->on_info;
-	for (sr = so->s_res; sr; sr=srnext) {
-		srnext = sr->s_next;
-		opc.sdn = sr->s_dn;
-		opc.sndn = sr->s_ndn;
-		opc.suuid = sr->s_uuid;
-		opc.sctxcsn = sr->s_csn;
-		opc.sreference = sr->s_isreference;
-		e = NULL;
-
-		if ( sr->s_mode != LDAP_SYNC_DELETE ) {
-			rc = be_entry_get_rw( op, &opc.sndn, NULL, NULL, 0, &e );
-			if ( rc ) {
-				ch_free( sr );
-				so->s_res = srnext;
-				continue;
-			}
-		}
-		rc = syncprov_sendresp( op, &opc, so, &e, sr->s_mode, 0 );
-
-		if ( e ) {
-			be_entry_release_rw( op, e, 0 );
+	if ( so->s_flags & PS_IS_DETACHED ) {
+		filter_free( so->s_op->ors_filter );
+		for ( ga = so->s_op->o_groups; ga; ga=gnext ) {
+			gnext = ga->ga_next;
+			ch_free( ga );
 		}
-		if ( rc )
-			break;
-
+		ch_free( so->s_op );
+	}
+	ch_free( so->s_base.bv_val );
+	for ( sr=so->s_res; sr; sr=srnext ) {
+		srnext = sr->s_next;
 		ch_free( sr );
-		so->s_res = srnext;
 	}
-	op->o_bd->bd_info = (BackendInfo *)on;
-	if ( !so->s_res )
-		so->s_restail = NULL;
-	return rc;
+	ldap_pvt_thread_mutex_destroy( &so->s_mutex );
+	ch_free( so );
 }
 
 /* Send a persistent search response */
 static int
-syncprov_sendresp( Operation *op, opcookie *opc, syncops *so, Entry **e, int mode, int queue )
+syncprov_sendresp( Operation *op, opcookie *opc, syncops *so,
+	Entry **e, int mode )
 {
 	slap_overinst *on = opc->son;
 
 	SlapReply rs = { REP_SEARCH };
 	LDAPControl *ctrls[2];
-	struct berval cookie;
+	struct berval cookie, csns[2];
 	Entry e_uuid = {0};
 	Attribute a_uuid = {0};
-	Operation sop = *so->s_op;
-	Opheader ohdr;
 
 	if ( so->s_op->o_abandon )
 		return SLAPD_ABANDON;
 
-	ohdr = *sop.o_hdr;
-	sop.o_hdr = &ohdr;
-	sop.o_tmpmemctx = op->o_tmpmemctx;
-	sop.o_bd = op->o_bd;
-	sop.o_controls = op->o_controls;
-	sop.o_private = op->o_private;
-
-	/* If queueing is allowed */
-	if ( queue ) {
-		ldap_pvt_thread_mutex_lock( &so->s_mutex );
-		/* If we're still in refresh mode, must queue */
-		if (so->s_flags & PS_IS_REFRESHING) {
-			return syncprov_qresp( opc, so, mode );
-		}
-		/* If connection is free but queue is non-empty,
-		 * try to flush the queue.
-		 */
-		if ( so->s_res ) {
-			rs.sr_err = syncprov_qplay( &sop, on, so );
-		}
-		/* If the connection is busy, must queue */
-		if ( sop.o_conn->c_writewaiter || rs.sr_err == LDAP_BUSY ) {
-			return syncprov_qresp( opc, so, mode );
-		}
-		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-
-		/* If syncprov_qplay returned any other error, bail out. */
-		if ( rs.sr_err ) {
-			return rs.sr_err;
-		}
-	} else {
-		/* Queueing not allowed and conn is busy, give up */
-		if ( sop.o_conn->c_writewaiter )
-			return LDAP_BUSY;
-	}
-
 	ctrls[1] = NULL;
-	slap_compose_sync_cookie( op, &cookie, &opc->sctxcsn, so->s_rid );
+	csns[0] = opc->sctxcsn;
+	BER_BVZERO( &csns[1] );
+	slap_compose_sync_cookie( op, &cookie, csns, so->s_rid, so->s_sid );
 
 	e_uuid.e_attrs = &a_uuid;
 	a_uuid.a_desc = slap_schema.si_ad_entryUUID;
 	a_uuid.a_nvals = &opc->suuid;
-	rs.sr_err = syncprov_state_ctrl( &sop, &rs, &e_uuid,
+	rs.sr_err = syncprov_state_ctrl( op, &rs, &e_uuid,
 		mode, ctrls, 0, 1, &cookie );
+	op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 
 	rs.sr_ctrls = ctrls;
 	op->o_bd->bd_info = (BackendInfo *)on->on_info;
@@ -829,8 +785,8 @@ syncprov_sendresp( Operation *op, opcook
 		if ( rs.sr_entry->e_private )
 			rs.sr_flags = REP_ENTRY_MUSTRELEASE;
 		if ( opc->sreference ) {
-			rs.sr_ref = get_entry_referrals( &sop, rs.sr_entry );
-			send_search_reference( &sop, &rs );
+			rs.sr_ref = get_entry_referrals( op, rs.sr_entry );
+			rs.sr_err = send_search_reference( op, &rs );
 			ber_bvarray_free( rs.sr_ref );
 			if ( !rs.sr_entry )
 				*e = NULL;
@@ -841,8 +797,8 @@ syncprov_sendresp( Operation *op, opcook
 		rs.sr_entry = *e;
 		if ( rs.sr_entry->e_private )
 			rs.sr_flags = REP_ENTRY_MUSTRELEASE;
-		rs.sr_attrs = sop.ors_attrs;
-		send_search_entry( &sop, &rs );
+		rs.sr_attrs = op->ors_attrs;
+		rs.sr_err = send_search_entry( op, &rs );
 		if ( !rs.sr_entry )
 			*e = NULL;
 		break;
@@ -854,60 +810,213 @@ syncprov_sendresp( Operation *op, opcook
 		if ( opc->sreference ) {
 			struct berval bv = BER_BVNULL;
 			rs.sr_ref = &bv;
-			send_search_reference( &sop, &rs );
+			rs.sr_err = send_search_reference( op, &rs );
 		} else {
-			send_search_entry( &sop, &rs );
+			rs.sr_err = send_search_entry( op, &rs );
 		}
 		break;
 	default:
 		assert(0);
 	}
-	op->o_tmpfree( rs.sr_ctrls[0], op->o_tmpmemctx );
-	op->o_private = sop.o_private;
-	rs.sr_ctrls = NULL;
-	/* Check queue again here; if we were hanging in a send and eventually
-	 * recovered, there may be more to send now. But don't check if the
-	 * original psearch has been abandoned.
-	 */
-	if ( so->s_op->o_abandon )
-		return SLAPD_ABANDON;
+	/* In case someone else freed it already? */
+	if ( rs.sr_ctrls ) {
+		op->o_tmpfree( rs.sr_ctrls[0], op->o_tmpmemctx );
+		rs.sr_ctrls = NULL;
+	}
 
-	if ( rs.sr_err == LDAP_SUCCESS && queue && so->s_res ) {
+	return rs.sr_err;
+}
+
+/* Play back queued responses */
+static int
+syncprov_qplay( Operation *op, slap_overinst *on, syncops *so )
+{
+	syncres *sr;
+	Entry *e;
+	opcookie opc;
+	int rc = 0;
+
+	opc.son = on;
+
+	for (;;) {
 		ldap_pvt_thread_mutex_lock( &so->s_mutex );
-		rs.sr_err = syncprov_qplay( &sop, on, so );
+		sr = so->s_res;
+		if ( sr )
+			so->s_res = sr->s_next;
+		if ( !so->s_res )
+			so->s_restail = NULL;
 		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
+
+		if ( !sr || so->s_op->o_abandon )
+			break;
+
+		opc.sdn = sr->s_dn;
+		opc.sndn = sr->s_ndn;
+		opc.suuid = sr->s_uuid;
+		opc.sctxcsn = sr->s_csn;
+		opc.sreference = sr->s_isreference;
+		e = NULL;
+
+		if ( sr->s_mode != LDAP_SYNC_DELETE ) {
+			rc = overlay_entry_get_ov( op, &opc.sndn, NULL, NULL, 0, &e, on );
+			if ( rc ) {
+				Debug( LDAP_DEBUG_SYNC, "syncprov_qplay: failed to get %s, "
+					"error (%d), ignoring...\n", opc.sndn.bv_val, rc, 0 );
+				ch_free( sr );
+				rc = 0;
+				continue;
+			}
+		}
+		rc = syncprov_sendresp( op, &opc, so, &e, sr->s_mode );
+
+		if ( e ) {
+			overlay_entry_release_ov( op, e, 0, on );
+		}
+
+		ch_free( sr );
+
+		if ( rc )
+			break;
 	}
-	return rs.sr_err;
+	return rc;
 }
 
+/* runqueue task for playing back queued responses */
+static void *
+syncprov_qtask( void *ctx, void *arg )
+{
+	struct re_s *rtask = arg;
+	syncops *so = rtask->arg;
+	slap_overinst *on = so->s_op->o_private;
+	OperationBuffer opbuf;
+	Operation *op;
+	BackendDB be;
+	int rc;
+
+	op = &opbuf.ob_op;
+	*op = *so->s_op;
+	op->o_hdr = &opbuf.ob_hdr;
+	op->o_controls = opbuf.ob_controls;
+	memset( op->o_controls, 0, sizeof(opbuf.ob_controls) );
+
+	*op->o_hdr = *so->s_op->o_hdr;
+
+	op->o_tmpmemctx = slap_sl_mem_create(SLAP_SLAB_SIZE, SLAP_SLAB_STACK, ctx, 1);
+	op->o_tmpmfuncs = &slap_sl_mfuncs;
+	op->o_threadctx = ctx;
+
+	/* syncprov_qplay expects a fake db */
+	be = *so->s_op->o_bd;
+	be.be_flags |= SLAP_DBFLAG_OVERLAY;
+	op->o_bd = &be;
+	op->o_private = NULL;
+	op->o_callback = NULL;
+
+	rc = syncprov_qplay( op, on, so );
+
+	/* decrement use count... */
+	syncprov_free_syncop( so );
+
+	/* wait until we get explicitly scheduled again */
+	ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+	ldap_pvt_runqueue_stoptask( &slapd_rq, rtask );
+	if ( rc == 0 ) {
+		ldap_pvt_runqueue_resched( &slapd_rq, rtask, 1 );
+	} else {
+		/* bail out on any error */
+		ldap_pvt_runqueue_remove( &slapd_rq, rtask );
+	}
+	ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+
+#if 0	/* FIXME: connection_close isn't exported from slapd.
+		 * should it be?
+		 */
+	if ( rc ) {
+		ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
+		if ( connection_state_closing( op->o_conn )) {
+			connection_close( op->o_conn );
+		}
+		ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+	}
+#endif
+	return NULL;
+}
+
+/* Start the task to play back queued psearch responses */
 static void
-syncprov_free_syncop( syncops *so )
+syncprov_qstart( syncops *so )
 {
-	syncres *sr, *srnext;
-	GroupAssertion *ga, *gnext;
+	int wake=0;
+	ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+	if ( !so->s_qtask ) {
+		so->s_qtask = ldap_pvt_runqueue_insert( &slapd_rq, RUNQ_INTERVAL,
+			syncprov_qtask, so, "syncprov_qtask",
+			so->s_op->o_conn->c_peer_name.bv_val );
+		++so->s_inuse;
+		wake = 1;
+	} else {
+		if (!ldap_pvt_runqueue_isrunning( &slapd_rq, so->s_qtask ) &&
+			!so->s_qtask->next_sched.tv_sec ) {
+			so->s_qtask->interval.tv_sec = 0;
+			ldap_pvt_runqueue_resched( &slapd_rq, so->s_qtask, 0 );
+			so->s_qtask->interval.tv_sec = RUNQ_INTERVAL;
+			++so->s_inuse;
+			wake = 1;
+		}
+	}
+	ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+	if ( wake )
+		slap_wake_listener();
+}
+
+/* Queue a persistent search response */
+static int
+syncprov_qresp( opcookie *opc, syncops *so, int mode )
+{
+	syncres *sr;
+	int sid;
+
+	/* Don't send changes back to their originator */
+	sid = slap_parse_csn_sid( &opc->sctxcsn );
+	if ( sid >= 0 && sid == so->s_sid )
+		return LDAP_SUCCESS;
+
+	sr = ch_malloc(sizeof(syncres) + opc->suuid.bv_len + 1 +
+		opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1 + opc->sctxcsn.bv_len + 1 );
+	sr->s_next = NULL;
+	sr->s_dn.bv_val = (char *)(sr + 1);
+	sr->s_dn.bv_len = opc->sdn.bv_len;
+	sr->s_mode = mode;
+	sr->s_isreference = opc->sreference;
+	sr->s_ndn.bv_val = lutil_strcopy( sr->s_dn.bv_val,
+		 opc->sdn.bv_val ) + 1;
+	sr->s_ndn.bv_len = opc->sndn.bv_len;
+	sr->s_uuid.bv_val = lutil_strcopy( sr->s_ndn.bv_val,
+		 opc->sndn.bv_val ) + 1;
+	sr->s_uuid.bv_len = opc->suuid.bv_len;
+	AC_MEMCPY( sr->s_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
+	sr->s_csn.bv_val = sr->s_uuid.bv_val + sr->s_uuid.bv_len + 1;
+	sr->s_csn.bv_len = opc->sctxcsn.bv_len;
+	strcpy( sr->s_csn.bv_val, opc->sctxcsn.bv_val );
 
 	ldap_pvt_thread_mutex_lock( &so->s_mutex );
-	so->s_inuse--;
-	if ( so->s_inuse > 0 ) {
-		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-		return;
+	if ( !so->s_res ) {
+		so->s_res = sr;
+	} else {
+		so->s_restail->s_next = sr;
 	}
-	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-	if ( so->s_flags & PS_IS_DETACHED ) {
-		filter_free( so->s_op->ors_filter );
-		for ( ga = so->s_op->o_groups; ga; ga=gnext ) {
-			gnext = ga->ga_next;
-			ch_free( ga );
-		}
-		ch_free( so->s_op );
+	so->s_restail = sr;
+
+	/* If the base of the psearch was modified, check it next time round */
+	if ( so->s_flags & PS_WROTE_BASE ) {
+		so->s_flags ^= PS_WROTE_BASE;
+		so->s_flags |= PS_FIND_BASE;
 	}
-	ch_free( so->s_base.bv_val );
-	for ( sr=so->s_res; sr; sr=srnext ) {
-		srnext = sr->s_next;
-		ch_free( sr );
+	if ( so->s_flags & PS_IS_DETACHED ) {
+		syncprov_qstart( so );
 	}
-	ldap_pvt_thread_mutex_destroy( &so->s_mutex );
-	ch_free( so );
+	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
+	return LDAP_SUCCESS;
 }
 
 static int
@@ -918,7 +1027,7 @@ syncprov_drop_psearch( syncops *so, int
 			ldap_pvt_thread_mutex_lock( &so->s_op->o_conn->c_mutex );
 		so->s_op->o_conn->c_n_ops_executing--;
 		so->s_op->o_conn->c_n_ops_completed++;
-		LDAP_STAILQ_REMOVE( &so->s_op->o_conn->c_ops, so->s_op, slap_op,
+		LDAP_STAILQ_REMOVE( &so->s_op->o_conn->c_ops, so->s_op, Operation,
 			o_next );
 		if ( lock )
 			ldap_pvt_thread_mutex_unlock( &so->s_op->o_conn->c_mutex );
@@ -985,11 +1094,12 @@ syncprov_matchops( Operation *op, opcook
 
 	fbase_cookie fc;
 	syncops *ss, *sprev, *snext;
-	Entry *e;
+	Entry *e = NULL;
 	Attribute *a;
 	int rc;
 	struct berval newdn;
 	int freefdn = 0;
+	BackendDB *b0 = op->o_bd, db;
 
 	fc.fdn = &op->o_req_ndn;
 	/* compute new DN */
@@ -1002,29 +1112,37 @@ syncprov_matchops( Operation *op, opcook
 		freefdn = 1;
 	}
 	if ( op->o_tag != LDAP_REQ_ADD ) {
-		op->o_bd->bd_info = (BackendInfo *)on->on_info;
-		rc = be_entry_get_rw( op, fc.fdn, NULL, NULL, 0, &e );
+		if ( !SLAP_ISOVERLAY( op->o_bd )) {
+			db = *op->o_bd;
+			op->o_bd = &db;
+		}
+		rc = overlay_entry_get_ov( op, fc.fdn, NULL, NULL, 0, &e, on );
 		/* If we're sending responses now, make a copy and unlock the DB */
 		if ( e && !saveit ) {
 			Entry *e2 = entry_dup( e );
-			be_entry_release_rw( op, e, 0 );
+			overlay_entry_release_ov( op, e, 0, on );
 			e = e2;
 		}
-		op->o_bd->bd_info = (BackendInfo *)on;
-		if ( rc ) return;
+		if ( rc ) {
+			op->o_bd = b0;
+			return;
+		}
 	} else {
 		e = op->ora_e;
 	}
 
-	if ( saveit ) {
+	if ( saveit || op->o_tag == LDAP_REQ_ADD ) {
 		ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
 		ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
 		opc->sreference = is_entry_referral( e );
-	}
-	if ( saveit || op->o_tag == LDAP_REQ_ADD ) {
 		a = attr_find( e->e_attrs, slap_schema.si_ad_entryUUID );
 		if ( a )
 			ber_dupbv_x( &opc->suuid, &a->a_nvals[0], op->o_tmpmemctx );
+	} else if ( op->o_tag == LDAP_REQ_MODRDN && !saveit ) {
+		op->o_tmpfree( opc->sndn.bv_val, op->o_tmpmemctx );
+		op->o_tmpfree( opc->sdn.bv_val, op->o_tmpmemctx );
+		ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
+		ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
 	}
 
 	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
@@ -1048,12 +1166,22 @@ syncprov_matchops( Operation *op, opcook
 				"search base has changed" );
 			sprev->s_next = snext;
 			syncprov_drop_psearch( ss, 1 );
+			ss = sprev;
 			continue;
 		}
 
+
 		/* If we're sending results now, look for this op in old matches */
 		if ( !saveit ) {
 			syncmatches *old;
+
+			/* Did we modify the search base? */
+			if ( dn_match( &op->o_req_ndn, &ss->s_base )) {
+				ldap_pvt_thread_mutex_lock( &ss->s_mutex );
+				ss->s_flags |= PS_WROTE_BASE;
+				ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
+			}
+
 			for ( sm=opc->smatches, old=(syncmatches *)&opc->smatches; sm;
 				old=sm, sm=sm->sm_next ) {
 				if ( sm->sm_op == ss ) {
@@ -1072,34 +1200,33 @@ syncprov_matchops( Operation *op, opcook
 				sm = op->o_tmpalloc( sizeof(syncmatches), op->o_tmpmemctx );
 				sm->sm_next = opc->smatches;
 				sm->sm_op = ss;
-				ss->s_inuse++;
+				ldap_pvt_thread_mutex_lock( &ss->s_mutex );
+				++ss->s_inuse;
+				ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
 				opc->smatches = sm;
 			} else {
 				/* if found send UPDATE else send ADD */
-				ss->s_inuse++;
-				ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
-				syncprov_sendresp( op, opc, ss, &e,
-					found ? LDAP_SYNC_MODIFY : LDAP_SYNC_ADD, 1 );
-				ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
-				ss->s_inuse--;
+				syncprov_qresp( opc, ss,
+					found ? LDAP_SYNC_MODIFY : LDAP_SYNC_ADD );
 			}
 		} else if ( !saveit && found ) {
 			/* send DELETE */
-			ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
-			syncprov_sendresp( op, opc, ss, NULL, LDAP_SYNC_DELETE, 1 );
-			ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
+			syncprov_qresp( opc, ss, LDAP_SYNC_DELETE );
 		}
 	}
 	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
 
 	if ( op->o_tag != LDAP_REQ_ADD && e ) {
-		op->o_bd->bd_info = (BackendInfo *)on->on_info;
-		be_entry_release_rw( op, e, 0 );
-		op->o_bd->bd_info = (BackendInfo *)on;
+		if ( !SLAP_ISOVERLAY( op->o_bd )) {
+			op->o_bd = &db;
+		}
+		overlay_entry_release_ov( op, e, 0, on );
+		op->o_bd = b0;
 	}
 	if ( freefdn ) {
 		op->o_tmpfree( fc.fdn->bv_val, op->o_tmpmemctx );
 	}
+	op->o_bd = b0;
 }
 
 static int
@@ -1154,16 +1281,13 @@ syncprov_op_cleanup( Operation *op, Slap
 static void
 syncprov_checkpoint( Operation *op, SlapReply *rs, slap_overinst *on )
 {
-	syncprov_info_t		*si = on->on_bi.bi_private;
+	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
 	Modifications mod;
 	Operation opm;
-	struct berval bv[2];
+	SlapReply rsm = { 0 };
 	slap_callback cb = {0};
-	int manage = get_manageDSAit(op);
 
-	mod.sml_values = bv;
-	bv[1].bv_val = NULL;
-	bv[0] = si->si_ctxcsn;
+	mod.sml_values = si->si_ctxcsn;
 	mod.sml_nvalues = NULL;
 	mod.sml_desc = slap_schema.si_ad_contextCSN;
 	mod.sml_op = LDAP_MOD_REPLACE;
@@ -1175,16 +1299,21 @@ syncprov_checkpoint( Operation *op, Slap
 	opm.o_tag = LDAP_REQ_MODIFY;
 	opm.o_callback = &cb;
 	opm.orm_modlist = &mod;
+	opm.orm_no_opattrs = 1;
 	opm.o_req_dn = op->o_bd->be_suffix[0];
 	opm.o_req_ndn = op->o_bd->be_nsuffix[0];
 	opm.o_bd->bd_info = on->on_info->oi_orig;
 	opm.o_managedsait = SLAP_CONTROL_NONCRITICAL;
-	opm.o_bd->be_modify( &opm, rs );
-	opm.o_managedsait = manage;
+	opm.o_no_schema_check = 1;
+	opm.o_bd->be_modify( &opm, &rsm );
+	if ( mod.sml_next != NULL ) {
+		slap_mods_free( mod.sml_next, 1 );
+	}
+	opm.orm_no_opattrs = 0;
 }
 
 static void
-syncprov_add_slog( Operation *op, struct berval *csn )
+syncprov_add_slog( Operation *op )
 {
 	opcookie *opc = op->o_callback->sc_private;
 	slap_overinst *on = opc->son;
@@ -1196,18 +1325,19 @@ syncprov_add_slog( Operation *op, struct
 	{
 		/* Allocate a record. UUIDs are not NUL-terminated. */
 		se = ch_malloc( sizeof( slog_entry ) + opc->suuid.bv_len + 
-			csn->bv_len + 1 );
+			op->o_csn.bv_len + 1 );
 		se->se_next = NULL;
 		se->se_tag = op->o_tag;
 
-		se->se_uuid.bv_val = (char *)(se+1);
+		se->se_uuid.bv_val = (char *)(&se[1]);
 		AC_MEMCPY( se->se_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
 		se->se_uuid.bv_len = opc->suuid.bv_len;
 
 		se->se_csn.bv_val = se->se_uuid.bv_val + opc->suuid.bv_len;
-		AC_MEMCPY( se->se_csn.bv_val, csn->bv_val, csn->bv_len );
-		se->se_csn.bv_val[csn->bv_len] = '\0';
-		se->se_csn.bv_len = csn->bv_len;
+		AC_MEMCPY( se->se_csn.bv_val, op->o_csn.bv_val, op->o_csn.bv_len );
+		se->se_csn.bv_val[op->o_csn.bv_len] = '\0';
+		se->se_csn.bv_len = op->o_csn.bv_len;
+		se->se_sid = slap_parse_csn_sid( &se->se_csn );
 
 		ldap_pvt_thread_mutex_lock( &sl->sl_mutex );
 		if ( sl->sl_head ) {
@@ -1224,9 +1354,6 @@ syncprov_add_slog( Operation *op, struct
 			sl->sl_mincsn.bv_len = se->se_csn.bv_len;
 			ch_free( se );
 			sl->sl_num--;
-			if ( !sl->sl_head ) {
-				sl->sl_tail = NULL;
-			}
 		}
 		ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
 	}
@@ -1245,12 +1372,14 @@ playlog_cb( Operation *op, SlapReply *rs
 /* enter with sl->sl_mutex locked, release before returning */
 static void
 syncprov_playlog( Operation *op, SlapReply *rs, sessionlog *sl,
-	struct berval *oldcsn, struct berval *ctxcsn )
+	sync_control *srs, BerVarray ctxcsn, int numcsns, int *sids )
 {
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	slog_entry *se;
 	int i, j, ndel, num, nmods, mmods;
+	char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
 	BerVarray uuids;
+	struct berval delcsn[2];
 
 	if ( !sl->sl_num ) {
 		ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
@@ -1263,19 +1392,49 @@ syncprov_playlog( Operation *op, SlapRep
 
 	uuids = op->o_tmpalloc( (num+1) * sizeof( struct berval ) +
 		num * UUID_LEN, op->o_tmpmemctx );
-
 	uuids[0].bv_val = (char *)(uuids + num + 1);
 
+	delcsn[0].bv_len = 0;
+	delcsn[0].bv_val = cbuf;
+	BER_BVZERO(&delcsn[1]);
+
 	/* Make a copy of the relevant UUIDs. Put the Deletes up front
 	 * and everything else at the end. Do this first so we can
 	 * unlock the list mutex.
 	 */
+	Debug( LDAP_DEBUG_SYNC, "srs csn %s\n",
+		srs->sr_state.ctxcsn[0].bv_val, 0, 0 );
 	for ( se=sl->sl_head; se; se=se->se_next ) {
-		if ( ber_bvcmp( &se->se_csn, oldcsn ) < 0 ) continue;
-		if ( ber_bvcmp( &se->se_csn, ctxcsn ) > 0 ) break;
+		int k;
+		Debug( LDAP_DEBUG_SYNC, "log csn %s\n", se->se_csn.bv_val, 0, 0 );
+		ndel = 1;
+		for ( k=0; k<srs->sr_state.numcsns; k++ ) {
+			if ( se->se_sid == srs->sr_state.sids[k] ) {
+				ndel = ber_bvcmp( &se->se_csn, &srs->sr_state.ctxcsn[k] );
+				break;
+			}
+		}
+		if ( ndel <= 0 ) {
+			Debug( LDAP_DEBUG_SYNC, "cmp %d, too old\n", ndel, 0, 0 );
+			continue;
+		}
+		ndel = 0;
+		for ( k=0; k<numcsns; k++ ) {
+			if ( se->se_sid == sids[k] ) {
+				ndel = ber_bvcmp( &se->se_csn, &ctxcsn[k] );
+				break;
+			}
+		}
+		if ( ndel > 0 ) {
+			Debug( LDAP_DEBUG_SYNC, "cmp %d, too new\n", ndel, 0, 0 );
+			break;
+		}
 		if ( se->se_tag == LDAP_REQ_DELETE ) {
 			j = i;
 			i++;
+			AC_MEMCPY( cbuf, se->se_csn.bv_val, se->se_csn.bv_len );
+			delcsn[0].bv_len = se->se_csn.bv_len;
+			delcsn[0].bv_val[delcsn[0].bv_len] = '\0';
 		} else {
 			nmods++;
 			j = num - nmods;
@@ -1320,11 +1479,7 @@ syncprov_playlog( Operation *op, SlapRep
 		SlapReply frs = { REP_RESULT };
 		int rc;
 		Filter mf, af;
-#ifdef LDAP_COMP_MATCH
-		AttributeAssertion eq = { NULL, BER_BVNULL, NULL };
-#else
-		AttributeAssertion eq;
-#endif
+		AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
 		slap_callback cb = {0};
 
 		fop = *op;
@@ -1356,6 +1511,7 @@ syncprov_playlog( Operation *op, SlapRep
 			mf.f_av_value = uuids[i];
 			cb.sc_private = NULL;
 			fop.ors_slimit = 1;
+			frs.sr_nentries = 0;
 			rc = fop.o_bd->be_search( &fop, &frs );
 
 			/* If entry was not found, add to delete list */
@@ -1366,9 +1522,15 @@ syncprov_playlog( Operation *op, SlapRep
 		fop.o_bd->bd_info = (BackendInfo *)on;
 	}
 	if ( ndel ) {
+		struct berval cookie;
+
+		slap_compose_sync_cookie( op, &cookie, delcsn, srs->sr_state.rid,
+			srs->sr_state.sid );
 		uuids[ndel].bv_val = NULL;
-		syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, NULL, 0, uuids, 1 );
+		syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, &cookie, 0, uuids, 1 );
+		op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 	}
+	op->o_tmpfree( uuids, op->o_tmpmemctx );
 }
 
 static int
@@ -1381,31 +1543,45 @@ syncprov_op_response( Operation *op, Sla
 
 	if ( rs->sr_err == LDAP_SUCCESS )
 	{
-		struct berval maxcsn = BER_BVNULL, curcsn = BER_BVNULL;
+		struct berval maxcsn = BER_BVNULL;
 		char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
+		int do_check = 0;
 
 		/* Update our context CSN */
 		cbuf[0] = '\0';
-		ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
-		slap_get_commit_csn( op, &maxcsn, &curcsn );
+		ldap_pvt_thread_rdwr_wlock( &si->si_csn_rwlock );
+		slap_get_commit_csn( op, &maxcsn );
 		if ( !BER_BVISNULL( &maxcsn ) ) {
+			int i, sid;
 			strcpy( cbuf, maxcsn.bv_val );
-			if ( ber_bvcmp( &maxcsn, &si->si_ctxcsn ) > 0 ) {
-				strcpy( si->si_ctxcsnbuf, cbuf );
-				si->si_ctxcsn.bv_len = maxcsn.bv_len;
+			sid = slap_parse_csn_sid( &maxcsn );
+			for ( i=0; i<si->si_numcsns; i++ ) {
+				if ( sid == si->si_sids[i] ) {
+					if ( ber_bvcmp( &maxcsn, &si->si_ctxcsn[i] ) > 0 ) {
+						ber_bvreplace( &si->si_ctxcsn[i], &maxcsn );
+					}
+					break;
+				}
+			}
+			/* It's a new SID for us */
+			if ( i == si->si_numcsns ) {
+				value_add_one( &si->si_ctxcsn, &maxcsn );
+				si->si_numcsns++;
+				si->si_sids = ch_realloc( si->si_sids, si->si_numcsns *
+					sizeof(int));
+				si->si_sids[i] = sid;
 			}
 		}
 
 		/* Don't do any processing for consumer contextCSN updates */
 		if ( SLAP_SYNC_SHADOW( op->o_bd ) && 
 			op->o_msgid == SLAP_SYNC_UPDATE_MSGID ) {
-			ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
 			return SLAP_CB_CONTINUE;
 		}
 
 		si->si_numops++;
 		if ( si->si_chkops || si->si_chktime ) {
-			int do_check=0;
 			if ( si->si_chkops && si->si_numops >= si->si_chkops ) {
 				do_check = 1;
 				si->si_numops = 0;
@@ -1415,11 +1591,14 @@ syncprov_op_response( Operation *op, Sla
 				do_check = 1;
 				si->si_chklast = op->o_time;
 			}
-			if ( do_check ) {
-				syncprov_checkpoint( op, rs, on );
-			}
 		}
-		ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
+
+		if ( do_check ) {
+			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
+			syncprov_checkpoint( op, rs, on );
+			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
+		}
 
 		opc->sctxcsn.bv_len = maxcsn.bv_len;
 		opc->sctxcsn.bv_val = cbuf;
@@ -1440,8 +1619,7 @@ syncprov_op_response( Operation *op, Sla
 				for ( sm = opc->smatches; sm; sm=sm->sm_next ) {
 					if ( sm->sm_op->s_op->o_abandon )
 						continue;
-					syncprov_sendresp( op, opc, sm->sm_op, NULL,
-						LDAP_SYNC_DELETE, 1 );
+					syncprov_qresp( opc, sm->sm_op, LDAP_SYNC_DELETE );
 				}
 				break;
 			}
@@ -1449,7 +1627,7 @@ syncprov_op_response( Operation *op, Sla
 
 		/* Add any log records */
 		if ( si->si_logs && op->o_tag != LDAP_REQ_ADD ) {
-			syncprov_add_slog( op, &curcsn );
+			syncprov_add_slog( op );
 		}
 
 	}
@@ -1472,19 +1650,17 @@ syncprov_op_compare( Operation *op, Slap
 	{
 		Entry e = {0};
 		Attribute a = {0};
-		struct berval bv[2];
 
 		e.e_name = op->o_bd->be_suffix[0];
 		e.e_nname = op->o_bd->be_nsuffix[0];
-
-		BER_BVZERO( &bv[1] );
-		bv[0] = si->si_ctxcsn;
+		e.e_attrs = &a;
 
 		a.a_desc = slap_schema.si_ad_contextCSN;
-		a.a_vals = bv;
-		a.a_nvals = a.a_vals;
 
-		ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
+
+		a.a_vals = si->si_ctxcsn;
+		a.a_nvals = a.a_vals;
 
 		rs->sr_err = access_allowed( op, &e, op->oq_compare.rs_ava->aa_desc,
 			&op->oq_compare.rs_ava->aa_value, ACL_COMPARE, NULL );
@@ -1513,7 +1689,7 @@ syncprov_op_compare( Operation *op, Slap
 
 return_results:;
 
-		ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 
 		send_ldap_result( op, rs );
 
@@ -1612,9 +1788,10 @@ syncprov_op_extended( Operation *op, Sla
 typedef struct searchstate {
 	slap_overinst *ss_on;
 	syncops *ss_so;
+	BerVarray ss_ctxcsn;
+	int *ss_sids;
+	int ss_numcsns;
 	int ss_present;
-	struct berval ss_ctxcsn;
-	char ss_csnbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
 } searchstate;
 
 static int
@@ -1628,9 +1805,17 @@ syncprov_search_cleanup( Operation *op,
 	return 0;
 }
 
+typedef struct SyncOperationBuffer {
+	Operation		sob_op;
+	Opheader		sob_hdr;
+	AttributeName	sob_extra;	/* not always present */
+	/* Further data allocated here */
+} SyncOperationBuffer;
+
 static void
-syncprov_detach_op( Operation *op, syncops *so )
+syncprov_detach_op( Operation *op, syncops *so, slap_overinst *on )
 {
+	SyncOperationBuffer *sopbuf2;
 	Operation *op2;
 	int i, alen = 0;
 	size_t size;
@@ -1642,34 +1827,36 @@ syncprov_detach_op( Operation *op, synco
 		alen += op->ors_attrs[i].an_name.bv_len + 1;
 	}
 	/* Make a new copy of the operation */
-	size = sizeof(Operation) + sizeof(Opheader) +
+	size = offsetof( SyncOperationBuffer, sob_extra ) +
 		(i ? ( (i+1) * sizeof(AttributeName) + alen) : 0) +
 		op->o_req_dn.bv_len + 1 +
 		op->o_req_ndn.bv_len + 1 +
 		op->o_ndn.bv_len + 1 +
 		so->s_filterstr.bv_len + 1;
-	op2 = (Operation *)ch_calloc( 1, size );
-	op2->o_hdr = (Opheader *)(op2+1);
+	sopbuf2 = ch_calloc( 1, size );
+	op2 = &sopbuf2->sob_op;
+	op2->o_hdr = &sopbuf2->sob_hdr;
 
 	/* Copy the fields we care about explicitly, leave the rest alone */
 	*op2->o_hdr = *op->o_hdr;
 	op2->o_tag = op->o_tag;
 	op2->o_time = op->o_time;
-	op2->o_bd = op->o_bd;
+	op2->o_bd = on->on_info->oi_origdb;
 	op2->o_request = op->o_request;
+	op2->o_private = on;
 
+	ptr = (char *) sopbuf2 + offsetof( SyncOperationBuffer, sob_extra );
 	if ( i ) {
-		op2->ors_attrs = (AttributeName *)(op2->o_hdr + 1);
-		ptr = (char *)(op2->ors_attrs+i+1);
+		op2->ors_attrs = (AttributeName *) ptr;
+		ptr = (char *) &op2->ors_attrs[i+1];
 		for (i=0; !BER_BVISNULL( &op->ors_attrs[i].an_name ); i++) {
 			op2->ors_attrs[i] = op->ors_attrs[i];
 			op2->ors_attrs[i].an_name.bv_val = ptr;
 			ptr = lutil_strcopy( ptr, op->ors_attrs[i].an_name.bv_val ) + 1;
 		}
 		BER_BVZERO( &op2->ors_attrs[i].an_name );
-	} else {
-		ptr = (char *)(op2->o_hdr + 1);
 	}
+
 	op2->o_authz = op->o_authz;
 	op2->o_ndn.bv_val = ptr;
 	ptr = lutil_strcopy(ptr, op->o_ndn.bv_val) + 1;
@@ -1683,7 +1870,15 @@ syncprov_detach_op( Operation *op, synco
 	op2->ors_filterstr.bv_val = ptr;
 	strcpy( ptr, so->s_filterstr.bv_val );
 	op2->ors_filterstr.bv_len = so->s_filterstr.bv_len;
-	op2->ors_filter = str2filter( ptr );
+
+	/* Skip the AND/GE clause that we stuck on in front */
+	if ( so->s_flags & PS_FIX_FILTER ) {
+		op2->ors_filter = op->ors_filter->f_and->f_next;
+		so->s_flags ^= PS_FIX_FILTER;
+	} else {
+		op2->ors_filter = op->ors_filter;
+	}
+	op2->ors_filter = filter_dup( op2->ors_filter, NULL );
 	so->s_op = op2;
 
 	/* Copy any cached group ACLs individually */
@@ -1695,6 +1890,8 @@ syncprov_detach_op( Operation *op, synco
 		g2->ga_next = op2->o_groups;
 		op2->o_groups = g2;
 	}
+	/* Don't allow any further group caching */
+	op2->o_do_not_cache = 1;
 
 	/* Add op2 to conn so abandon will find us */
 	ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
@@ -1703,6 +1900,9 @@ syncprov_detach_op( Operation *op, synco
 	LDAP_STAILQ_INSERT_TAIL( &op->o_conn->c_ops, op2, o_next );
 	so->s_flags |= PS_IS_DETACHED;
 	ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+
+	/* Prevent anyone else from trying to send a result for this op */
+	op->o_abandon = 1;
 }
 
 static int
@@ -1725,15 +1925,48 @@ syncprov_search_response( Operation *op,
 			return SLAP_CB_CONTINUE;
 		}
 		a = attr_find( rs->sr_entry->e_attrs, slap_schema.si_ad_entryCSN );
+		if ( a == NULL && rs->sr_operational_attrs != NULL ) {
+			a = attr_find( rs->sr_operational_attrs, slap_schema.si_ad_entryCSN );
+		}
 		if ( a ) {
-			/* Make sure entry is less than the snaphot'd contextCSN */
-			if ( ber_bvcmp( &a->a_nvals[0], &ss->ss_ctxcsn ) > 0 )
-				return LDAP_SUCCESS;
+			int i, sid;
+			sid = slap_parse_csn_sid( &a->a_nvals[0] );
 
-			/* Don't send the ctx entry twice */
-			if ( !BER_BVISNULL( &srs->sr_state.ctxcsn ) &&
-				bvmatch( &a->a_nvals[0], &srs->sr_state.ctxcsn ) )
+			/* Don't send changed entries back to the originator */
+			if ( sid == srs->sr_state.sid && srs->sr_state.numcsns ) {
+				Debug( LDAP_DEBUG_SYNC,
+					"Entry %s changed by peer, ignored\n",
+					rs->sr_entry->e_name.bv_val, 0, 0 );
 				return LDAP_SUCCESS;
+			}
+			/* Make sure entry is less than the snapshot'd contextCSN */
+			for ( i=0; i<ss->ss_numcsns; i++ ) {
+				if ( sid == ss->ss_sids[i] && ber_bvcmp( &a->a_nvals[0],
+					&ss->ss_ctxcsn[i] ) > 0 ) {
+					Debug( LDAP_DEBUG_SYNC,
+						"Entry %s CSN %s greater than snapshot %s\n",
+						rs->sr_entry->e_name.bv_val,
+						a->a_nvals[0].bv_val,
+						ss->ss_ctxcsn[i].bv_val );
+					return LDAP_SUCCESS;
+				}
+			}
+
+			/* Don't send old entries twice */
+			if ( srs->sr_state.ctxcsn ) {
+				for ( i=0; i<srs->sr_state.numcsns; i++ ) {
+					if ( sid == srs->sr_state.sids[i] &&
+						ber_bvcmp( &a->a_nvals[0],
+							&srs->sr_state.ctxcsn[i] )<= 0 ) {
+						Debug( LDAP_DEBUG_SYNC,
+							"Entry %s CSN %s older or equal to ctx %s\n",
+							rs->sr_entry->e_name.bv_val,
+							a->a_nvals[0].bv_val,
+							srs->sr_state.ctxcsn[i].bv_val );
+						return LDAP_SUCCESS;
+					}
+				}
+			}
 		}
 		rs->sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2,
 			op->o_tmpmemctx );
@@ -1743,8 +1976,8 @@ syncprov_search_response( Operation *op,
 	} else if ( rs->sr_type == REP_RESULT && rs->sr_err == LDAP_SUCCESS ) {
 		struct berval cookie;
 
-		slap_compose_sync_cookie( op, &cookie, &ss->ss_ctxcsn,
-			srs->sr_state.rid );
+		slap_compose_sync_cookie( op, &cookie, ss->ss_ctxcsn,
+			srs->sr_state.rid, srs->sr_state.sid );
 
 		/* Is this a regular refresh? */
 		if ( !ss->ss_so ) {
@@ -1754,26 +1987,26 @@ syncprov_search_response( Operation *op,
 			rs->sr_err = syncprov_done_ctrl( op, rs, rs->sr_ctrls,
 				0, 1, &cookie, ss->ss_present ?  LDAP_SYNC_REFRESH_PRESENTS :
 					LDAP_SYNC_REFRESH_DELETES );
+			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 		} else {
-			int locked = 0;
 		/* It's RefreshAndPersist, transition to Persist phase */
-			syncprov_sendinfo( op, rs, ( ss->ss_present && rs->sr_nentries ) ?
+			syncprov_sendinfo( op, rs, ss->ss_present ?
 	 			LDAP_TAG_SYNC_REFRESH_PRESENT : LDAP_TAG_SYNC_REFRESH_DELETE,
 				&cookie, 1, NULL, 0 );
-			/* Flush any queued persist messages */
-			if ( ss->ss_so->s_res ) {
-				ldap_pvt_thread_mutex_lock( &ss->ss_so->s_mutex );
-				locked = 1;
-				syncprov_qplay( op, on, ss->ss_so );
-			}
+			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
+
+			/* Detach this Op from frontend control */
+			ldap_pvt_thread_mutex_lock( &ss->ss_so->s_mutex );
 
 			/* Turn off the refreshing flag */
 			ss->ss_so->s_flags ^= PS_IS_REFRESHING;
-			if ( locked )
-				ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
 
-			/* Detach this Op from frontend control */
-			syncprov_detach_op( op, ss->ss_so );
+			syncprov_detach_op( op, ss->ss_so, on );
+
+			/* If there are queued responses, fire them off */
+			if ( ss->ss_so->s_res )
+				syncprov_qstart( ss->ss_so );
+			ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
 
 			return LDAP_SUCCESS;
 		}
@@ -1788,12 +2021,13 @@ syncprov_op_search( Operation *op, SlapR
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
 	slap_callback	*cb;
-	int gotstate = 0, nochange = 0, do_present = 1;
+	int gotstate = 0, nochange = 0, do_present;
 	syncops *sop = NULL;
 	searchstate *ss;
 	sync_control *srs;
-	struct berval ctxcsn;
-	char csnbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
+	BerVarray ctxcsn;
+	int i, *sids, numcsns;
+	struct berval mincsn;
 
 	if ( !(op->o_sync_mode & SLAP_SYNC_REFRESH) ) return SLAP_CB_CONTINUE;
 
@@ -1802,6 +2036,8 @@ syncprov_op_search( Operation *op, SlapR
 		return rs->sr_err;
 	}
 
+	do_present = si->si_nopres ? 0 : 1;
+
 	srs = op->o_controls[slap_cids.sc_LDAPsync];
 	op->o_managedsait = SLAP_CONTROL_NONCRITICAL;
 
@@ -1816,14 +2052,16 @@ syncprov_op_search( Operation *op, SlapR
 		fc.fbase = 0;
 		so.s_eid = NOID;
 		so.s_op = op;
-		so.s_flags = PS_IS_REFRESHING;
+		so.s_flags = PS_IS_REFRESHING | PS_FIND_BASE;
 		/* syncprov_findbase expects to be called as a callback... */
 		sc.sc_private = &opc;
 		opc.son = on;
+		ldap_pvt_thread_mutex_init( &so.s_mutex );
 		cb = op->o_callback;
 		op->o_callback = &sc;
 		rs->sr_err = syncprov_findbase( op, &fc );
 		op->o_callback = cb;
+		ldap_pvt_thread_mutex_destroy( &so.s_mutex );
 
 		if ( rs->sr_err != LDAP_SUCCESS ) {
 			send_ldap_result( op, rs );
@@ -1833,6 +2071,7 @@ syncprov_op_search( Operation *op, SlapR
 		*sop = so;
 		ldap_pvt_thread_mutex_init( &sop->s_mutex );
 		sop->s_rid = srs->sr_state.rid;
+		sop->s_sid = srs->sr_state.sid;
 		sop->s_inuse = 1;
 
 		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
@@ -1842,44 +2081,101 @@ syncprov_op_search( Operation *op, SlapR
 	}
 
 	/* snapshot the ctxcsn */
-	ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
-	strcpy( csnbuf, si->si_ctxcsnbuf );
-	ctxcsn.bv_len = si->si_ctxcsn.bv_len;
-	ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
-	ctxcsn.bv_val = csnbuf;
+	ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
+	numcsns = si->si_numcsns;
+	if ( numcsns ) {
+		ber_bvarray_dup_x( &ctxcsn, si->si_ctxcsn, op->o_tmpmemctx );
+		sids = op->o_tmpalloc( numcsns * sizeof(int), op->o_tmpmemctx );
+		for ( i=0; i<numcsns; i++ )
+			sids[i] = si->si_sids[i];
+	} else {
+		ctxcsn = NULL;
+		sids = NULL;
+	}
+	ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 	
 	/* If we have a cookie, handle the PRESENT lookups */
-	if ( !BER_BVISNULL( &srs->sr_state.ctxcsn )) {
+	if ( srs->sr_state.ctxcsn ) {
 		sessionlog *sl;
+		int i, j;
 
-		/* The cookie was validated when it was parsed, just use it */
+		/* If we don't have any CSN of our own yet, pretend nothing
+		 * has changed.
+		 */
+		if ( !numcsns )
+			goto no_change;
 
-		/* If just Refreshing and nothing has changed, shortcut it */
-		if ( bvmatch( &srs->sr_state.ctxcsn, &ctxcsn )) {
-			nochange = 1;
-			if ( !(op->o_sync_mode & SLAP_SYNC_PERSIST) ) {
-				LDAPControl	*ctrls[2];
-
-				ctrls[0] = NULL;
-				ctrls[1] = NULL;
-				syncprov_done_ctrl( op, rs, ctrls, 0, 0,
-					NULL, LDAP_SYNC_REFRESH_DELETES );
-				rs->sr_ctrls = ctrls;
-				rs->sr_err = LDAP_SUCCESS;
-				send_ldap_result( op, rs );
-				rs->sr_ctrls = NULL;
-				return rs->sr_err;
+		/* If there are SIDs we don't recognize in the cookie, drop them */
+		for (i=0; i<srs->sr_state.numcsns; ) {
+			for (j=0; j<numcsns; j++) {
+				if ( srs->sr_state.sids[i] == sids[j] ) {
+					break;
+				}
+			}
+			/* not found */
+			if ( j == numcsns ) {
+				struct berval tmp = srs->sr_state.ctxcsn[i];
+				j = srs->sr_state.numcsns - 1;
+				srs->sr_state.ctxcsn[i] = srs->sr_state.ctxcsn[j];
+				tmp.bv_len = 0;
+				srs->sr_state.ctxcsn[j] = tmp;
+				srs->sr_state.numcsns = j;
+				srs->sr_state.sids[i] = srs->sr_state.sids[j];
+				continue;
+			}
+			i++;
+		}
+
+		/* Find the smallest CSN */
+		mincsn = srs->sr_state.ctxcsn[0];
+		for ( i=1; i<srs->sr_state.numcsns; i++ ) {
+			if ( ber_bvcmp( &mincsn, &srs->sr_state.ctxcsn[i] ) > 0 )
+				mincsn = srs->sr_state.ctxcsn[i];
+		}
+
+		/* If nothing has changed, shortcut it */
+		if ( srs->sr_state.numcsns == numcsns ) {
+			int i, j, changed = 0;
+			for ( i=0; i<srs->sr_state.numcsns; i++ ) {
+				for ( j=0; j<numcsns; j++ ) {
+					if ( srs->sr_state.sids[i] != sids[j] )
+						continue;
+					if ( !bvmatch( &srs->sr_state.ctxcsn[i], &ctxcsn[j] ))
+						changed = 1;
+					break;
+				}
+				if ( changed )
+					break;
+			}
+			if ( !changed ) {
+no_change:		nochange = 1;
+				if ( !(op->o_sync_mode & SLAP_SYNC_PERSIST) ) {
+					LDAPControl	*ctrls[2];
+
+					ctrls[0] = NULL;
+					ctrls[1] = NULL;
+					syncprov_done_ctrl( op, rs, ctrls, 0, 0,
+						NULL, LDAP_SYNC_REFRESH_DELETES );
+					rs->sr_ctrls = ctrls;
+					rs->sr_err = LDAP_SUCCESS;
+					send_ldap_result( op, rs );
+					rs->sr_ctrls = NULL;
+					return rs->sr_err;
+				}
+				goto shortcut;
 			}
-			goto shortcut;
 		}
 		/* Do we have a sessionlog for this search? */
 		sl=si->si_logs;
 		if ( sl ) {
 			ldap_pvt_thread_mutex_lock( &sl->sl_mutex );
-			if ( ber_bvcmp( &srs->sr_state.ctxcsn, &sl->sl_mincsn ) >= 0 ) {
+			/* Are there any log entries, and is the consumer state
+			 * present in the session log?
+			 */
+			if ( sl->sl_num > 0 && ber_bvcmp( &mincsn, &sl->sl_mincsn ) >= 0 ) {
 				do_present = 0;
 				/* mutex is unlocked in playlog */
-				syncprov_playlog( op, rs, sl, &srs->sr_state.ctxcsn, &ctxcsn );
+				syncprov_playlog( op, rs, sl, srs, ctxcsn, numcsns, sids );
 			} else {
 				ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
 			}
@@ -1887,17 +2183,20 @@ syncprov_op_search( Operation *op, SlapR
 		/* Is the CSN still present in the database? */
 		if ( syncprov_findcsn( op, FIND_CSN ) != LDAP_SUCCESS ) {
 			/* No, so a reload is required */
-#if 0		/* the consumer doesn't seem to send this hint */
-			if ( op->o_sync_rhint == 0 ) {
+			/* the 2.2 consumer doesn't send this hint */
+			if ( si->si_usehint && srs->sr_rhint == 0 ) {
+				if ( ctxcsn )
+					ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
 				send_ldap_error( op, rs, LDAP_SYNC_REFRESH_REQUIRED, "sync cookie is stale" );
 				return rs->sr_err;
 			}
-#endif
 		} else {
 			gotstate = 1;
 			/* If changed and doing Present lookup, send Present UUIDs */
 			if ( do_present && syncprov_findcsn( op, FIND_PRESENT ) !=
 				LDAP_SUCCESS ) {
+				if ( ctxcsn )
+					ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
 				send_ldap_result( op, rs );
 				return rs->sr_err;
 			}
@@ -1927,10 +2226,12 @@ shortcut:
 #ifdef LDAP_COMP_MATCH
 		fava->f_ava->aa_cf = NULL;
 #endif
-		ber_dupbv_x( &fava->f_ava->aa_value, &srs->sr_state.ctxcsn, op->o_tmpmemctx );
+		ber_dupbv_x( &fava->f_ava->aa_value, &mincsn, op->o_tmpmemctx );
 		fava->f_next = op->ors_filter;
 		op->ors_filter = fand;
 		filter2bv_x( op, op->ors_filter, &op->ors_filterstr );
+		if ( sop )
+			sop->s_flags |= PS_FIX_FILTER;
 	}
 
 	/* Let our callback add needed info to returned entries */
@@ -1939,19 +2240,15 @@ shortcut:
 	ss->ss_on = on;
 	ss->ss_so = sop;
 	ss->ss_present = do_present;
-	ss->ss_ctxcsn.bv_len = ctxcsn.bv_len;
-	ss->ss_ctxcsn.bv_val = ss->ss_csnbuf;
-	strcpy( ss->ss_ctxcsn.bv_val, ctxcsn.bv_val );
+	ss->ss_ctxcsn = ctxcsn;
+	ss->ss_numcsns = numcsns;
+	ss->ss_sids = sids;
 	cb->sc_response = syncprov_search_response;
 	cb->sc_cleanup = syncprov_search_cleanup;
 	cb->sc_private = ss;
 	cb->sc_next = op->o_callback;
 	op->o_callback = cb;
 
-#if 0	/* I don't think we need to shortcircuit back-bdb any more */
-	op->o_sync_mode &= SLAP_CONTROL_MASK;
-#endif
-
 	/* If this is a persistent search and no changes were reported during
 	 * the refresh phase, just invoke the response callback to transition
 	 * us into persist phase
@@ -1985,26 +2282,35 @@ syncprov_operational(
 					break;
 			}
 
-			if ( !a ) {
-				for ( ap = &rs->sr_operational_attrs; *ap; ap=&(*ap)->a_next );
+			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
+			if ( si->si_ctxcsn ) {
+				if ( !a ) {
+					for ( ap = &rs->sr_operational_attrs; *ap;
+						ap=&(*ap)->a_next );
 
-				a = ch_malloc( sizeof(Attribute));
-				a->a_desc = slap_schema.si_ad_contextCSN;
-				a->a_vals = ch_malloc( 2 * sizeof(struct berval));
-				a->a_vals[1].bv_val = NULL;
-				a->a_nvals = a->a_vals;
-				a->a_next = NULL;
-				a->a_flags = 0;
-				*ap = a;
-			}
-
-			ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
-			if ( !ap ) {
-				strcpy( a->a_vals[0].bv_val, si->si_ctxcsnbuf );
-			} else {
-				ber_dupbv( &a->a_vals[0], &si->si_ctxcsn );
+					a = attr_alloc( slap_schema.si_ad_contextCSN );
+					*ap = a;
+				}
+
+				if ( !ap ) {
+					if ( !rs->sr_flags & REP_ENTRY_MODIFIABLE ) {
+						rs->sr_entry = entry_dup( rs->sr_entry );
+						rs->sr_flags |=
+							REP_ENTRY_MODIFIABLE|REP_ENTRY_MUSTBEFREED;
+						a = attr_find( rs->sr_entry->e_attrs,
+							slap_schema.si_ad_contextCSN );
+					}
+					if ( a->a_nvals != a->a_vals ) {
+						ber_bvarray_free( a->a_nvals );
+					}
+					a->a_nvals = NULL;
+					ber_bvarray_free( a->a_vals );
+					a->a_vals = NULL;
+				}
+				ber_bvarray_dup_x( &a->a_vals, si->si_ctxcsn, NULL );
+				ber_bvarray_dup_x( &a->a_nvals, si->si_ctxcsn, NULL );
 			}
-			ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 		}
 	}
 	return SLAP_CB_CONTINUE;
@@ -2012,7 +2318,9 @@ syncprov_operational(
 
 enum {
 	SP_CHKPT = 1,
-	SP_SESSL
+	SP_SESSL,
+	SP_NOPRES,
+	SP_USEHINT
 };
 
 static ConfigDriver sp_cf_gen;
@@ -2026,6 +2334,14 @@ static ConfigTable spcfg[] = {
 		sp_cf_gen, "( OLcfgOvAt:1.2 NAME 'olcSpSessionlog' "
 			"DESC 'Session log size in ops' "
 			"SYNTAX OMsInteger SINGLE-VALUE )", NULL, NULL },
+	{ "syncprov-nopresent", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_NOPRES,
+		sp_cf_gen, "( OLcfgOvAt:1.3 NAME 'olcSpNoPresent' "
+			"DESC 'Omit Present phase processing' "
+			"SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
+	{ "syncprov-reloadhint", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_USEHINT,
+		sp_cf_gen, "( OLcfgOvAt:1.4 NAME 'olcSpReloadHint' "
+			"DESC 'Observe Reload Hint in Request control' "
+			"SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
 	{ NULL, NULL, 0, 0, 0, ARG_IGNORED }
 };
 
@@ -2034,7 +2350,7 @@ static ConfigOCs spocs[] = {
 		"NAME 'olcSyncProvConfig' "
 		"DESC 'SyncRepl Provider configuration' "
 		"SUP olcOverlayConfig "
-		"MAY ( olcSpCheckpoint $ olcSpSessionlog ) )",
+		"MAY ( olcSpCheckpoint $ olcSpSessionlog $ olcSpNoPresent ) )",
 			Cft_Overlay, spcfg },
 	{ NULL, 0, NULL }
 };
@@ -2051,9 +2367,9 @@ sp_cf_gen(ConfigArgs *c)
 		case SP_CHKPT:
 			if ( si->si_chkops || si->si_chktime ) {
 				struct berval bv;
-				bv.bv_len = sprintf( c->msg, "%d %d",
+				bv.bv_len = sprintf( c->cr_msg, "%d %d",
 					si->si_chkops, si->si_chktime );
-				bv.bv_val = c->msg;
+				bv.bv_val = c->cr_msg;
 				value_add_one( &c->rvalue_vals, &bv );
 			} else {
 				rc = 1;
@@ -2066,6 +2382,20 @@ sp_cf_gen(ConfigArgs *c)
 				rc = 1;
 			}
 			break;
+		case SP_NOPRES:
+			if ( si->si_nopres ) {
+				c->value_int = 1;
+			} else {
+				rc = 1;
+			}
+			break;
+		case SP_USEHINT:
+			if ( si->si_usehint ) {
+				c->value_int = 1;
+			} else {
+				rc = 1;
+			}
+			break;
 		}
 		return rc;
 	} else if ( c->op == LDAP_MOD_DELETE ) {
@@ -2080,22 +2410,62 @@ sp_cf_gen(ConfigArgs *c)
 			else
 				rc = LDAP_NO_SUCH_ATTRIBUTE;
 			break;
+		case SP_NOPRES:
+			if ( si->si_nopres )
+				si->si_nopres = 0;
+			else
+				rc = LDAP_NO_SUCH_ATTRIBUTE;
+			break;
+		case SP_USEHINT:
+			if ( si->si_usehint )
+				si->si_usehint = 0;
+			else
+				rc = LDAP_NO_SUCH_ATTRIBUTE;
+			break;
 		}
 		return rc;
 	}
 	switch ( c->type ) {
 	case SP_CHKPT:
-		si->si_chkops = atoi( c->argv[1] );
-		si->si_chktime = atoi( c->argv[2] ) * 60;
+		if ( lutil_atoi( &si->si_chkops, c->argv[1] ) != 0 ) {
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint ops # \"%s\"",
+				c->argv[0], c->argv[1] );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->cr_msg, 0 );
+			return ARG_BAD_CONF;
+		}
+		if ( si->si_chkops <= 0 ) {
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint ops # \"%d\"",
+				c->argv[0], si->si_chkops );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->cr_msg, 0 );
+			return ARG_BAD_CONF;
+		}
+		if ( lutil_atoi( &si->si_chktime, c->argv[2] ) != 0 ) {
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint time \"%s\"",
+				c->argv[0], c->argv[1] );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->cr_msg, 0 );
+			return ARG_BAD_CONF;
+		}
+		if ( si->si_chktime <= 0 ) {
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint time \"%d\"",
+				c->argv[0], si->si_chkops );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->cr_msg, 0 );
+			return ARG_BAD_CONF;
+		}
+		si->si_chktime *= 60;
 		break;
 	case SP_SESSL: {
 		sessionlog *sl;
 		int size = c->value_int;
 
 		if ( size < 0 ) {
-			sprintf( c->msg, "%s size %d is negative",
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s size %d is negative",
 				c->argv[0], size );
-			Debug( LDAP_DEBUG_CONFIG, "%s: %s\n", c->log, c->msg, 0 );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->cr_msg, 0 );
 			return ARG_BAD_CONF;
 		}
 		sl = si->si_logs;
@@ -2111,6 +2481,12 @@ sp_cf_gen(ConfigArgs *c)
 		sl->sl_size = size;
 		}
 		break;
+	case SP_NOPRES:
+		si->si_nopres = c->value_int;
+		break;
+	case SP_USEHINT:
+		si->si_usehint = c->value_int;
+		break;
 	}
 	return rc;
 }
@@ -2133,21 +2509,27 @@ syncprov_db_otask(
  */
 static int
 syncprov_db_open(
-    BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
 	slap_overinst   *on = (slap_overinst *) be->bd_info;
 	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
 
-	Connection conn;
-	char opbuf[OPERATION_BUFFER_SIZE];
-	char ctxcsnbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
-	Operation *op = (Operation *)opbuf;
-	Entry *e;
+	Connection conn = { 0 };
+	OperationBuffer opbuf;
+	Operation *op;
+	Entry *e = NULL;
 	Attribute *a;
 	int rc;
 	void *thrctx = NULL;
 
+	if ( !SLAP_LASTMOD( be )) {
+		Debug( LDAP_DEBUG_ANY,
+			"syncprov_db_open: invalid config, lastmod must be enabled\n", 0, 0, 0 );
+		return -1;
+	}
+
 	if ( slapMode & SLAP_TOOL_MODE ) {
 		return 0;
 	}
@@ -2158,60 +2540,62 @@ syncprov_db_open(
 	}
 
 	thrctx = ldap_pvt_thread_pool_context();
-	connection_fake_init( &conn, op, thrctx );
+	connection_fake_init( &conn, &opbuf, thrctx );
+	op = &opbuf.ob_op;
 	op->o_bd = be;
 	op->o_dn = be->be_rootdn;
 	op->o_ndn = be->be_rootndn;
 
-	ctxcsnbuf[0] = '\0';
-
-	op->o_bd->bd_info = on->on_info->oi_orig;
-	rc = be_entry_get_rw( op, be->be_nsuffix, NULL,
-		slap_schema.si_ad_contextCSN, 0, &e );
+	rc = overlay_entry_get_ov( op, be->be_nsuffix, NULL,
+		slap_schema.si_ad_contextCSN, 0, &e, on );
 
 	if ( e ) {
 		ldap_pvt_thread_t tid;
 
 		a = attr_find( e->e_attrs, slap_schema.si_ad_contextCSN );
 		if ( a ) {
-			si->si_ctxcsn.bv_len = a->a_nvals[0].bv_len;
-			if ( si->si_ctxcsn.bv_len >= sizeof(si->si_ctxcsnbuf ))
-				si->si_ctxcsn.bv_len = sizeof(si->si_ctxcsnbuf)-1;
-			strncpy( si->si_ctxcsnbuf, a->a_nvals[0].bv_val,
-				si->si_ctxcsn.bv_len );
-			si->si_ctxcsnbuf[si->si_ctxcsn.bv_len] = '\0';
-			strcpy( ctxcsnbuf, si->si_ctxcsnbuf );
-		}
-		be_entry_release_rw( op, e, 0 );
-		op->o_bd->bd_info = (BackendInfo *)on;
-		op->o_req_dn = be->be_suffix[0];
-		op->o_req_ndn = be->be_nsuffix[0];
-		op->ors_scope = LDAP_SCOPE_SUBTREE;
-		ldap_pvt_thread_create( &tid, 0, syncprov_db_otask, op );
-		ldap_pvt_thread_join( tid, NULL );
-	} else if ( SLAP_SYNC_SHADOW( op->o_bd )) {
-		/* If we're also a consumer, and we didn't find the context entry,
-		 * then don't generate anything, wait for our provider to send it
-		 * to us.
-		 */
-		goto out;
+			int i;
+			ber_bvarray_dup_x( &si->si_ctxcsn, a->a_vals, NULL );
+			for ( i = 0; !BER_BVISNULL( &a->a_vals[i] ); i++ );
+			si->si_numcsns = i;
+			si->si_sids = slap_parse_csn_sids( si->si_ctxcsn, i, NULL );
+		}
+		overlay_entry_release_ov( op, e, 0, on );
+		if ( si->si_ctxcsn ) {
+			op->o_req_dn = be->be_suffix[0];
+			op->o_req_ndn = be->be_nsuffix[0];
+			op->ors_scope = LDAP_SCOPE_SUBTREE;
+			ldap_pvt_thread_create( &tid, 0, syncprov_db_otask, op );
+			ldap_pvt_thread_join( tid, NULL );
+		}
 	}
 
-	if ( BER_BVISEMPTY( &si->si_ctxcsn ) ) {
-		slap_get_csn( op, si->si_ctxcsnbuf, sizeof(si->si_ctxcsnbuf),
-				&si->si_ctxcsn, 0 );
-	}
+	/* Didn't find a contextCSN, should we generate one? */
+	if ( !si->si_ctxcsn ) {
+		char csnbuf[ LDAP_LUTIL_CSNSTR_BUFSIZE ];
+		struct berval csn;
+
+		if ( SLAP_SYNC_SHADOW( op->o_bd )) {
+		/* If we're also a consumer, then don't generate anything.
+		 * Wait for our provider to send it to us, or for a local
+		 * modify if we have multimaster.
+		 */
+			goto out;
+		}
+		csn.bv_val = csnbuf;
+		csn.bv_len = sizeof( csnbuf );
+		slap_get_csn( op, &csn, 0 );
+		value_add_one( &si->si_ctxcsn, &csn );
+		si->si_numcsns = 1;
+		si->si_sids = ch_malloc( sizeof(int) );
+		si->si_sids[0] = slap_serverID;
 
-	/* If our ctxcsn is different from what was read from the root
-	 * entry, make sure we do a checkpoint on close
-	 */
-	if ( strcmp( si->si_ctxcsnbuf, ctxcsnbuf )) {
+		/* make sure we do a checkpoint on close */
 		si->si_numops++;
 	}
 
 out:
 	op->o_bd->bd_info = (BackendInfo *)on;
-	ldap_pvt_thread_pool_context_reset( thrctx );
 	return 0;
 }
 
@@ -2219,7 +2603,8 @@ out:
  */
 static int
 syncprov_db_close(
-    BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
     slap_overinst   *on = (slap_overinst *) be->bd_info;
@@ -2229,19 +2614,19 @@ syncprov_db_close(
 		return 0;
 	}
 	if ( si->si_numops ) {
-		Connection conn;
-		char opbuf[OPERATION_BUFFER_SIZE];
-		Operation *op = (Operation *)opbuf;
+		Connection conn = {0};
+		OperationBuffer opbuf;
+		Operation *op;
 		SlapReply rs = {REP_RESULT};
 		void *thrctx;
 
 		thrctx = ldap_pvt_thread_pool_context();
-		connection_fake_init( &conn, op, thrctx );
+		connection_fake_init( &conn, &opbuf, thrctx );
+		op = &opbuf.ob_op;
 		op->o_bd = be;
 		op->o_dn = be->be_rootdn;
 		op->o_ndn = be->be_rootndn;
 		syncprov_checkpoint( op, &rs, on );
-		ldap_pvt_thread_pool_context_reset( thrctx );
 	}
 
     return 0;
@@ -2249,18 +2634,25 @@ syncprov_db_close(
 
 static int
 syncprov_db_init(
-	BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
 	slap_overinst	*on = (slap_overinst *)be->bd_info;
 	syncprov_info_t	*si;
 
+	if ( SLAP_ISGLOBALOVERLAY( be ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"syncprov must be instantiated within a database.\n",
+			0, 0, 0 );
+		return 1;
+	}
+
 	si = ch_calloc(1, sizeof(syncprov_info_t));
 	on->on_bi.bi_private = si;
-	ldap_pvt_thread_mutex_init( &si->si_csn_mutex );
+	ldap_pvt_thread_rdwr_init( &si->si_csn_rwlock );
 	ldap_pvt_thread_mutex_init( &si->si_ops_mutex );
 	ldap_pvt_thread_mutex_init( &si->si_mods_mutex );
-	si->si_ctxcsn.bv_val = si->si_ctxcsnbuf;
 
 	csn_anlist[0].an_desc = slap_schema.si_ad_entryCSN;
 	csn_anlist[0].an_name = slap_schema.si_ad_entryCSN->ad_cname;
@@ -2275,16 +2667,32 @@ syncprov_db_init(
 
 static int
 syncprov_db_destroy(
-	BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
 	slap_overinst	*on = (slap_overinst *)be->bd_info;
 	syncprov_info_t	*si = (syncprov_info_t *)on->on_bi.bi_private;
 
 	if ( si ) {
+		if ( si->si_logs ) {
+			slog_entry *se = si->si_logs->sl_head;
+
+			while ( se ) {
+				slog_entry *se_next = se->se_next;
+				ch_free( se );
+				se = se_next;
+			}
+				
+			ch_free( si->si_logs );
+		}
+		if ( si->si_ctxcsn )
+			ber_bvarray_free( si->si_ctxcsn );
+		if ( si->si_sids )
+			ch_free( si->si_sids );
 		ldap_pvt_thread_mutex_destroy( &si->si_mods_mutex );
 		ldap_pvt_thread_mutex_destroy( &si->si_ops_mutex );
-		ldap_pvt_thread_mutex_destroy( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_destroy( &si->si_csn_rwlock );
 		ch_free( si );
 	}
 
@@ -2315,8 +2723,13 @@ static int syncprov_parseCtrl (
 		return LDAP_PROTOCOL_ERROR;
 	}
 
+	if ( BER_BVISNULL( &ctrl->ldctl_value ) ) {
+		rs->sr_text = "Sync control value is absent";
+		return LDAP_PROTOCOL_ERROR;
+	}
+
 	if ( BER_BVISEMPTY( &ctrl->ldctl_value ) ) {
-		rs->sr_text = "Sync control value is empty (or absent)";
+		rs->sr_text = "Sync control value is empty";
 		return LDAP_PROTOCOL_ERROR;
 	}
 
@@ -2358,6 +2771,7 @@ static int syncprov_parseCtrl (
 			rs->sr_text = "Sync control : cookie decoding error";
 			return LDAP_PROTOCOL_ERROR;
 		}
+		tag = ber_peek_tag( ber, &len );
 	}
 	if ( tag == LDAP_TAG_RELOAD_HINT ) {
 		if (( ber_scanf( ber, /*{*/ "b", &rhint )) == LBER_ERROR ) {
@@ -2373,8 +2787,8 @@ static int syncprov_parseCtrl (
 	sr->sr_rhint = rhint;
 	if (!BER_BVISNULL(&cookie)) {
 		ber_dupbv_x( &sr->sr_state.octet_str, &cookie, op->o_tmpmemctx );
-		slap_parse_sync_cookie( &sr->sr_state, op->o_tmpmemctx );
-		if ( sr->sr_state.rid == -1 ) {
+		if ( slap_parse_sync_cookie( &sr->sr_state, op->o_tmpmemctx ) ||
+			sr->sr_state.rid == -1 ) {
 			rs->sr_text = "Sync control : cookie parsing error";
 			return LDAP_PROTOCOL_ERROR;
 		}
@@ -2399,12 +2813,12 @@ static int syncprov_parseCtrl (
 static slap_overinst 		syncprov;
 
 int
-syncprov_init()
+syncprov_initialize()
 {
 	int rc;
 
 	rc = register_supported_control( LDAP_CONTROL_SYNC,
-		SLAP_CTRL_HIDE|SLAP_CTRL_SEARCH, NULL,
+		SLAP_CTRL_SEARCH, NULL,
 		syncprov_parseCtrl, &slap_cids.sc_LDAPsync );
 	if ( rc != LDAP_SUCCESS ) {
 		Debug( LDAP_DEBUG_ANY,
@@ -2432,6 +2846,8 @@ syncprov_init()
 
 	syncprov.on_bi.bi_cf_ocs = spocs;
 
+	generic_filter.f_desc = slap_schema.si_ad_objectClass;
+
 	rc = config_register_schema( spcfg, spocs );
 	if ( rc ) return rc;
 
@@ -2442,7 +2858,7 @@ syncprov_init()
 int
 init_module( int argc, char *argv[] )
 {
-	return syncprov_init();
+	return syncprov_initialize();
 }
 #endif /* SLAPD_OVER_SYNCPROV == SLAPD_MOD_DYNAMIC */