dlm: use rsbtbl as resource directory

Remove the dir hash table (dirtbl), and use
the rsb hash table (rsbtbl) as the resource
directory.  It has always been an unnecessary
duplication of information.

This improves efficiency by using a single rsbtbl
lookup in many cases where both rsbtbl and dirtbl
lookups were needed previously.

This eliminates the need to handle cases of rsbtbl
and dirtbl being out of sync.

In many cases there will be memory savings because
the dir hash table no longer exists.

Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 819 insertions, 203 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index bdafb65..d9ee1b9 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -90,6 +90,7 @@ static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
 static int receive_extralen(struct dlm_message *ms);
 static void do_purge(struct dlm_ls *ls, int nodeid, int pid);
 static void del_timeout(struct dlm_lkb *lkb);
+static void toss_rsb(struct kref *kref);
 
 /*
  * Lock compatibilty matrix - thanks Steve
@@ -170,9 +171,11 @@ void dlm_print_lkb(struct dlm_lkb *lkb)
 
 static void dlm_print_rsb(struct dlm_rsb *r)
 {
-	printk(KERN_ERR "rsb: nodeid %d flags %lx first %x rlc %d name %s\n",
-	       r->res_nodeid, r->res_flags, r->res_first_lkid,
-	       r->res_recover_locks_count, r->res_name);
+	printk(KERN_ERR "rsb: nodeid %d master %d dir %d flags %lx first %x "
+	       "rlc %d name %s\n",
+	       r->res_nodeid, r->res_master_nodeid, r->res_dir_nodeid,
+	       r->res_flags, r->res_first_lkid, r->res_recover_locks_count,
+	       r->res_name);
 }
 
 void dlm_dump_rsb(struct dlm_rsb *r)
@@ -327,6 +330,37 @@ static void queue_bast(struct dlm_rsb *r, struct dlm_lkb *lkb, int rqmode)
  * Basic operations on rsb's and lkb's
  */
 
+/* This is only called to add a reference when the code already holds
+   a valid reference to the rsb, so there's no need for locking. */
+
+static inline void hold_rsb(struct dlm_rsb *r)
+{
+	kref_get(&r->res_ref);
+}
+
+void dlm_hold_rsb(struct dlm_rsb *r)
+{
+	hold_rsb(r);
+}
+
+/* When all references to the rsb are gone it's transferred to
+   the tossed list for later disposal. */
+
+static void put_rsb(struct dlm_rsb *r)
+{
+	struct dlm_ls *ls = r->res_ls;
+	uint32_t bucket = r->res_bucket;
+
+	spin_lock(&ls->ls_rsbtbl[bucket].lock);
+	kref_put(&r->res_ref, toss_rsb);
+	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
+}
+
+void dlm_put_rsb(struct dlm_rsb *r)
+{
+	put_rsb(r);
+}
+
 static int pre_rsb_struct(struct dlm_ls *ls)
 {
 	struct dlm_rsb *r1, *r2;
@@ -411,11 +445,10 @@ static int rsb_cmp(struct dlm_rsb *r, const char *name, int nlen)
 }
 
 int dlm_search_rsb_tree(struct rb_root *tree, char *name, int len,
-			unsigned int flags, struct dlm_rsb **r_ret)
+			struct dlm_rsb **r_ret)
 {
 	struct rb_node *node = tree->rb_node;
 	struct dlm_rsb *r;
-	int error = 0;
 	int rc;
 
 	while (node) {
@@ -432,10 +465,8 @@ int dlm_search_rsb_tree(struct rb_root *tree, char *name, int len,
 	return -EBADR;
 
  found:
-	if (r->res_nodeid && (flags & R_MASTER))
-		error = -ENOTBLK;
 	*r_ret = r;
-	return error;
+	return 0;
 }
 
 static int rsb_insert(struct dlm_rsb *rsb, struct rb_root *tree)
@@ -467,124 +498,587 @@ static int rsb_insert(struct dlm_rsb *rsb, struct rb_root *tree)
 	return 0;
 }
 
-static int _search_rsb(struct dlm_ls *ls, char *name, int len, int b,
-		       unsigned int flags, struct dlm_rsb **r_ret)
+/*
+ * Find rsb in rsbtbl and potentially create/add one
+ *
+ * Delaying the release of rsb's has a similar benefit to applications keeping
+ * NL locks on an rsb, but without the guarantee that the cached master value
+ * will still be valid when the rsb is reused.  Apps aren't always smart enough
+ * to keep NL locks on an rsb that they may lock again shortly; this can lead
+ * to excessive master lookups and removals if we don't delay the release.
+ *
+ * Searching for an rsb means looking through both the normal list and toss
+ * list.  When found on the toss list the rsb is moved to the normal list with
+ * ref count of 1; when found on normal list the ref count is incremented.
+ *
+ * rsb's on the keep list are being used locally and refcounted.
+ * rsb's on the toss list are not being used locally, and are not refcounted.
+ *
+ * The toss list rsb's were either
+ * - previously used locally but not any more (were on keep list, then
+ *   moved to toss list when last refcount dropped)
+ * - created and put on toss list as a directory record for a lookup
+ *   (we are the dir node for the res, but are not using the res right now,
+ *   but some other node is)
+ *
+ * The purpose of find_rsb() is to return a refcounted rsb for local use.
+ * So, if the given rsb is on the toss list, it is moved to the keep list
+ * before being returned.
+ *
+ * toss_rsb() happens when all local usage of the rsb is done, i.e. no
+ * more refcounts exist, so the rsb is moved from the keep list to the
+ * toss list.
+ *
+ * rsb's on both keep and toss lists are used for doing a name to master
+ * lookups.  rsb's that are in use locally (and being refcounted) are on
+ * the keep list, rsb's that are not in use locally (not refcounted) and
+ * only exist for name/master lookups are on the toss list.
+ *
+ * rsb's on the toss list who's dir_nodeid is not local can have stale
+ * name/master mappings.  So, remote requests on such rsb's can potentially
+ * return with an error, which means the mapping is stale and needs to
+ * be updated with a new lookup.  (The idea behind MASTER UNCERTAIN and
+ * first_lkid is to keep only a single outstanding request on an rsb
+ * while that rsb has a potentially stale master.)
+ */
+
+static int find_rsb_dir(struct dlm_ls *ls, char *name, int len,
+			uint32_t hash, uint32_t b,
+			int dir_nodeid, int from_nodeid,
+			unsigned int flags, struct dlm_rsb **r_ret)
 {
-	struct dlm_rsb *r;
+	struct dlm_rsb *r = NULL;
+	int our_nodeid = dlm_our_nodeid();
+	int from_local = 0;
+	int from_other = 0;
+	int from_dir = 0;
+	int create = 0;
 	int error;
 
-	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, flags, &r);
-	if (!error) {
-		kref_get(&r->res_ref);
-		goto out;
+	if (flags & R_RECEIVE_REQUEST) {
+		if (from_nodeid == dir_nodeid)
+			from_dir = 1;
+		else
+			from_other = 1;
+	} else if (flags & R_REQUEST) {
+		from_local = 1;
+	}
+
+	/*
+	 * flags & R_RECEIVE_RECOVER is from dlm_recover_master_copy, so
+	 * from_nodeid has sent us a lock in dlm_recover_locks, believing
+	 * we're the new master.  Our local recovery may not have set
+	 * res_master_nodeid to our_nodeid yet, so allow either.  Don't
+	 * create the rsb; dlm_recover_process_copy() will handle EBADR
+	 * by resending.
+	 *
+	 * If someone sends us a request, we are the dir node, and we do
+	 * not find the rsb anywhere, then recreate it.  This happens if
+	 * someone sends us a request after we have removed/freed an rsb
+	 * from our toss list.  (They sent a request instead of lookup
+	 * because they are using an rsb from their toss list.)
+	 */
+
+	if (from_local || from_dir ||
+	    (from_other && (dir_nodeid == our_nodeid))) {
+		create = 1;
 	}
-	if (error == -ENOTBLK)
-		goto out;
 
-	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, flags, &r);
+ retry:
+	if (create) {
+		error = pre_rsb_struct(ls);
+		if (error < 0)
+			goto out;
+	}
+
+	spin_lock(&ls->ls_rsbtbl[b].lock);
+
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
 	if (error)
-		goto out;
+		goto do_toss;
+	
+	/*
+	 * rsb is active, so we can't check master_nodeid without lock_rsb.
+	 */
 
-	rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
-	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
+	kref_get(&r->res_ref);
+	error = 0;
+	goto out_unlock;
+
+
+ do_toss:
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
 	if (error)
-		return error;
+		goto do_new;
 
-	if (dlm_no_directory(ls))
-		goto out;
+	/*
+	 * rsb found inactive (master_nodeid may be out of date unless
+	 * we are the dir_nodeid or were the master)  No other thread
+	 * is using this rsb because it's on the toss list, so we can
+	 * look at or update res_master_nodeid without lock_rsb.
+	 */
 
-	if (r->res_nodeid == -1) {
+	if ((r->res_master_nodeid != our_nodeid) && from_other) {
+		/* our rsb was not master, and another node (not the dir node)
+		   has sent us a request */
+		log_debug(ls, "find_rsb toss from_other %d master %d dir %d %s",
+			  from_nodeid, r->res_master_nodeid, dir_nodeid,
+			  r->res_name);
+		error = -ENOTBLK;
+		goto out_unlock;
+	}
+
+	if ((r->res_master_nodeid != our_nodeid) && from_dir) {
+		/* don't think this should ever happen */
+		log_error(ls, "find_rsb toss from_dir %d master %d",
+			  from_nodeid, r->res_master_nodeid);
+		dlm_print_rsb(r);
+		/* fix it and go on */
+		r->res_master_nodeid = our_nodeid;
+		r->res_nodeid = 0;
 		rsb_clear_flag(r, RSB_MASTER_UNCERTAIN);
 		r->res_first_lkid = 0;
-	} else if (r->res_nodeid > 0) {
+	}
+
+	if (from_local && (r->res_master_nodeid != our_nodeid)) {
+		/* Because we have held no locks on this rsb,
+		   res_master_nodeid could have become stale. */
 		rsb_set_flag(r, RSB_MASTER_UNCERTAIN);
 		r->res_first_lkid = 0;
+	}
+
+	rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
+	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
+	goto out_unlock;
+
+
+ do_new:
+	/*
+	 * rsb not found
+	 */
+
+	if (error == -EBADR && !create)
+		goto out_unlock;
+
+	error = get_rsb_struct(ls, name, len, &r);
+	if (error == -EAGAIN) {
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+		goto retry;
+	}
+	if (error)
+		goto out_unlock;
+
+	r->res_hash = hash;
+	r->res_bucket = b;
+	r->res_dir_nodeid = dir_nodeid;
+	kref_init(&r->res_ref);
+
+	if (from_dir) {
+		/* want to see how often this happens */
+		log_debug(ls, "find_rsb new from_dir %d recreate %s",
+			  from_nodeid, r->res_name);
+		r->res_master_nodeid = our_nodeid;
+		r->res_nodeid = 0;
+		goto out_add;
+	}
+
+	if (from_other && (dir_nodeid != our_nodeid)) {
+		/* should never happen */
+		log_error(ls, "find_rsb new from_other %d dir %d our %d %s",
+			  from_nodeid, dir_nodeid, our_nodeid, r->res_name);
+		dlm_free_rsb(r);
+		error = -ENOTBLK;
+		goto out_unlock;
+	}
+
+	if (from_other) {
+		log_debug(ls, "find_rsb new from_other %d dir %d %s",
+			  from_nodeid, dir_nodeid, r->res_name);
+	}
+
+	if (dir_nodeid == our_nodeid) {
+		/* When we are the dir nodeid, we can set the master
+		   node immediately */
+		r->res_master_nodeid = our_nodeid;
+		r->res_nodeid = 0;
 	} else {
-		DLM_ASSERT(r->res_nodeid == 0, dlm_print_rsb(r););
-		DLM_ASSERT(!rsb_flag(r, RSB_MASTER_UNCERTAIN),);
+		/* set_master will send_lookup to dir_nodeid */
+		r->res_master_nodeid = 0;
+		r->res_nodeid = -1;
 	}
+
+ out_add:
+	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
+ out_unlock:
+	spin_unlock(&ls->ls_rsbtbl[b].lock);
  out:
 	*r_ret = r;
 	return error;
 }
 
+/* During recovery, other nodes can send us new MSTCPY locks (from
+   dlm_recover_locks) before we've made ourself master (in
+   dlm_recover_masters). */
+
+static int find_rsb_nodir(struct dlm_ls *ls, char *name, int len,
+			  uint32_t hash, uint32_t b,
+			  int dir_nodeid, int from_nodeid,
+			  unsigned int flags, struct dlm_rsb **r_ret)
+{
+	struct dlm_rsb *r = NULL;
+	int our_nodeid = dlm_our_nodeid();
+	int recover = (flags & R_RECEIVE_RECOVER);
+	int error;
+
+ retry:
+	error = pre_rsb_struct(ls);
+	if (error < 0)
+		goto out;
+
+	spin_lock(&ls->ls_rsbtbl[b].lock);
+
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
+	if (error)
+		goto do_toss;
+
+	/*
+	 * rsb is active, so we can't check master_nodeid without lock_rsb.
+	 */
+
+	kref_get(&r->res_ref);
+	goto out_unlock;
+
+
+ do_toss:
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
+	if (error)
+		goto do_new;
+
+	/*
+	 * rsb found inactive. No other thread is using this rsb because
+	 * it's on the toss list, so we can look at or update
+	 * res_master_nodeid without lock_rsb.
+	 */
+
+	if (!recover && (r->res_master_nodeid != our_nodeid) && from_nodeid) {
+		/* our rsb is not master, and another node has sent us a
+		   request; this should never happen */
+		log_error(ls, "find_rsb toss from_nodeid %d master %d dir %d",
+			  from_nodeid, r->res_master_nodeid, dir_nodeid);
+		dlm_print_rsb(r);
+		error = -ENOTBLK;
+		goto out_unlock;
+	}
+
+	if (!recover && (r->res_master_nodeid != our_nodeid) &&
+	    (dir_nodeid == our_nodeid)) {
+		/* our rsb is not master, and we are dir; may as well fix it;
+		   this should never happen */
+		log_error(ls, "find_rsb toss our %d master %d dir %d",
+			  our_nodeid, r->res_master_nodeid, dir_nodeid);
+		dlm_print_rsb(r);
+		r->res_master_nodeid = our_nodeid;
+		r->res_nodeid = 0;
+	}
+
+	rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
+	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
+	goto out_unlock;
+
+
+ do_new:
+	/*
+	 * rsb not found
+	 */
+
+	error = get_rsb_struct(ls, name, len, &r);
+	if (error == -EAGAIN) {
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+		goto retry;
+	}
+	if (error)
+		goto out_unlock;
+
+	r->res_hash = hash;
+	r->res_bucket = b;
+	r->res_dir_nodeid = dir_nodeid;
+	r->res_master_nodeid = dir_nodeid;
+	r->res_nodeid = (dir_nodeid == our_nodeid) ? 0 : dir_nodeid;
+	kref_init(&r->res_ref);
+
+	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
+ out_unlock:
+	spin_unlock(&ls->ls_rsbtbl[b].lock);
+ out:
+	*r_ret = r;
+	return error;
+}
+
+static int find_rsb(struct dlm_ls *ls, char *name, int len, int from_nodeid,
+		    unsigned int flags, struct dlm_rsb **r_ret)
+{
+	uint32_t hash, b;
+	int dir_nodeid;
+
+	if (len > DLM_RESNAME_MAXLEN)
+		return -EINVAL;
+
+	hash = jhash(name, len, 0);
+	b = hash & (ls->ls_rsbtbl_size - 1);
+
+	dir_nodeid = dlm_hash2nodeid(ls, hash);
+
+	if (dlm_no_directory(ls))
+		return find_rsb_nodir(ls, name, len, hash, b, dir_nodeid,
+				      from_nodeid, flags, r_ret);
+	else
+		return find_rsb_dir(ls, name, len, hash, b, dir_nodeid,
+				      from_nodeid, flags, r_ret);
+}
+
+/* we have received a request and found that res_master_nodeid != our_nodeid,
+   so we need to return an error or make ourself the master */
+
+static int validate_master_nodeid(struct dlm_ls *ls, struct dlm_rsb *r,
+				  int from_nodeid)
+{
+	if (dlm_no_directory(ls)) {
+		log_error(ls, "find_rsb keep from_nodeid %d master %d dir %d",
+			  from_nodeid, r->res_master_nodeid,
+			  r->res_dir_nodeid);
+		dlm_print_rsb(r);
+		return -ENOTBLK;
+	}
+
+	if (from_nodeid != r->res_dir_nodeid) {
+		/* our rsb is not master, and another node (not the dir node)
+	   	   has sent us a request.  this is much more common when our
+	   	   master_nodeid is zero, so limit debug to non-zero.  */
+
+		if (r->res_master_nodeid) {
+			log_debug(ls, "validate master from_other %d master %d "
+				  "dir %d first %x %s", from_nodeid,
+				  r->res_master_nodeid, r->res_dir_nodeid,
+				  r->res_first_lkid, r->res_name);
+		}
+		return -ENOTBLK;
+	} else {
+		/* our rsb is not master, but the dir nodeid has sent us a
+	   	   request; this could happen with master 0 / res_nodeid -1 */
+
+		if (r->res_master_nodeid) {
+			log_error(ls, "validate master from_dir %d master %d "
+				  "first %x %s",
+				  from_nodeid, r->res_master_nodeid,
+				  r->res_first_lkid, r->res_name);
+		}
+
+		r->res_master_nodeid = dlm_our_nodeid();
+		r->res_nodeid = 0;
+		return 0;
+	}
+}
+
 /*
- * Find rsb in rsbtbl and potentially create/add one
+ * We're the dir node for this res and another node wants to know the
+ * master nodeid.  During normal operation (non recovery) this is only
+ * called from receive_lookup(); master lookups when the local node is
+ * the dir node are done by find_rsb().
  *
- * Delaying the release of rsb's has a similar benefit to applications keeping
- * NL locks on an rsb, but without the guarantee that the cached master value
- * will still be valid when the rsb is reused.  Apps aren't always smart enough
- * to keep NL locks on an rsb that they may lock again shortly; this can lead
- * to excessive master lookups and removals if we don't delay the release.
+ * normal operation, we are the dir node for a resource
+ * . _request_lock
+ * . set_master
+ * . send_lookup
+ * . receive_lookup
+ * . dlm_master_lookup flags 0
  *
- * Searching for an rsb means looking through both the normal list and toss
- * list.  When found on the toss list the rsb is moved to the normal list with
- * ref count of 1; when found on normal list the ref count is incremented.
+ * recover directory, we are rebuilding dir for all resources
+ * . dlm_recover_directory
+ * . dlm_rcom_names
+ *   remote node sends back the rsb names it is master of and we are dir of
+ * . dlm_master_lookup RECOVER_DIR (fix_master 0, from_master 1)
+ *   we either create new rsb setting remote node as master, or find existing
+ *   rsb and set master to be the remote node.
+ *
+ * recover masters, we are finding the new master for resources
+ * . dlm_recover_masters
+ * . recover_master
+ * . dlm_send_rcom_lookup
+ * . receive_rcom_lookup
+ * . dlm_master_lookup RECOVER_MASTER (fix_master 1, from_master 0)
  */
 
-static int find_rsb(struct dlm_ls *ls, char *name, int namelen,
-		    unsigned int flags, struct dlm_rsb **r_ret)
+int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, char *name, int len,
+		      unsigned int flags, int *r_nodeid, int *result)
 {
 	struct dlm_rsb *r = NULL;
-	uint32_t hash, bucket;
-	int error;
+	uint32_t hash, b;
+	int from_master = (flags & DLM_LU_RECOVER_DIR);
+	int fix_master = (flags & DLM_LU_RECOVER_MASTER);
+	int our_nodeid = dlm_our_nodeid();
+	int dir_nodeid, error, toss_list = 0;
 
-	if (namelen > DLM_RESNAME_MAXLEN) {
-		error = -EINVAL;
-		goto out;
+	if (len > DLM_RESNAME_MAXLEN)
+		return -EINVAL;
+
+	if (from_nodeid == our_nodeid) {
+		log_error(ls, "dlm_master_lookup from our_nodeid %d flags %x",
+			  our_nodeid, flags);
+		return -EINVAL;
 	}
 
-	if (dlm_no_directory(ls))
-		flags |= R_CREATE;
+	hash = jhash(name, len, 0);
+	b = hash & (ls->ls_rsbtbl_size - 1);
 
-	hash = jhash(name, namelen, 0);
-	bucket = hash & (ls->ls_rsbtbl_size - 1);
+	dir_nodeid = dlm_hash2nodeid(ls, hash);
+	if (dir_nodeid != our_nodeid) {
+		log_error(ls, "dlm_master_lookup from %d dir %d our %d h %x %d",
+			  from_nodeid, dir_nodeid, our_nodeid, hash,
+			  ls->ls_num_nodes);
+		*r_nodeid = -1;
+		return -EINVAL;
+	}
 
  retry:
-	if (flags & R_CREATE) {
-		error = pre_rsb_struct(ls);
-		if (error < 0)
-			goto out;
+	error = pre_rsb_struct(ls);
+	if (error < 0)
+		return error;
+
+	spin_lock(&ls->ls_rsbtbl[b].lock);
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
+	if (!error) {
+		/* because the rsb is active, we need to lock_rsb before
+		   checking/changing re_master_nodeid */
+
+		hold_rsb(r);
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+		lock_rsb(r);
+		goto found;
 	}
 
-	spin_lock(&ls->ls_rsbtbl[bucket].lock);
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
+	if (error)
+		goto not_found;
 
-	error = _search_rsb(ls, name, namelen, bucket, flags, &r);
-	if (!error)
-		goto out_unlock;
+	/* because the rsb is inactive (on toss list), it's not refcounted
+	   and lock_rsb is not used, but is protected by the rsbtbl lock */
 
-	if (error == -EBADR && !(flags & R_CREATE))
-		goto out_unlock;
+	toss_list = 1;
+ found:
+	if (r->res_dir_nodeid != our_nodeid) {
+		/* should not happen, but may as well fix it and carry on */
+		log_error(ls, "dlm_master_lookup res_dir %d our %d %s",
+			  r->res_dir_nodeid, our_nodeid, r->res_name);
+		r->res_dir_nodeid = our_nodeid;
+	}
+
+	if (fix_master && dlm_is_removed(ls, r->res_master_nodeid)) {
+		/* Recovery uses this function to set a new master when
+		   the previous master failed.  Setting NEW_MASTER will
+		   force dlm_recover_masters to call recover_master on this
+		   rsb even though the res_nodeid is no longer removed. */
+
+		r->res_master_nodeid = from_nodeid;
+		r->res_nodeid = from_nodeid;
+		rsb_set_flag(r, RSB_NEW_MASTER);
+
+		if (toss_list) {
+			/* I don't think we should ever find it on toss list. */
+			log_error(ls, "dlm_master_lookup fix_master on toss");
+			dlm_dump_rsb(r);
+		}
+	}
 
-	/* the rsb was found but wasn't a master copy */
-	if (error == -ENOTBLK)
-		goto out_unlock;
+	if (from_master && (r->res_master_nodeid != from_nodeid)) {
+		/* this will happen if from_nodeid became master during
+		   a previous recovery cycle, and we aborted the previous
+		   cycle before recovering this master value */
 
-	error = get_rsb_struct(ls, name, namelen, &r);
+		log_limit(ls, "dlm_master_lookup from_master %d "
+			  "master_nodeid %d res_nodeid %d first %x %s",
+			  from_nodeid, r->res_master_nodeid, r->res_nodeid,
+			  r->res_first_lkid, r->res_name);
+
+		if (r->res_master_nodeid == our_nodeid) {
+			log_error(ls, "from_master %d our_master", from_nodeid);
+			dlm_dump_rsb(r);
+			dlm_send_rcom_lookup_dump(r, from_nodeid);
+			goto out_found;
+		}
+
+		r->res_master_nodeid = from_nodeid;
+		r->res_nodeid = from_nodeid;
+		rsb_set_flag(r, RSB_NEW_MASTER);
+	}
+
+	if (!r->res_master_nodeid) {
+		/* this will happen if recovery happens while we're looking
+		   up the master for this rsb */
+
+		log_debug(ls, "dlm_master_lookup master 0 to %d first %x %s",
+			  from_nodeid, r->res_first_lkid, r->res_name);
+		r->res_master_nodeid = from_nodeid;
+		r->res_nodeid = from_nodeid;
+	}
+
+	if (!from_master && !fix_master &&
+	    (r->res_master_nodeid == from_nodeid)) {
+		/* this can happen when the master sends remove, the dir node
+		   finds the rsb on the keep list and ignores the remove,
+		   and the former master sends a lookup */
+
+		log_limit(ls, "dlm_master_lookup from master %d flags %x "
+			  "first %x %s", from_nodeid, flags,
+			  r->res_first_lkid, r->res_name);
+	}
+
+ out_found:
+	*r_nodeid = r->res_master_nodeid;
+	if (result)
+		*result = DLM_LU_MATCH;
+
+	if (toss_list) {
+		r->res_toss_time = jiffies;
+		/* the rsb was inactive (on toss list) */
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+	} else {
+		/* the rsb was active */
+		unlock_rsb(r);
+		put_rsb(r);
+	}
+	return 0;
+
+ not_found:
+	error = get_rsb_struct(ls, name, len, &r);
 	if (error == -EAGAIN) {
-		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
 		goto retry;
 	}
 	if (error)
 		goto out_unlock;
 
 	r->res_hash = hash;
-	r->res_bucket = bucket;
-	r->res_nodeid = -1;
+	r->res_bucket = b;
+	r->res_dir_nodeid = our_nodeid;
+	r->res_master_nodeid = from_nodeid;
+	r->res_nodeid = from_nodeid;
 	kref_init(&r->res_ref);
+	r->res_toss_time = jiffies;
 
-	/* With no directory, the master can be set immediately */
-	if (dlm_no_directory(ls)) {
-		int nodeid = dlm_dir_nodeid(r);
-		if (nodeid == dlm_our_nodeid())
-			nodeid = 0;
-		r->res_nodeid = nodeid;
+	error = rsb_insert(r, &ls->ls_rsbtbl[b].toss);
+	if (error) {
+		/* should never happen */
+		dlm_free_rsb(r);
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+		goto retry;
 	}
-	error = rsb_insert(r, &ls->ls_rsbtbl[bucket].keep);
+
+	if (result)
+		*result = DLM_LU_ADD;
+	*r_nodeid = from_nodeid;
+	error = 0;
  out_unlock:
-	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
- out:
-	*r_ret = r;
+	spin_unlock(&ls->ls_rsbtbl[b].lock);
 	return error;
 }
 
@@ -605,17 +1099,27 @@ static void dlm_dump_rsb_hash(struct dlm_ls *ls, uint32_t hash)
 	}
 }
 
-/* This is only called to add a reference when the code already holds
-   a valid reference to the rsb, so there's no need for locking. */
-
-static inline void hold_rsb(struct dlm_rsb *r)
+void dlm_dump_rsb_name(struct dlm_ls *ls, char *name, int len)
 {
-	kref_get(&r->res_ref);
-}
+	struct dlm_rsb *r = NULL;
+	uint32_t hash, b;
+	int error;
 
-void dlm_hold_rsb(struct dlm_rsb *r)
-{
-	hold_rsb(r);
+	hash = jhash(name, len, 0);
+	b = hash & (ls->ls_rsbtbl_size - 1);
+
+	spin_lock(&ls->ls_rsbtbl[b].lock);
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
+	if (!error)
+		goto out_dump;
+
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
+	if (error)
+		goto out;
+ out_dump:
+	dlm_dump_rsb(r);
+ out:
+	spin_unlock(&ls->ls_rsbtbl[b].lock);
 }
 
 static void toss_rsb(struct kref *kref)
@@ -634,24 +1138,6 @@ static void toss_rsb(struct kref *kref)
 	}
 }
 
-/* When all references to the rsb are gone it's transferred to
-   the tossed list for later disposal. */
-
-static void put_rsb(struct dlm_rsb *r)
-{
-	struct dlm_ls *ls = r->res_ls;
-	uint32_t bucket = r->res_bucket;
-
-	spin_lock(&ls->ls_rsbtbl[bucket].lock);
-	kref_put(&r->res_ref, toss_rsb);
-	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
-}
-
-void dlm_put_rsb(struct dlm_rsb *r)
-{
-	put_rsb(r);
-}
-
 /* See comment for unhold_lkb */
 
 static void unhold_rsb(struct dlm_rsb *r)
@@ -1138,27 +1624,13 @@ static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms)
 	return error;
 }
 
-static void dir_remove(struct dlm_rsb *r)
-{
-	int to_nodeid;
-
-	if (dlm_no_directory(r->res_ls))
-		return;
-
-	to_nodeid = dlm_dir_nodeid(r);
-	if (to_nodeid != dlm_our_nodeid())
-		send_remove(r);
-	else
-		dlm_dir_remove_entry(r->res_ls, to_nodeid,
-				     r->res_name, r->res_length);
-}
-
 /* FIXME: make this more efficient */
 
 static int shrink_bucket(struct dlm_ls *ls, int b)
 {
 	struct rb_node *n;
 	struct dlm_rsb *r;
+	int our_nodeid = dlm_our_nodeid();
 	int count = 0, found;
 
 	for (;;) {
@@ -1166,6 +1638,17 @@ static int shrink_bucket(struct dlm_ls *ls, int b)
 		spin_lock(&ls->ls_rsbtbl[b].lock);
 		for (n = rb_first(&ls->ls_rsbtbl[b].toss); n; n = rb_next(n)) {
 			r = rb_entry(n, struct dlm_rsb, res_hashnode);
+
+			/* If we're the directory record for this rsb, and
+			   we're not the master of it, then we need to wait
+			   for the master node to send us a dir remove for
+			   before removing the dir record. */
+
+			if (!dlm_no_directory(ls) && !is_master(r) &&
+			    (dlm_dir_nodeid(r) == our_nodeid)) {
+				continue;
+			}
+
 			if (!time_after_eq(jiffies, r->res_toss_time +
 					   dlm_config.ci_toss_secs * HZ))
 				continue;
@@ -1182,8 +1665,15 @@ static int shrink_bucket(struct dlm_ls *ls, int b)
 			rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
 			spin_unlock(&ls->ls_rsbtbl[b].lock);
 
-			if (is_master(r))
-				dir_remove(r);
+			/* We're the master of this rsb but we're not
+			   the directory record, so we need to tell the
+			   dir node to remove the dir record. */
+
+			if (!dlm_no_directory(ls) && is_master(r) &&
+			    (dlm_dir_nodeid(r) != our_nodeid)) {
+				send_remove(r);
+			}
+
 			dlm_free_rsb(r);
 			count++;
 		} else {
@@ -2078,8 +2568,7 @@ static void send_blocking_asts_all(struct dlm_rsb *r, struct dlm_lkb *lkb)
 
 static int set_master(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
-	struct dlm_ls *ls = r->res_ls;
-	int i, error, dir_nodeid, ret_nodeid, our_nodeid = dlm_our_nodeid();
+	int our_nodeid = dlm_our_nodeid();
 
 	if (rsb_flag(r, RSB_MASTER_UNCERTAIN)) {
 		rsb_clear_flag(r, RSB_MASTER_UNCERTAIN);
@@ -2093,53 +2582,35 @@ static int set_master(struct dlm_rsb *r, struct dlm_lkb *lkb)
 		return 1;
 	}
 
-	if (r->res_nodeid == 0) {
+	if (r->res_master_nodeid == our_nodeid) {
 		lkb->lkb_nodeid = 0;
 		return 0;
 	}
 
-	if (r->res_nodeid > 0) {
-		lkb->lkb_nodeid = r->res_nodeid;
+	if (r->res_master_nodeid) {
+		lkb->lkb_nodeid = r->res_master_nodeid;
 		return 0;
 	}
 
-	DLM_ASSERT(r->res_nodeid == -1, dlm_dump_rsb(r););
-
-	dir_nodeid = dlm_dir_nodeid(r);
-
-	if (dir_nodeid != our_nodeid) {
-		r->res_first_lkid = lkb->lkb_id;
-		send_lookup(r, lkb);
-		return 1;
-	}
-
-	for (i = 0; i < 2; i++) {
-		/* It's possible for dlm_scand to remove an old rsb for
-		   this same resource from the toss list, us to create
-		   a new one, look up the master locally, and find it
-		   already exists just before dlm_scand does the
-		   dir_remove() on the previous rsb. */
-
-		error = dlm_dir_lookup(ls, our_nodeid, r->res_name,
-				       r->res_length, &ret_nodeid);
-		if (!error)
-			break;
-		log_debug(ls, "dir_lookup error %d %s", error, r->res_name);
-		schedule();
-	}
-	if (error && error != -EEXIST)
-		return error;
-
-	if (ret_nodeid == our_nodeid) {
-		r->res_first_lkid = 0;
+	if (dlm_dir_nodeid(r) == our_nodeid) {
+		/* This is a somewhat unusual case; find_rsb will usually
+		   have set res_master_nodeid when dir nodeid is local, but
+		   there are cases where we become the dir node after we've
+		   past find_rsb and go through _request_lock again.
+		   confirm_master() or process_lookup_list() needs to be
+		   called after this. */
+		log_debug(r->res_ls, "set_master %x self master %d dir %d %s",
+			  lkb->lkb_id, r->res_master_nodeid, r->res_dir_nodeid,
+			  r->res_name);
+		r->res_master_nodeid = our_nodeid;
 		r->res_nodeid = 0;
 		lkb->lkb_nodeid = 0;
-	} else {
-		r->res_first_lkid = lkb->lkb_id;
-		r->res_nodeid = ret_nodeid;
-		lkb->lkb_nodeid = ret_nodeid;
+		return 0;
 	}
-	return 0;
+
+	r->res_first_lkid = lkb->lkb_id;
+	send_lookup(r, lkb);
+	return 1;
 }
 
 static void process_lookup_list(struct dlm_rsb *r)
@@ -2584,7 +3055,7 @@ static void do_unlock_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
 }
 
 /* returns: 0 did nothing, -DLM_ECANCEL canceled lock */
- 
+
 static int do_cancel(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
 	int error;
@@ -2708,11 +3179,11 @@ static int request_lock(struct dlm_ls *ls, struct dlm_lkb *lkb, char *name,
 
 	error = validate_lock_args(ls, lkb, args);
 	if (error)
-		goto out;
+		return error;
 
-	error = find_rsb(ls, name, len, R_CREATE, &r);
+	error = find_rsb(ls, name, len, 0, R_REQUEST, &r);
 	if (error)
-		goto out;
+		return error;
 
 	lock_rsb(r);
 
@@ -2723,8 +3194,6 @@ static int request_lock(struct dlm_ls *ls, struct dlm_lkb *lkb, char *name,
 
 	unlock_rsb(r);
 	put_rsb(r);
-
- out:
 	return error;
 }
 
@@ -3406,8 +3875,11 @@ static int receive_request(struct dlm_ls *ls, struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
+	int from_nodeid;
 	int error, namelen;
 
+	from_nodeid = ms->m_header.h_nodeid;
+
 	error = create_lkb(ls, &lkb);
 	if (error)
 		goto fail;
@@ -3420,9 +3892,16 @@ static int receive_request(struct dlm_ls *ls, struct dlm_message *ms)
 		goto fail;
 	}
 
+	/* The dir node is the authority on whether we are the master
+	   for this rsb or not, so if the master sends us a request, we should
+	   recreate the rsb if we've destroyed it.   This race happens when we
+	   send a remove message to the dir node at the same time that the dir
+	   node sends us a request for the rsb. */
+
 	namelen = receive_extralen(ms);
 
-	error = find_rsb(ls, ms->m_extra, namelen, R_MASTER, &r);
+	error = find_rsb(ls, ms->m_extra, namelen, from_nodeid,
+			 R_RECEIVE_REQUEST, &r);
 	if (error) {
 		__put_lkb(ls, lkb);
 		goto fail;
@@ -3430,6 +3909,16 @@ static int receive_request(struct dlm_ls *ls, struct dlm_message *ms)
 
 	lock_rsb(r);
 
+	if (r->res_master_nodeid != dlm_our_nodeid()) {
+		error = validate_master_nodeid(ls, r, from_nodeid);
+		if (error) {
+			unlock_rsb(r);
+			put_rsb(r);
+			__put_lkb(ls, lkb);
+			goto fail;
+		}
+	}
+
 	attach_lkb(r, lkb);
 	error = do_request(r, lkb);
 	send_request_reply(r, lkb, error);
@@ -3445,6 +3934,23 @@ static int receive_request(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 
  fail:
+	/* TODO: instead of returning ENOTBLK, add the lkb to res_lookup
+	   and do this receive_request again from process_lookup_list once
+	   we get the lookup reply.  This would avoid a many repeated
+	   ENOTBLK request failures when the lookup reply designating us
+	   as master is delayed. */
+
+	/* We could repeatedly return -EBADR here if our send_remove() is
+	   delayed in being sent/arriving/being processed on the dir node.
+	   Another node would repeatedly lookup up the master, and the dir
+	   node would continue returning our nodeid until our send_remove
+	   took effect. */
+
+	if (error != -ENOTBLK) {
+		log_limit(ls, "receive_request %x from %d %d",
+			  ms->m_lkid, from_nodeid, error);
+	}
+
 	setup_stub_lkb(ls, ms);
 	send_request_reply(&ls->ls_stub_rsb, &ls->ls_stub_lkb, error);
 	return error;
@@ -3651,49 +4157,110 @@ static int receive_bast(struct dlm_ls *ls, struct dlm_message *ms)
 
 static void receive_lookup(struct dlm_ls *ls, struct dlm_message *ms)
 {
-	int len, error, ret_nodeid, dir_nodeid, from_nodeid, our_nodeid;
+	int len, error, ret_nodeid, from_nodeid, our_nodeid;
 
 	from_nodeid = ms->m_header.h_nodeid;
 	our_nodeid = dlm_our_nodeid();
 
 	len = receive_extralen(ms);
 
-	dir_nodeid = dlm_hash2nodeid(ls, ms->m_hash);
-	if (dir_nodeid != our_nodeid) {
-		log_error(ls, "lookup dir_nodeid %d from %d",
-			  dir_nodeid, from_nodeid);
-		error = -EINVAL;
-		ret_nodeid = -1;
-		goto out;
-	}
-
-	error = dlm_dir_lookup(ls, from_nodeid, ms->m_extra, len, &ret_nodeid);
+	error = dlm_master_lookup(ls, from_nodeid, ms->m_extra, len, 0,
+				  &ret_nodeid, NULL);
 
 	/* Optimization: we're master so treat lookup as a request */
 	if (!error && ret_nodeid == our_nodeid) {
 		receive_request(ls, ms);
 		return;
 	}
- out:
 	send_lookup_reply(ls, ms, ret_nodeid, error);
 }
 
 static void receive_remove(struct dlm_ls *ls, struct dlm_message *ms)
 {
-	int len, dir_nodeid, from_nodeid;
+	char name[DLM_RESNAME_MAXLEN+1];
+	struct dlm_rsb *r;
+	uint32_t hash, b;
+	int rv, len, dir_nodeid, from_nodeid;
 
 	from_nodeid = ms->m_header.h_nodeid;
 
 	len = receive_extralen(ms);
 
+	if (len > DLM_RESNAME_MAXLEN) {
+		log_error(ls, "receive_remove from %d bad len %d",
+			  from_nodeid, len);
+		return;
+	}
+
 	dir_nodeid = dlm_hash2nodeid(ls, ms->m_hash);
 	if (dir_nodeid != dlm_our_nodeid()) {
-		log_error(ls, "remove dir entry dir_nodeid %d from %d",
-			  dir_nodeid, from_nodeid);
+		log_error(ls, "receive_remove from %d bad nodeid %d",
+			  from_nodeid, dir_nodeid);
 		return;
 	}
 
-	dlm_dir_remove_entry(ls, from_nodeid, ms->m_extra, len);
+	/* Look for name on rsbtbl.toss, if it's there, kill it.
+	   If it's on rsbtbl.keep, it's being used, and we should ignore this
+	   message.  This is an expected race between the dir node sending a
+	   request to the master node at the same time as the master node sends
+	   a remove to the dir node.  The resolution to that race is for the
+	   dir node to ignore the remove message, and the master node to
+	   recreate the master rsb when it gets a request from the dir node for
+	   an rsb it doesn't have. */
+
+	memset(name, 0, sizeof(name));
+	memcpy(name, ms->m_extra, len);
+
+	hash = jhash(name, len, 0);
+	b = hash & (ls->ls_rsbtbl_size - 1);
+
+	spin_lock(&ls->ls_rsbtbl[b].lock);
+
+	rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
+	if (rv) {
+		/* verify the rsb is on keep list per comment above */
+		rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
+		if (rv) {
+			/* should not happen */
+			log_error(ls, "receive_remove from %d not found %s",
+				  from_nodeid, name);
+			spin_unlock(&ls->ls_rsbtbl[b].lock);
+			return;
+		}
+		if (r->res_master_nodeid != from_nodeid) {
+			/* should not happen */
+			log_error(ls, "receive_remove keep from %d master %d",
+				  from_nodeid, r->res_master_nodeid);
+			dlm_print_rsb(r);
+			spin_unlock(&ls->ls_rsbtbl[b].lock);
+			return;
+		}
+
+		log_debug(ls, "receive_remove from %d master %d first %x %s",
+			  from_nodeid, r->res_master_nodeid, r->res_first_lkid,
+			  name);
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+		return;
+	}
+
+	if (r->res_master_nodeid != from_nodeid) {
+		log_error(ls, "receive_remove toss from %d master %d",
+			  from_nodeid, r->res_master_nodeid);
+		dlm_print_rsb(r);
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+		return;
+	}
+
+	if (kref_put(&r->res_ref, kill_rsb)) {
+		rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+		dlm_free_rsb(r);
+	} else {
+		log_error(ls, "receive_remove from %d rsb ref error",
+			  from_nodeid);
+		dlm_print_rsb(r);
+		spin_unlock(&ls->ls_rsbtbl[b].lock);
+	}
 }
 
 static void receive_purge(struct dlm_ls *ls, struct dlm_message *ms)
@@ -3706,6 +4273,7 @@ static int receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
 	int error, mstype, result;
+	int from_nodeid = ms->m_header.h_nodeid;
 
 	error = find_lkb(ls, ms->m_remid, &lkb);
 	if (error)
@@ -3723,8 +4291,7 @@ static int receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	error = remove_from_waiters(lkb, DLM_MSG_REQUEST_REPLY);
 	if (error) {
 		log_error(ls, "receive_request_reply %x remote %d %x result %d",
-			  lkb->lkb_id, ms->m_header.h_nodeid, ms->m_lkid,
-			  ms->m_result);
+			  lkb->lkb_id, from_nodeid, ms->m_lkid, ms->m_result);
 		dlm_dump_rsb(r);
 		goto out;
 	}
@@ -3732,8 +4299,9 @@ static int receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	/* Optimization: the dir node was also the master, so it took our
 	   lookup as a request and sent request reply instead of lookup reply */
 	if (mstype == DLM_MSG_LOOKUP) {
-		r->res_nodeid = ms->m_header.h_nodeid;
-		lkb->lkb_nodeid = r->res_nodeid;
+		r->res_master_nodeid = from_nodeid;
+		r->res_nodeid = from_nodeid;
+		lkb->lkb_nodeid = from_nodeid;
 	}
 
 	/* this is the value returned from do_request() on the master */
@@ -3767,18 +4335,30 @@ static int receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	case -EBADR:
 	case -ENOTBLK:
 		/* find_rsb failed to find rsb or rsb wasn't master */
-		log_debug(ls, "receive_request_reply %x %x master diff %d %d",
-			  lkb->lkb_id, lkb->lkb_flags, r->res_nodeid, result);
-		r->res_nodeid = -1;
-		lkb->lkb_nodeid = -1;
+		log_limit(ls, "receive_request_reply %x from %d %d "
+			  "master %d dir %d first %x %s", lkb->lkb_id,
+			  from_nodeid, result, r->res_master_nodeid,
+			  r->res_dir_nodeid, r->res_first_lkid, r->res_name);
+
+		if (r->res_dir_nodeid != dlm_our_nodeid() &&
+		    r->res_master_nodeid != dlm_our_nodeid()) {
+			/* cause _request_lock->set_master->send_lookup */
+			r->res_master_nodeid = 0;
+			r->res_nodeid = -1;
+			lkb->lkb_nodeid = -1;
+		}
 
 		if (is_overlap(lkb)) {
 			/* we'll ignore error in cancel/unlock reply */
 			queue_cast_overlap(r, lkb);
 			confirm_master(r, result);
 			unhold_lkb(lkb); /* undoes create_lkb() */
-		} else
+		} else {
 			_request_lock(r, lkb);
+
+			if (r->res_master_nodeid == dlm_our_nodeid())
+				confirm_master(r, 0);
+		}
 		break;
 
 	default:
@@ -3994,6 +4574,7 @@ static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
 	int error, ret_nodeid;
+	int do_lookup_list = 0;
 
 	error = find_lkb(ls, ms->m_lkid, &lkb);
 	if (error) {
@@ -4001,7 +4582,7 @@ static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
 		return;
 	}
 
-	/* ms->m_result is the value returned by dlm_dir_lookup on dir node
+	/* ms->m_result is the value returned by dlm_master_lookup on dir node
 	   FIXME: will a non-zero error ever be returned? */
 
 	r = lkb->lkb_resource;
@@ -4013,12 +4594,37 @@ static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
 		goto out;
 
 	ret_nodeid = ms->m_nodeid;
+
+	/* We sometimes receive a request from the dir node for this
+	   rsb before we've received the dir node's loookup_reply for it.
+	   The request from the dir node implies we're the master, so we set
+	   ourself as master in receive_request_reply, and verify here that
+	   we are indeed the master. */
+
+	if (r->res_master_nodeid && (r->res_master_nodeid != ret_nodeid)) {
+		/* This should never happen */
+		log_error(ls, "receive_lookup_reply %x from %d ret %d "
+			  "master %d dir %d our %d first %x %s",
+			  lkb->lkb_id, ms->m_header.h_nodeid, ret_nodeid,
+			  r->res_master_nodeid, r->res_dir_nodeid,
+			  dlm_our_nodeid(), r->res_first_lkid, r->res_name);
+	}
+
 	if (ret_nodeid == dlm_our_nodeid()) {
+		r->res_master_nodeid = ret_nodeid;
 		r->res_nodeid = 0;
-		ret_nodeid = 0;
+		do_lookup_list = 1;
 		r->res_first_lkid = 0;
+	} else if (ret_nodeid == -1) {
+		/* the remote node doesn't believe it's the dir node */
+		log_error(ls, "receive_lookup_reply %x from %d bad ret_nodeid",
+			  lkb->lkb_id, ms->m_header.h_nodeid);
+		r->res_master_nodeid = 0;
+		r->res_nodeid = -1;
+		lkb->lkb_nodeid = -1;
 	} else {
-		/* set_master() will copy res_nodeid to lkb_nodeid */
+		/* set_master() will set lkb_nodeid from r */
+		r->res_master_nodeid = ret_nodeid;
 		r->res_nodeid = ret_nodeid;
 	}
 
@@ -4033,7 +4639,7 @@ static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	_request_lock(r, lkb);
 
  out_list:
-	if (!ret_nodeid)
+	if (do_lookup_list)
 		process_lookup_list(r);
  out:
 	unlock_rsb(r);
@@ -4047,7 +4653,7 @@ static void _receive_message(struct dlm_ls *ls, struct dlm_message *ms,
 	int error = 0, noent = 0;
 
 	if (!dlm_is_member(ls, ms->m_header.h_nodeid)) {
-		log_debug(ls, "ignore non-member message %d from %d %x %x %d",
+		log_limit(ls, "receive %d from non-member %d %x %x %d",
 			  ms->m_type, ms->m_header.h_nodeid, ms->m_lkid,
 			  ms->m_remid, ms->m_result);
 		return;
@@ -4174,6 +4780,15 @@ static void dlm_receive_message(struct dlm_ls *ls, struct dlm_message *ms,
 				int nodeid)
 {
 	if (dlm_locking_stopped(ls)) {
+		/* If we were a member of this lockspace, left, and rejoined,
+		   other nodes may still be sending us messages from the
+		   lockspace generation before we left. */
+		if (!ls->ls_generation) {
+			log_limit(ls, "receive %d from %d ignore old gen",
+				  ms->m_type, nodeid);
+			return;
+		}
+
 		dlm_add_requestqueue(ls, nodeid, ms);
 	} else {
 		dlm_wait_requestqueue(ls);
@@ -4798,6 +5413,7 @@ int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc)
 	struct dlm_rsb *r;
 	struct dlm_lkb *lkb;
 	uint32_t remid = 0;
+	int from_nodeid = rc->rc_header.h_nodeid;
 	int error;
 
 	if (rl->rl_parent_lkid) {
@@ -4815,21 +5431,21 @@ int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc)
 	   we make ourselves master, dlm_recover_masters() won't touch the
 	   MSTCPY locks we've received early. */
 
-	error = find_rsb(ls, rl->rl_name, le16_to_cpu(rl->rl_namelen), 0, &r);
+	error = find_rsb(ls, rl->rl_name, le16_to_cpu(rl->rl_namelen),
+			 from_nodeid, R_RECEIVE_RECOVER, &r);
 	if (error)
 		goto out;
 
+	lock_rsb(r);
+
 	if (dlm_no_directory(ls) && (dlm_dir_nodeid(r) != dlm_our_nodeid())) {
 		log_error(ls, "dlm_recover_master_copy remote %d %x not dir",
-			  rc->rc_header.h_nodeid, remid);
+			  from_nodeid, remid);
 		error = -EBADR;
-		put_rsb(r);
-		goto out;
+		goto out_unlock;
 	}
 
-	lock_rsb(r);
-
-	lkb = search_remid(r, rc->rc_header.h_nodeid, remid);
+	lkb = search_remid(r, from_nodeid, remid);
 	if (lkb) {
 		error = -EEXIST;
 		goto out_remid;
@@ -4866,7 +5482,7 @@ int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc)
  out:
 	if (error && error != -EEXIST)
 		log_debug(ls, "dlm_recover_master_copy remote %d %x error %d",
-			  rc->rc_header.h_nodeid, remid, error);
+			  from_nodeid, remid, error);
 	rl->rl_result = cpu_to_le32(error);
 	return error;
 }