dlmmaster.c

linux2.6.16版本

	int curnode;
	unsigned long *orig_bm;
	unsigned long *cur_bm;
	unsigned long diff_bm[BITS_TO_LONGS(O2NM_MAX_NODES)];
};

enum dlm_node_state_change
{
	NODE_DOWN = -1,
	NODE_NO_CHANGE = 0,
	NODE_UP
};

static void dlm_bitmap_diff_iter_init(struct dlm_bitmap_diff_iter *iter,
				      unsigned long *orig_bm,
				      unsigned long *cur_bm)
{
	unsigned long p1, p2;
	int i;

	iter->curnode = -1;
	iter->orig_bm = orig_bm;
	iter->cur_bm = cur_bm;

	for (i = 0; i < BITS_TO_LONGS(O2NM_MAX_NODES); i++) {
       		p1 = *(iter->orig_bm + i);
	       	p2 = *(iter->cur_bm + i);
		iter->diff_bm[i] = (p1 & ~p2) | (p2 & ~p1);
	}
}

static int dlm_bitmap_diff_iter_next(struct dlm_bitmap_diff_iter *iter,
				     enum dlm_node_state_change *state)
{
	int bit;

	if (iter->curnode >= O2NM_MAX_NODES)
		return -ENOENT;

	bit = find_next_bit(iter->diff_bm, O2NM_MAX_NODES,
			    iter->curnode+1);
	if (bit >= O2NM_MAX_NODES) {
		iter->curnode = O2NM_MAX_NODES;
		return -ENOENT;
	}

	/* if it was there in the original then this node died */
	if (test_bit(bit, iter->orig_bm))
		*state = NODE_DOWN;
	else
		*state = NODE_UP;

	iter->curnode = bit;
	return bit;
}


static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
				    struct dlm_lock_resource *res,
				    struct dlm_master_list_entry *mle,
				    int blocked)
{
	struct dlm_bitmap_diff_iter bdi;
	enum dlm_node_state_change sc;
	int node;
	int ret = 0;

	mlog(0, "something happened such that the "
	     "master process may need to be restarted!\n");

	assert_spin_locked(&mle->spinlock);

	dlm_bitmap_diff_iter_init(&bdi, mle->vote_map, mle->node_map);
	node = dlm_bitmap_diff_iter_next(&bdi, &sc);
	while (node >= 0) {
		if (sc == NODE_UP) {
			/* a node came up.  clear any old vote from
			 * the response map and set it in the vote map
			 * then restart the mastery. */
			mlog(ML_NOTICE, "node %d up while restarting\n", node);

			/* redo the master request, but only for the new node */
			mlog(0, "sending request to new node\n");
			clear_bit(node, mle->response_map);
			set_bit(node, mle->vote_map);
		} else {
			mlog(ML_ERROR, "node down! %d\n", node);

			/* if the node wasn't involved in mastery skip it,
			 * but clear it out from the maps so that it will
			 * not affect mastery of this lockres */
			clear_bit(node, mle->response_map);
			clear_bit(node, mle->vote_map);
			if (!test_bit(node, mle->maybe_map))
				goto next;

			/* if we're already blocked on lock mastery, and the
			 * dead node wasn't the expected master, or there is
			 * another node in the maybe_map, keep waiting */
			if (blocked) {
				int lowest = find_next_bit(mle->maybe_map,
						       O2NM_MAX_NODES, 0);

				/* act like it was never there */
				clear_bit(node, mle->maybe_map);

			       	if (node != lowest)
					goto next;

				mlog(ML_ERROR, "expected master %u died while "
				     "this node was blocked waiting on it!\n",
				     node);
				lowest = find_next_bit(mle->maybe_map,
						       O2NM_MAX_NODES,
						       lowest+1);
				if (lowest < O2NM_MAX_NODES) {
					mlog(0, "still blocked. waiting "
					     "on %u now\n", lowest);
					goto next;
				}

				/* mle is an MLE_BLOCK, but there is now
				 * nothing left to block on.  we need to return
				 * all the way back out and try again with
				 * an MLE_MASTER. dlm_do_local_recovery_cleanup
				 * has already run, so the mle refcount is ok */
				mlog(0, "no longer blocking. we can "
				     "try to master this here\n");
				mle->type = DLM_MLE_MASTER;
				memset(mle->maybe_map, 0,
				       sizeof(mle->maybe_map));
				memset(mle->response_map, 0,
				       sizeof(mle->maybe_map));
				memcpy(mle->vote_map, mle->node_map,
				       sizeof(mle->node_map));
				mle->u.res = res;
				set_bit(dlm->node_num, mle->maybe_map);

				ret = -EAGAIN;
				goto next;
			}

			clear_bit(node, mle->maybe_map);
			if (node > dlm->node_num)
				goto next;

			mlog(0, "dead node in map!\n");
			/* yuck. go back and re-contact all nodes
			 * in the vote_map, removing this node. */
			memset(mle->response_map, 0,
			       sizeof(mle->response_map));
		}
		ret = -EAGAIN;
next:
		node = dlm_bitmap_diff_iter_next(&bdi, &sc);
	}
	return ret;
}


/*
 * DLM_MASTER_REQUEST_MSG
 *
 * returns: 0 on success,
 *          -errno on a network error
 *
 * on error, the caller should assume the target node is "dead"
 *
 */

static int dlm_do_master_request(struct dlm_master_list_entry *mle, int to)
{
	struct dlm_ctxt *dlm = mle->dlm;
	struct dlm_master_request request;
	int ret, response=0, resend;

	memset(&request, 0, sizeof(request));
	request.node_idx = dlm->node_num;

	BUG_ON(mle->type == DLM_MLE_MIGRATION);

	if (mle->type != DLM_MLE_MASTER) {
		request.namelen = mle->u.name.len;
		memcpy(request.name, mle->u.name.name, request.namelen);
	} else {
		request.namelen = mle->u.res->lockname.len;
		memcpy(request.name, mle->u.res->lockname.name,
			request.namelen);
	}

again:
	ret = o2net_send_message(DLM_MASTER_REQUEST_MSG, dlm->key, &request,
				 sizeof(request), to, &response);
	if (ret < 0)  {
		if (ret == -ESRCH) {
			/* should never happen */
			mlog(ML_ERROR, "TCP stack not ready!\n");
			BUG();
		} else if (ret == -EINVAL) {
			mlog(ML_ERROR, "bad args passed to o2net!\n");
			BUG();
		} else if (ret == -ENOMEM) {
			mlog(ML_ERROR, "out of memory while trying to send "
			     "network message!  retrying\n");
			/* this is totally crude */
			msleep(50);
			goto again;
		} else if (!dlm_is_host_down(ret)) {
			/* not a network error. bad. */
			mlog_errno(ret);
			mlog(ML_ERROR, "unhandled error!");
			BUG();
		}
		/* all other errors should be network errors,
		 * and likely indicate node death */
		mlog(ML_ERROR, "link to %d went down!\n", to);
		goto out;
	}

	ret = 0;
	resend = 0;
	spin_lock(&mle->spinlock);
	switch (response) {
		case DLM_MASTER_RESP_YES:
			set_bit(to, mle->response_map);
			mlog(0, "node %u is the master, response=YES\n", to);
			mle->master = to;
			break;
		case DLM_MASTER_RESP_NO:
			mlog(0, "node %u not master, response=NO\n", to);
			set_bit(to, mle->response_map);
			break;
		case DLM_MASTER_RESP_MAYBE:
			mlog(0, "node %u not master, response=MAYBE\n", to);
			set_bit(to, mle->response_map);
			set_bit(to, mle->maybe_map);
			break;
		case DLM_MASTER_RESP_ERROR:
			mlog(0, "node %u hit an error, resending\n", to);
			resend = 1;
			response = 0;
			break;
		default:
			mlog(ML_ERROR, "bad response! %u\n", response);
			BUG();
	}
	spin_unlock(&mle->spinlock);
	if (resend) {
		/* this is also totally crude */
		msleep(50);
		goto again;
	}

out:
	return ret;
}

/*
 * locks that can be taken here:
 * dlm->spinlock
 * res->spinlock
 * mle->spinlock
 * dlm->master_list
 *
 * if possible, TRIM THIS DOWN!!!
 */
int dlm_master_request_handler(struct o2net_msg *msg, u32 len, void *data)
{
	u8 response = DLM_MASTER_RESP_MAYBE;
	struct dlm_ctxt *dlm = data;
	struct dlm_lock_resource *res;
	struct dlm_master_request *request = (struct dlm_master_request *) msg->buf;
	struct dlm_master_list_entry *mle = NULL, *tmpmle = NULL;
	char *name;
	unsigned int namelen;
	int found, ret;
	int set_maybe;

	if (!dlm_grab(dlm))
		return DLM_MASTER_RESP_NO;

	if (!dlm_domain_fully_joined(dlm)) {
		response = DLM_MASTER_RESP_NO;
		goto send_response;
	}

	name = request->name;
	namelen = request->namelen;

	if (namelen > DLM_LOCKID_NAME_MAX) {
		response = DLM_IVBUFLEN;
		goto send_response;
	}

way_up_top:
	spin_lock(&dlm->spinlock);
	res = __dlm_lookup_lockres(dlm, name, namelen);
	if (res) {
		spin_unlock(&dlm->spinlock);

		/* take care of the easy cases up front */
		spin_lock(&res->spinlock);
		if (res->state & DLM_LOCK_RES_RECOVERING) {
			spin_unlock(&res->spinlock);
			mlog(0, "returning DLM_MASTER_RESP_ERROR since res is "
			     "being recovered\n");
			response = DLM_MASTER_RESP_ERROR;
			if (mle)
				kmem_cache_free(dlm_mle_cache, mle);
			goto send_response;
		}

		if (res->owner == dlm->node_num) {
			u32 flags = DLM_ASSERT_MASTER_MLE_CLEANUP;
			spin_unlock(&res->spinlock);
			// mlog(0, "this node is the master\n");
			response = DLM_MASTER_RESP_YES;
			if (mle)
				kmem_cache_free(dlm_mle_cache, mle);

			/* this node is the owner.
			 * there is some extra work that needs to
			 * happen now.  the requesting node has
			 * caused all nodes up to this one to
			 * create mles.  this node now needs to
			 * go back and clean those up. */
			mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
			     dlm->node_num, res->lockname.len, res->lockname.name);
			ret = dlm_dispatch_assert_master(dlm, res, 1,
							 request->node_idx,
							 flags);
			if (ret < 0) {
				mlog(ML_ERROR, "failed to dispatch assert "
				     "master work\n");
				response = DLM_MASTER_RESP_ERROR;
			}
			goto send_response;
		} else if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
			spin_unlock(&res->spinlock);
			// mlog(0, "node %u is the master\n", res->owner);
			response = DLM_MASTER_RESP_NO;
			if (mle)
				kmem_cache_free(dlm_mle_cache, mle);
			goto send_response;
		}

		/* ok, there is no owner.  either this node is
		 * being blocked, or it is actively trying to
		 * master this lock. */
		if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
			mlog(ML_ERROR, "lock with no owner should be "
			     "in-progress!\n");
			BUG();
		}

		// mlog(0, "lockres is in progress...\n");
		spin_lock(&dlm->master_lock);
		found = dlm_find_mle(dlm, &tmpmle, name, namelen);
		if (!found) {
			mlog(ML_ERROR, "no mle found for this lock!\n");
			BUG();
		}
		set_maybe = 1;
		spin_lock(&tmpmle->spinlock);
		if (tmpmle->type == DLM_MLE_BLOCK) {
			// mlog(0, "this node is waiting for "
			// "lockres to be mastered\n");
			response = DLM_MASTER_RESP_NO;
		} else if (tmpmle->type == DLM_MLE_MIGRATION) {
			mlog(0, "node %u is master, but trying to migrate to "
			     "node %u.\n", tmpmle->master, tmpmle->new_master);
			if (tmpmle->master == dlm->node_num) {
				response = DLM_MASTER_RESP_YES;
				mlog(ML_ERROR, "no owner on lockres, but this "
				     "node is trying to migrate it to %u?!\n",
				     tmpmle->new_master);
				BUG();
			} else {
				/* the real master can respond on its own */
				response = DLM_MASTER_RESP_NO;
			}
		} else if (tmpmle->master != DLM_LOCK_RES_OWNER_UNKNOWN) {
			set_maybe = 0;
			if (tmpmle->master == dlm->node_num)
				response = DLM_MASTER_RESP_YES;
			else
				response = DLM_MASTER_RESP_NO;
		} else {
			// mlog(0, "this node is attempting to "
			// "master lockres\n");
			response = DLM_MASTER_RESP_MAYBE;
		}
		if (set_maybe)
			set_bit(request->node_idx, tmpmle->maybe_map);
		spin_unlock(&tmpmle->spinlock);

		spin_unlock(&dlm->master_lock);
		spin_unlock(&res->spinlock);

		/* keep the mle attached to heartbeat events */
		dlm_put_mle(tmpmle);
		if (mle)
			kmem_cache_free(dlm_mle_cache, mle);
		goto send_response;
	}

	/*
	 * lockres doesn't exist on this node
	 * if there is an MLE_BLOCK, return NO
	 * if there is an MLE_MASTER, return MAYBE
	 * otherwise, add an MLE_BLOCK, return NO
	 */
	spin_lock(&dlm->master_lock);
	found = dlm_find_mle(dlm, &tmpmle, name, namelen);
	if (!found) {
		/* this lockid has never been seen on this node yet */
		// mlog(0, "no mle found\n");
		if (!mle) {
			spin_unlock(&dlm->master_lock);
			spin_unlock(&dlm->spinlock);

			mle = (struct dlm_master_list_entry *)
				kmem_cache_alloc(dlm_mle_cache, GFP_KERNEL);
			if (!mle) {
				// bad bad bad... this sucks.
				response = DLM_MASTER_RESP_ERROR;
				goto send_response;
			}
			spin_lock(&dlm->spinlock);
			dlm_init_mle(mle, DLM_MLE_BLOCK, dlm, NULL,
					 name, namelen);
			spin_unlock(&dlm->spinlock);
			goto way_up_top;
		}

		// mlog(0, "this is second time thru, already allocated, "
		// "add the block.\n");
		set_bit(request->node_idx, mle->maybe_map);
		list_add(&mle->list, &dlm->master_list);
		response = DLM_MASTER_RESP_NO;
	} else {
		// mlog(0, "mle was found\n");
		set_maybe = 1;
		spin_lock(&tmpmle->spinlock);
		if (tmpmle->type == DLM_MLE_BLOCK)
			response = DLM_MASTER_RESP_NO;
		else if (tmpmle->type == DLM_MLE_MIGRATION) {
			mlog(0, "migration mle was found (%u->%u)\n",
			     tmpmle->master, tmpmle->new_master);
			if (tmpmle->master == dlm->node_num) {
				mlog(ML_ERROR, "no lockres, but migration mle "
				     "says that this node is master!\n");
				BUG();
			}
			/* real master can respond on its own */
			response = DLM_MASTER_RESP_NO;
		} else {
			if (tmpmle->master == dlm->node_num) {
				response = DLM_MASTER_RESP_YES;
				set_maybe = 0;
			} else
				response = DLM_MASTER_RESP_MAYBE;
		}
		if (set_maybe)
			set_bit(request->node_idx, tmpmle->maybe_map);
		spin_unlock(&tmpmle->spinlock);
	}
	spin_unlock(&dlm->master_lock);
	spin_unlock(&dlm->spinlock);

	if (found) {
		/* keep the mle attached to heartbeat events */
		dlm_put_mle(tmpmle);
	}
send_response:
	dlm_put(dlm);
	return response;
}

/*
 * DLM_ASSERT_MASTER_MSG
 */


/*
 * NOTE: this can be used for debugging
 * can periodically run all locks owned by this node
 * and re-assert across the cluster...