ctdb_call.c

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/* 
   ctdb_call protocol code

   Copyright (C) Andrew Tridgell  2006

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
/*
  see http://wiki.samba.org/index.php/Samba_%26_Clustering for
  protocol design and packet details
*/
#include "includes.h"
#include "lib/events/events.h"
#include "lib/tdb/include/tdb.h"
#include "lib/util/dlinklist.h"
#include "system/network.h"
#include "system/filesys.h"
#include "../include/ctdb_private.h"

/*
  find the ctdb_db from a db index
 */
 struct ctdb_db_context *find_ctdb_db(struct ctdb_context *ctdb, uint32_t id)
{
	struct ctdb_db_context *ctdb_db;

	for (ctdb_db=ctdb->db_list; ctdb_db; ctdb_db=ctdb_db->next) {
		if (ctdb_db->db_id == id) {
			break;
		}
	}
	return ctdb_db;
}


/*
  a varient of input packet that can be used in lock requeue
*/
static void ctdb_call_input_pkt(void *p, struct ctdb_req_header *hdr)
{
	struct ctdb_context *ctdb = talloc_get_type(p, struct ctdb_context);
	ctdb_input_pkt(ctdb, hdr);
}


/*
  send an error reply
*/
static void ctdb_send_error(struct ctdb_context *ctdb, 
			    struct ctdb_req_header *hdr, uint32_t status,
			    const char *fmt, ...) PRINTF_ATTRIBUTE(4,5);
static void ctdb_send_error(struct ctdb_context *ctdb, 
			    struct ctdb_req_header *hdr, uint32_t status,
			    const char *fmt, ...)
{
	va_list ap;
	struct ctdb_reply_error *r;
	char *msg;
	int msglen, len;

	va_start(ap, fmt);
	msg = talloc_vasprintf(ctdb, fmt, ap);
	if (msg == NULL) {
		ctdb_fatal(ctdb, "Unable to allocate error in ctdb_send_error\n");
	}
	va_end(ap);

	msglen = strlen(msg)+1;
	len = offsetof(struct ctdb_reply_error, msg);
	r = ctdb_transport_allocate(ctdb, msg, CTDB_REPLY_ERROR, len + msglen, 
				    struct ctdb_reply_error);
	CTDB_NO_MEMORY_FATAL(ctdb, r);

	r->hdr.destnode  = hdr->srcnode;
	r->hdr.reqid     = hdr->reqid;
	r->status        = status;
	r->msglen        = msglen;
	memcpy(&r->msg[0], msg, msglen);

	ctdb_queue_packet(ctdb, &r->hdr);

	talloc_free(msg);
}


/*
  send a redirect reply
*/
static void ctdb_call_send_redirect(struct ctdb_context *ctdb, 
				    TDB_DATA key,
				    struct ctdb_req_call *c, 
				    struct ctdb_ltdb_header *header)
{
	
	uint32_t lmaster = ctdb_lmaster(ctdb, &key);
	if (ctdb->vnn == lmaster) {
		c->hdr.destnode = header->dmaster;
	} else if ((c->hopcount % ctdb->tunable.max_redirect_count) == 0) {
		c->hdr.destnode = lmaster;
	} else {
		c->hdr.destnode = header->dmaster;
	}
	c->hopcount++;
	ctdb_queue_packet(ctdb, &c->hdr);
}


/*
  send a dmaster reply

  caller must have the chainlock before calling this routine. Caller must be
  the lmaster
*/
static void ctdb_send_dmaster_reply(struct ctdb_db_context *ctdb_db,
				    struct ctdb_ltdb_header *header,
				    TDB_DATA key, TDB_DATA data,
				    uint32_t new_dmaster,
				    uint32_t reqid)
{
	struct ctdb_context *ctdb = ctdb_db->ctdb;
	struct ctdb_reply_dmaster *r;
	int ret, len;
	TALLOC_CTX *tmp_ctx;

	if (ctdb->vnn != ctdb_lmaster(ctdb, &key)) {
		DEBUG(0,(__location__ " Caller is not lmaster!\n"));
		return;
	}

	header->dmaster = new_dmaster;
	ret = ctdb_ltdb_store(ctdb_db, key, header, data);
	if (ret != 0) {
		ctdb_fatal(ctdb, "ctdb_req_dmaster unable to update dmaster");
		return;
	}

	/* put the packet on a temporary context, allowing us to safely free
	   it below even if ctdb_reply_dmaster() has freed it already */
	tmp_ctx = talloc_new(ctdb);

	/* send the CTDB_REPLY_DMASTER */
	len = offsetof(struct ctdb_reply_dmaster, data) + key.dsize + data.dsize;
	r = ctdb_transport_allocate(ctdb, tmp_ctx, CTDB_REPLY_DMASTER, len,
				    struct ctdb_reply_dmaster);
	CTDB_NO_MEMORY_FATAL(ctdb, r);

	r->hdr.destnode  = new_dmaster;
	r->hdr.reqid     = reqid;
	r->rsn           = header->rsn;
	r->keylen        = key.dsize;
	r->datalen       = data.dsize;
	r->db_id         = ctdb_db->db_id;
	memcpy(&r->data[0], key.dptr, key.dsize);
	memcpy(&r->data[key.dsize], data.dptr, data.dsize);

	ctdb_queue_packet(ctdb, &r->hdr);

	talloc_free(tmp_ctx);
}

/*
  send a dmaster request (give another node the dmaster for a record)

  This is always sent to the lmaster, which ensures that the lmaster
  always knows who the dmaster is. The lmaster will then send a
  CTDB_REPLY_DMASTER to the new dmaster
*/
static void ctdb_call_send_dmaster(struct ctdb_db_context *ctdb_db, 
				   struct ctdb_req_call *c, 
				   struct ctdb_ltdb_header *header,
				   TDB_DATA *key, TDB_DATA *data)
{
	struct ctdb_req_dmaster *r;
	struct ctdb_context *ctdb = ctdb_db->ctdb;
	int len;
	uint32_t lmaster = ctdb_lmaster(ctdb, key);

	if (lmaster == ctdb->vnn) {
		ctdb_send_dmaster_reply(ctdb_db, header, *key, *data, 
					c->hdr.srcnode, c->hdr.reqid);
		return;
	}
	
	len = offsetof(struct ctdb_req_dmaster, data) + key->dsize + data->dsize;
	r = ctdb_transport_allocate(ctdb, ctdb, CTDB_REQ_DMASTER, len, 
				    struct ctdb_req_dmaster);
	CTDB_NO_MEMORY_FATAL(ctdb, r);
	r->hdr.destnode  = lmaster;
	r->hdr.reqid     = c->hdr.reqid;
	r->db_id         = c->db_id;
	r->rsn           = header->rsn;
	r->dmaster       = c->hdr.srcnode;
	r->keylen        = key->dsize;
	r->datalen       = data->dsize;
	memcpy(&r->data[0], key->dptr, key->dsize);
	memcpy(&r->data[key->dsize], data->dptr, data->dsize);

	header->dmaster = c->hdr.srcnode;
	if (ctdb_ltdb_store(ctdb_db, *key, header, *data) != 0) {
		ctdb_fatal(ctdb, "Failed to store record in ctdb_call_send_dmaster");
	}
	
	ctdb_queue_packet(ctdb, &r->hdr);

	talloc_free(r);
}

/*
  called when a CTDB_REPLY_DMASTER packet comes in, or when the lmaster
  gets a CTDB_REQUEST_DMASTER for itself. We become the dmaster.

  must be called with the chainlock held. This function releases the chainlock
*/
static void ctdb_become_dmaster(struct ctdb_db_context *ctdb_db, 
				uint32_t reqid, TDB_DATA key, TDB_DATA data,
				uint64_t rsn)
{
	struct ctdb_call_state *state;
	struct ctdb_context *ctdb = ctdb_db->ctdb;
	struct ctdb_ltdb_header header;

	DEBUG(2,("vnn %u dmaster response %08x\n", ctdb->vnn, ctdb_hash(&key)));

	ZERO_STRUCT(header);
	header.rsn = rsn + 1;
	header.dmaster = ctdb->vnn;

	if (ctdb_ltdb_store(ctdb_db, key, &header, data) != 0) {
		ctdb_fatal(ctdb, "ctdb_reply_dmaster store failed\n");
		ctdb_ltdb_unlock(ctdb_db, key);
		return;
	}

	state = ctdb_reqid_find(ctdb, reqid, struct ctdb_call_state);

	if (state == NULL) {
		DEBUG(0,("vnn %u Invalid reqid %u in ctdb_become_dmaster\n",
			 ctdb->vnn, reqid));
		ctdb_ltdb_unlock(ctdb_db, key);
		return;
	}

	if (reqid != state->reqid) {
		/* we found a record  but it was the wrong one */
		DEBUG(0, ("Dropped orphan in ctdb_become_dmaster with reqid:%u\n",reqid));
		ctdb_ltdb_unlock(ctdb_db, key);
		return;
	}

	ctdb_call_local(ctdb_db, &state->call, &header, state, &data, ctdb->vnn);

	ctdb_ltdb_unlock(ctdb_db, state->call.key);

	state->state = CTDB_CALL_DONE;
	if (state->async.fn) {
		state->async.fn(state);
	}
}



/*
  called when a CTDB_REQ_DMASTER packet comes in

  this comes into the lmaster for a record when the current dmaster
  wants to give up the dmaster role and give it to someone else
*/
void ctdb_request_dmaster(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
{
	struct ctdb_req_dmaster *c = (struct ctdb_req_dmaster *)hdr;
	TDB_DATA key, data, data2;
	struct ctdb_ltdb_header header;
	struct ctdb_db_context *ctdb_db;
	int ret;

	key.dptr = c->data;
	key.dsize = c->keylen;
	data.dptr = c->data + c->keylen;
	data.dsize = c->datalen;

	ctdb_db = find_ctdb_db(ctdb, c->db_id);
	if (!ctdb_db) {
		ctdb_send_error(ctdb, hdr, -1,
				"Unknown database in request. db_id==0x%08x",
				c->db_id);
		return;
	}
	
	/* fetch the current record */
	ret = ctdb_ltdb_lock_fetch_requeue(ctdb_db, key, &header, hdr, &data2,
					   ctdb_call_input_pkt, ctdb, False);
	if (ret == -1) {
		ctdb_fatal(ctdb, "ctdb_req_dmaster failed to fetch record");
		return;
	}
	if (ret == -2) {
		DEBUG(2,(__location__ " deferring ctdb_request_dmaster\n"));
		return;
	}

	if (ctdb_lmaster(ctdb, &key) != ctdb->vnn) {
		DEBUG(0,("vnn %u dmaster request to non-lmaster lmaster=%u gen=%u curgen=%u\n",
			 ctdb->vnn, ctdb_lmaster(ctdb, &key), 
			 hdr->generation, ctdb->vnn_map->generation));
		ctdb_fatal(ctdb, "ctdb_req_dmaster to non-lmaster");
	}

	DEBUG(2,("vnn %u dmaster request on %08x for %u from %u\n", 
		 ctdb->vnn, ctdb_hash(&key), c->dmaster, c->hdr.srcnode));

	/* its a protocol error if the sending node is not the current dmaster */
	if (header.dmaster != hdr->srcnode) {
		DEBUG(0,("vnn %u dmaster request non-master %u dmaster=%u key %08x dbid 0x%08x gen=%u curgen=%u\n",
			 ctdb->vnn, hdr->srcnode, header.dmaster, ctdb_hash(&key),
			 ctdb_db->db_id, hdr->generation, ctdb->vnn_map->generation));
		ctdb_fatal(ctdb, "ctdb_req_dmaster from non-master");
		return;
	}

	/* use the rsn from the sending node */
	header.rsn = c->rsn;

	/* check if the new dmaster is the lmaster, in which case we
	   skip the dmaster reply */
	if (c->dmaster == ctdb->vnn) {
		ctdb_become_dmaster(ctdb_db, hdr->reqid, key, data, c->rsn);
	} else {
		ctdb_send_dmaster_reply(ctdb_db, &header, key, data, c->dmaster, hdr->reqid);
		ctdb_ltdb_unlock(ctdb_db, key);
	}
}


/*
  called when a CTDB_REQ_CALL packet comes in
*/
void ctdb_request_call(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
{
	struct ctdb_req_call *c = (struct ctdb_req_call *)hdr;
	TDB_DATA data;
	struct ctdb_reply_call *r;
	int ret, len;
	struct ctdb_ltdb_header header;
	struct ctdb_call call;
	struct ctdb_db_context *ctdb_db;

	ctdb_db = find_ctdb_db(ctdb, c->db_id);
	if (!ctdb_db) {
		ctdb_send_error(ctdb, hdr, -1,
				"Unknown database in request. db_id==0x%08x",
				c->db_id);
		return;
	}

	call.call_id  = c->callid;
	call.key.dptr = c->data;
	call.key.dsize = c->keylen;
	call.call_data.dptr = c->data + c->keylen;