samba-mirror/ctdb/server/ctdb_recover.c

/* 
   ctdb recovery code

   Copyright (C) Andrew Tridgell  2007
   Copyright (C) Ronnie Sahlberg  2007

   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/>.
*/
#include "includes.h"
#include "lib/events/events.h"
#include "lib/tdb/include/tdb.h"
#include "system/network.h"
#include "system/filesys.h"
#include "system/wait.h"
#include "../include/ctdb_private.h"
#include "lib/util/dlinklist.h"
#include "db_wrap.h"

/*
  lock all databases - mark only
 */
static int ctdb_lock_all_databases_mark(struct ctdb_context *ctdb)
{
	struct ctdb_db_context *ctdb_db;
	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("Attempt to mark all databases locked when not frozen\n"));
		return -1;
	}
	for (ctdb_db=ctdb->db_list;ctdb_db;ctdb_db=ctdb_db->next) {
		if (tdb_lockall_mark(ctdb_db->ltdb->tdb) != 0) {
			return -1;
		}
	}
	return 0;
}

/*
  lock all databases - unmark only
 */
static int ctdb_lock_all_databases_unmark(struct ctdb_context *ctdb)
{
	struct ctdb_db_context *ctdb_db;
	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("Attempt to unmark all databases locked when not frozen\n"));
		return -1;
	}
	for (ctdb_db=ctdb->db_list;ctdb_db;ctdb_db=ctdb_db->next) {
		if (tdb_lockall_unmark(ctdb_db->ltdb->tdb) != 0) {
			return -1;
		}
	}
	return 0;
}


int 
ctdb_control_getvnnmap(struct ctdb_context *ctdb, uint32_t opcode, TDB_DATA indata, TDB_DATA *outdata)
{
	CHECK_CONTROL_DATA_SIZE(0);
	struct ctdb_vnn_map_wire *map;
	size_t len;

	len = offsetof(struct ctdb_vnn_map_wire, map) + sizeof(uint32_t)*ctdb->vnn_map->size;
	map = talloc_size(outdata, len);
	CTDB_NO_MEMORY_VOID(ctdb, map);

	map->generation = ctdb->vnn_map->generation;
	map->size = ctdb->vnn_map->size;
	memcpy(map->map, ctdb->vnn_map->map, sizeof(uint32_t)*map->size);

	outdata->dsize = len;
	outdata->dptr  = (uint8_t *)map;

	return 0;
}

int 
ctdb_control_setvnnmap(struct ctdb_context *ctdb, uint32_t opcode, TDB_DATA indata, TDB_DATA *outdata)
{
	struct ctdb_vnn_map_wire *map = (struct ctdb_vnn_map_wire *)indata.dptr;

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("Attempt to set vnnmap when not frozen\n"));
		return -1;
	}

	talloc_free(ctdb->vnn_map);

	ctdb->vnn_map = talloc(ctdb, struct ctdb_vnn_map);
	CTDB_NO_MEMORY(ctdb, ctdb->vnn_map);

	ctdb->vnn_map->generation = map->generation;
	ctdb->vnn_map->size       = map->size;
	ctdb->vnn_map->map = talloc_array(ctdb->vnn_map, uint32_t, map->size);
	CTDB_NO_MEMORY(ctdb, ctdb->vnn_map->map);

	memcpy(ctdb->vnn_map->map, map->map, sizeof(uint32_t)*map->size);

	return 0;
}

int 
ctdb_control_getdbmap(struct ctdb_context *ctdb, uint32_t opcode, TDB_DATA indata, TDB_DATA *outdata)
{
	uint32_t i, len;
	struct ctdb_db_context *ctdb_db;
	struct ctdb_dbid_map *dbid_map;

	CHECK_CONTROL_DATA_SIZE(0);

	len = 0;
	for(ctdb_db=ctdb->db_list;ctdb_db;ctdb_db=ctdb_db->next){
		len++;
	}


	outdata->dsize = offsetof(struct ctdb_dbid_map, dbs) + sizeof(dbid_map->dbs[0])*len;
	outdata->dptr  = (unsigned char *)talloc_zero_size(outdata, outdata->dsize);
	if (!outdata->dptr) {
		DEBUG(0, (__location__ " Failed to allocate dbmap array\n"));
		exit(1);
	}

	dbid_map = (struct ctdb_dbid_map *)outdata->dptr;
	dbid_map->num = len;
	for (i=0,ctdb_db=ctdb->db_list;ctdb_db;i++,ctdb_db=ctdb_db->next){
		dbid_map->dbs[i].dbid       = ctdb_db->db_id;
		dbid_map->dbs[i].persistent = ctdb_db->persistent;
	}

	return 0;
}

int 
ctdb_control_getnodemap(struct ctdb_context *ctdb, uint32_t opcode, TDB_DATA indata, TDB_DATA *outdata)
{
	uint32_t i, num_nodes;
	struct ctdb_node_map *node_map;

	CHECK_CONTROL_DATA_SIZE(0);

	num_nodes = ctdb->num_nodes;

	outdata->dsize = offsetof(struct ctdb_node_map, nodes) + num_nodes*sizeof(struct ctdb_node_and_flags);
	outdata->dptr  = (unsigned char *)talloc_zero_size(outdata, outdata->dsize);
	if (!outdata->dptr) {
		DEBUG(0, (__location__ " Failed to allocate nodemap array\n"));
		exit(1);
	}

	node_map = (struct ctdb_node_map *)outdata->dptr;
	node_map->num = num_nodes;
	for (i=0; i<num_nodes; i++) {
		inet_aton(ctdb->nodes[i]->address.address, &node_map->nodes[i].sin.sin_addr);
		node_map->nodes[i].pnn   = ctdb->nodes[i]->pnn;
		node_map->nodes[i].flags = ctdb->nodes[i]->flags;
	}

	return 0;
}

struct getkeys_params {
	struct ctdb_context *ctdb;
	uint32_t lmaster;
	uint32_t rec_count;
	struct getkeys_rec {
		TDB_DATA key;
		TDB_DATA data;
	} *recs;
};

static int traverse_getkeys(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *p)
{
	struct getkeys_params *params = (struct getkeys_params *)p;
	uint32_t lmaster;

	lmaster = ctdb_lmaster(params->ctdb, &key);

	/* only include this record if the lmaster matches or if
	   the wildcard lmaster (-1) was specified.
	*/
	if ((params->lmaster != CTDB_LMASTER_ANY) && (params->lmaster != lmaster)) {
		return 0;
	}

	params->recs = talloc_realloc(NULL, params->recs, struct getkeys_rec, params->rec_count+1);
	key.dptr = talloc_memdup(params->recs, key.dptr, key.dsize);
	data.dptr = talloc_memdup(params->recs, data.dptr, data.dsize);
	params->recs[params->rec_count].key = key;
	params->recs[params->rec_count].data = data;
	params->rec_count++;

	return 0;
}

/*
  pul a bunch of records from a ltdb, filtering by lmaster
 */
int32_t ctdb_control_pull_db(struct ctdb_context *ctdb, TDB_DATA indata, TDB_DATA *outdata)
{
	struct ctdb_control_pulldb *pull;
	struct ctdb_db_context *ctdb_db;
	struct getkeys_params params;
	struct ctdb_control_pulldb_reply *reply;
	int i;
	size_t len = 0;

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("rejecting ctdb_control_pull_db when not frozen\n"));
		return -1;
	}

	pull = (struct ctdb_control_pulldb *)indata.dptr;
	
	ctdb_db = find_ctdb_db(ctdb, pull->db_id);
	if (!ctdb_db) {
		DEBUG(0,(__location__ " Unknown db\n"));
		return -1;
	}

	params.ctdb = ctdb;
	params.lmaster = pull->lmaster;

	params.rec_count = 0;
	params.recs = talloc_array(outdata, struct getkeys_rec, 0);
	CTDB_NO_MEMORY(ctdb, params.recs);

	if (ctdb_lock_all_databases_mark(ctdb) != 0) {
		DEBUG(0,(__location__ " Failed to get lock on entired db - failing\n"));
		return -1;
	}

	tdb_traverse_read(ctdb_db->ltdb->tdb, traverse_getkeys, &params);

	ctdb_lock_all_databases_unmark(ctdb);

	reply = talloc(outdata, struct ctdb_control_pulldb_reply);
	CTDB_NO_MEMORY(ctdb, reply);

	reply->db_id = pull->db_id;
	reply->count = params.rec_count;

	len = offsetof(struct ctdb_control_pulldb_reply, data);

	for (i=0;i<reply->count;i++) {
		struct ctdb_rec_data *rec;
		rec = ctdb_marshall_record(outdata, 0, params.recs[i].key, NULL, params.recs[i].data);
		reply = talloc_realloc_size(outdata, reply, rec->length + len);
		memcpy(len+(uint8_t *)reply, rec, rec->length);
		len += rec->length;
		talloc_free(rec);
	}

	talloc_free(params.recs);

	outdata->dptr = (uint8_t *)reply;
	outdata->dsize = len;

	return 0;
}

/*
  push a bunch of records into a ltdb, filtering by rsn
 */
int32_t ctdb_control_push_db(struct ctdb_context *ctdb, TDB_DATA indata)
{
	struct ctdb_control_pulldb_reply *reply = (struct ctdb_control_pulldb_reply *)indata.dptr;
	struct ctdb_db_context *ctdb_db;
	int i, ret;
	struct ctdb_rec_data *rec;

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("rejecting ctdb_control_push_db when not frozen\n"));
		return -1;
	}

	if (indata.dsize < offsetof(struct ctdb_control_pulldb_reply, data)) {
		DEBUG(0,(__location__ " invalid data in pulldb reply\n"));
		return -1;
	}

	ctdb_db = find_ctdb_db(ctdb, reply->db_id);
	if (!ctdb_db) {
		DEBUG(0,(__location__ " Unknown db 0x%08x\n", reply->db_id));
		return -1;
	}

	if (ctdb_lock_all_databases_mark(ctdb) != 0) {
		DEBUG(0,(__location__ " Failed to get lock on entired db - failing\n"));
		return -1;
	}

	rec = (struct ctdb_rec_data *)&reply->data[0];

	DEBUG(3,("starting push of %u records for dbid 0x%x\n",
		 reply->count, reply->db_id));

	for (i=0;i<reply->count;i++) {
		TDB_DATA key, data;
		struct ctdb_ltdb_header *hdr, header;

		key.dptr = &rec->data[0];
		key.dsize = rec->keylen;
		data.dptr = &rec->data[key.dsize];
		data.dsize = rec->datalen;

		if (data.dsize < sizeof(struct ctdb_ltdb_header)) {
			DEBUG(0,(__location__ " bad ltdb record\n"));
			goto failed;
		}
		hdr = (struct ctdb_ltdb_header *)data.dptr;
		data.dptr += sizeof(*hdr);
		data.dsize -= sizeof(*hdr);

		ret = ctdb_ltdb_fetch(ctdb_db, key, &header, NULL, NULL);
		if (ret != 0) {
			DEBUG(0, (__location__ " Unable to fetch record\n"));
			goto failed;
		}
		/* The check for dmaster gives priority to the dmaster
		   if the rsn values are equal */
		if (header.rsn < hdr->rsn ||
		    (header.dmaster != ctdb->pnn && header.rsn == hdr->rsn)) {
			ret = ctdb_ltdb_store(ctdb_db, key, hdr, data);
			if (ret != 0) {
				DEBUG(0, (__location__ " Unable to store record\n"));
				goto failed;
			}
		}

		rec = (struct ctdb_rec_data *)(rec->length + (uint8_t *)rec);
	}	    

	DEBUG(3,("finished push of %u records for dbid 0x%x\n",
		 reply->count, reply->db_id));

	ctdb_lock_all_databases_unmark(ctdb);
	return 0;

failed:
	ctdb_lock_all_databases_unmark(ctdb);
	return -1;
}


static int traverse_setdmaster(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *p)
{
	uint32_t *dmaster = (uint32_t *)p;
	struct ctdb_ltdb_header *header = (struct ctdb_ltdb_header *)data.dptr;
	int ret;

	header->dmaster = *dmaster;

	ret = tdb_store(tdb, key, data, TDB_REPLACE);
	if (ret) {
		DEBUG(0,(__location__ " failed to write tdb data back  ret:%d\n",ret));
		return ret;
	}
	return 0;
}

int32_t ctdb_control_set_dmaster(struct ctdb_context *ctdb, TDB_DATA indata)
{
	struct ctdb_control_set_dmaster *p = (struct ctdb_control_set_dmaster *)indata.dptr;
	struct ctdb_db_context *ctdb_db;

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("rejecting ctdb_control_set_dmaster when not frozen\n"));
		return -1;
	}

	ctdb_db = find_ctdb_db(ctdb, p->db_id);
	if (!ctdb_db) {
		DEBUG(0,(__location__ " Unknown db 0x%08x\n", p->db_id));
		return -1;
	}

	if (ctdb_lock_all_databases_mark(ctdb) != 0) {
		DEBUG(0,(__location__ " Failed to get lock on entired db - failing\n"));
		return -1;
	}

	tdb_traverse(ctdb_db->ltdb->tdb, traverse_setdmaster, &p->dmaster);

	ctdb_lock_all_databases_unmark(ctdb);
	
	return 0;
}

struct ctdb_set_recmode_state {
	struct ctdb_context *ctdb;
	struct ctdb_req_control *c;
	uint32_t recmode;
	int fd[2];
	struct timed_event *te;
	struct fd_event *fde;
	pid_t child;
};

/*
  called when the 'recovered' event script has finished
 */
static void ctdb_recovered_callback(struct ctdb_context *ctdb, int status, void *p)
{
	struct ctdb_set_recmode_state *state = talloc_get_type(p, struct ctdb_set_recmode_state);

	ctdb_start_monitoring(ctdb);

	if (status == 0) {
		ctdb->recovery_mode = state->recmode;
	} else {
		DEBUG(0,(__location__ " recovered event script failed (status %d)\n", status));
	}

	ctdb_request_control_reply(ctdb, state->c, NULL, status, NULL);
	talloc_free(state);
}

/*
  called if our set_recmode child times out. this would happen if
  ctdb_recovery_lock() would block.
 */
static void ctdb_set_recmode_timeout(struct event_context *ev, struct timed_event *te, 
					 struct timeval t, void *private_data)
{
	struct ctdb_set_recmode_state *state = talloc_get_type(private_data, 
					   struct ctdb_set_recmode_state);

	ctdb_request_control_reply(state->ctdb, state->c, NULL, -1, "timeout in ctdb_set_recmode");
	talloc_free(state);
}


/* when we free the recmode state we must kill any child process.
*/
static int set_recmode_destructor(struct ctdb_set_recmode_state *state)
{
	kill(state->child, SIGKILL);
	waitpid(state->child, NULL, 0);
	return 0;
}

/* this is called when the client process has completed ctdb_recovery_lock()
   and has written data back to us through the pipe.
*/
static void set_recmode_handler(struct event_context *ev, struct fd_event *fde, 
			     uint16_t flags, void *private_data)
{
	struct ctdb_set_recmode_state *state= talloc_get_type(private_data, 
					     struct ctdb_set_recmode_state);
	char c = 0;
	int ret;

	/* we got a response from our child process so we can abort the
	   timeout.
	*/
	talloc_free(state->te);
	state->te = NULL;


	/* read the childs status when trying to lock the reclock file.
	   child wrote 0 if everything is fine and 1 if it did manage
	   to lock the file, which would be a problem since that means
	   we got a request to exit from recovery but we could still lock
	   the file   which at this time SHOULD be locked by the recovery
	   daemon on the recmaster
	*/		
	ret = read(state->fd[0], &c, 1);
	if (ret != 1 || c != 0) {
		ctdb_request_control_reply(state->ctdb, state->c, NULL, -1, "managed to lock reclock file from inside daemon");
		talloc_free(state);
		return;
	}


	ctdb_stop_monitoring(state->ctdb);

	/* call the events script to tell all subsystems that we have recovered */
	ret = ctdb_event_script_callback(state->ctdb, 
					 timeval_current_ofs(state->ctdb->tunable.script_timeout, 0),
					 state, 
					 ctdb_recovered_callback, 
					 state, "recovered");
	if (ret != 0) {
		ctdb_request_control_reply(state->ctdb, state->c, NULL, -1, "failed to run eventscript from set_recmode");
		talloc_free(state);
		return;
	}
}

/*
  set the recovery mode
 */
int32_t ctdb_control_set_recmode(struct ctdb_context *ctdb, 
				 struct ctdb_req_control *c,
				 TDB_DATA indata, bool *async_reply,
				 const char **errormsg)
{
	uint32_t recmode = *(uint32_t *)indata.dptr;
	int ret;
	struct ctdb_set_recmode_state *state;
	pid_t parent = getpid();

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("Attempt to change recovery mode to %u when not frozen\n", 
			 recmode));
		(*errormsg) = "Cannot change recovery mode while not frozen";
		return -1;
	}

	if (recmode != CTDB_RECOVERY_NORMAL ||
	    ctdb->recovery_mode != CTDB_RECOVERY_ACTIVE) {
		ctdb->recovery_mode = recmode;
		return 0;
	}

	/* some special handling when ending recovery mode */
	state = talloc(ctdb, struct ctdb_set_recmode_state);
	CTDB_NO_MEMORY(ctdb, state);

	/* For the rest of what needs to be done, we need to do this in
	   a child process since 
	   1, the call to ctdb_recovery_lock() can block if the cluster
	      filesystem is in the process of recovery.
	   2, running of the script may take a while.
	*/
	ret = pipe(state->fd);
	if (ret != 0) {
		talloc_free(state);
		DEBUG(0,(__location__ " Failed to open pipe for set_recmode child\n"));
		return -1;
	}

	state->child = fork();
	if (state->child == (pid_t)-1) {
		close(state->fd[0]);
		close(state->fd[1]);
		talloc_free(state);
		return -1;
	}

	if (state->child == 0) {
		char cc = 0;
		close(state->fd[0]);

		/* we should not be able to get the lock on the nodes list, 
		  as it should  be held by the recovery master 
		*/
		if (ctdb_recovery_lock(ctdb, false)) {
			DEBUG(0,("ERROR: recovery lock file %s not locked when recovering!\n", ctdb->recovery_lock_file));
			cc = 1;
		}

		write(state->fd[1], &cc, 1);
		/* make sure we die when our parent dies */
		while (kill(parent, 0) == 0 || errno != ESRCH) {
			sleep(5);
		}
		_exit(0);
	}
	close(state->fd[1]);

	talloc_set_destructor(state, set_recmode_destructor);

	state->te = event_add_timed(ctdb->ev, state, timeval_current_ofs(3, 0),
			ctdb_set_recmode_timeout, state);

	state->fde = event_add_fd(ctdb->ev, state, state->fd[0],
				EVENT_FD_READ|EVENT_FD_AUTOCLOSE,
				set_recmode_handler,
				(void *)state);
	if (state->fde == NULL) {
		talloc_free(state);
		return -1;
	}

	state->ctdb    = ctdb;
	state->recmode = recmode;
	state->c       = talloc_steal(state, c);

	*async_reply = true;

	return 0;
}

/*
  callback for ctdb_control_max_rsn
 */
static int traverse_max_rsn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *p)
{
	struct ctdb_ltdb_header *h = (struct ctdb_ltdb_header *)data.dptr;
	uint64_t *max_rsn = (uint64_t *)p;

	if (data.dsize >= sizeof(*h)) {
		(*max_rsn) = MAX(*max_rsn, h->rsn);
	}
	return 0;
}

/*
  get max rsn across an entire db
 */
int32_t ctdb_control_max_rsn(struct ctdb_context *ctdb, TDB_DATA indata, TDB_DATA *outdata)
{
	struct ctdb_db_context *ctdb_db;
	uint32_t db_id = *(uint32_t *)indata.dptr;
	uint64_t max_rsn = 0;
	int ret;

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("rejecting ctdb_control_max_rsn when not frozen\n"));
		return -1;
	}

	ctdb_db = find_ctdb_db(ctdb, db_id);
	if (!ctdb_db) {
		DEBUG(0,(__location__ " Unknown db\n"));
		return -1;
	}

	if (ctdb_lock_all_databases_mark(ctdb) != 0) {
		DEBUG(0,(__location__ " Failed to get lock on entired db - failing\n"));
		return -1;
	}

	ret = tdb_traverse_read(ctdb_db->ltdb->tdb, traverse_max_rsn, &max_rsn);
	if (ret < 0) {
		DEBUG(0,(__location__ " traverse failed in ctdb_control_max_rsn\n"));
		return -1;
	}

	ctdb_lock_all_databases_unmark(ctdb);

	outdata->dptr = (uint8_t *)talloc(outdata, uint64_t);
	if (!outdata->dptr) {
		return -1;
	}
	(*(uint64_t *)outdata->dptr) = max_rsn;
	outdata->dsize = sizeof(uint64_t);

	return 0;
}


/*
  callback for ctdb_control_set_rsn_nonempty
 */
static int traverse_set_rsn_nonempty(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *p)
{
	struct ctdb_ltdb_header *h = (struct ctdb_ltdb_header *)data.dptr;
	uint64_t *rsn = (uint64_t *)p;

	if (data.dsize > sizeof(*h)) {
		h->rsn = *rsn;
		if (tdb_store(tdb, key, data, TDB_REPLACE) != 0) {
			return -1;
		}
	}
	return 0;
}

/*
  set rsn for all non-empty records in a database to a given rsn
 */
int32_t ctdb_control_set_rsn_nonempty(struct ctdb_context *ctdb, TDB_DATA indata, TDB_DATA *outdata)
{
	struct ctdb_control_set_rsn_nonempty *p = (struct ctdb_control_set_rsn_nonempty *)indata.dptr;
	struct ctdb_db_context *ctdb_db;
	int ret;

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("rejecting ctdb_control_set_rsn_nonempty when not frozen\n"));
		return -1;
	}

	ctdb_db = find_ctdb_db(ctdb, p->db_id);
	if (!ctdb_db) {
		DEBUG(0,(__location__ " Unknown db\n"));
		return -1;
	}

	if (ctdb_lock_all_databases_mark(ctdb) != 0) {
		DEBUG(0,(__location__ " Failed to get lock on entired db - failing\n"));
		return -1;
	}

	ret = tdb_traverse(ctdb_db->ltdb->tdb, traverse_set_rsn_nonempty, &p->rsn);
	if (ret < 0) {
		DEBUG(0,(__location__ " traverse failed in ctdb_control_set_rsn_nonempty\n"));
		return -1;
	}

	ctdb_lock_all_databases_unmark(ctdb);

	return 0;
}


/*
  callback for ctdb_control_delete_low_rsn
 */
static int traverse_delete_low_rsn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *p)
{
	struct ctdb_ltdb_header *h = (struct ctdb_ltdb_header *)data.dptr;
	uint64_t *rsn = (uint64_t *)p;

	if (data.dsize < sizeof(*h) || h->rsn < *rsn) {
		if (tdb_delete(tdb, key) != 0) {
			return -1;
		}
	}
	return 0;
}

/*
  delete any records with a rsn < the given rsn
 */
int32_t ctdb_control_delete_low_rsn(struct ctdb_context *ctdb, TDB_DATA indata, TDB_DATA *outdata)
{
	struct ctdb_control_delete_low_rsn *p = (struct ctdb_control_delete_low_rsn *)indata.dptr;
	struct ctdb_db_context *ctdb_db;
	int ret;

	if (ctdb->freeze_mode != CTDB_FREEZE_FROZEN) {
		DEBUG(0,("rejecting ctdb_control_delete_low_rsn when not frozen\n"));
		return -1;
	}

	ctdb_db = find_ctdb_db(ctdb, p->db_id);
	if (!ctdb_db) {
		DEBUG(0,(__location__ " Unknown db\n"));
		return -1;
	}

	if (ctdb_lock_all_databases_mark(ctdb) != 0) {
		DEBUG(0,(__location__ " Failed to get lock on entired db - failing\n"));
		return -1;
	}

	ret = tdb_traverse(ctdb_db->ltdb->tdb, traverse_delete_low_rsn, &p->rsn);
	if (ret < 0) {
		DEBUG(0,(__location__ " traverse failed in ctdb_control_delete_low_rsn\n"));
		return -1;
	}

	ctdb_lock_all_databases_unmark(ctdb);

	return 0;
}


/*
  try and get the recovery lock in shared storage - should only work
  on the recovery master recovery daemon. Anywhere else is a bug
 */
bool ctdb_recovery_lock(struct ctdb_context *ctdb, bool keep)
{
	struct flock lock;

	if (ctdb->recovery_lock_fd != -1) {
		close(ctdb->recovery_lock_fd);
	}
	ctdb->recovery_lock_fd = open(ctdb->recovery_lock_file, O_RDWR|O_CREAT, 0600);
	if (ctdb->recovery_lock_fd == -1) {
		DEBUG(0,("Unable to open %s - (%s)\n", 
			 ctdb->recovery_lock_file, strerror(errno)));
		return false;
	}

	set_close_on_exec(ctdb->recovery_lock_fd);

	lock.l_type = F_WRLCK;
	lock.l_whence = SEEK_SET;
	lock.l_start = 0;
	lock.l_len = 1;
	lock.l_pid = 0;

	if (fcntl(ctdb->recovery_lock_fd, F_SETLK, &lock) != 0) {
		close(ctdb->recovery_lock_fd);
		ctdb->recovery_lock_fd = -1;
		return false;
	}

	if (!keep) {
		close(ctdb->recovery_lock_fd);
		ctdb->recovery_lock_fd = -1;
	}

	return true;
}