lvm2/daemons/clvmd/clvmd-singlenode.c

/*
 * Copyright (C) 2009 Red Hat, Inc. All rights reserved.
 *
 * This file is part of LVM2.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "clvmd-common.h"

#include <pthread.h>

#include "locking.h"
#include "clvm.h"
#include "clvmd-comms.h"
#include "lvm-functions.h"
#include "clvmd.h"

#include <sys/un.h>
#include <sys/socket.h>
#include <fcntl.h>

static const char SINGLENODE_CLVMD_SOCKNAME[] = DEFAULT_RUN_DIR "/clvmd_singlenode.sock";
static int listen_fd = -1;

static struct dm_hash_table *_locks;
static int _lockid;

struct lock {
	int lockid;
	int mode;
	int excl;
};

static void close_comms(void)
{
	if (listen_fd != -1 && close(listen_fd))
		stack;
	(void)unlink(SINGLENODE_CLVMD_SOCKNAME);
	listen_fd = -1;
}

static int init_comms(void)
{
	mode_t old_mask;
	struct sockaddr_un addr = { .sun_family = AF_UNIX };

	if (!dm_strncpy(addr.sun_path, SINGLENODE_CLVMD_SOCKNAME,
			sizeof(addr.sun_path))) {
		DEBUGLOG("%s: singlenode socket name too long.",
			 SINGLENODE_CLVMD_SOCKNAME);
		return -1;
	}

	close_comms();

	(void) dm_prepare_selinux_context(SINGLENODE_CLVMD_SOCKNAME, S_IFSOCK);
	old_mask = umask(0077);

	listen_fd = socket(PF_UNIX, SOCK_STREAM, 0);
	if (listen_fd < 0) {
		DEBUGLOG("Can't create local socket: %s\n", strerror(errno));
		goto error;
	}
	/* Set Close-on-exec */
	if (fcntl(listen_fd, F_SETFD, 1)) {
		DEBUGLOG("Setting CLOEXEC on client fd failed: %s\n", strerror(errno));
		goto error;
	}

	if (bind(listen_fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
		DEBUGLOG("Can't bind local socket: %s\n", strerror(errno));
		goto error;
	}
	if (listen(listen_fd, 10) < 0) {
		DEBUGLOG("Can't listen local socket: %s\n", strerror(errno));
		goto error;
	}

	umask(old_mask);
	(void) dm_prepare_selinux_context(NULL, 0);
	return 0;
error:
	umask(old_mask);
	(void) dm_prepare_selinux_context(NULL, 0);
	close_comms();
	return -1;
}

static int _init_cluster(void)
{
	int r;

	if (!(_locks = dm_hash_create(128))) {
		DEBUGLOG("Failed to allocate single-node hash table.\n");
		return 1;
	}

	r = init_comms();
	if (r) {
		dm_hash_destroy(_locks);
		return r;
	}

	DEBUGLOG("Single-node cluster initialised.\n");
	return 0;
}

static void _cluster_closedown(void)
{
	close_comms();

	DEBUGLOG("cluster_closedown\n");
	destroy_lvhash();
	dm_hash_destroy(_locks);
	_locks = NULL;
	_lockid = 0;
}

static void _get_our_csid(char *csid)
{
	int nodeid = 1;
	memcpy(csid, &nodeid, sizeof(int));
}

static int _csid_from_name(char *csid, const char *name)
{
	return 1;
}

static int _name_from_csid(const char *csid, char *name)
{
	sprintf(name, "SINGLENODE");
	return 0;
}

static int _get_num_nodes(void)
{
	return 1;
}

/* Node is now known to be running a clvmd */
static void _add_up_node(const char *csid)
{
}

/* Call a callback for each node, so the caller knows whether it's up or down */
static int _cluster_do_node_callback(struct local_client *master_client,
				     void (*callback)(struct local_client *,
				     const char *csid, int node_up))
{
	return 0;
}

int _lock_file(const char *file, uint32_t flags);

static pthread_mutex_t _lock_mutex = PTHREAD_MUTEX_INITIALIZER;
/* Using one common condition for all locks for simplicity */
static pthread_cond_t _lock_cond = PTHREAD_COND_INITIALIZER;

/* Real locking */
static int _lock_resource(const char *resource, int mode, int flags, int *lockid)
{
	struct lock *lck;

	DEBUGLOG("Locking resource %s, flags=%d, mode=%d\n",
		 resource, flags, mode);

	mode &= LCK_TYPE_MASK;
	pthread_mutex_lock(&_lock_mutex);
retry:
	if (!(lck = dm_hash_lookup(_locks, resource))) {
		/* Add new locked resource */
		if (!(lck = dm_zalloc(sizeof(struct lock))) ||
		    !dm_hash_insert(_locks, resource, lck))
			goto bad;

		lck->lockid = ++_lockid;
		goto out;
	}

        /* Update/convert lock */
	if (flags == LCKF_CONVERT) {
		if (lck->excl)
			mode = LCK_EXCL;
	} else if ((lck->mode == LCK_WRITE) || (lck->mode == LCK_EXCL)) {
		DEBUGLOG("Resource %s already %s locked (%d)...\n", resource,
			 (lck->mode == LCK_WRITE) ? "write" : "exclusively", lck->lockid);
		goto maybe_retry;
	} else if (lck->mode > mode) {
		DEBUGLOG("Resource %s already locked and %s lock requested...\n",
			 resource,
			 (mode == LCK_READ) ? "READ" :
			 (mode == LCK_WRITE) ? "WRITE" : "EXCLUSIVE");
		goto maybe_retry;
	}

out:
	*lockid = lck->lockid;
	lck->mode = mode;
	lck->excl |= (mode == LCK_EXCL);
	DEBUGLOG("Locked resource %s, lockid=%d, mode=%d\n", resource, lck->lockid, mode);
	pthread_cond_broadcast(&_lock_cond); /* wakeup waiters */
	pthread_mutex_unlock(&_lock_mutex);

	return 0;

maybe_retry:
	if (!(flags & LCK_NONBLOCK)) {
		pthread_cond_wait(&_lock_cond, &_lock_mutex);
		DEBUGLOG("Resource %s RETRYING lock...\n", resource);
		goto retry;
	}
bad:
	DEBUGLOG("Failed to lock resource %s\n", resource);
	pthread_mutex_unlock(&_lock_mutex);

	return 1; /* fail */
}

static int _unlock_resource(const char *resource, int lockid)
{
	struct lock *lck;

	if (lockid < 0) {
		DEBUGLOG("Not tracking unlock of lockid -1: %s, lockid=%d\n",
			 resource, lockid);
		return 0;
	}

	DEBUGLOG("Unlocking resource %s, lockid=%d\n", resource, lockid);
	pthread_mutex_lock(&_lock_mutex);

	if (!(lck = dm_hash_lookup(_locks, resource))) {
		pthread_mutex_unlock(&_lock_mutex);
		DEBUGLOG("Resource %s, lockid=%d is not locked.\n", resource, lockid);
		return 1;
	}

	if (lck->lockid != lockid) {
		pthread_mutex_unlock(&_lock_mutex);
		DEBUGLOG("Resource %s has wrong lockid %d, expected %d.\n",
			 resource, lck->lockid, lockid);
		return 1;
	}

	dm_hash_remove(_locks, resource);
	dm_free(lck);
	pthread_cond_broadcast(&_lock_cond); /* wakeup waiters */
	pthread_mutex_unlock(&_lock_mutex);

	return 0;
}

static int _is_quorate(void)
{
	return 1;
}

static int _get_main_cluster_fd(void)
{
	return listen_fd;
}

static int _cluster_fd_callback(struct local_client *fd, char *buf, int len,
				const char *csid,
				struct local_client **new_client)
{
	return 1;
}

static int _cluster_send_message(const void *buf, int msglen,
				 const char *csid,
				 const char *errtext)
{
	return 0;
}

static int _get_cluster_name(char *buf, int buflen)
{
	strncpy(buf, "localcluster", buflen);
	buf[buflen - 1] = 0;
	return 0;
}

static struct cluster_ops _cluster_singlenode_ops = {
	.name                     = "singlenode",
	.cluster_init_completed   = NULL,
	.cluster_send_message     = _cluster_send_message,
	.name_from_csid           = _name_from_csid,
	.csid_from_name           = _csid_from_name,
	.get_num_nodes            = _get_num_nodes,
	.cluster_fd_callback      = _cluster_fd_callback,
	.get_main_cluster_fd      = _get_main_cluster_fd,
	.cluster_do_node_callback = _cluster_do_node_callback,
	.is_quorate               = _is_quorate,
	.get_our_csid             = _get_our_csid,
	.add_up_node              = _add_up_node,
	.reread_config            = NULL,
	.cluster_closedown        = _cluster_closedown,
	.get_cluster_name         = _get_cluster_name,
	.sync_lock                = _lock_resource,
	.sync_unlock              = _unlock_resource,
};

struct cluster_ops *init_singlenode_cluster(void)
{
	if (!_init_cluster())
		return &_cluster_singlenode_ops;
	else
		return NULL;
}