// SPDX-License-Identifier: GPL-2.0
/*
* This file is part of the Distributed Network Block Device 3
*
* Copyright(c) 2011-2012 Johann Latocha <johann@latocha.de>
*
* This file may be licensed under the terms of of the
* GNU General Public License Version 2 (the ``GPL'').
*
* Software distributed under the License is distributed
* on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
* express or implied. See the GPL for the specific language
* governing rights and limitations.
*
* You should have received a copy of the GPL along with this
* program. If not, go to http://www.gnu.org/licenses/gpl.html
* or write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <dnbd3/config/client.h>
#include <dnbd3/version.h>
#include "dnbd3_main.h"
#include "blk.h"
int major;
static unsigned int max_devs = NUMBER_DEVICES;
static dnbd3_device_t *dnbd3_devices;
struct device *dnbd3_device_to_dev(dnbd3_device_t *dev)
{
return disk_to_dev(dev->disk);
}
int is_same_server(const dnbd3_server_t *const a, const dnbd3_server_t *const b)
{
return (a->host.type == b->host.type) && (a->host.port == b->host.port) &&
(0 == memcmp(a->host.addr, b->host.addr, (a->host.type == HOST_IP4 ? 4 : 16)));
}
/**
* Get a free slot pointer from the alt_servers list. Tries to find an
* entirely empty slot first, then looks for a slot with a server that
* wasn't reachable recently, finally returns NULL if none of the
* conditions match.
* The caller has to hold dev->alt_servers_lock.
*/
static inline dnbd3_server_t *get_free_alt_server(dnbd3_device_t *const dev)
{
int i;
for (i = 0; i < NUMBER_SERVERS; ++i) {
if (dev->alt_servers[i].host.type == 0)
return &dev->alt_servers[i];
}
for (i = 0; i < NUMBER_SERVERS; ++i) {
if (dev->alt_servers[i].failures > 10)
return &dev->alt_servers[i];
}
return NULL;
}
/**
* Returns pointer to existing entry in alt_servers that matches the given
* alt server, or NULL if not found.
*/
dnbd3_server_t *get_existing_server(const dnbd3_host_t *const newserver, dnbd3_device_t *const dev)
{
int i;
for (i = 0; i < NUMBER_SERVERS; ++i) {
if ((newserver->type == dev->alt_servers[i].host.type) &&
(newserver->port == dev->alt_servers[i].host.port) &&
(0 == memcmp(newserver->addr, dev->alt_servers[i].host.addr,
(newserver->type == HOST_IP4 ? 4 : 16)))) {
return &dev->alt_servers[i];
}
}
return NULL;
}
int dnbd3_add_server(dnbd3_device_t *dev, dnbd3_host_t *host)
{
int result;
dnbd3_server_t *alt_server;
/* protect access to 'alt_servers' */
mutex_lock(&dev->alt_servers_lock);
alt_server = get_existing_server(host, dev);
// ADD
if (alt_server != NULL) {
// Exists
result = -EEXIST;
} else {
// OK add
alt_server = get_free_alt_server(dev);
if (alt_server == NULL) {
result = -ENOSPC;
} else {
alt_server->host = *host;
alt_server->failures = 0;
result = 0;
}
}
mutex_unlock(&dev->alt_servers_lock);
return result;
}
int dnbd3_rem_server(dnbd3_device_t *dev, dnbd3_host_t *host)
{
dnbd3_server_t *alt_server;
int result;
/* protect access to 'alt_servers' */
mutex_lock(&dev->alt_servers_lock);
alt_server = get_existing_server(host, dev);
// REMOVE
if (alt_server == NULL) {
// Not found
result = -ENOENT;
} else {
// Remove
alt_server->host.type = 0;
result = 0;
}
mutex_unlock(&dev->alt_servers_lock);
return result;
}
static int __init dnbd3_init(void)
{
int i;
dnbd3_devices = kcalloc(max_devs, sizeof(*dnbd3_devices), GFP_KERNEL);
if (!dnbd3_devices)
return -ENOMEM;
// initialize block device
major = register_blkdev(0, "dnbd3");
if (major == 0) {
pr_err("register_blkdev failed\n");
return -EIO;
}
pr_info("kernel module in version %s loaded\n", DNBD3_VERSION);
pr_debug("machine type %s\n", DNBD3_ENDIAN_MODE);
// add MAX_NUMBER_DEVICES devices
for (i = 0; i < max_devs; i++) {
if (dnbd3_blk_add_device(&dnbd3_devices[i], i) != 0) {
pr_err("dnbd3_blk_add_device failed\n");
// TODO: delete all devices added so far.
// It could happen that it's not the first one that fails.
// Also call unregister_blkdev and free memory.
return -EIO;
}
}
pr_info("init successful (%i devices)\n", max_devs);
return 0;
}
static void __exit dnbd3_exit(void)
{
int i;
pr_debug("exiting kernel module...\n");
for (i = 0; i < max_devs; i++)
dnbd3_blk_del_device(&dnbd3_devices[i]);
unregister_blkdev(major, "dnbd3");
kfree(dnbd3_devices);
pr_info("exit kernel module done\n");
}
module_init(dnbd3_init);
module_exit(dnbd3_exit);
MODULE_DESCRIPTION("Distributed Network Block Device 3");
MODULE_LICENSE("GPL");
MODULE_VERSION(DNBD3_VERSION);
module_param(max_devs, int, 0444);
MODULE_PARM_DESC(max_devs, "number of network block devices to initialize (default: 8)");