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* 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
* All rights reserved.
*
* 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 2 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.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/buffer_head.h>
#include <linux/connector.h>
#include <linux/dst.h>
#include <linux/device.h>
#include <linux/jhash.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <net/sock.h>
static int dst_major;
static DEFINE_MUTEX(dst_hash_lock);
static struct list_head *dst_hashtable;
static unsigned int dst_hashtable_size = 128;
module_param(dst_hashtable_size, uint, 0644);
static char dst_name[] = "Dementianting goldfish";
static DEFINE_IDR(dst_index_idr);
static struct cb_id cn_dst_id = { CN_DST_IDX, CN_DST_VAL };
/*
* DST sysfs tree for device called 'storage':
*
* /sys/bus/dst/devices/storage/
* /sys/bus/dst/devices/storage/type : 192.168.4.80:1025
* /sys/bus/dst/devices/storage/size : 800
* /sys/bus/dst/devices/storage/name : storage
*/
static int dst_dev_match(struct device *dev, struct device_driver *drv)
{
return 1;
}
static struct bus_type dst_dev_bus_type = {
.name = "dst",
.match = &dst_dev_match,
};
static void dst_node_release(struct device *dev)
{
struct dst_info *info = container_of(dev, struct dst_info, device);
kfree(info);
}
static struct device dst_node_dev = {
.bus = &dst_dev_bus_type,
.release = &dst_node_release
};
/*
* Setting size of the node after it was changed.
*/
static void dst_node_set_size(struct dst_node *n)
{
struct block_device *bdev;
set_capacity(n->disk, n->size >> 9);
bdev = bdget_disk(n->disk, 0);
if (bdev) {
mutex_lock(&bdev->bd_inode->i_mutex);
i_size_write(bdev->bd_inode, n->size);
mutex_unlock(&bdev->bd_inode->i_mutex);
bdput(bdev);
}
}
/*
* Distributed storage request processing function.
*/
static int dst_request(struct request_queue *q, struct bio *bio)
{
struct dst_node *n = q->queuedata;
int err = -EIO;
if (bio_empty_barrier(bio) && !blk_queue_discard(q)) {
/*
* This is a dirty^Wnice hack, but if we complete this
* operation with -EOPNOTSUPP like intended, XFS
* will stuck and freeze the machine. This may be
* not particulary XFS problem though, but it is the
* only FS which sends empty barrier at umount time
* I worked with.
*
* Empty barriers are not allowed anyway, see 51fd77bd9f512
* for example, although later it was changed to
* bio_rw_flagged(bio, BIO_RW_DISCARD) only, which does not
* work in this case.
*/
//err = -EOPNOTSUPP;
err = 0;
goto end_io;
}
bio_get(bio);
return dst_process_bio(n, bio);
end_io:
bio_endio(bio, err);
return err;
}
/*
* Open/close callbacks for appropriate block device.
*/
static int dst_bdev_open(struct block_device *bdev, fmode_t mode)
{
struct dst_node *n = bdev->bd_disk->private_data;
dst_node_get(n);
return 0;
}
static int dst_bdev_release(struct gendisk *disk, fmode_t mode)
{
struct dst_node *n = disk->private_data;
dst_node_put(n);
return 0;
}
static struct block_device_operations dst_blk_ops = {
.open = dst_bdev_open,
.release = dst_bdev_release,
.owner = THIS_MODULE,
};
/*
* Block layer binding - disk is created when array is fully configured
* by userspace request.
*/
static int dst_node_create_disk(struct dst_node *n)
{
int err = -ENOMEM;
u32 index = 0;
n->queue = blk_init_queue(NULL, NULL);
if (!n->queue)
goto err_out_exit;
n->queue->queuedata = n;
blk_queue_make_request(n->queue, dst_request);
blk_queue_max_phys_segments(n->queue, n->max_pages);
blk_queue_max_hw_segments(n->queue, n->max_pages);
err = -ENOMEM;
n->disk = alloc_disk(1);
if (!n->disk)
goto err_out_free_queue;
if (!(n->state->permissions & DST_PERM_WRITE)) {
printk(KERN_INFO "DST node %s attached read-only.\n", n->name);
set_disk_ro(n->disk, 1);
}
if (!idr_pre_get(&dst_index_idr, GFP_KERNEL))
goto err_out_put;
mutex_lock(&dst_hash_lock);
err = idr_get_new(&dst_index_idr, NULL, &index);
mutex_unlock(&dst_hash_lock);
if (err)
goto err_out_put;
n->disk->major = dst_major;
n->disk->first_minor = index;
n->disk->fops = &dst_blk_ops;
n->disk->queue = n->queue;
n->disk->private_data = n;
snprintf(n->disk->disk_name, sizeof(n->disk->disk_name), "dst-%s", n->name);
return 0;
err_out_put:
put_disk(n->disk);
err_out_free_queue:
blk_cleanup_queue(n->queue);
err_out_exit:
return err;
}
/*
* Sysfs machinery: show device's size.
*/
static ssize_t dst_show_size(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dst_info *info = container_of(dev, struct dst_info, device);
return sprintf(buf, "%llu\n", info->size);
}
/*
* Show local exported device.
*/
static ssize_t dst_show_local(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dst_info *info = container_of(dev, struct dst_info, device);
return sprintf(buf, "%s\n", info->local);
}
/*
* Shows type of the remote node - device major/minor number
* for local nodes and address (af_inet ipv4/ipv6 only) for remote nodes.
*/
static ssize_t dst_show_type(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dst_info *info = container_of(dev, struct dst_info, device);
int family = info->net.addr.sa_family;
if (family == AF_INET) {
struct sockaddr_in *sin = (struct sockaddr_in *)&info->net.addr;
return sprintf(buf, "%u.%u.%u.%u:%d\n",
NIPQUAD(sin->sin_addr.s_addr), ntohs(sin->sin_port));
} else if (family == AF_INET6) {
struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&info->net.addr;
return sprintf(buf,
"%pi6:%d\n",
&sin->sin6_addr, ntohs(sin->sin6_port));
} else {
int i, sz = PAGE_SIZE - 2; /* 0 symbol and '\n' below */
int size, addrlen = info->net.addr.sa_data_len;
unsigned char *a = (unsigned char *)&info->net.addr.sa_data;
char *buf_orig = buf;
size = snprintf(buf, sz, "family: %d, addrlen: %u, addr: ",
family, addrlen);
sz -= size;
buf += size;
for (i=0; i<addrlen; ++i) {
if (sz < 3)
break;
size = snprintf(buf, sz, "%02x ", a[i]);
sz -= size;
buf += size;
}
buf += sprintf(buf, "\n");
return buf - buf_orig;
}
return 0;
}
static struct device_attribute dst_node_attrs[] = {
__ATTR(size, 0444, dst_show_size, NULL),
__ATTR(type, 0444, dst_show_type, NULL),
__ATTR(local, 0444, dst_show_local, NULL),
};
static int dst_create_node_attributes(struct dst_node *n)
{
int err, i;
for (i=0; i<ARRAY_SIZE(dst_node_attrs); ++i) {
err = device_create_file(&n->info->device,
&dst_node_attrs[i]);
if (err)
goto err_out_remove_all;
}
return 0;
err_out_remove_all:
while (--i >= 0)
device_remove_file(&n->info->device,
&dst_node_attrs[i]);
return err;
}
static void dst_remove_node_attributes(struct dst_node *n)
{
int i;
for (i=0; i<ARRAY_SIZE(dst_node_attrs); ++i)
device_remove_file(&n->info->device,
&dst_node_attrs[i]);
}
/*
* Sysfs cleanup and initialization.
* Shows number of useful parameters.
*/
static void dst_node_sysfs_exit(struct dst_node *n)
{
if (n->info) {
dst_remove_node_attributes(n);
device_unregister(&n->info->device);
n->info = NULL;
}
}
static int dst_node_sysfs_init(struct dst_node *n)
{
int err;
n->info = kzalloc(sizeof(struct dst_info), GFP_KERNEL);
if (!n->info)
return -ENOMEM;
memcpy(&n->info->device, &dst_node_dev, sizeof(struct device));
n->info->size = n->size;
dev_set_name(&n->info->device, "dst-%s", n->name);
err = device_register(&n->info->device);
if (err) {
dprintk(KERN_ERR "Failed to register node '%s', err: %d.\n",
n->name, err);
goto err_out_exit;
}
dst_create_node_attributes(n);
return 0;
err_out_exit:
kfree(n->info);
n->info = NULL;
return err;
}
/*
* DST node hash tables machinery.
*/
static inline unsigned int dst_hash(char *str, unsigned int size)
{
return (jhash(str, size, 0) % dst_hashtable_size);
}
static void dst_node_remove(struct dst_node *n)
{
mutex_lock(&dst_hash_lock);
list_del_init(&n->node_entry);
mutex_unlock(&dst_hash_lock);
}
static void dst_node_add(struct dst_node *n)
{
unsigned hash = dst_hash(n->name, sizeof(n->name));
mutex_lock(&dst_hash_lock);
list_add_tail(&n->node_entry, &dst_hashtable[hash]);
mutex_unlock(&dst_hash_lock);
}
/*
* Cleaning node when it is about to be freed.
* There are still users of the socket though,
* so connection cleanup should be protected.
*/
static void dst_node_cleanup(struct dst_node *n)
{
struct dst_state *st = n->state;
if (!st)
return;
if (n->queue) {
blk_cleanup_queue(n->queue);
mutex_lock(&dst_hash_lock);
idr_remove(&dst_index_idr, n->disk->first_minor);
mutex_unlock(&dst_hash_lock);
put_disk(n->disk);
}
if (n->bdev) {
sync_blockdev(n->bdev);
blkdev_put(n->bdev, FMODE_READ|FMODE_WRITE);
}
dst_state_lock(st);
st->need_exit = 1;
dst_state_exit_connected(st);
dst_state_unlock(st);
wake_up(&st->thread_wait);
dst_state_put(st);
n->state = NULL;
}
/*
* Free security attributes attached to given node.
*/
static void dst_security_exit(struct dst_node *n)
{
struct dst_secure *s, *tmp;
list_for_each_entry_safe(s, tmp, &n->security_list, sec_entry) {
list_del(&s->sec_entry);
kfree(s);
}
}
/*
* Free node when there are no more users.
* Actually node has to be freed on behalf od userspace process,
* since there are number of threads, which are embedded in the
* node, so they can not exit and free node from there, that is
* why there is a wakeup if reference counter is not equal to zero.
*/
void dst_node_put(struct dst_node *n)
{
if (unlikely(!n))
return;
dprintk("%s: n: %p, refcnt: %d.\n",
__func__, n, atomic_read(&n->refcnt));
if (atomic_dec_and_test(&n->refcnt)) {
dst_node_remove(n);
n->trans_scan_timeout = 0;
dst_node_cleanup(n);
thread_pool_destroy(n->pool);
dst_node_sysfs_exit(n);
dst_node_crypto_exit(n);
dst_security_exit(n);
dst_node_trans_exit(n);
kfree(n);
dprintk("%s: freed n: %p.\n", __func__, n);
} else {
wake_up(&n->wait);
}
}
/*
* This function finds devices major/minor numbers for given pathname.
*/
static int dst_lookup_device(const char *path, dev_t *dev)
{
int err;
struct nameidata nd;
struct inode *inode;
err = path_lookup(path, LOOKUP_FOLLOW, &nd);
if (err)
return err;
inode = nd.path.dentry->d_inode;
if (!inode) {
err = -ENOENT;
goto out;
}
if (!S_ISBLK(inode->i_mode)) {
err = -ENOTBLK;
goto out;
}
*dev = inode->i_rdev;
out:
path_put(&nd.path);
return err;
}
/*
* Setting up export device: lookup by the name, get its size
* and setup listening socket, which will accept clients, which
* will submit IO for given storage.
*/
static int dst_setup_export(struct dst_node *n, struct dst_ctl *ctl,
struct dst_export_ctl *le)
{
int err;
dev_t dev = 0; /* gcc likes to scream here */
snprintf(n->info->local, sizeof(n->info->local), "%s", le->device);
err = dst_lookup_device(le->device, &dev);
if (err)
return err;
n->bdev = open_by_devnum(dev, FMODE_READ|FMODE_WRITE);
if (!n->bdev)
return -ENODEV;
if (n->size != 0)
n->size = min_t(loff_t, n->bdev->bd_inode->i_size, n->size);
else
n->size = n->bdev->bd_inode->i_size;
n->info->size = n->size;
err = dst_node_init_listened(n, le);
if (err)
goto err_out_cleanup;
return 0;
err_out_cleanup:
blkdev_put(n->bdev, FMODE_READ|FMODE_WRITE);
n->bdev = NULL;
return err;
}
/* Empty thread pool callbacks for the network processing threads. */
static inline void *dst_thread_network_init(void *data)
{
dprintk("%s: data: %p.\n", __func__, data);
return data;
}
static inline void dst_thread_network_cleanup(void *data)
{
dprintk("%s: data: %p.\n", __func__, data);
}
/*
* Allocate DST node and initialize some of its parameters.
*/
static struct dst_node *dst_alloc_node(struct dst_ctl *ctl,
int (*start)(struct dst_node *),
int num)
{
struct dst_node *n;
int err;
n = kzalloc(sizeof(struct dst_node), GFP_KERNEL);
if (!n)
return NULL;
INIT_LIST_HEAD(&n->node_entry);
INIT_LIST_HEAD(&n->security_list);
mutex_init(&n->security_lock);
init_waitqueue_head(&n->wait);
n->trans_scan_timeout = msecs_to_jiffies(ctl->trans_scan_timeout);
if (!n->trans_scan_timeout)
n->trans_scan_timeout = HZ;
n->trans_max_retries = ctl->trans_max_retries;
if (!n->trans_max_retries)
n->trans_max_retries = 10;
/*
* Pretty much arbitrary default numbers.
* 32 matches maximum number of pages in bio originated from ext3 (31).
*/
n->max_pages = ctl->max_pages;
if (!n->max_pages)
n->max_pages = 32;
if (n->max_pages > 1024)
n->max_pages = 1024;
n->start = start;
n->size = ctl->size;
atomic_set(&n->refcnt, 1);
atomic_long_set(&n->gen, 0);
snprintf(n->name, sizeof(n->name), "%s", ctl->name);
err = dst_node_sysfs_init(n);
if (err)
goto err_out_free;
n->pool = thread_pool_create(num, n->name, dst_thread_network_init,
dst_thread_network_cleanup, n);
if (IS_ERR(n->pool)) {
err = PTR_ERR(n->pool);
goto err_out_sysfs_exit;
}
dprintk("%s: n: %p, name: %s.\n", __func__, n, n->name);
return n;
err_out_sysfs_exit:
dst_node_sysfs_exit(n);
err_out_free:
kfree(n);
return NULL;
}
/*
* Starting a node, connected to the remote server:
* register block device and initialize transaction mechanism.
* In revers order though.
*
* It will autonegotiate some parameters with the remote node
* and update local if needed.
*
* Transaction initialization should be the last thing before
* starting the node, since transaction should include not only
* block IO, but also crypto related data (if any), which are
* initialized separately.
*/
static int dst_start_remote(struct dst_node *n)
{
int err;
err = dst_node_trans_init(n, sizeof(struct dst_trans));
if (err)
return err;
err = dst_node_create_disk(n);
if (err)
return err;
dst_node_set_size(n);
add_disk(n->disk);
dprintk("DST: started remote node '%s', minor: %d.\n", n->name, n->disk->first_minor);
return 0;
}
/*
* Adding remote node and initialize connection.
*/
static int dst_add_remote(struct dst_node *n, struct dst_ctl *ctl,
void *data, unsigned int size)
{
int err;
struct dst_network_ctl *rctl = data;
if (n)
return -EEXIST;
if (size != sizeof(struct dst_network_ctl))
return -EINVAL;
n = dst_alloc_node(ctl, dst_start_remote, 1);
if (!n)
return -ENOMEM;
memcpy(&n->info->net, rctl, sizeof(struct dst_network_ctl));
err = dst_node_init_connected(n, rctl);
if (err)
goto err_out_free;
dst_node_add(n);
return 0;
err_out_free:
dst_node_put(n);
return err;
}
/*
* Adding export node: initializing block device and listening socket.
*/
static int dst_add_export(struct dst_node *n, struct dst_ctl *ctl,
void *data, unsigned int size)
{
int err;
struct dst_export_ctl *le = data;
if (n)
return -EEXIST;
if (size != sizeof(struct dst_export_ctl))
return -EINVAL;
n = dst_alloc_node(ctl, dst_start_export, 2);
if (!n)
return -EINVAL;
err = dst_setup_export(n, ctl, le);
if (err)
goto err_out_free;
dst_node_add(n);
return 0;
err_out_free:
dst_node_put(n);
return err;
}
static int dst_node_remove_unload(struct dst_node *n)
{
printk(KERN_INFO "STOPPED name: '%s', size: %llu.\n",
n->name, n->size);
if (n->disk)
del_gendisk(n->disk);
dst_node_remove(n);
dst_node_sysfs_exit(n);
/*
* This is not a hack. Really.
* Node's reference counter allows to implement fine grained
* node freeing, but since all transactions (which hold node's
* reference counter) are processed in the dedicated thread,
* it is possible that reference will hit zero in that thread,
* so we will not be able to exit thread and cleanup the node.
*
* So, we remove disk, so no new activity is possible, and
* wait until all pending transaction are completed (either
* in receiving thread or by timeout in workqueue), in this
* case reference counter will be less or equal to 2 (once set in
* dst_alloc_node() and then in connector message parser;
* or when we force module unloading, and connector message
* parser does not hold a reference, in this case reference
* counter will be equal to 1),
* and subsequent dst_node_put() calls will free the node.
*/
dprintk("%s: going to sleep with %d refcnt.\n", __func__, atomic_read(&n->refcnt));
wait_event(n->wait, atomic_read(&n->refcnt) <= 2);
dst_node_put(n);
return 0;
}
/*
* Remove node from the hash table.
*/
static int dst_del_node(struct dst_node *n, struct dst_ctl *ctl,
void *data, unsigned int size)
{
if (!n)
return -ENODEV;
return dst_node_remove_unload(n);
}
/*
* Initialize crypto processing for given node.
*/
static int dst_crypto_init(struct dst_node *n, struct dst_ctl *ctl,
void *data, unsigned int size)
{
struct dst_crypto_ctl *crypto = data;
if (!n)
return -ENODEV;
if (size != sizeof(struct dst_crypto_ctl) + crypto->hash_keysize +
crypto->cipher_keysize)
return -EINVAL;
if (n->trans_cache)
return -EEXIST;
return dst_node_crypto_init(n, crypto);
}
/*
* Security attributes for given node.
*/
static int dst_security_init(struct dst_node *n, struct dst_ctl *ctl,
void *data, unsigned int size)
{
struct dst_secure *s;
if (!n)
return -ENODEV;
if (size != sizeof(struct dst_secure_user))
return -EINVAL;
s = kmalloc(sizeof(struct dst_secure), GFP_KERNEL);
if (!s)
return -ENOMEM;
memcpy(&s->sec, data, size);
mutex_lock(&n->security_lock);
list_add_tail(&s->sec_entry, &n->security_list);
mutex_unlock(&n->security_lock);
return 0;
}
/*
* Kill'em all!
*/
static int dst_start_node(struct dst_node *n, struct dst_ctl *ctl,
void *data, unsigned int size)
{
int err;
if (!n)
return -ENODEV;
if (n->trans_cache)
return 0;
err = n->start(n);
if (err)
return err;
printk(KERN_INFO "STARTED name: '%s', size: %llu.\n", n->name, n->size);
return 0;
}
typedef int (*dst_command_func)(struct dst_node *n, struct dst_ctl *ctl,
void *data, unsigned int size);
/*
* List of userspace commands.
*/
static dst_command_func dst_commands[] = {
[DST_ADD_REMOTE] = &dst_add_remote,
[DST_ADD_EXPORT] = &dst_add_export,
[DST_DEL_NODE] = &dst_del_node,
[DST_CRYPTO] = &dst_crypto_init,
[DST_SECURITY] = &dst_security_init,
[DST_START] = &dst_start_node,
};
/*
* Configuration parser.
*/
static void cn_dst_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
struct dst_ctl *ctl;
int err;
struct dst_ctl_ack ack;
struct dst_node *n = NULL, *tmp;
unsigned int hash;
if (!cap_raised(nsp->eff_cap, CAP_SYS_ADMIN)) {
err = -EPERM;
goto out;
}
if (msg->len < sizeof(struct dst_ctl)) {
err = -EBADMSG;
goto out;
}
ctl = (struct dst_ctl *)msg->data;
if (ctl->cmd >= DST_CMD_MAX) {
err = -EINVAL;
goto out;
}
hash = dst_hash(ctl->name, sizeof(ctl->name));
mutex_lock(&dst_hash_lock);
list_for_each_entry(tmp, &dst_hashtable[hash], node_entry) {
if (!memcmp(tmp->name, ctl->name, sizeof(tmp->name))) {
n = tmp;
dst_node_get(n);
break;
}
}
mutex_unlock(&dst_hash_lock);
err = dst_commands[ctl->cmd](n, ctl, msg->data + sizeof(struct dst_ctl),
msg->len - sizeof(struct dst_ctl));
dst_node_put(n);
out:
memcpy(&ack.msg, msg, sizeof(struct cn_msg));
ack.msg.ack = msg->ack + 1;
ack.msg.len = sizeof(struct dst_ctl_ack) - sizeof(struct cn_msg);
ack.error = err;
cn_netlink_send(&ack.msg, 0, GFP_KERNEL);
}
/*
* Global initialization: sysfs, hash table, block device registration,
* connector and various caches.
*/
static int __init dst_sysfs_init(void)
{
return bus_register(&dst_dev_bus_type);
}
static void dst_sysfs_exit(void)
{
bus_unregister(&dst_dev_bus_type);
}
static int __init dst_hashtable_init(void)
{
unsigned int i;
dst_hashtable = kcalloc(dst_hashtable_size, sizeof(struct list_head),
GFP_KERNEL);
if (!dst_hashtable)
return -ENOMEM;
for (i=0; i<dst_hashtable_size; ++i)
INIT_LIST_HEAD(&dst_hashtable[i]);
return 0;
}
static void dst_hashtable_exit(void)
{
unsigned int i;
struct dst_node *n, *tmp;
for (i=0; i<dst_hashtable_size; ++i) {
list_for_each_entry_safe(n, tmp, &dst_hashtable[i], node_entry) {
dst_node_remove_unload(n);
}
}
kfree(dst_hashtable);
}
static int __init dst_sys_init(void)
{
int err = -ENOMEM;
err = dst_hashtable_init();
if (err)
goto err_out_exit;
err = dst_export_init();
if (err)
goto err_out_hashtable_exit;
err = register_blkdev(dst_major, DST_NAME);
if (err < 0)
goto err_out_export_exit;
if (err)
dst_major = err;
err = dst_sysfs_init();
if (err)
goto err_out_unregister;
err = cn_add_callback(&cn_dst_id, "DST", cn_dst_callback);
if (err)
goto err_out_sysfs_exit;
printk(KERN_INFO "Distributed storage, '%s' release.\n", dst_name);
return 0;
err_out_sysfs_exit:
dst_sysfs_exit();
err_out_unregister:
unregister_blkdev(dst_major, DST_NAME);
err_out_export_exit:
dst_export_exit();
err_out_hashtable_exit:
dst_hashtable_exit();
err_out_exit:
return err;
}
static void __exit dst_sys_exit(void)
{
cn_del_callback(&cn_dst_id);
unregister_blkdev(dst_major, DST_NAME);
dst_hashtable_exit();
dst_sysfs_exit();
dst_export_exit();
}
module_init(dst_sys_init);
module_exit(dst_sys_exit);
MODULE_DESCRIPTION("Distributed storage");
MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_LICENSE("GPL");
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