mirror of
https://github.com/schoebel/mars
synced 2024-12-09 16:26:18 +00:00
98 lines
2.4 KiB
C
98 lines
2.4 KiB
C
/*
|
|
* MARS Long Distance Replication Software
|
|
*
|
|
* This file is part of MARS project: http://schoebel.github.io/mars/
|
|
*
|
|
* Copyright (C) 2010-2014 Thomas Schoebel-Theuer
|
|
* Copyright (C) 2011-2014 1&1 Internet AG
|
|
*
|
|
* 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.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along
|
|
* with this program; if not, write to the Free Software Foundation, Inc.,
|
|
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*/
|
|
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/semaphore.h>
|
|
|
|
#include "lamport.h"
|
|
|
|
|
|
struct semaphore lamport_sem = __SEMAPHORE_INITIALIZER(lamport_sem, 1); // TODO: replace with spinlock if possible (first check)
|
|
struct timespec lamport_now = {};
|
|
|
|
void get_lamport(struct timespec *now)
|
|
{
|
|
int diff;
|
|
|
|
down(&lamport_sem);
|
|
|
|
*now = CURRENT_TIME;
|
|
diff = timespec_compare(now, &lamport_now);
|
|
if (diff >= 0) {
|
|
timespec_add_ns(now, 1);
|
|
memcpy(&lamport_now, now, sizeof(lamport_now));
|
|
timespec_add_ns(&lamport_now, 1);
|
|
} else {
|
|
timespec_add_ns(&lamport_now, 1);
|
|
memcpy(now, &lamport_now, sizeof(*now));
|
|
}
|
|
|
|
up(&lamport_sem);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(get_lamport);
|
|
|
|
void set_lamport(struct timespec *old)
|
|
{
|
|
int diff;
|
|
|
|
protect_timespec(old);
|
|
|
|
down(&lamport_sem);
|
|
|
|
diff = timespec_compare(old, &lamport_now);
|
|
if (diff >= 0) {
|
|
memcpy(&lamport_now, old, sizeof(lamport_now));
|
|
timespec_add_ns(&lamport_now, 1);
|
|
}
|
|
|
|
up(&lamport_sem);
|
|
}
|
|
EXPORT_SYMBOL_GPL(set_lamport);
|
|
|
|
|
|
/* Protect against illegal values, e.g. from currupt filesystems etc.
|
|
*/
|
|
|
|
int max_lamport_future = 30 * 24 * 3600;
|
|
|
|
bool protect_timespec(struct timespec *check)
|
|
{
|
|
struct timespec limit = CURRENT_TIME;
|
|
bool res = false;
|
|
|
|
limit.tv_sec += max_lamport_future;
|
|
if (unlikely(check->tv_sec >= limit.tv_sec)) {
|
|
down(&lamport_sem);
|
|
timespec_add_ns(&lamport_now, 1);
|
|
memcpy(check, &lamport_now, sizeof(*check));
|
|
if (unlikely(check->tv_sec > limit.tv_sec))
|
|
max_lamport_future += check->tv_sec - limit.tv_sec;
|
|
up(&lamport_sem);
|
|
res = true;
|
|
}
|
|
return res;
|
|
}
|