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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2018-2020 Junjiro R. Okajima
*
* This program, aufs 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, see <http://www.gnu.org/licenses/>.
*/
/*
* simple long counter wrapper
*/
#ifndef __AUFS_LCNT_H__
#define __AUFS_LCNT_H__
#ifdef __KERNEL__
#include "debug.h"
#define AuLCntATOMIC 1
#define AuLCntPCPUCNT 2
/*
* why does percpu_refcount require extra synchronize_rcu()s in
* au_br_do_free()
*/
#define AuLCntPCPUREF 3
/* #define AuLCntChosen AuLCntATOMIC */
#define AuLCntChosen AuLCntPCPUCNT
/* #define AuLCntChosen AuLCntPCPUREF */
#if AuLCntChosen == AuLCntATOMIC
#include <linux/atomic.h>
typedef atomic_long_t au_lcnt_t;
static inline int au_lcnt_init(au_lcnt_t *cnt, void *release __maybe_unused)
{
atomic_long_set(cnt, 0);
return 0;
}
static inline void au_lcnt_wait_for_fin(au_lcnt_t *cnt __maybe_unused)
{
/* empty */
}
static inline void au_lcnt_fin(au_lcnt_t *cnt __maybe_unused,
int do_sync __maybe_unused)
{
/* empty */
}
static inline void au_lcnt_inc(au_lcnt_t *cnt)
{
atomic_long_inc(cnt);
}
static inline void au_lcnt_dec(au_lcnt_t *cnt)
{
atomic_long_dec(cnt);
}
static inline long au_lcnt_read(au_lcnt_t *cnt, int do_rev __maybe_unused)
{
return atomic_long_read(cnt);
}
#endif
#if AuLCntChosen == AuLCntPCPUCNT
#include <linux/percpu_counter.h>
typedef struct percpu_counter au_lcnt_t;
static inline int au_lcnt_init(au_lcnt_t *cnt, void *release __maybe_unused)
{
return percpu_counter_init(cnt, 0, GFP_NOFS);
}
static inline void au_lcnt_wait_for_fin(au_lcnt_t *cnt __maybe_unused)
{
/* empty */
}
static inline void au_lcnt_fin(au_lcnt_t *cnt, int do_sync __maybe_unused)
{
percpu_counter_destroy(cnt);
}
static inline void au_lcnt_inc(au_lcnt_t *cnt)
{
percpu_counter_inc(cnt);
}
static inline void au_lcnt_dec(au_lcnt_t *cnt)
{
percpu_counter_dec(cnt);
}
static inline long au_lcnt_read(au_lcnt_t *cnt, int do_rev __maybe_unused)
{
s64 n;
n = percpu_counter_sum(cnt);
BUG_ON(n < 0);
if (LONG_MAX != LLONG_MAX
&& n > LONG_MAX)
AuWarn1("%s\n", "wrap-around");
return n;
}
#endif
#if AuLCntChosen == AuLCntPCPUREF
#include <linux/percpu-refcount.h>
typedef struct percpu_ref au_lcnt_t;
static inline int au_lcnt_init(au_lcnt_t *cnt, percpu_ref_func_t *release)
{
if (!release)
release = percpu_ref_exit;
return percpu_ref_init(cnt, release, /*percpu mode*/0, GFP_NOFS);
}
static inline void au_lcnt_wait_for_fin(au_lcnt_t *cnt __maybe_unused)
{
synchronize_rcu();
}
static inline void au_lcnt_fin(au_lcnt_t *cnt, int do_sync)
{
percpu_ref_kill(cnt);
if (do_sync)
au_lcnt_wait_for_fin(cnt);
}
static inline void au_lcnt_inc(au_lcnt_t *cnt)
{
percpu_ref_get(cnt);
}
static inline void au_lcnt_dec(au_lcnt_t *cnt)
{
percpu_ref_put(cnt);
}
/*
* avoid calling this func as possible.
*/
static inline long au_lcnt_read(au_lcnt_t *cnt, int do_rev)
{
long l;
percpu_ref_switch_to_atomic_sync(cnt);
l = atomic_long_read(&cnt->count);
if (do_rev)
percpu_ref_switch_to_percpu(cnt);
/* percpu_ref is initialized by 1 instead of 0 */
return l - 1;
}
#endif
#ifdef CONFIG_AUFS_DEBUG
#define AuLCntZero(val) do { \
long l = val; \
if (l) \
AuDbg("%s = %ld\n", #val, l); \
} while (0)
#else
#define AuLCntZero(val) do {} while (0)
#endif
#endif /* __KERNEL__ */
#endif /* __AUFS_LCNT_H__ */
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