/* $NetBSD: tmpfs_mem.c,v 1.14 2023/04/29 06:29:55 riastradh Exp $ */

/* $NetBSD: tmpfs_mem.c,v 1.14 2023/04/29 06:29:55 riastradh Exp $ */

/*
* Copyright (c) 2010, 2011, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Mindaugas Rasiukevicius.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/*
* tmpfs memory allocation routines.
* Implements memory usage accounting and limiting.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: tmpfs_mem.c,v 1.14 2023/04/29 06:29:55 riastradh Exp $");

#include <sys/param.h>
#include <sys/atomic.h>
#include <sys/kmem.h>
#include <sys/namei.h>
#include <sys/pool.h>

#include <fs/tmpfs/tmpfs.h>

extern struct pool tmpfs_dirent_pool;
extern struct pool tmpfs_node_pool;

void
tmpfs_mntmem_init(struct tmpfs_mount *mp, uint64_t memlimit)
{

mutex_init(&mp->tm_acc_lock, MUTEX_DEFAULT, IPL_NONE);
mp->tm_mem_limit = memlimit;
mp->tm_bytes_used = 0;
}

void
tmpfs_mntmem_destroy(struct tmpfs_mount *mp)
{

KASSERT(mp->tm_bytes_used == 0);
mutex_destroy(&mp->tm_acc_lock);
}

int
tmpfs_mntmem_set(struct tmpfs_mount *mp, uint64_t memlimit)
{
int error;

mutex_enter(&mp->tm_acc_lock);
if (round_page(mp->tm_bytes_used) >= memlimit)
error = EBUSY;
else {
error = 0;
mp->tm_mem_limit = memlimit;
}
mutex_exit(&mp->tm_acc_lock);
return error;
}

/*
* tmpfs_mem_info: return the number of available memory pages.
*
* => If 'total' is true, then return _total_ amount of pages.
* => If false, then return the amount of _free_ memory pages.
*
* Remember to remove uvmexp.freetarg from the returned value to avoid
* excessive memory usage.
*/
size_t
tmpfs_mem_info(bool total)
{
size_t size = 0;

size += uvmexp.swpgavail;
if (!total) {
size -= uvmexp.swpgonly;
}
size += uvm_availmem(true);
size += uvmexp.filepages;
if (size > uvmexp.wired) {
size -= uvmexp.wired;
} else {
size = 0;
}
return size;
}

uint64_t
tmpfs_bytes_max(struct tmpfs_mount *mp)
{
psize_t freepages = tmpfs_mem_info(false);
int freetarg = uvmexp.freetarg; // XXX unlocked
uint64_t avail_mem;

if (freepages < freetarg) {
freepages = 0;
} else {
freepages -= freetarg;
}
avail_mem = round_page(mp->tm_bytes_used) + (freepages << PAGE_SHIFT);
return MIN(mp->tm_mem_limit, avail_mem);
}

size_t
tmpfs_pages_avail(struct tmpfs_mount *mp)
{

return (tmpfs_bytes_max(mp) - mp->tm_bytes_used) >> PAGE_SHIFT;
}

bool
tmpfs_mem_incr(struct tmpfs_mount *mp, size_t sz)
{
uint64_t lim;

mutex_enter(&mp->tm_acc_lock);
lim = tmpfs_bytes_max(mp);
if (mp->tm_bytes_used + sz >= lim) {
mutex_exit(&mp->tm_acc_lock);
return false;
}
mp->tm_bytes_used += sz;
mutex_exit(&mp->tm_acc_lock);
return true;
}

void
tmpfs_mem_decr(struct tmpfs_mount *mp, size_t sz)
{

mutex_enter(&mp->tm_acc_lock);
KASSERT(mp->tm_bytes_used >= sz);
mp->tm_bytes_used -= sz;
mutex_exit(&mp->tm_acc_lock);
}

struct tmpfs_dirent *
tmpfs_dirent_get(struct tmpfs_mount *mp)
{

if (!tmpfs_mem_incr(mp, sizeof(struct tmpfs_dirent))) {
return NULL;
}
return pool_get(&tmpfs_dirent_pool, PR_WAITOK);
}

void
tmpfs_dirent_put(struct tmpfs_mount *mp, struct tmpfs_dirent *de)
{

tmpfs_mem_decr(mp, sizeof(struct tmpfs_dirent));
pool_put(&tmpfs_dirent_pool, de);
}

struct tmpfs_node *
tmpfs_node_get(struct tmpfs_mount *mp)
{

if (atomic_inc_uint_nv(&mp->tm_nodes_cnt) >= mp->tm_nodes_max) {
atomic_dec_uint(&mp->tm_nodes_cnt);
return NULL;
}
if (!tmpfs_mem_incr(mp, sizeof(struct tmpfs_node))) {
atomic_dec_uint(&mp->tm_nodes_cnt);
return NULL;
}
return pool_get(&tmpfs_node_pool, PR_WAITOK);
}

void
tmpfs_node_put(struct tmpfs_mount *mp, struct tmpfs_node *tn)
{

atomic_dec_uint(&mp->tm_nodes_cnt);
tmpfs_mem_decr(mp, sizeof(struct tmpfs_node));
pool_put(&tmpfs_node_pool, tn);
}

/*
* Quantum size to round-up the tmpfs names in order to reduce re-allocations.
*/

#define TMPFS_NAME_QUANTUM (32)

char *
tmpfs_strname_alloc(struct tmpfs_mount *mp, size_t len)
{
const size_t sz = roundup2(len, TMPFS_NAME_QUANTUM);

KASSERT(sz > 0 && sz <= 1024);
if (!tmpfs_mem_incr(mp, sz)) {
return NULL;
}
return kmem_alloc(sz, KM_SLEEP);
}

void
tmpfs_strname_free(struct tmpfs_mount *mp, char *str, size_t len)
{
const size_t sz = roundup2(len, TMPFS_NAME_QUANTUM);

KASSERT(sz > 0 && sz <= 1024);
tmpfs_mem_decr(mp, sz);
kmem_free(str, sz);
}

bool
tmpfs_strname_neqlen(struct componentname *fcnp, struct componentname *tcnp)
{
const size_t fln = fcnp->cn_namelen;
const size_t tln = tcnp->cn_namelen;

return (fln != tln) || memcmp(fcnp->cn_nameptr, tcnp->cn_nameptr, fln);
}