tmpfs_mem.c

Branch :

Show log
Commit
Author : mvs
Date : 2025-11-21 09:49:33
Hash : 17872957
Message : Modify the behavior of tmpfs limitations. Keep the global memory limit of all tmpfs instances, however each instance mounted with '-s' option decreases available limit by given value. This value can't be greater than available space. The instance mounted with with '-s' option consumes it's own limit and does no impact to other tmpfs instances. The instances mounted without '-s' option share all available limit and do not affect on instances mounted with '-s'. Now it is impossible to mount instance with '-s' option if passed value is greater than available limit. Tested with dbp(1) by kirill, ok mpi For example, this machine has 2G of RAM, so tmpfs is limited with 1G. Please note, the +- 1Mb depends of how 'dd', 'df' and 'mount_tmpfs' expose the sizes. # mount_tmpfs tmpfs /mnt/t0 # mount_tmpfs tmpfs /mnt/t1 # mount_tmpfs -s 720M tmpfs /mnt/t2 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 257M 0B 257M 0% /mnt/t0 tmpfs 257M 0B 257M 0% /mnt/t1 tmpfs 720M 4.0K 720M 1% /mnt/t2 # dd if=/dev/zero of=/mnt/t0/f0 bs=1M count=256 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 257M 256M 560K 100% /mnt/t0 tmpfs 560K 0B 560K 0% /mnt/t1 tmpfs 720M 4.0K 720M 1% /mnt/t2 # mount_tmpfs -s 1M tmpfs /mnt/t3 mount_tmpfs: tmpfs on /mnt/t3: Invalid argument # mount_tmpfs -s 1K tmpfs /mnt/t3 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 257M 256M 556K 100% /mnt/t0 tmpfs 556K 0B 556K 0% /mnt/t1 tmpfs 720M 4.0K 720M 1% /mnt/t2 tmpfs 4.0K 4.0K 0B 100% /mnt/t3 # mount_tmpfs tmpfs /mnt/t3 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 257M 256M 560K 100% /mnt/t0 tmpfs 560K 0B 560K 0% /mnt/t1 tmpfs 720M 4.0K 720M 1% /mnt/t2 tmpfs 560K 0B 560K 0% /mnt/t3 # dd if=/dev/zero of=/mnt/t2/f0 bs=1M count=128 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 257M 256M 560K 100% /mnt/t0 tmpfs 560K 0B 560K 0% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 # rm -rf /mnt/t0/f0 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 257M 0B 257M 0% /mnt/t0 tmpfs 257M 0B 257M 0% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 # mount_tmpfs -s 128M tmpfs /mnt/t3 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 129M 0B 129M 0% /mnt/t0 tmpfs 129M 0B 129M 0% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 tmpfs 128M 4.0K 128M 1% /mnt/t3 # dd if=/dev/zero of=/mnt/t0/f0 bs=1M count=32 # dd if=/dev/zero of=/mnt/t1/f0 bs=1M count=64 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 193M 32.0M 161M 17% /mnt/t0 tmpfs 225M 64.0M 161M 29% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 # mount_tmpfs -s 128M tmpfs /mnt/t3 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 64.5M 32.0M 32.5M 50% /mnt/t0 tmpfs 96.5M 64.0M 32.5M 67% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 tmpfs 128M 4.0K 128M 1% /mnt/t3 # dd if=/dev/zero of=/mnt/t1/f1 bs=1M count=64 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 129M 32.0M 96.5M 25% /mnt/t0 tmpfs 225M 128M 96.5M 58% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 # mount_tmpfs -s 128M tmpfs /mnt/t3 mount_tmpfs: tmpfs on /mnt/t3: Invalid argument # mount_tmpfs -s 96M tmpfs /mnt/t3 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 32.5M 32.0M 560K 99% /mnt/t0 tmpfs 129M 128M 560K 100% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 tmpfs 96.0M 4.0K 96.0M 1% /mnt/t3 # mount_tmpfs tmpfs /mnt/t4 # mount_tmpfs tmpfs /mnt/t5 # mount_tmpfs tmpfs /mnt/t6 # mount_tmpfs tmpfs /mnt/t7 # mount_tmpfs tmpfs /mnt/t8 # df -t tmpfs -h Filesystem Size Used Avail Capacity Mounted on tmpfs 32.5M 32.0M 560K 99% /mnt/t0 tmpfs 129M 128M 560K 100% /mnt/t1 tmpfs 720M 128M 592M 18% /mnt/t2 tmpfs 96.0M 4.0K 96.0M 1% /mnt/t3 tmpfs 560K 0B 560K 0% /mnt/t4 tmpfs 560K 0B 560K 0% /mnt/t5 tmpfs 560K 0B 560K 0% /mnt/t6 tmpfs 560K 0B 560K 0% /mnt/t7 tmpfs 560K 0B 560K 0% /mnt/t8

sys/tmpfs/tmpfs_mem.c

/*	$OpenBSD: tmpfs_mem.c,v 1.11 2025/11/21 09:49:33 mvs Exp $	*/
/*	$NetBSD: tmpfs_mem.c,v 1.4 2011/05/24 01:09:47 rmind Exp $	*/

/*
 * Copyright (c) 2010, 2011 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/param.h>
#include <sys/namei.h>
#include <sys/pool.h>
#include <sys/vnode.h>
#include <sys/malloc.h>

#include <tmpfs/tmpfs.h>

extern struct pool	tmpfs_dirent_pool;
extern struct pool	tmpfs_node_pool;

uint64_t tmpfs_bytes_limit;
uint64_t tmpfs_bytes_used = 0;

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

	rw_init(&mp->tm_acc_lock, "tacclk");
	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); */
}

uint64_t
tmpfs_pages_total(struct tmpfs_mount *mp)
{
	uint64_t total;

	if (mp->tm_mem_limit)
		total = mp->tm_mem_limit;
	else {
		total = tmpfs_bytes_limit - tmpfs_bytes_used +
		    mp->tm_bytes_used;
	}

	return (total >> PAGE_SHIFT);
}

uint64_t
tmpfs_pages_avail(struct tmpfs_mount *mp)
{
	uint64_t free;

	rw_assert_anylock(&mp->tm_acc_lock);

	if (mp->tm_mem_limit)
		free = mp->tm_mem_limit - mp->tm_bytes_used;
	else
		free = tmpfs_bytes_limit - tmpfs_bytes_used;

	return (free >> PAGE_SHIFT);
}

int
tmpfs_mem_incr(struct tmpfs_mount *mp, size_t sz)
{
	int ret = 0;

	rw_enter_write(&mp->tm_acc_lock);

	if (mp->tm_mem_limit) {
		if ((mp->tm_mem_limit - mp->tm_bytes_used) < sz)
			goto out;
	} else {
		if ((tmpfs_bytes_limit - tmpfs_bytes_used) < sz)
			goto out;
		tmpfs_bytes_used += sz;
	}

	mp->tm_bytes_used += sz;

	ret = 1;
out:
	rw_exit_write(&mp->tm_acc_lock);

	return ret;
}

void
tmpfs_mem_decr(struct tmpfs_mount *mp, size_t sz)
{
	rw_enter_write(&mp->tm_acc_lock);
	KASSERT(mp->tm_bytes_used >= sz);
	if (mp->tm_mem_limit == 0)
		tmpfs_bytes_used -= sz;
	mp->tm_bytes_used -= sz;
	rw_exit_write(&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_ZERO|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)
{

	mp->tm_nodes_cnt++;
	if (mp->tm_nodes_cnt > mp->tm_nodes_max) {
		mp->tm_nodes_cnt--;
		return NULL;
	}
	if (!tmpfs_mem_incr(mp, sizeof(struct tmpfs_node))) {
		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)
{

	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)
#define	roundup2(x, y)	(((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */

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 malloc(sz, M_TEMP, M_WAITOK); /* XXX */
}

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);
	free(str, M_TEMP, sz);
}

int
tmpfs_strname_neqlen(struct componentname *fcnp, struct componentname *tcnp)
{
	const size_t fln = roundup2(fcnp->cn_namelen, TMPFS_NAME_QUANTUM);
	const size_t tln = roundup2(tcnp->cn_namelen, TMPFS_NAME_QUANTUM);

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

IABSD.fr/src/sys/tmpfs/tmpfs_mem.c

Commit

IABSD.fr/src /sys/tmpfs/tmpfs_mem.c