lvm2/lib/mm/memlock.c

/*
 * Copyright (C) 2003-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
 *
 * This file is part of LVM2.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "lib.h"
#include "memlock.h"
#include "defaults.h"
#include "config.h"
#include "toolcontext.h"

#include <limits.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <sys/resource.h>

#ifndef DEVMAPPER_SUPPORT

void memlock_inc(struct cmd_context *cmd)
{
	return;
}
void memlock_dec(struct cmd_context *cmd)
{
	return;
}
int memlock(void)
{
	return 0;
}
void memlock_init(struct cmd_context *cmd)
{
	return;
}

#else				/* DEVMAPPER_SUPPORT */

static size_t _size_stack;
static size_t _size_malloc_tmp;
static size_t _size_malloc = 2000000;

static void *_malloc_mem = NULL;
static int _memlock_count = 0;
static int _memlock_count_daemon = 0;
static int _priority;
static int _default_priority;

/* list of maps, that are unconditionaly ignored */
static const char * const _ignore_maps[] = {
    "[vdso]",
    "[vsyscall]",
};

/* default blacklist for maps */
static const char * const _blacklist_maps[] = {
    "locale/locale-archive",
    "gconv/gconv-modules.cache",
    "/libreadline.so.",	/* not using readline during mlock */
    "/libncurses.so.",	/* not using readline during mlock */
    "/libdl-",		/* not using dlopen,dlsym during mlock */
    /* "/libdevmapper-event.so" */
};

typedef enum { LVM_MLOCK, LVM_MUNLOCK } lvmlock_t;

struct maps_stats {
	size_t r_size;
	size_t w_size;
	size_t x_size;
};
static struct maps_stats _ms; /* statistic for maps locking */

static void _touch_memory(void *mem, size_t size)
{
	size_t pagesize = lvm_getpagesize();
	void *pos = mem;
	void *end = mem + size - sizeof(long);

	while (pos < end) {
		*(long *) pos = 1;
		pos += pagesize;
	}
}

static void _allocate_memory(void)
{
	void *stack_mem, *temp_malloc_mem;

	if ((stack_mem = alloca(_size_stack)))
		_touch_memory(stack_mem, _size_stack);

	if ((temp_malloc_mem = malloc(_size_malloc_tmp)))
		_touch_memory(temp_malloc_mem, _size_malloc_tmp);

	if ((_malloc_mem = malloc(_size_malloc)))
		_touch_memory(_malloc_mem, _size_malloc);

	free(temp_malloc_mem);
}

static void _release_memory(void)
{
	free(_malloc_mem);
}

/*
 * mlock/munlock memory areas from /proc/self/maps
 * format described in kernel/Documentation/filesystem/proc.txt
 */
static int _maps_line(struct cmd_context *cmd, lvmlock_t lock,
		      const char* line, struct maps_stats* ms)
{
	const struct config_node *cn;
	struct config_value *cv;
	long from, to;
	int pos, i;
	char fr, fw, fx, fp;
	size_t sz;

	if (sscanf(line, "%lx-%lx %c%c%c%c%n",
		   &from, &to, &fr, &fw, &fx, &fp, &pos) != 6) {
		log_error("Failed to parse maps line: %s", line);
		return 0;
	}

	/* skip  ---p,  select with r,w,x */
	if (fr != 'r')
		return 1;

	/* always ignored areas */
	for (i = 0; i < sizeof(_ignore_maps) / sizeof(_ignore_maps[0]); ++i)
		if (strstr(line + pos, _ignore_maps[i]))
			return 1;

	sz = to - from;
	log_debug("%s %10ldKiB %12lx - %12lx %c%c%c%c %s",
		  (lock == LVM_MLOCK) ? "Mlock" : "Munlock",
		  ((long)sz + 1023) / 1024, from, to, fr, fw, fx, fp, line + pos);

	if (!(cn = find_config_tree_node(cmd, "activation/mlock_filter"))) {
		/* If no blacklist configured, use an internal set */
		for (i = 0; i < sizeof(_blacklist_maps) / sizeof(_blacklist_maps[0]); ++i)
			if (strstr(line + pos, _blacklist_maps[i])) {
				log_debug("Filtered by string '%s' (%s)",
					  _blacklist_maps[i], line);
				return 1;
			}
	} else {
		for (cv = cn->v; cv; cv = cv->next) {
			if ((cv->type != CFG_STRING) || !cv->v.str[0]) {
				log_error("Ignoring invalid string in config file "
					  "activation/mlock_filter");
				continue;
			}
			if (strstr(line + pos, cv->v.str)) {
				log_debug("Filtered by string '%s' (%s)",
					  cv->v.str, line);
				return 1;
			}
		}
	}

	if (fr == 'r')
		ms->r_size += sz;
	if (fw == 'w')
		ms->w_size += sz;
	if (fx == 'x')
		ms->x_size += sz;

	if (lock == LVM_MLOCK) {
		if (mlock((const void*)from, sz) < 0) {
			log_sys_error("mlock", line);
			return 0;
		}
	} else {
		if (munlock((const void*)from, sz) < 0) {
			log_sys_error("munlock", line);
			return 0;
		}
	}

	return 1;
}

static int _memlock_maps(struct cmd_context *cmd, lvmlock_t lock, struct maps_stats* ms)
{
	static const char selfmaps[] = "/self/maps";
	char *procselfmaps = alloca(strlen(cmd->proc_dir) + sizeof(selfmaps));
	FILE *fh;
	char *line = NULL;
	size_t len;
	ssize_t r;
	int ret = 0;

	if (find_config_tree_bool(cmd, "activation/use_mlockall",
				  DEFAULT_USE_MLOCKALL)) {
#ifdef MCL_CURRENT
		if (lock == LVM_MLOCK) {
			if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
				log_sys_error("mlockall", "");
				return 0;
			}
		} else {
			if (munlockall()) {
				log_sys_error("munlockall", "");
				return 0;
			}
		}
		return 1;
#else
		return 0;
#endif
	}

	strcpy(procselfmaps, cmd->proc_dir);
	strcat(procselfmaps, selfmaps);

	if ((fh = fopen(procselfmaps, "r")) == NULL) {
		log_sys_error("fopen", procselfmaps);
		return 0;
	}

	while ((r = getline(&line, &len, fh)) != -1) {
		line[r > 0 ? r - 1 : 0] = '\0'; /* remove \n */
		if (!(ret = _maps_line(cmd, lock, line, ms)))
			break;
	}

	free(line);
	fclose(fh);

	log_debug("Mapped sizes:  r=%ld,  w=%ld,  x=%ld",
		  (long)ms->r_size,  (long)ms->w_size, (long)ms->x_size);

	return ret;
}

/* Stop memory getting swapped out */
static void _lock_mem(struct cmd_context *cmd)
{
	_allocate_memory();

	memset(&_ms, 0, sizeof(_ms));
	if (_memlock_maps(cmd, LVM_MLOCK, &_ms))
		log_very_verbose("Locking memory");

	errno = 0;
	if (((_priority = getpriority(PRIO_PROCESS, 0)) == -1) && errno)
		log_sys_error("getpriority", "");
	else
		if (setpriority(PRIO_PROCESS, 0, _default_priority))
			log_error("setpriority %d failed: %s",
				  _default_priority, strerror(errno));
}

static void _unlock_mem(struct cmd_context *cmd)
{
	struct maps_stats ums = { 0 };

	if (_memlock_maps(cmd, LVM_MUNLOCK, &ums))
		log_very_verbose("Unlocking memory");

	if (memcmp(&_ms, &ums, sizeof(ums)))
		log_error(INTERNAL_ERROR "Maps size mismatch (%ld,%ld,%ld) != (%ld,%ld,%ld)",
			  (long)_ms.r_size, (long)_ms.w_size, (long)_ms.x_size,
			  (long)ums.r_size, (long)ums.w_size, (long)ums.x_size);

	_release_memory();
	if (setpriority(PRIO_PROCESS, 0, _priority))
		log_error("setpriority %u failed: %s", _priority,
			  strerror(errno));
}

static void _lock_mem_if_needed(struct cmd_context *cmd) {
	if ((_memlock_count + _memlock_count_daemon) == 1)
		_lock_mem(cmd);
}

static void _unlock_mem_if_possible(struct cmd_context *cmd) {
	if ((_memlock_count + _memlock_count_daemon) == 0)
		_unlock_mem(cmd);
}

void memlock_inc(struct cmd_context *cmd)
{
	++_memlock_count;
	_lock_mem_if_needed(cmd);
	log_debug("memlock_count inc to %d", _memlock_count);
}

void memlock_dec(struct cmd_context *cmd)
{
	if (!_memlock_count)
		log_error(INTERNAL_ERROR "_memlock_count has dropped below 0.");
	--_memlock_count;
	_unlock_mem_if_possible(cmd);
	log_debug("memlock_count dec to %d", _memlock_count);
}

/*
 * The memlock_*_daemon functions will force the mlockall() call that we need
 * to stay in memory, but they will have no effect on device scans (unlike
 * normal memlock_inc and memlock_dec). Memory is kept locked as long as either
 * of memlock or memlock_daemon is in effect.
 */

void memlock_inc_daemon(struct cmd_context *cmd)
{
	++_memlock_count_daemon;
	_lock_mem_if_needed(cmd);
	log_debug("memlock_count_daemon inc to %d", _memlock_count_daemon);
}

void memlock_dec_daemon(struct cmd_context *cmd)
{
	if (!_memlock_count_daemon)
		log_error(INTERNAL_ERROR "_memlock_count_daemon has dropped below 0.");
	--_memlock_count_daemon;
	_unlock_mem_if_possible(cmd);
	log_debug("memlock_count_daemon dec to %d", _memlock_count_daemon);
}

/*
 * This disregards the daemon (dmeventd) locks, since we use memlock() to check
 * whether it is safe to run a device scan, which would normally coincide with
 * !memlock() -- but the daemon global memory lock breaks this assumption, so
 * we do not take those into account here.
 */
int memlock(void)
{
	return _memlock_count;
}

void memlock_init(struct cmd_context *cmd)
{
	_size_stack = find_config_tree_int(cmd,
				      "activation/reserved_stack",
				      DEFAULT_RESERVED_STACK) * 1024;
	_size_malloc_tmp = find_config_tree_int(cmd,
					   "activation/reserved_memory",
					   DEFAULT_RESERVED_MEMORY) * 1024;
	_default_priority = find_config_tree_int(cmd,
					    "activation/process_priority",
					    DEFAULT_PROCESS_PRIORITY);
}

#endif