lvm2/lib/filters/filter.c

/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004 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 General Public License v.2.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "lib.h"
#include "dev-cache.h"
#include "filter.h"
#include "lvm-string.h"
#include "config.h"
#include "metadata.h"

#include <dirent.h>
#include <unistd.h>
#include <ctype.h>
#include <fcntl.h>
#include <limits.h>

#define NUMBER_OF_MAJORS 4096

/* FIXME Make this sparse */
/* 0 means LVM won't use this major number. */
static int _max_partitions_by_major[NUMBER_OF_MAJORS];

typedef struct {
	const char *name;
	const int max_partitions;
} device_info_t;

static int _md_major = -1;

int md_major(void)
{
	return _md_major;
}

/*
 * Devices are only checked for partition tables if their minor number
 * is a multiple of the number corresponding to their type below
 * i.e. this gives the granularity of whole-device minor numbers.
 * Use 1 if the device is not partitionable.
 *
 * The list can be supplemented with devices/types in the config file.
 */
static const device_info_t device_info[] = {
	{"ide", 64},		/* IDE disk */
	{"sd", 16},		/* SCSI disk */
	{"md", 1},		/* Multiple Disk driver (SoftRAID) */
	{"loop", 1},		/* Loop device */
	{"dasd", 4},		/* DASD disk (IBM S/390, zSeries) */
	{"dac960", 8},		/* DAC960 */
	{"nbd", 16},		/* Network Block Device */
	{"ida", 16},		/* Compaq SMART2 */
	{"cciss", 16},		/* Compaq CCISS array */
	{"ubd", 16},		/* User-mode virtual block device */
	{"ataraid", 16},	/* ATA Raid */
	{"drbd", 16},		/* Distributed Replicated Block Device */
	{"emcpower", 16},	/* EMC Powerpath */
	{"power2", 16},		/* EMC Powerpath */
	{"i2o_block", 16},	/* i2o Block Disk */
	{"iseries/vd", 8},	/* iSeries disks */
	{"gnbd", 1},		/* Network block device */
	{"ramdisk", 1},		/* RAM disk */
	{NULL, 0}
};

static int _passes_lvm_type_device_filter(struct dev_filter *f,
					  struct device *dev)
{
	const char *name = dev_name(dev);
	int ret = 0;
	uint64_t size;

	/* Is this a recognised device type? */
	if (!_max_partitions_by_major[MAJOR(dev->dev)]) {
		log_debug("%s: Skipping: Unrecognised LVM device type %"
			  PRIu64, name, (uint64_t) MAJOR(dev->dev));
		return 0;
	}

	/* Check it's accessible */
	if (!dev_open_flags(dev, O_RDONLY, 0, 1)) {
		log_debug("%s: Skipping: open failed", name);
		return 0;
	}
	
	/* Check it's not too small */
	if (!dev_get_size(dev, &size)) {
		log_debug("%s: Skipping: dev_get_size failed", name);
		goto out;
	}

	if (size < PV_MIN_SIZE) {
		log_debug("%s: Skipping: Too small to hold a PV", name);
		goto out;
	}

	if (is_partitioned_dev(dev)) {
		log_debug("%s: Skipping: Partition table signature found",
			  name);
		goto out;
	}

	ret = 1;

      out:
	dev_close(dev);

	return ret;
}

static int _scan_proc_dev(const char *proc, const struct config_node *cn)
{
	char line[80];
	char proc_devices[PATH_MAX];
	FILE *pd = NULL;
	int i, j = 0;
	int line_maj = 0;
	int blocksection = 0;
	size_t dev_len = 0;
	struct config_value *cv;
	char *name;


	if (!*proc) {
		log_verbose("No proc filesystem found: using all block device "
			    "types");
		for (i = 0; i < NUMBER_OF_MAJORS; i++)
			_max_partitions_by_major[i] = 1;
		return 1;
	}

	/* All types unrecognised initially */
	memset(_max_partitions_by_major, 0, sizeof(int) * NUMBER_OF_MAJORS);

	if (lvm_snprintf(proc_devices, sizeof(proc_devices),
			 "%s/devices", proc) < 0) {
		log_error("Failed to create /proc/devices string");
		return 0;
	}

	if (!(pd = fopen(proc_devices, "r"))) {
		log_sys_error("fopen", proc_devices);
		return 0;
	}

	while (fgets(line, 80, pd) != NULL) {
		i = 0;
		while (line[i] == ' ' && line[i] != '\0')
			i++;

		/* If it's not a number it may be name of section */
		line_maj = atoi(((char *) (line + i)));
		if (!line_maj) {
			blocksection = (line[i] == 'B') ? 1 : 0;
			continue;
		}

		/* We only want block devices ... */
		if (!blocksection)
			continue;

		/* Find the start of the device major name */
		while (line[i] != ' ' && line[i] != '\0')
			i++;
		while (line[i] == ' ' && line[i] != '\0')
			i++;

		/* Look for md device */
		if (!strncmp("md", line + i, 2) && isspace(*(line + i + 2)))
			_md_major = line_maj;

		/* Go through the valid device names and if there is a
		   match store max number of partitions */
		for (j = 0; device_info[j].name != NULL; j++) {

			dev_len = strlen(device_info[j].name);
			if (dev_len <= strlen(line + i) &&
			    !strncmp(device_info[j].name, line + i, dev_len) &&
			    (line_maj < NUMBER_OF_MAJORS)) {
				_max_partitions_by_major[line_maj] =
				    device_info[j].max_partitions;
				break;
			}
		}

		if (!cn)
			continue;

		/* Check devices/types for local variations */
		for (cv = cn->v; cv; cv = cv->next) {
			if (cv->type != CFG_STRING) {
				log_error("Expecting string in devices/types "
					  "in config file");
				return 0;
			}
			dev_len = strlen(cv->v.str);
			name = cv->v.str;
			cv = cv->next;
			if (!cv || cv->type != CFG_INT) {
				log_error("Max partition count missing for %s "
					  "in devices/types in config file",
					  name);
				return 0;
			}
			if (!cv->v.i) {
				log_error("Zero partition count invalid for "
					  "%s in devices/types in config file",
					  name);
				return 0;
			}
			if (dev_len <= strlen(line + i) &&
			    !strncmp(name, line + i, dev_len) &&
			    (line_maj < NUMBER_OF_MAJORS)) {
				_max_partitions_by_major[line_maj] = cv->v.i;
				break;
			}
		}
	}
	fclose(pd);
	return 1;
}

int max_partitions(int major)
{
	return _max_partitions_by_major[major];
}

struct dev_filter *lvm_type_filter_create(const char *proc,
					  const struct config_node *cn)
{
	struct dev_filter *f;

	if (!(f = dbg_malloc(sizeof(struct dev_filter)))) {
		log_error("LVM type filter allocation failed");
		return NULL;
	}

	f->passes_filter = _passes_lvm_type_device_filter;
	f->destroy = lvm_type_filter_destroy;
	f->private = NULL;

	if (!_scan_proc_dev(proc, cn)) {
		stack;
		return NULL;
	}

	return f;
}

void lvm_type_filter_destroy(struct dev_filter *f)
{
	dbg_free(f);
	return;
}