init/do_mounts_dm.c

/* do_mounts_dm.c
 * Copyright (C) 2010 The Chromium OS Authors <chromium-os-dev@chromium.org>
 *                    All Rights Reserved.
 * Based on do_mounts_md.c
 *
 * This file is released under the GPL.
 */
#include <linux/async.h>
#include <linux/ctype.h>
#include <linux/device-mapper.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/delay.h>

#include "do_mounts.h"

#define DM_MAX_DEVICES 256
#define DM_MAX_TARGETS 256
#define DM_MAX_NAME 32
#define DM_MAX_UUID 129
#define DM_NO_UUID "none"

#define DM_MSG_PREFIX "init"

/* Separators used for parsing the dm= argument. */
#define DM_FIELD_SEP " "
#define DM_LINE_SEP ","
#define DM_ANY_SEP DM_FIELD_SEP DM_LINE_SEP

/*
 * When the device-mapper and any targets are compiled into the kernel
 * (not a module), one or more device-mappers may be created and used
 * as the root device at boot time with the parameters given with the
 * boot line dm=...
 *
 * Multiple device-mappers can be stacked specifing the number of
 * devices. A device can have multiple targets if the the number of
 * targets is specified.
 *
 * TODO(taysom:defect 32847)
 * In the future, the <num> field will be mandatory.
 *
 * <device>        ::= [<num>] <device-mapper>+
 * <device-mapper> ::= <head> "," <target>+
 * <head>          ::= <name> <uuid> <mode> [<num>]
 * <target>        ::= <start> <length> <type> <options> ","
 * <mode>          ::= "ro" | "rw"
 * <uuid>          ::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | "none"
 * <type>          ::= "verity" | "bootcache" | ...
 *
 * Example:
 * 2 vboot none ro 1,
 *     0 1768000 bootcache
 *       device=aa55b119-2a47-8c45-946a-5ac57765011f+1
 *       signature=76e9be054b15884a9fa85973e9cb274c93afadb6
 *       cache_start=1768000 max_blocks=100000 size_limit=23 max_trace=20000,
 *   vroot none ro 1,
 *     0 1740800 verity payload=254:0 hashtree=254:0 hashstart=1740800 alg=sha1
 *       root_hexdigest=76e9be054b15884a9fa85973e9cb274c93afadb6
 *       salt=5b3549d54d6c7a3837b9b81ed72e49463a64c03680c47835bef94d768e5646fe
 *
 * Notes:
 *  1. uuid is a label for the device and we set it to "none".
 *  2. The <num> field will be optional initially and assumed to be 1.
 *     Once all the scripts that set these fields have been set, it will
 *     be made mandatory.
 */

struct dm_setup_target {
	sector_t begin;
	sector_t length;
	char *type;
	char *params;
	/* simple singly linked list */
	struct dm_setup_target *next;
};

struct dm_device {
	int minor;
	int ro;
	char name[DM_MAX_NAME];
	char uuid[DM_MAX_UUID];
	unsigned long num_targets;
	struct dm_setup_target *target;
	int target_count;
	struct dm_device *next;
};

struct dm_option {
	char *start;
	char *next;
	size_t len;
	char delim;
};

static struct {
	unsigned long num_devices;
	char *str;
} dm_setup_args __initdata;

static __initdata int dm_early_setup;

static int __init get_dm_option(struct dm_option *opt, const char *accept)
{
	char *str = opt->next;
	char *endp;

	if (!str)
		return 0;

	str = skip_spaces(str);
	opt->start = str;
	endp = strpbrk(str, accept);
	if (!endp) {  /* act like strchrnul */
		opt->len = strlen(str);
		endp = str + opt->len;
	} else {
		opt->len = endp - str;
	}
	opt->delim = *endp;
	if (*endp == 0) {
		/* Don't advance past the nul. */
		opt->next = endp;
	} else {
		opt->next = endp + 1;
	}
	return opt->len != 0;
}

static int __init dm_setup_cleanup(struct dm_device *devices)
{
	struct dm_device *dev = devices;

	while (dev) {
		struct dm_device *old_dev = dev;
		struct dm_setup_target *target = dev->target;
		while (target) {
			struct dm_setup_target *old_target = target;
			kfree(target->type);
			kfree(target->params);
			target = target->next;
			kfree(old_target);
			dev->target_count--;
		}
		BUG_ON(dev->target_count);
		dev = dev->next;
		kfree(old_dev);
	}
	return 0;
}

static char * __init dm_parse_device(struct dm_device *dev, char *str)
{
	struct dm_option opt;
	size_t len;

	/* Grab the logical name of the device to be exported to udev */
	opt.next = str;
	if (!get_dm_option(&opt, DM_FIELD_SEP)) {
		DMERR("failed to parse device name");
		goto parse_fail;
	}
	len = min(opt.len + 1, sizeof(dev->name));
	strlcpy(dev->name, opt.start, len);  /* includes nul */

	/* Grab the UUID value or "none" */
	if (!get_dm_option(&opt, DM_FIELD_SEP)) {
		DMERR("failed to parse device uuid");
		goto parse_fail;
	}
	len = min(opt.len + 1, sizeof(dev->uuid));
	strlcpy(dev->uuid, opt.start, len);

	/* Determine if the table/device will be read only or read-write */
	get_dm_option(&opt, DM_ANY_SEP);
	if (!strncmp("ro", opt.start, opt.len)) {
		dev->ro = 1;
	} else if (!strncmp("rw", opt.start, opt.len)) {
		dev->ro = 0;
	} else {
		DMERR("failed to parse table mode");
		goto parse_fail;
	}

	/* Optional number field */
	/* XXX: The <num> field will be mandatory in the next round */
	if (opt.delim == DM_FIELD_SEP[0]) {
		if (!get_dm_option(&opt, DM_LINE_SEP))
			return NULL;
		dev->num_targets = simple_strtoul(opt.start, NULL, 10);
	} else {
		dev->num_targets = 1;
	}
	if (dev->num_targets > DM_MAX_TARGETS) {
		DMERR("too many targets %lu > %d",
			dev->num_targets, DM_MAX_TARGETS);
	}
	return opt.next;

parse_fail:
	return NULL;
}

static char * __init dm_parse_targets(struct dm_device *dev, char *str)
{
	struct dm_option opt;
	struct dm_setup_target **target = &dev->target;
	unsigned long num_targets = dev->num_targets;
	unsigned long i;

	/* Targets are defined as per the table format but with a
	 * comma as a newline separator. */
	opt.next = str;
	for (i = 0; i < num_targets; i++) {
		*target = kzalloc(sizeof(struct dm_setup_target), GFP_KERNEL);
		if (!*target) {
			DMERR("failed to allocate memory for target %s<%ld>",
				dev->name, i);
			goto parse_fail;
		}
		dev->target_count++;

		if (!get_dm_option(&opt, DM_FIELD_SEP)) {
			DMERR("failed to parse starting sector"
				" for target %s<%ld>", dev->name, i);
			goto parse_fail;
		}
		(*target)->begin = simple_strtoull(opt.start, NULL, 10);

		if (!get_dm_option(&opt, DM_FIELD_SEP)) {
			DMERR("failed to parse length for target %s<%ld>",
				dev->name, i);
			goto parse_fail;
		}
		(*target)->length = simple_strtoull(opt.start, NULL, 10);

		if (get_dm_option(&opt, DM_FIELD_SEP))
			(*target)->type = kstrndup(opt.start, opt.len,
							GFP_KERNEL);
		if (!((*target)->type)) {
			DMERR("failed to parse type for target %s<%ld>",
				dev->name, i);
			goto parse_fail;
		}
		if (get_dm_option(&opt, DM_LINE_SEP))
			(*target)->params = kstrndup(opt.start, opt.len,
							GFP_KERNEL);
		if (!((*target)->params)) {
			DMERR("failed to parse params for target %s<%ld>",
				dev->name, i);
			goto parse_fail;
		}
		target = &((*target)->next);
	}
	DMDEBUG("parsed %d targets", dev->target_count);

	return opt.next;

parse_fail:
	return NULL;
}

static struct dm_device * __init dm_parse_args(void)
{
	struct dm_device *devices = NULL;
	struct dm_device **tail = &devices;
	struct dm_device *dev;
	char *str = dm_setup_args.str;
	unsigned long num_devices = dm_setup_args.num_devices;
	unsigned long i;

	if (!str)
		return NULL;
	for (i = 0; i < num_devices; i++) {
		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
		if (!dev) {
			DMERR("failed to allocated memory for dev");
			goto error;
		}
		*tail = dev;
		tail = &dev->next;
		/*
		 * devices are given minor numbers 0 - n-1
		 * in the order they are found in the arg
		 * string.
		 */
		dev->minor = i;
		str = dm_parse_device(dev, str);
		if (!str)	/* NULL indicates error in parsing, bail */
			goto error;

		str = dm_parse_targets(dev, str);
		if (!str)
			goto error;
	}
	return devices;
error:
	dm_setup_cleanup(devices);
	return NULL;
}

/*
 * Parse the command-line parameters given our kernel, but do not
 * actually try to invoke the DM device now; that is handled by
 * dm_setup_drives after the low-level disk drivers have initialised.
 * dm format is described at the top of the file.
 *
 * Because dm minor numbers are assigned in assending order starting with 0,
 * You can assume the first device is /dev/dm-0, the next device is /dev/dm-1,
 * and so forth.
 */
static int __init dm_setup(char *str)
{
	struct dm_option opt;
	unsigned long num_devices;

	if (!str) {
		DMDEBUG("str is NULL");
		goto parse_fail;
	}
	opt.next = str;
	if (!get_dm_option(&opt, DM_FIELD_SEP))
		goto parse_fail;
	if (isdigit(opt.start[0])) {	/* XXX: Optional number field */
		num_devices = simple_strtoul(opt.start, NULL, 10);
		str = opt.next;
	} else {
		num_devices = 1;
		/* Don't advance str */
	}
	if (num_devices > DM_MAX_DEVICES) {
		DMDEBUG("too many devices %lu > %d",
			num_devices, DM_MAX_DEVICES);
	}
	dm_setup_args.str = str;
	dm_setup_args.num_devices = num_devices;
	DMINFO("will configure %lu devices", num_devices);
	dm_early_setup = 1;
	return 1;

parse_fail:
	DMWARN("Invalid arguments supplied to dm=.");
	return 0;
}

static void __init dm_setup_drives(void)
{
	struct mapped_device *md = NULL;
	struct dm_table *table = NULL;
	struct dm_setup_target *target;
	struct dm_device *dev;
	char *uuid = NULL;
	fmode_t fmode = FMODE_READ;
	struct dm_device *devices;

	devices = dm_parse_args();

	for (dev = devices; dev; dev = dev->next) {
		if (dm_create(dev->minor, &md)) {
			DMDEBUG("failed to create the device");
			goto dm_create_fail;
		}
		DMDEBUG("created device '%s'", dm_device_name(md));

		/*
		 * In addition to flagging the table below, the disk must be
		 * set explicitly ro/rw.
		 */
		set_disk_ro(dm_disk(md), dev->ro);

		if (!dev->ro)
			fmode |= FMODE_WRITE;
		if (dm_table_create(&table, fmode, dev->target_count, md)) {
			DMDEBUG("failed to create the table");
			goto dm_table_create_fail;
		}

		dm_lock_md_type(md);

		for (target = dev->target; target; target = target->next) {
			DMINFO("adding target '%llu %llu %s %s'",
			       (unsigned long long) target->begin,
			       (unsigned long long) target->length,
			       target->type, target->params);
			if (dm_table_add_target(table, target->type,
						target->begin,
						target->length,
						target->params)) {
				DMDEBUG("failed to add the target"
					" to the table");
				goto add_target_fail;
			}
		}
		if (dm_table_complete(table)) {
			DMDEBUG("failed to complete the table");
			goto table_complete_fail;
		}

		/* Suspend the device so that we can bind it to the table. */
		if (dm_suspend(md, 0)) {
			DMDEBUG("failed to suspend the device pre-bind");
			goto suspend_fail;
		}

		/* Initial table load: acquire type of table. */
		dm_set_md_type(md, dm_table_get_type(table));

		/* Setup md->queue to reflect md's type. */
		if (dm_setup_md_queue(md, table)) {
			DMWARN("unable to set up device queue for new table.");
			goto setup_md_queue_fail;
		}

		/*
		 * Bind the table to the device. This is the only way
		 * to associate md->map with the table and set the disk
		 * capacity directly.
		 */
		if (dm_swap_table(md, table)) {  /* should return NULL. */
			DMDEBUG("failed to bind the device to the table");
			goto table_bind_fail;
		}

		/* Finally, resume and the device should be ready. */
		if (dm_resume(md)) {
			DMDEBUG("failed to resume the device");
			goto resume_fail;
		}

		/* Export the dm device via the ioctl interface */
		if (!strcmp(DM_NO_UUID, dev->uuid))
			uuid = NULL;
		if (dm_ioctl_export(md, dev->name, uuid)) {
			DMDEBUG("failed to export device with given"
				" name and uuid");
			goto export_fail;
		}

		dm_unlock_md_type(md);

		DMINFO("dm-%d is ready", dev->minor);
	}
	dm_setup_cleanup(devices);
	return;

export_fail:
resume_fail:
table_bind_fail:
setup_md_queue_fail:
suspend_fail:
table_complete_fail:
add_target_fail:
	dm_unlock_md_type(md);
dm_table_create_fail:
	dm_put(md);
dm_create_fail:
	DMWARN("starting dm-%d (%s) failed",
	       dev->minor, dev->name);
	dm_setup_cleanup(devices);
}

__setup("dm=", dm_setup);

void __init dm_run_setup(void)
{
	if (!dm_early_setup)
		return;
	DMINFO("attempting early device configuration.");
	dm_setup_drives();
}