dm-ioctl.c

Linux Kernel 2.6.9 for OMAP1710

{
	int r = 0;
	struct mapped_device *md;

	md = find_device(param);
	if (!md)
		return -ENXIO;

	if (!dm_suspended(md))
		r = dm_suspend(md);

	if (!r)
		r = __dev_status(md, param);

	dm_put(md);
	return r;
}

static int do_resume(struct dm_ioctl *param)
{
	int r = 0;
	struct hash_cell *hc;
	struct mapped_device *md;
	struct dm_table *new_map;

	down_write(&_hash_lock);

	hc = __find_device_hash_cell(param);
	if (!hc) {
		DMWARN("device doesn't appear to be in the dev hash table.");
		up_write(&_hash_lock);
		return -ENXIO;
	}

	md = hc->md;
	dm_get(md);

	new_map = hc->new_map;
	hc->new_map = NULL;
	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;

	up_write(&_hash_lock);

	/* Do we need to load a new map ? */
	if (new_map) {
		/* Suspend if it isn't already suspended */
		if (!dm_suspended(md))
			dm_suspend(md);

		r = dm_swap_table(md, new_map);
		if (r) {
			dm_put(md);
			dm_table_put(new_map);
			return r;
		}

		if (dm_table_get_mode(new_map) & FMODE_WRITE)
			set_disk_ro(dm_disk(md), 0);
		else
			set_disk_ro(dm_disk(md), 1);

		dm_table_put(new_map);
	}

	if (dm_suspended(md))
		r = dm_resume(md);

	if (!r)
		r = __dev_status(md, param);

	dm_put(md);
	return r;
}

/*
 * Set or unset the suspension state of a device.
 * If the device already is in the requested state we just return its status.
 */
static int dev_suspend(struct dm_ioctl *param, size_t param_size)
{
	if (param->flags & DM_SUSPEND_FLAG)
		return do_suspend(param);

	return do_resume(param);
}

/*
 * Copies device info back to user space, used by
 * the create and info ioctls.
 */
static int dev_status(struct dm_ioctl *param, size_t param_size)
{
	int r;
	struct mapped_device *md;

	md = find_device(param);
	if (!md)
		return -ENXIO;

	r = __dev_status(md, param);
	dm_put(md);
	return r;
}

/*
 * Build up the status struct for each target
 */
static void retrieve_status(struct dm_table *table,
			    struct dm_ioctl *param, size_t param_size)
{
	unsigned int i, num_targets;
	struct dm_target_spec *spec;
	char *outbuf, *outptr;
	status_type_t type;
	size_t remaining, len, used = 0;

	outptr = outbuf = get_result_buffer(param, param_size, &len);

	if (param->flags & DM_STATUS_TABLE_FLAG)
		type = STATUSTYPE_TABLE;
	else
		type = STATUSTYPE_INFO;

	/* Get all the target info */
	num_targets = dm_table_get_num_targets(table);
	for (i = 0; i < num_targets; i++) {
		struct dm_target *ti = dm_table_get_target(table, i);

		remaining = len - (outptr - outbuf);
		if (remaining <= sizeof(struct dm_target_spec)) {
			param->flags |= DM_BUFFER_FULL_FLAG;
			break;
		}

		spec = (struct dm_target_spec *) outptr;

		spec->status = 0;
		spec->sector_start = ti->begin;
		spec->length = ti->len;
		strncpy(spec->target_type, ti->type->name,
			sizeof(spec->target_type));

		outptr += sizeof(struct dm_target_spec);
		remaining = len - (outptr - outbuf);
		if (remaining <= 0) {
			param->flags |= DM_BUFFER_FULL_FLAG;
			break;
		}

		/* Get the status/table string from the target driver */
		if (ti->type->status) {
			if (ti->type->status(ti, type, outptr, remaining)) {
				param->flags |= DM_BUFFER_FULL_FLAG;
				break;
			}
		} else
			outptr[0] = '\0';

		outptr += strlen(outptr) + 1;
		used = param->data_start + (outptr - outbuf);

		outptr = align_ptr(outptr);
		spec->next = outptr - outbuf;
	}

	if (used)
		param->data_size = used;

	param->target_count = num_targets;
}

/*
 * Wait for a device to report an event
 */
static int dev_wait(struct dm_ioctl *param, size_t param_size)
{
	int r;
	struct mapped_device *md;
	struct dm_table *table;

	md = find_device(param);
	if (!md)
		return -ENXIO;

	/*
	 * Wait for a notification event
	 */
	if (dm_wait_event(md, param->event_nr)) {
		r = -ERESTARTSYS;
		goto out;
	}

	/*
	 * The userland program is going to want to know what
	 * changed to trigger the event, so we may as well tell
	 * him and save an ioctl.
	 */
	r = __dev_status(md, param);
	if (r)
		goto out;

	table = dm_get_table(md);
	if (table) {
		retrieve_status(table, param, param_size);
		dm_table_put(table);
	}

 out:
	dm_put(md);
	return r;
}

static inline int get_mode(struct dm_ioctl *param)
{
	int mode = FMODE_READ | FMODE_WRITE;

	if (param->flags & DM_READONLY_FLAG)
		mode = FMODE_READ;

	return mode;
}

static int next_target(struct dm_target_spec *last, uint32_t next, void *end,
		       struct dm_target_spec **spec, char **target_params)
{
	*spec = (struct dm_target_spec *) ((unsigned char *) last + next);
	*target_params = (char *) (*spec + 1);

	if (*spec < (last + 1))
		return -EINVAL;

	return invalid_str(*target_params, end);
}

static int populate_table(struct dm_table *table,
			  struct dm_ioctl *param, size_t param_size)
{
	int r;
	unsigned int i = 0;
	struct dm_target_spec *spec = (struct dm_target_spec *) param;
	uint32_t next = param->data_start;
	void *end = (void *) param + param_size;
	char *target_params;

	if (!param->target_count) {
		DMWARN("populate_table: no targets specified");
		return -EINVAL;
	}

	for (i = 0; i < param->target_count; i++) {

		r = next_target(spec, next, end, &spec, &target_params);
		if (r) {
			DMWARN("unable to find target");
			return r;
		}

		r = dm_table_add_target(table, spec->target_type,
					(sector_t) spec->sector_start,
					(sector_t) spec->length,
					target_params);
		if (r) {
			DMWARN("error adding target to table");
			return r;
		}

		next = spec->next;
	}

	return dm_table_complete(table);
}

static int table_load(struct dm_ioctl *param, size_t param_size)
{
	int r;
	struct hash_cell *hc;
	struct dm_table *t;

	r = dm_table_create(&t, get_mode(param), param->target_count);
	if (r)
		return r;

	r = populate_table(t, param, param_size);
	if (r) {
		dm_table_put(t);
		return r;
	}

	down_write(&_hash_lock);
	hc = __find_device_hash_cell(param);
	if (!hc) {
		DMWARN("device doesn't appear to be in the dev hash table.");
		up_write(&_hash_lock);
		return -ENXIO;
	}

	if (hc->new_map)
		dm_table_put(hc->new_map);
	hc->new_map = t;
	param->flags |= DM_INACTIVE_PRESENT_FLAG;

	r = __dev_status(hc->md, param);
	up_write(&_hash_lock);
	return r;
}

static int table_clear(struct dm_ioctl *param, size_t param_size)
{
	int r;
	struct hash_cell *hc;

	down_write(&_hash_lock);

	hc = __find_device_hash_cell(param);
	if (!hc) {
		DMWARN("device doesn't appear to be in the dev hash table.");
		up_write(&_hash_lock);
		return -ENXIO;
	}

	if (hc->new_map) {
		dm_table_put(hc->new_map);
		hc->new_map = NULL;
	}

	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;

	r = __dev_status(hc->md, param);
	up_write(&_hash_lock);
	return r;
}

/*
 * Retrieves a list of devices used by a particular dm device.
 */
static void retrieve_deps(struct dm_table *table,
			  struct dm_ioctl *param, size_t param_size)
{
	unsigned int count = 0;
	struct list_head *tmp;
	size_t len, needed;
	struct dm_dev *dd;
	struct dm_target_deps *deps;

	deps = get_result_buffer(param, param_size, &len);

	/*
	 * Count the devices.
	 */
	list_for_each (tmp, dm_table_get_devices(table))
		count++;

	/*
	 * Check we have enough space.
	 */
	needed = sizeof(*deps) + (sizeof(*deps->dev) * count);
	if (len < needed) {
		param->flags |= DM_BUFFER_FULL_FLAG;
		return;
	}

	/*
	 * Fill in the devices.
	 */
	deps->count = count;
	count = 0;
	list_for_each_entry (dd, dm_table_get_devices(table), list)
		deps->dev[count++] = huge_encode_dev(dd->bdev->bd_dev);

	param->data_size = param->data_start + needed;
}

static int table_deps(struct dm_ioctl *param, size_t param_size)
{
	int r = 0;
	struct mapped_device *md;
	struct dm_table *table;

	md = find_device(param);
	if (!md)
		return -ENXIO;

	r = __dev_status(md, param);
	if (r)
		goto out;

	table = dm_get_table(md);
	if (table) {
		retrieve_deps(table, param, param_size);
		dm_table_put(table);
	}

 out:
	dm_put(md);
	return r;
}

/*
 * Return the status of a device as a text string for each
 * target.
 */
static int table_status(struct dm_ioctl *param, size_t param_size)
{
	int r;
	struct mapped_device *md;
	struct dm_table *table;

	md = find_device(param);
	if (!md)
		return -ENXIO;

	r = __dev_status(md, param);
	if (r)
		goto out;

	table = dm_get_table(md);
	if (table) {
		retrieve_status(table, param, param_size);
		dm_table_put(table);
	}

 out:
	dm_put(md);
	return r;
}

/*-----------------------------------------------------------------
 * Implementation of open/close/ioctl on the special char
 * device.
 *---------------------------------------------------------------*/
static ioctl_fn lookup_ioctl(unsigned int cmd)
{
	static struct {
		int cmd;
		ioctl_fn fn;
	} _ioctls[] = {
		{DM_VERSION_CMD, NULL},	/* version is dealt with elsewhere */
		{DM_REMOVE_ALL_CMD, remove_all},
		{DM_LIST_DEVICES_CMD, list_devices},

		{DM_DEV_CREATE_CMD, dev_create},
		{DM_DEV_REMOVE_CMD, dev_remove},
		{DM_DEV_RENAME_CMD, dev_rename},
		{DM_DEV_SUSPEND_CMD, dev_suspend},
		{DM_DEV_STATUS_CMD, dev_status},
		{DM_DEV_WAIT_CMD, dev_wait},

		{DM_TABLE_LOAD_CMD, table_load},
		{DM_TABLE_CLEAR_CMD, table_clear},
		{DM_TABLE_DEPS_CMD, table_deps},
		{DM_TABLE_STATUS_CMD, table_status},

		{DM_LIST_VERSIONS_CMD, list_versions}
	};

	return (cmd >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[cmd].fn;
}

/*
 * As well as checking the version compatibility this always
 * copies the kernel interface version out.
 */
static int check_version(unsigned int cmd, struct dm_ioctl __user *user)
{
	uint32_t version[3];
	int r = 0;

	if (copy_from_user(version, user->version, sizeof(version)))
		return -EFAULT;

	if ((DM_VERSION_MAJOR != version[0]) ||
	    (DM_VERSION_MINOR < version[1])) {
		DMWARN("ioctl interface mismatch: "
		       "kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
		       DM_VERSION_MAJOR, DM_VERSION_MINOR,
		       DM_VERSION_PATCHLEVEL,
		       version[0], version[1], version[2], cmd);
		r = -EINVAL;
	}

	/*
	 * Fill in the kernel version.
	 */
	version[0] = DM_VERSION_MAJOR;
	version[1] = DM_VERSION_MINOR;
	version[2] = DM_VERSION_PATCHLEVEL;
	if (copy_to_user(user->version, version, sizeof(version)))
		return -EFAULT;

	return r;
}

static void free_params(struct dm_ioctl *param)
{
	vfree(param);
}

static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl **param)
{
	struct dm_ioctl tmp, *dmi;

	if (copy_from_user(&tmp, user, sizeof(tmp)))
		return -EFAULT;

	if (tmp.data_size < sizeof(tmp))
		return -EINVAL;

	dmi = (struct dm_ioctl *) vmalloc(tmp.data_size);
	if (!dmi)
		return -ENOMEM;

	if (copy_from_user(dmi, user, tmp.data_size)) {
		vfree(dmi);
		return -EFAULT;
	}

	*param = dmi;
	return 0;
}

static int validate_params(uint cmd, struct dm_ioctl *param)
{
	/* Always clear this flag */
	param->flags &= ~DM_BUFFER_FULL_FLAG;

	/* Ignores parameters */
	if (cmd == DM_REMOVE_ALL_CMD ||
	    cmd == DM_LIST_DEVICES_CMD ||
	    cmd == DM_LIST_VERSIONS_CMD)
		return 0;

	/* Unless creating, either name or uuid but not both */
	if (cmd != DM_DEV_CREATE_CMD) {
		if ((!*param->uuid && !*param->name) ||
		    (*param->uuid && *param->name)) {
			DMWARN("one of name or uuid must be supplied, cmd(%u)",
			       cmd);
			return -EINVAL;
		}
	}

	/* Ensure strings are terminated */
	param->name[DM_NAME_LEN - 1] = '\0';
	param->uuid[DM_UUID_LEN - 1] = '\0';

	return 0;
}

static int ctl_ioctl(struct inode *inode, struct file *file,
		     uint command, ulong u)
{
	int r = 0;
	unsigned int cmd;
	struct dm_ioctl *param;
	struct dm_ioctl __user *user = (struct dm_ioctl __user *) u;
	ioctl_fn fn = NULL;
	size_t param_size;

	/* only root can play with this */
	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (_IOC_TYPE(command) != DM_IOCTL)
		return -ENOTTY;

	cmd = _IOC_NR(command);

	/*
	 * Check the interface version passed in.  This also
	 * writes out the kernel's interface version.
	 */
	r = check_version(cmd, user);
	if (r)
		return r;

	/*
	 * Nothing more to do for the version command.
	 */
	if (cmd == DM_VERSION_CMD)
		return 0;

	fn = lookup_ioctl(cmd);
	if (!fn) {
		DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
		return -ENOTTY;
	}

	/*
	 * Trying to avoid low memory issues when a device is
	 * suspended.
	 */
	current->flags |= PF_MEMALLOC;

	/*
	 * Copy the parameters into kernel space.
	 */
	r = copy_params(user, &param);
	if (r) {
		current->flags &= ~PF_MEMALLOC;
		return r;
	}

	/*
	 * FIXME: eventually we will remove the PF_MEMALLOC flag
	 * here.  However the tools still do nasty things like
	 * 'load' while a device is suspended.
	 */

	r = validate_params(cmd, param);
	if (r)
		goto out;

	param_size = param->data_size;
	param->data_size = sizeof(*param);
	r = fn(param, param_size);

	/*
	 * Copy the results back to userland.
	 */
	if (!r && copy_to_user(user, param, param->data_size))
		r = -EFAULT;

 out:
	free_params(param);
	current->flags &= ~PF_MEMALLOC;
	return r;
}

static struct file_operations _ctl_fops = {
	.ioctl	 = ctl_ioctl,
	.owner	 = THIS_MODULE,
};

static struct miscdevice _dm_misc = {
	.minor 		= MISC_DYNAMIC_MINOR,
	.name  		= DM_NAME,
	.devfs_name 	= "mapper/control",
	.fops  		= &_ctl_fops
};

/*
 * Create misc character device and link to DM_DIR/control.
 */
int __init dm_interface_init(void)
{
	int r;

	r = dm_hash_init();
	if (r)
		return r;

	r = misc_register(&_dm_misc);
	if (r) {
		DMERR("misc_register failed for control device");
		dm_hash_exit();
		return r;
	}

	DMINFO("%d.%d.%d%s initialised: %s", DM_VERSION_MAJOR,
	       DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL, DM_VERSION_EXTRA,
	       DM_DRIVER_EMAIL);
	return 0;
}

void dm_interface_exit(void)
{
	if (misc_deregister(&_dm_misc) < 0)
		DMERR("misc_deregister failed for control device");

	dm_hash_exit();
}