dm: do not forward ioctls from logical volumes to the underlying device

A logical volume can map to just part of underlying physical volume.
In this case, it must be treated like a partition.

Based on a patch from Alasdair G Kergon.

Cc: Alasdair G Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
static int parse_features(struct dm_arg_set *as, struct multipath *m)
{
	int r;
	unsigned argc;
	struct dm_target *ti = m->ti;
	const char *arg_name;

	static struct dm_arg _args[] = {
		{0, 5, "invalid number of feature args"},
		{1, 50, "pg_init_retries must be between 1 and 50"},
		{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
	};

	r = dm_read_arg_group(_args, as, &argc, &ti->error);
	if (r)
		return -EINVAL;

	if (!argc)
		return 0;

	do {
		arg_name = dm_shift_arg(as);
		argc--;

		if (!strcasecmp(arg_name, "queue_if_no_path")) {
			r = queue_if_no_path(m, 1, 0);
			continue;
		}

		if (!strcasecmp(arg_name, "pg_init_retries") &&
		    (argc >= 1)) {
			r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
			argc--;
			continue;
		}

		if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
		    (argc >= 1)) {
			r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
			argc--;
			continue;
		}

		ti->error = "Unrecognised multipath feature request";
		r = -EINVAL;
	} while (argc && !r);

	return r;
}

static int parse_features(struct dm_arg_set *as, struct multipath *m)
{
	int r;
	unsigned argc;
	struct dm_target *ti = m->ti;
	const char *arg_name;

	static struct dm_arg _args[] = {
		{0, 5, "invalid number of feature args"},
		{1, 50, "pg_init_retries must be between 1 and 50"},
		{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
	};

	r = dm_read_arg_group(_args, as, &argc, &ti->error);
	if (r)
		return -EINVAL;

	if (!argc)
		return 0;

	do {
		arg_name = dm_shift_arg(as);
		argc--;

		if (!strcasecmp(arg_name, "queue_if_no_path")) {
			r = queue_if_no_path(m, 1, 0);
			continue;
		}

		if (!strcasecmp(arg_name, "pg_init_retries") &&
		    (argc >= 1)) {
			r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
			argc--;
			continue;
		}

		if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
		    (argc >= 1)) {
			r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
			argc--;
			continue;
		}

		ti->error = "Unrecognised multipath feature request";
		r = -EINVAL;
	} while (argc && !r);

	return r;
}
