[PATCH] md: allow available size of component devices to be set via sysfs

        the device before this offset us not touched, unless it is

        used for storing metadata (Formats 1.1 and 1.2).

      size

        The amount of the device, after the offset, that can be used

        for storage of data.  This will normally be the same as the

	component_size.  This can be written while assembling an

        array.  If a value less than the current component_size is

        written, component_size will be reduced to this value.

An active md device will also contain and entry for each active device

in the array.  These are named

static struct rdev_sysfs_entry rdev_offset =

__ATTR(offset, 0644, offset_show, offset_store);

static ssize_t

rdev_size_show(mdk_rdev_t *rdev, char *page)

{

	return sprintf(page, "%llu\n", (unsigned long long)rdev->size);

}

static ssize_t

rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)

{

	char *e;

	unsigned long long size = simple_strtoull(buf, &e, 10);

	if (e==buf || (*e && *e != '\n'))

		return -EINVAL;

	if (rdev->mddev->pers)

		return -EBUSY;

	rdev->size = size;

	if (size < rdev->mddev->size || rdev->mddev->size == 0)

		rdev->mddev->size = size;

	return len;

}

static struct rdev_sysfs_entry rdev_size =

__ATTR(size, 0644, rdev_size_show, rdev_size_store);

static struct attribute *rdev_default_attrs[] = {

	&rdev_state.attr,

	&rdev_super.attr,

	&rdev_errors.attr,

	&rdev_slot.attr,

	&rdev_offset.attr,

	&rdev_size.attr,

	NULL,

};

static ssize_t