'reconfig_mutex' will be grabbed before these ioctls, suspend array
before holding the lock, so that io won't concurrent with array
reconfiguration through ioctls.

This is not hot path, so performance is not concerned.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-13-yukuai1@huaweicloud.com