we need to make sure that subsystem lock is taken during ctrl's list
traversing. nvmet_ns_changed function is not static and can be used from
various callers simultaneously.
Signed-off-by: NMax Gurtovoy <maxg@mellanox.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>