This ensures device names don't get prematurely reused.  Instead add a
deleted flag to skip already deleted devices in mddev_get and other
places that only want to see live mddevs.
Reported-by: NLogan Gunthorpe <logang@deltatee.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NLogan Gunthorpe <logang@deltatee.com>
Signed-off-by: NSong Liu <song@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>