Add another cache device to existing bcache disk

[johnw <johnw.mail@xxxxxxxxx>]

Hi, I have existing bcache0 disk/device(1 backing disk, and 1 cache
disk), is there any way to add another cache disk to the bcache0
disk/device?

Do I need detach the existing cache disk first?

Where I register the cache2 disk to the bcache0 device, I see the error
message as below in the dmesg log

bcache: register_bcache() error : device already registered
[  308.037636] bcache: bch_cached_dev_attach() Can't attach sda: already
attached
[  453.414692] bcache: __cached_dev_store() Can't attach
17ac5b8f-d787-4e46-96b7-c5ee53eb6d19
               : cache set not found

Thanks.

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