Re: [PATCH 19/20] bcache: remove a superflous lookup_bdev all

[Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>]

On Wed, Nov 18, 2020 at 04:54:51PM +0800, Coly Li wrote:
> On 11/18/20 4:47 PM, Christoph Hellwig wrote:
> > Don't bother to call lookup_bdev for just a slightly different error
> > message without any functional change.
> > 
> > Signed-off-by: Christoph Hellwig <hch@xxxxxx>ist
> 
> Hi Christoph,
> 
> NACK. This removing error message is frequently triggered and observed,
> and distinct a busy device and an already registered device is important
> (the first one is critical error and second one is not).
> 
> Remove such error message will be a functional regression.

What normal operation causes this error message to be emitted?  And what
can a user do with it?

thanks,

greg k-h