bch_cached_dev_attach() The obsoleted large bucket layout is unsupported, set the bcache device into read-only

bch_cached_dev_attach() The obsoleted large bucket layout is unsupported, set the bcache device into read-only

[Rolf Fokkens]

Hi all,

Apparently some bcache users are hit by the message in the subject, see
https://bugzilla.redhat.com/show_bug.cgi?id=1922485

I personally cannot reproduce this, but if the provided info is correct,
a certain kernel upgrade will break existing bcache setups. Is this
really true?

If so, this is a breaking change, which is very harmful.

I hope some of you have suggestions for the people who apparently are
impacted by this.

Best,

Rolf Fokkens

Re: bch_cached_dev_attach() The obsoleted large bucket layout is unsupported, set the bcache device into read-only

[Coly Li]

On 2/6/21 7:49 PM, Rolf Fokkens wrote:
> Hi all,
> 
> Apparently some bcache users are hit by the message in the subject, see
> https://bugzilla.redhat.com/show_bug.cgi?id=1922485
> 
> I personally cannot reproduce this, but if the provided info is correct,
> a certain kernel upgrade will break existing bcache setups. Is this
> really true?
> 
> If so, this is a breaking change, which is very harmful.
> 
> I hope some of you have suggestions for the people who apparently are
> impacted by this.

This is a regression and fixed in 5.11-rc6 by commit 0df28cad06eb
("bcache: only check feature sets when sb->version >=
BCACHE_SB_VERSION_CDEV_WITH_FEATURES").

Also the fix has been in stable kernels already last week. The fix
should go into distribution very soon IMHO.

Thanks.

Coly Li