From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [bcachefs][tier] kernel BUG at drivers/md/bcache/super.c:1561! after double changing state of device Date: Thu, 25 Aug 2016 18:10:29 -0800 Message-ID: <20160826021029.upgpx4iji2opabjw@kmo-pixel> References: <3bfada34-3dd7-8e28-036a-8c027848f90d@mejor.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Received: from mail-pf0-f172.google.com ([209.85.192.172]:36582 "EHLO mail-pf0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751393AbcHZCKq (ORCPT ); Thu, 25 Aug 2016 22:10:46 -0400 Received: by mail-pf0-f172.google.com with SMTP id h186so23221052pfg.3 for ; Thu, 25 Aug 2016 19:10:33 -0700 (PDT) Content-Disposition: inline In-Reply-To: <3bfada34-3dd7-8e28-036a-8c027848f90d@mejor.pl> Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: Marcin =?utf-8?B?TWlyb3PFgmF3?= , chris@cooperteam.net Cc: linux-bcache@vger.kernel.org On Thu, Aug 25, 2016 at 02:03:33PM +0200, Marcin Mirosław wrote: > https://lwn.net/Articles/655183/ : > "Caveat: don't try to use tiering and checksumming or compression at the > same time yet, the read path needs to be reworked to handle both at the > same time." > > Is it sill valid? No, I did do that read path reworking, they should work. However, I haven't been focusing on or exercising the multi device stuff in quite awhile - my main priority has been making single device filesystems rock solid and finishing off compression and such. Tiering ought to work, but can you hold off on exercising anything else? e.g. the active/RO transition stuff - I'm going to have to spend a fair amount of time digging into that code and figuring out what makes sense when the time comes. The checksum error is highly concerning though - that was related to messing with cache0/state, correct? I think Christopher is using tiering with checksumming enabled, can you confirm?