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From: Coly Li <colyli@suse.de>
To: Constantin Runge <c.runge@cssbook.de>
Cc: linux-bcache@vger.kernel.org
Subject: Re: Obsoleted large bucket layout message once
Date: Thu, 18 Feb 2021 11:33:30 +0800	[thread overview]
Message-ID: <66f67289-2142-1361-d10b-0fe520b80cd1@suse.de> (raw)
In-Reply-To: <de528a90-6d3d-d324-ca22-73b635d5153f@cssbook.de>

On 2/16/21 11:06 PM, Constantin Runge wrote:
> Hi everybody,
> 
> when registering and mounting my bcache devices (unortunately my root
> filesystem), the kernel informed me about `Detected obsoleted large
> bucket layout, all attached bcache device will be read-only'.
> 
> Subsequently, my root fs was, in fact, read-only. Thus, I have no logs
> for you unfortunately. As far as I remember, bcache-super-show showed
> the same bucket and block sizes as always (except that the backing
> device showed a clean cache state):
> 
>> bcache-super-show /dev/sda6
> sb.magic        ok
> sb.first_sector        8 [match]
> sb.csum            C5EB3BA8CA523D61 [match]
> sb.version        4 [backing device]
> 
> dev.label        (empty)
> dev.uuid        264d1acc-8461-4ddc-a825-f0acdeea3ede
> dev.sectors_per_block    1
> dev.sectors_per_bucket    1024
> dev.data.first_sector    2048
> dev.data.cache_mode    1 [writeback]
> dev.data.cache_state    2 [dirty]
> 
> cset.uuid        755901be-a101-4581-b1d0-4d21d1619f27
>> bcache-super-show /dev/sdb3
> sb.magic        ok
> sb.first_sector        8 [match]
> sb.csum            BDA92F1E72DBA095 [match]
> sb.version        3 [cache device]
> 
> dev.label        (empty)
> dev.uuid        25151c1a-904e-492e-b99b-6d07e13b047a
> dev.sectors_per_block    1
> dev.sectors_per_bucket    1024
> dev.cache.first_sector    1024
> dev.cache.cache_sectors    907564032
> dev.cache.total_sectors    907565056
> dev.cache.ordered    yes
> dev.cache.discard    no
> dev.cache.pos        0
> dev.cache.replacement    0 [lru]
> 
> cset.uuid        755901be-a101-4581-b1d0-4d21d1619f27
> 
> 
> For debugging purposes I tried to mount and chroot into my backing
> device directly, using a loopback interface. I was not able to find an
> offset for `losetup -f -o <offset> /dev/sda6', so that `mount -o loop
> /dev/loop0 /mnt/mnt0' would not tell me that there was no filesystem.
> Also, `for i in {0.2000}; do dd if=/dev/sda6 skip=$i | file -; done'
> from [1] showed `data' for every offset.
> 
> After getting a little desperate, I booted into an older kernel
> (although I didn't update my kernel or my bcache-tools since the last
> boot) and everything worked. I then booted back into my current system
> and everything worked again.
> 
> Is this a bug with bcache or do I need to change my setup to prevent
> this from happening again? My bcache devices were created sometime
> around 2015 or 2016.
> 
> System info:
> uname -a: `Linux Horus 5.10.10-gentoo #1 SMP PREEMPT Mon Feb 15 15:00:49
> CET 2021 x86_64 Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz GenuineIntel
> GNU/Linux'
> bcache-tools version: 1.1
> The older kernel is a 5.8.11-gentoo with voluntary preempt.
> 
> Best regards and thanks,
> Constantin
> 
> 
>   [1]
> https://stackoverflow.com/questions/22820492/how-to-revert-bcache-device-to-regular-device
> 

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"). This patch has been in stable
kernel for a while, the distribution maintainer should have it in time.

Thanks.

Coly Li

      reply	other threads:[~2021-02-18  3:34 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-16 15:06 Obsoleted large bucket layout message once Constantin Runge
2021-02-18  3:33 ` Coly Li [this message]

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