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From: Graham Cobb <g.btrfs@cobb.uk.net>
To: Nikolay Borisov <nborisov@suse.com>,
	Anand Jain <anand.jain@oracle.com>,
	linux-btrfs@vger.kernel.org
Subject: Re: [Not TLS] Re: [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev
Date: Fri, 4 Oct 2019 10:08:42 +0100	[thread overview]
Message-ID: <8f0fd5a3-c389-b39a-6f22-a17e25cff481@cobb.uk.net> (raw)
In-Reply-To: <93c711f8-dc77-dcc2-52b0-fc46487ff16e@suse.com>

On 04/10/2019 09:11, Nikolay Borisov wrote:
> 
> 
> On 4.10.19 г. 10:50 ч., Anand Jain wrote:
>> btrfs_free_extra_devids() reorgs fs_devices::latest_bdev
>> to point to the bdev with greatest device::generation number.
>> For a typical-missing device the generation number is zero so
>> fs_devices::latest_bdev will never point to it.
>>
>> But if the missing device is due to alienating [1], then
>> device::generation is not-zero and if it is >= to rest of
>> device::generation in the list, then fs_devices::latest_bdev
>> ends up pointing to the missing device and reports the error
>> like this [2]
>>
>> [1]
>> mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
>> mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
>> sleep 3 # avoid racing with udev's useless scans if needed
>> btrfs dev add -f /dev/sdb /btrfs
> 
> Hm, here I think the correct way is to refuse adding /dev/sdb to an
> existing fs if it's detected to be part of a different one. I.e it
> should require wipefs to be done.

I disagree. -f means "force overwrite of existing filesystem on the
given disk(s)". It shouldn't be any different whether the existing fs is
btrfs or something else.

Graham

  reply	other threads:[~2019-10-04  9:08 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-04  7:49 [PATCH 0/4] btrfs: fix issues due to alien device Anand Jain
2019-10-04  7:50 ` [PATCH 1/4] btrfs: drop useless goto in open_fs_devices Anand Jain
2019-10-04  8:12   ` Nikolay Borisov
2019-10-04  7:50 ` [PATCH 2/4] btrfs: delete identified alien device " Anand Jain
2019-10-04  8:18   ` Nikolay Borisov
2019-10-06  2:47     ` [PATCH v2 " Anand Jain
2019-10-06 11:44       ` Nikolay Borisov
2019-10-06  2:51     ` [PATCH " Anand Jain
2019-10-04  7:50 ` [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev Anand Jain
2019-10-04  8:11   ` Nikolay Borisov
2019-10-04  9:08     ` Graham Cobb [this message]
2019-10-04  9:20       ` [Not TLS] " Nikolay Borisov
2019-10-04  7:50 ` [PATCH 4/4] btrfs: free alien device due to device add Anand Jain
2019-10-04  8:19 ` [PATCH 0/4] btrfs: fix issues due to alien device Nikolay Borisov
2019-10-07  9:42   ` Anand Jain

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