From: Anand Jain <anand.jain@oracle.com>
To: Josef Bacik <josef@toxicpanda.com>,
dsterba@suse.cz, linux-btrfs@vger.kernel.org,
syzbot+4cfe71a4da060be47502@syzkaller.appspotmail.com
Subject: Re: [PATCH add reported by] btrfs: fix rw_devices count in __btrfs_free_extra_devids
Date: Tue, 6 Oct 2020 21:12:18 +0800 [thread overview]
Message-ID: <6a59bb52-1603-74ca-9bd8-7b30888a4842@oracle.com> (raw)
In-Reply-To: <7b481788-110e-b2a7-607c-2f443f30f663@toxicpanda.com>
On 25/9/20 10:28 pm, Josef Bacik wrote:
> On 9/25/20 6:11 AM, Anand Jain wrote:
>> On 24/9/20 10:02 pm, Josef Bacik wrote:
>>> On 9/24/20 7:25 AM, David Sterba wrote:
>>>> On Wed, Sep 23, 2020 at 09:42:17AM -0400, Josef Bacik wrote:
>>>>> On 9/23/20 12:42 AM, Anand Jain wrote:
>>>>>> On 22/9/20 9:08 pm, Josef Bacik wrote:
>>>>>>> On 9/22/20 8:33 AM, Anand Jain wrote:
>>>>
>>>>> Yeah I mean we do something in btrfs_init_dev_replace(), like when
>>>>> we search for
>>>>> the key, we double check to make sure we don't have a devid ==
>>>>> BTRFS_DEV_REPLACE_DEVID in our devices if we don't find a key.
>>
>>
>>>>> If we do we
>>>>> return -EIO and bail out of the mount. Thanks,
>>
>>
>> I read fast and missed the bailout part before.
>>
>> If we bailout the mount, it means a btrfs rootfs can fail to boot up.
>>
>> To recover from it, the user has to remove the trespassing/extra device
>> manually and reboot.
>> For a non-rootfs, the user would have to remove the device manually
>> and run
>> 'btrfs dev scan --forget' to free up the extra devices.
>> What we are doing now is removing the extra/trespassing device
>> internally.
>>
>> IMO. The case of trespassing/extra device trying to sabotage the setup
>> is a bit different from a corrupted device, in the former case
>> resilience is preferred?
>>
>
> Well this doesn't happen in real life right? This is purely from a
> fuzzing standpoint, so while resilience should be the first thing we
> shoot for, I'd rather not spend a long time trying to make it work.
>
> In the case of just randomly deleting a device, I don't think that's a
> decision that the kernel can/should make, we should require a user to
> intervene at that point. That makes failure the best option here, thanks,
>
It makes sense to me, its different from what we had before.
Made those changes in v2.
Thanks, Anand
> Josef
next prev parent reply other threads:[~2020-10-06 13:12 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 12:30 [PATCH] btrfs: fix rw_devices count in __btrfs_free_extra_devids Anand Jain
2020-09-22 12:33 ` [PATCH add reported by] " Anand Jain
2020-09-22 13:08 ` Josef Bacik
2020-09-23 4:42 ` Anand Jain
2020-09-23 13:42 ` Josef Bacik
2020-09-24 5:19 ` Anand Jain
2020-09-24 11:25 ` David Sterba
2020-09-24 14:02 ` Josef Bacik
2020-09-25 10:11 ` Anand Jain
2020-09-25 14:28 ` Josef Bacik
2020-10-06 13:12 ` Anand Jain [this message]
2020-09-22 12:33 Anand Jain
2020-10-06 13:08 ` [PATCH] btrfs: fix devid 0 without a replace item by failing the mount Anand Jain
2020-10-06 13:12 ` [PATCH v2] " Anand Jain
2020-10-06 14:54 ` [PATCH] " kernel test robot
2020-10-06 14:54 ` kernel test robot
2020-10-07 2:07 ` Anand Jain
2020-10-07 2:07 ` Anand Jain
2020-10-12 2:51 ` [kbuild-all] " Rong Chen
2020-10-12 2:51 ` Rong Chen
2020-10-06 16:44 ` kernel test robot
2020-10-06 16:44 ` kernel test robot
2020-10-06 13:12 [PATCH v2] " Anand Jain
2020-10-12 5:26 ` [PATCH v2 add prerequisite-patch-id] " Anand Jain
2020-10-21 4:02 ` [PATCH RESEND " Anand Jain
2020-10-12 5:36 ` [PATCH " Anand Jain
2020-10-21 5:49 ` [PATCH RESEND " kernel test robot
2020-10-21 5:49 ` kernel test robot
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