Re: [PATCH, RFC] btrfs-progs: require mkfs -f force option to overwrite filesystem or partition table

[Tsutomu Itoh <t-itoh@jp.fujitsu.com>]

On 2013/02/26 9:07, Eric Sandeen wrote:
> On 2/25/13 5:39 PM, Tsutomu Itoh wrote:
>> On 2013/02/21 0:37, Stefan Behrens wrote:
>>> On Thu, 14 Feb 2013 12:30:03 -0600, Eric Sandeen wrote:
>>>> The core of this is shamelessly stolen from xfsprogs.
>>>>
>>>> Use blkid to detect an existing filesystem or partition
>>>> table on any of the target devices.  If something is found,
>>>> require the '-f' option to overwrite it, hopefully avoiding
>>>> disaster due to mistyped devicenames, etc.
>>>>
>>>> # mkfs.btrfs /dev/sda1
>>>>
>>>> WARNING! - Btrfs v0.20-rc1-59-gd00279c-dirty IS EXPERIMENTAL
>>>> WARNING! - see http://btrfs.wiki.kernel.org before using
>>>>
>>>> /dev/sda1 appears to contain an existing filesystem (xfs).
>>>> Use the -f option to force overwrite.
>>>> #
>>>>
>>>> This does introduce a requirement on libblkid.
>>>>
>>>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>>>
>>> This means that it is now required to change all occurrences of
>>> "mkfs.btrfs" to "mkfs.btrfs -f" everywhere. Can't we first establish a
>>
>> I also think so.
>> It means -f is not significant to me, I think.
>> (Most of my test scripts fails without -f. So I'll always type "mkfs.btrfs -f")
>>
>> Therefore I want you to revert commit:2a2d8e1962e8b6cda7b0a7584f6d2fb95d442cb6.
>>    btrfs-progs: require mkfs -f force option to overwrite filesystem or partition table
>>
>> How do you think about it?
>
> What if you submit a patch to look at an environment variable,
> BTRFS_CLOBBERS_ALL=1 which causes it to not require -f to overwrite?
> Then you can just set it once at the top of your test environment,
> and not change every instance?

Yes. But,
 >> (Most of my test scripts fails without -f. So I'll always type "mkfs.btrfs -f")
is one example.

Almost everyone types "mkfs.btrfs -f" (or BTRFS_CLOBBERS_ALL=1 :)
unconditionally, I think.
So, I think -f option is almost meaningless.

> Otherwise, I guess I think:
>
> WARNING! - Btrfs v0.20-rc1-212-gf6ef8b5 IS EXPERIMENTAL
>
> and we need to expect that things might change ...

EXPERIMENTAL... It's certainly so.
However, I think that we should not add the option that it troubles
a lot of people.

Thanks,
Tsutomu

>
> -Eric
>
>> Thanks,
>> Tsutomu
>>
>>> time period of 100 years where the -f option is tolerated and ignored,
>>> and then in 2113 we require that the users add the -f option?
>>>
>>> (Just had to do this string replacement everywhere, and had to add -f to
>>> xfstest's _scratch_mkfs in common.rc as well). Sigh.
>>>
>>
>