On 14.09.19 г. 7:59 ч., Zygo Blaxell wrote:
> On Fri, Sep 13, 2019 at 09:14:08AM -0700, Josef Bacik wrote:
>> On Thu, Sep 12, 2019 at 07:55:01PM -0400, Zygo Blaxell wrote:
>>> Currently, the command:
>>>
>>> btrfs balance start -dconvert=single,soft .
>>>
>>> on a Raspberry Pi produces the following kernel message:
>>>
>>> BTRFS error (device mmcblk0p2): balance: invalid convert data profile
>>> single
>>>
>>> This fails because we use is_power_of_2(unsigned long) to validate
>>> the new data profile, the constant for 'single' profile uses bit 48,
>>> and there are only 32 bits in a long on ARM.
>>>
>>> Fix by open-coding the check using u64 variables.
>>>
>>> Tested by completing the original balance command on several Raspberry
>>> Pis.
>>>
>>> Signed-off-by: Zygo Blaxell <ce3g8...@umail.furryterror.org>
>>
>> Honestly I'd rather we fixed is_power_of_2 to work on 32bit, that way any
>> other
>> users don't get bitten by the same problem. Thanks,
>
> is_power_of_2 doesn't live in the btrfs tree. I considered modifying it,
> but worried about side-effects elsewhere (i.e. breaking some other 32-bit
> device I've never heard of).
>
> What do you think about using the IS_ALIGNED macro?
THe problem is that is_power_of_2 is defined as a function that takes an
unsigned long which is defined as able to hold at least 32 bits. One
possible change will be do change it to being a macro. However, as you
note, this might lead to subtle breakage elsewhere. Furthermore other
functions in log2.h are also defined with unsigned long as their input
params.
>
>> Josef
