On 13/09/2019 01:55, 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>
> ---
> fs/btrfs/volumes.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 88a323a453d8..252c6049c6b7 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -3906,7 +3906,11 @@ static int alloc_profile_is_valid(u64 flags, int
> extended)
> return !extended; /* "0" is valid for usual profiles */
>
> /* true if exactly one bit set */
> - return is_power_of_2(flags);
> + /*
> + * Don't use is_power_of_2(unsigned long) because it won't work
> + * for the single profile (1ULL << 48) on 32-bit CPUs.
> + */
> + return flags != 0 && (flags & (flags - 1)) == 0;
Would
flags && IS_ALIGNED(flags)
Work as well? IS_ALIGNED() should be type-save due to the typeof():
#define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
Or maybe I'm missing something subtle?
Thanks,
Johannes
--
Johannes Thumshirn SUSE Labs Filesystems
jthumsh...@suse.de +49 911 74053 689
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