From 7a54789074a54f64addf5b49bf1994f478337a83 Mon Sep 17 00:00:00 2001 From: Zygo Blaxell Date: Thu, 12 Sep 2019 19:55:01 -0400 Subject: [PATCH] btrfs: fix balance convert to single on 32-bit host CPUs 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. Fixes: 818255feece6 ("btrfs: use common helper instead of open coding a bit test") CC: stable@vger.kernel.org # 4.20+ Signed-off-by: Zygo Blaxell Reviewed-by: David Sterba Signed-off-by: David Sterba --- 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 cdd7af424033..bdfe4493e43a 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3845,7 +3845,11 @@ 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; } static inline int balance_need_close(struct btrfs_fs_info *fs_info)