From: Qu Wenruo <wqu@xxxxxxxx> commit fab273595507a9ec7035df6d5512a955d80a80ba upstream. [BUG] With v5.3 kernel, we can't convert to SINGLE profile: # btrfs balance start -f -dconvert=single $mnt ERROR: error during balancing '/mnt/btrfs': Invalid argument # dmesg -t | tail validate_convert_profile: data profile=0x1000000000000 allowed=0x20 is_valid=1 final=0x1000000000000 ret=1 BTRFS error (device dm-3): balance: invalid convert data profile single [CAUSE] With the extra debug output added, it shows that the @allowed bit is lacking the special in-memory only SINGLE profile bit. Thus we fail at that (profile & ~allowed) check. This regression is caused by commit 081db89b13cb ("btrfs: use raid_attr to get allowed profiles for balance conversion") and the fact that we don't use any bit to indicate SINGLE profile on-disk, but uses special in-memory only bit to help distinguish different profiles. [FIX] Add that BTRFS_AVAIL_ALLOC_BIT_SINGLE to @allowed, so the code should be the same as it was and fix the regression. Reported-by: Chris Murphy <lists@xxxxxxxxxxxxxxxxx> Fixes: 081db89b13cb ("btrfs: use raid_attr to get allowed profiles for balance conversion") CC: stable@xxxxxxxxxxxxxxx # 5.3+ Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/btrfs/volumes.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4072,7 +4072,13 @@ int btrfs_balance(struct btrfs_fs_info * } num_devices = btrfs_num_devices(fs_info); - allowed = 0; + + /* + * SINGLE profile on-disk has no profile bit, but in-memory we have a + * special bit for it, to make it easier to distinguish. Thus we need + * to set it manually, or balance would refuse the profile. + */ + allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE; for (i = 0; i < ARRAY_SIZE(btrfs_raid_array); i++) if (num_devices >= btrfs_raid_array[i].devs_min) allowed |= btrfs_raid_array[i].bg_flag;