btrfs: use mask for all RAID1* profiles in btrfs_calc_avail_data_space

There's a sequence of hard coded values for RAID1 profiles that are
already stored in the raid_attr table that should be used instead.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/super.c

@@ -2243,12 +2243,8 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
 
 	if (type & BTRFS_BLOCK_GROUP_RAID0)
 		num_stripes = nr_devices;
-	else if (type & BTRFS_BLOCK_GROUP_RAID1)
-		num_stripes = 2;
-	else if (type & BTRFS_BLOCK_GROUP_RAID1C3)
-		num_stripes = 3;
-	else if (type & BTRFS_BLOCK_GROUP_RAID1C4)
-		num_stripes = 4;
+	else if (type & BTRFS_BLOCK_GROUP_RAID1_MASK)
+		num_stripes = rattr->ncopies;
 	else if (type & BTRFS_BLOCK_GROUP_RAID10)
 		num_stripes = 4;