btrfs: use raid_attr table in calc_stripe_length for nparity

The table is already used for ncopies, replace open coding of stripes
with the raid_attr value.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9b78e72..687eacb 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6480,19 +6480,14 @@ static u64 calc_stripe_length(u64 type, u64 chunk_len, int num_stripes)
 {
        int index = btrfs_bg_flags_to_raid_index(type);
        int ncopies = btrfs_raid_array[index].ncopies;
+       const int nparity = btrfs_raid_array[index].nparity;
        int data_stripes;
 
-       switch (type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
-       case BTRFS_BLOCK_GROUP_RAID5:
-               data_stripes = num_stripes - 1;
-               break;
-       case BTRFS_BLOCK_GROUP_RAID6:
-               data_stripes = num_stripes - 2;
-               break;
-       default:
+       if (nparity)
+               data_stripes = num_stripes - nparity;
+       else
                data_stripes = num_stripes / ncopies;
-               break;
-       }
+
        return div_u64(chunk_len, data_stripes);
 }