btrfs: factor out helper for counting data stripes

Factor the sequence of ifs to a helper, the 'data stripes' here means
the number of stripes without redundancy and parity.

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

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index bbc195c97c740345fa566e5d99f802c908def9e6..e9caba25ddb61f38f3e6eb82f85227ee8b04659c 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3474,6 +3474,18 @@ static int chunk_devid_filter(struct extent_buffer *leaf,
        return 1;
 }
 
+static u64 calc_data_stripes(u64 type, int num_stripes)
+{
+       const int index = btrfs_bg_flags_to_raid_index(type);
+       const int ncopies = btrfs_raid_array[index].ncopies;
+       const int nparity = btrfs_raid_array[index].nparity;
+
+       if (nparity)
+               return num_stripes - nparity;
+       else
+               return num_stripes / ncopies;
+}
+
 /* [pstart, pend) */
 static int chunk_drange_filter(struct extent_buffer *leaf,
                               struct btrfs_chunk *chunk,
@@ -3483,22 +3495,15 @@ static int chunk_drange_filter(struct extent_buffer *leaf,
        int num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
        u64 stripe_offset;
        u64 stripe_length;
+       u64 type;
        int factor;
        int i;
 
        if (!(bargs->flags & BTRFS_BALANCE_ARGS_DEVID))
                return 0;
 
-       if (btrfs_chunk_type(leaf, chunk) & (BTRFS_BLOCK_GROUP_DUP |
-            BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10)) {
-               factor = num_stripes / 2;
-       } else if (btrfs_chunk_type(leaf, chunk) & BTRFS_BLOCK_GROUP_RAID5) {
-               factor = num_stripes - 1;
-       } else if (btrfs_chunk_type(leaf, chunk) & BTRFS_BLOCK_GROUP_RAID6) {
-               factor = num_stripes - 2;
-       } else {
-               factor = num_stripes;
-       }
+       type = btrfs_chunk_type(leaf, chunk);
+       factor = calc_data_stripes(type, num_stripes);
 
        for (i = 0; i < num_stripes; i++) {
                stripe = btrfs_stripe_nr(chunk, i);