btrfs: remove unused btrfs_is_parity_mirror()

btrfs_is_parity_mirror() has been unused since commit 4886ff7
("btrfs: introduce a new helper to submit write bio for repair").
Remove it as the code was refactored and we don't need the helper
anymore.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -5963,24 +5963,6 @@ unsigned long btrfs_full_stripe_len(struct btrfs_fs_info *fs_info,
 	return len;
 }
 
-int btrfs_is_parity_mirror(struct btrfs_fs_info *fs_info, u64 logical, u64 len)
-{
-	struct btrfs_chunk_map *map;
-	int ret = 0;
-
-	if (!btrfs_fs_incompat(fs_info, RAID56))
-		return 0;
-
-	map = btrfs_get_chunk_map(fs_info, logical, len);
-
-	if (!WARN_ON(IS_ERR(map))) {
-		if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
-			ret = 1;
-		btrfs_free_chunk_map(map);
-	}
-	return ret;
-}
-
 static int find_live_mirror(struct btrfs_fs_info *fs_info,
 			    struct btrfs_chunk_map *map, int first,
 			    int dev_replace_is_ongoing)

fs/btrfs/volumes.h

@@ -741,8 +741,6 @@ int btrfs_run_dev_stats(struct btrfs_trans_handle *trans);
 void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_device *srcdev);
 void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev);
 void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev);
-int btrfs_is_parity_mirror(struct btrfs_fs_info *fs_info,
-			   u64 logical, u64 len);
 unsigned long btrfs_full_stripe_len(struct btrfs_fs_info *fs_info,
 				    u64 logical);
 u64 btrfs_calc_stripe_length(const struct btrfs_chunk_map *map);