btrfs: remove the unused parameter @len for btrfs_bio_fits_in_stripe()

The parameter @len is not really used in btrfs_bio_fits_in_stripe(),
just remove it.

It got removed in 420343131970 ("btrfs: let callers of
btrfs_get_io_geometry pass the em"), before that btrfs_get_chunk_map
utilized it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e020447..80e9627 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6127,17 +6127,17 @@ static bool need_full_stripe(enum btrfs_map_op op)
  * @em:      mapping containing the logical extent
  * @op:      type of operation - write or read
  * @logical: address that we want to figure out the geometry of
- * @len:     the length of IO we are going to perform, starting at @logical
  * @io_geom: pointer used to return values
  *
  * Returns < 0 in case a chunk for the given logical address cannot be found,
  * usually shouldn't happen unless @logical is corrupted, 0 otherwise.
  */
 int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, struct extent_map *em,
-			  enum btrfs_map_op op, u64 logical, u64 len,
+			  enum btrfs_map_op op, u64 logical,
 			  struct btrfs_io_geometry *io_geom)
 {
 	struct map_lookup *map;
+	u64 len;
 	u64 offset;
 	u64 stripe_offset;
 	u64 stripe_nr;
@@ -6243,7 +6243,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 	em = btrfs_get_chunk_map(fs_info, logical, *length);
 	ASSERT(!IS_ERR(em));
 
-	ret = btrfs_get_io_geometry(fs_info, em, op, logical, *length, &geom);
+	ret = btrfs_get_io_geometry(fs_info, em, op, logical, &geom);
 	if (ret < 0)
 		return ret;