btrfs: remove stripe size local variable from insert_dev_extents()

It's not needed to have a local variable to store the stripe size at
insert_dev_extents(), we can just take from the chunk map as it's only
used once and typing 'map->stripe_size' is not much more verbose than
simply typing 'stripe_size'. So remove the local variable.

This was added before the recent addition of a dedicated structure for
chunk mappings because the stripe size was encoded in the 'orig_block_len'
field of an extent_map structure, so the use of the local variable made
things more readable.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-group.c

@@ -2597,7 +2597,6 @@ static int insert_dev_extents(struct btrfs_trans_handle *trans,
 	struct btrfs_device *device;
 	struct btrfs_chunk_map *map;
 	u64 dev_offset;
-	u64 stripe_size;
 	int i;
 	int ret = 0;
 
@@ -2605,8 +2604,6 @@ static int insert_dev_extents(struct btrfs_trans_handle *trans,
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
-	stripe_size = map->stripe_size;
-
 	/*
 	 * Take the device list mutex to prevent races with the final phase of
 	 * a device replace operation that replaces the device object associated
@@ -2622,7 +2619,7 @@ static int insert_dev_extents(struct btrfs_trans_handle *trans,
 		dev_offset = map->stripes[i].physical;
 
 		ret = insert_dev_extent(trans, device, chunk_offset, dev_offset,
-				       stripe_size);
+					map->stripe_size);
 		if (ret)
 			break;
 	}