btrfs: cleanup extent buffer readahead

We're going to pass around more information when we allocate extent
buffers, in order to make that cleaner how we do readahead.  Most of the
callers have the parent node that we're getting our blockptr from, with
the sole exception of relocation which simply has the bytenr it wants to
read.

Add a helper that takes the current arguments that we need (bytenr and
gen), and add another helper for simply reading the slot out of a node.
In followup patches the helper that takes all the extra arguments will
be expanded, and the simpler helper won't need to have it's arguments
adjusted.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index ed4163b54f75..814abc0b3ff3 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -7071,12 +7071,8 @@ static void readahead_tree_node_children(struct extent_buffer *node)
 	int i;
 	const int nr_items = btrfs_header_nritems(node);
 
-	for (i = 0; i < nr_items; i++) {
-		u64 start;
-
-		start = btrfs_node_blockptr(node, i);
-		readahead_tree_block(node->fs_info, start);
-	}
+	for (i = 0; i < nr_items; i++)
+		btrfs_readahead_node_child(node, i);
 }
 
 int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)