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, 9 insertions, 36 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index d2d5854d51a7..0ff866328a4f 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2226,7 +2226,7 @@ static void reada_for_search(struct btrfs_fs_info *fs_info,
 		search = btrfs_node_blockptr(node, nr);
 		if ((search <= target && target - search <= 65536) ||
 		    (search > target && search - target <= 65536)) {
-			readahead_tree_block(fs_info, search);
+			btrfs_readahead_node_child(node, nr);
 			nread += blocksize;
 		}
 		nscan++;
@@ -2235,16 +2235,11 @@ static void reada_for_search(struct btrfs_fs_info *fs_info,
 	}
 }
 
-static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
-				       struct btrfs_path *path, int level)
+static noinline void reada_for_balance(struct btrfs_path *path, int level)
 {
+	struct extent_buffer *parent;
 	int slot;
 	int nritems;
-	struct extent_buffer *parent;
-	struct extent_buffer *eb;
-	u64 gen;
-	u64 block1 = 0;
-	u64 block2 = 0;
 
 	parent = path->nodes[level + 1];
 	if (!parent)
@@ -2253,32 +2248,10 @@ static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
 	nritems = btrfs_header_nritems(parent);
 	slot = path->slots[level + 1];
 
-	if (slot > 0) {
-		block1 = btrfs_node_blockptr(parent, slot - 1);
-		gen = btrfs_node_ptr_generation(parent, slot - 1);
-		eb = find_extent_buffer(fs_info, block1);
-		/*
-		 * if we get -eagain from btrfs_buffer_uptodate, we
-		 * don't want to return eagain here.  That will loop
-		 * forever
-		 */
-		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
-			block1 = 0;
-		free_extent_buffer(eb);
-	}
-	if (slot + 1 < nritems) {
-		block2 = btrfs_node_blockptr(parent, slot + 1);
-		gen = btrfs_node_ptr_generation(parent, slot + 1);
-		eb = find_extent_buffer(fs_info, block2);
-		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
-			block2 = 0;
-		free_extent_buffer(eb);
-	}
-
-	if (block1)
-		readahead_tree_block(fs_info, block1);
-	if (block2)
-		readahead_tree_block(fs_info, block2);
+	if (slot > 0)
+		btrfs_readahead_node_child(parent, slot - 1);
+	if (slot + 1 < nritems)
+		btrfs_readahead_node_child(parent, slot + 1);
 }
 
 
@@ -2454,7 +2427,7 @@ setup_nodes_for_search(struct btrfs_trans_handle *trans,
 			goto again;
 		}
 
-		reada_for_balance(fs_info, p, level);
+		reada_for_balance(p, level);
 		sret = split_node(trans, root, p, level);
 
 		BUG_ON(sret > 0);
@@ -2473,7 +2446,7 @@ setup_nodes_for_search(struct btrfs_trans_handle *trans,
 			goto again;
 		}
 
-		reada_for_balance(fs_info, p, level);
+		reada_for_balance(p, level);
 		sret = balance_level(trans, root, p, level);
 
 		if (sret) {