Btrfs: do less aggressive btree readahead

[linux-2.6-omap-h63xx.git] / fs / btrfs / ctree.c

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 9e46c07768167f53f9ae0c9b6ffdb5ce8641f56e..2603ee539b7ae100f0677ffbe9bd6ebc392652e4 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1210,8 +1210,7 @@ static noinline void reada_for_search(struct btrfs_root *root,
        struct btrfs_disk_key disk_key;
        u32 nritems;
        u64 search;
-       u64 lowest_read;
-       u64 highest_read;
+       u64 target;
        u64 nread = 0;
        int direction = path->reada;
        struct extent_buffer *eb;
@@ -1235,8 +1234,7 @@ static noinline void reada_for_search(struct btrfs_root *root,
                return;
        }
 
-       highest_read = search;
-       lowest_read = search;
+       target = search;
 
        nritems = btrfs_header_nritems(node);
        nr = slot;
@@ -1256,24 +1254,15 @@ static noinline void reada_for_search(struct btrfs_root *root,
                                break;
                }
                search = btrfs_node_blockptr(node, nr);
-               if ((search >= lowest_read && search <= highest_read) ||
-                   (search < lowest_read && lowest_read - search <= 16384) ||
-                   (search > highest_read && search - highest_read <= 16384)) {
+               if ((search <= target && target - search <= 65536) ||
+                   (search > target && search - target <= 65536)) {
                        readahead_tree_block(root, search, blocksize,
                                     btrfs_node_ptr_generation(node, nr));
                        nread += blocksize;
                }
                nscan++;
-               if (path->reada < 2 && (nread > (64 * 1024) || nscan > 32))
+               if ((nread > 65536 || nscan > 32))
                        break;
-
-               if (nread > (256 * 1024) || nscan > 128)
-                       break;
-
-               if (search < lowest_read)
-                       lowest_read = search;
-               if (search > highest_read)
-                       highest_read = search;
        }
 }