Btrfs: very simple readdir readahead

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f96bd92155cc2d183a2323c3f115f8f113991ef4..e76fcd80db6a45fce3f127c0ef789aeba6c37067 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -332,6 +332,34 @@ static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
        return d_splice_alias(inode, dentry);
 }
 
+static void reada_leaves(struct btrfs_root *root, struct btrfs_path *path)
+{
+       struct buffer_head *bh;
+       struct btrfs_node *node;
+       int i;
+       int nritems;
+       u64 objectid;
+       u64 item_objectid;
+       u64 blocknr;
+       int slot;
+
+       if (!path->nodes[1])
+               return;
+       node = btrfs_buffer_node(path->nodes[1]);
+       slot = path->slots[1];
+       objectid = btrfs_disk_key_objectid(&node->ptrs[slot].key);
+       nritems = btrfs_header_nritems(&node->header);
+       for (i = slot; i < nritems; i++) {
+               item_objectid = btrfs_disk_key_objectid(&node->ptrs[i].key);
+               if (item_objectid != objectid)
+                       break;
+               blocknr = btrfs_node_blockptr(node, i);
+               bh = sb_getblk(root->fs_info->sb, blocknr);
+               ll_rw_block(READ, 1, &bh);
+               brelse(bh);
+       }
+
+}
 static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 {
        struct inode *inode = filp->f_path.dentry->d_inode;
@@ -358,6 +386,7 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
                goto err;
        }
        advance = 0;
+       reada_leaves(root, &path);
        while(1) {
                leaf = btrfs_buffer_leaf(path.nodes[0]);
                nritems = btrfs_header_nritems(&leaf->header);
@@ -370,13 +399,8 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
                                leaf = btrfs_buffer_leaf(path.nodes[0]);
                                nritems = btrfs_header_nritems(&leaf->header);
                                slot = path.slots[0];
-#if 0
-                               page_cache_readahead(
-                                    inode->i_sb->s_bdev->bd_inode->i_mapping,
-                                    &filp->f_ra, filp,
-                                    path.nodes[0]->b_blocknr >>
-                                    (PAGE_CACHE_SHIFT - inode->i_blkbits), 1);
-#endif
+                               if (path.nodes[1] && path.slots[1] == 0)
+                                       reada_leaves(root, &path);
                        } else {
                                slot++;
                                path.slots[0]++;