Btrfs: very simple readdir readahead

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

1 files changed, 31 insertions, 7 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f96bd92155cc..e76fcd80db6a 100644
--- 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]++;