Btrfs: early work to file_write in big extents
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index e2fc6f0..6b76fd9 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1249,6 +1249,60 @@
return ret;
}
+int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
+ *root, struct btrfs_path *path, u32 data_size)
+{
+ int ret = 0;
+ int slot;
+ int slot_orig;
+ struct btrfs_leaf *leaf;
+ struct buffer_head *leaf_buf;
+ u32 nritems;
+ unsigned int data_end;
+ unsigned int old_data;
+ unsigned int old_size;
+ int i;
+
+ slot_orig = path->slots[0];
+ leaf_buf = path->nodes[0];
+ leaf = btrfs_buffer_leaf(leaf_buf);
+
+ nritems = btrfs_header_nritems(&leaf->header);
+ data_end = leaf_data_end(root, leaf);
+
+ if (btrfs_leaf_free_space(root, leaf) < data_size)
+ BUG();
+ slot = path->slots[0];
+ old_data = btrfs_item_end(leaf->items + slot);
+
+ BUG_ON(slot < 0);
+ BUG_ON(slot >= nritems);
+
+ /*
+ * item0..itemN ... dataN.offset..dataN.size .. data0.size
+ */
+ /* first correct the data pointers */
+ for (i = slot; i < nritems; i++) {
+ u32 ioff = btrfs_item_offset(leaf->items + i);
+ btrfs_set_item_offset(leaf->items + i,
+ ioff - data_size);
+ }
+ /* shift the data */
+ btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
+ data_end - data_size, btrfs_leaf_data(leaf) +
+ data_end, old_data - data_end);
+ data_end = old_data;
+ old_size = btrfs_item_size(leaf->items + slot);
+ btrfs_set_item_size(leaf->items + slot, old_size + data_size);
+ btrfs_mark_buffer_dirty(leaf_buf);
+
+ ret = 0;
+ if (btrfs_leaf_free_space(root, leaf) < 0)
+ BUG();
+ check_leaf(root, path, 0);
+ return ret;
+}
+
/*
* Given a key and some data, insert an item into the tree.
* This does all the path init required, making room in the tree if needed.