Btrfs: progress on file_write
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 6b76fd9..43d4779 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1249,6 +1249,63 @@
return ret;
}
+int btrfs_truncate_item(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ u32 new_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_start;
+ unsigned int old_size;
+ unsigned int size_diff;
+ 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);
+
+ slot = path->slots[0];
+ old_data_start = btrfs_item_offset(leaf->items + slot);
+ old_size = btrfs_item_size(leaf->items + slot);
+ BUG_ON(old_size <= new_size);
+ size_diff = old_size - new_size;
+
+ 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 + size_diff);
+ }
+ /* shift the data */
+printk("truncate item, new_size %u old_size %u, diff %u, bufp %p, dst, %p, num %u, old_data_start %u, data_end %u\n", new_size, old_size, size_diff, leaf, btrfs_leaf_data(leaf) + data_end + size_diff, old_data_start-data_end, old_data_start, data_end);
+ btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
+ data_end + size_diff, btrfs_leaf_data(leaf) +
+ data_end, old_data_start + new_size - data_end);
+ btrfs_set_item_size(leaf->items + slot, new_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;
+}
+
int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, u32 data_size)
{