+/**
+ * __btrfs_delalloc_reserve_space - reserve data and metadata space for
+ * delalloc
+ * @inode: inode we're writing to
+ * @start: start range we are writing to
+ * @len: how long the range we are writing to
+ *
+ * TODO: This function will finally replace old btrfs_delalloc_reserve_space()
+ *
+ * This will do the following things
+ *
+ * o reserve space in data space info for num bytes
+ * and reserve precious corresponding qgroup space
+ * (Done in check_data_free_space)
+ *
+ * o reserve space for metadata space, based on the number of outstanding
+ * extents and how much csums will be needed
+ * also reserve metadata space in a per root over-reserve method.
+ * o add to the inodes->delalloc_bytes
+ * o add it to the fs_info's delalloc inodes list.
+ * (Above 3 all done in delalloc_reserve_metadata)
+ *
+ * Return 0 for success
+ * Return <0 for error(-ENOSPC or -EQUOT)
+ */
+int __btrfs_delalloc_reserve_space(struct inode *inode, u64 start, u64 len)
+{
+ int ret;
+
+ ret = __btrfs_check_data_free_space(inode, start, len);
+ if (ret < 0)
+ return ret;
+ ret = btrfs_delalloc_reserve_metadata(inode, len);
+ if (ret < 0)
+ __btrfs_free_reserved_data_space(inode, start, len);
+ return ret;
+}
+