u64 ntfs_lookup_inode_by_name (ntfs_inode * dir_ni, const ntfschar * uname, const int uname_len);
Look for an inode with name uname in the directory with inode dir_ni. ntfs_lookup_inode_by_name walks the contents of the directory looking for the Unicode name. If the name is found in the directory, the corresponding inode number (>= 0) is returned as a mft reference in cpu format, i.e. it is a 64-bit number containing the sequence number.
On error, a negative value is returned corresponding to the error code. In particular if the inode is not found -ENOENT is returned. Note that you can't just check the return value for being negative, you have to check the inode number for being negative which you can extract using MREC(return value).
Note, uname_len does not include the (optional) terminating NULL character.