udf: Support splicing to file

Add explicit support for splicing from pipe to file through
iter_file_splice_write(). Commit 36e2c742 ("fs: don't allow splice
read/write without explicit ops") removed the default .splice_write
operation which effectively removed UDF support for splicing from pipe.

Fixes: 36e2c742 ("fs: don't allow splice read/write without explicit ops")
Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/r/202209081443.593ab12-yujie.liu@intel.comSigned-off-by: Jan Kara <jack@suse.cz>

fs/udf/file.c

@@ -252,6 +252,7 @@ const struct file_operations udf_file_operations = {
 	.release		= udf_release_file,
 	.fsync			= generic_file_fsync,
 	.splice_read		= generic_file_splice_read,
+	.splice_write		= iter_file_splice_write,
 	.llseek			= generic_file_llseek,
 };