ecryptfs: convert to file_write_and_wait in ->fsync

This change is mainly for documentation/completeness, as ecryptfs never
calls mapping_set_error, and so will never return a previous writeback
error.

Signed-off-by: Jeff Layton <jlayton@redhat.com>

fs/ecryptfs/file.c

@@ -328,7 +328,7 @@ ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
 	int rc;
 
-	rc = filemap_write_and_wait(file->f_mapping);
+	rc = file_write_and_wait(file);
 	if (rc)
 		return rc;