fuse: check fallocate mode

Don't allow new fallocate modes until we figure out what (if anything) that
takes.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

fs/fuse/file.c

@@ -2972,6 +2972,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 	bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) ||
 			   (mode & FALLOC_FL_PUNCH_HOLE);
 
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+		return -EOPNOTSUPP;
+
 	if (fc->no_fallocate)
 		return -EOPNOTSUPP;