fs: don't randomize struct kiocb fields

This is a size sensitive structure and randomizing can introduce extra
padding that breaks io_uring's fixed size expectations. There are few
fields here as it is, half of which need a fixed order to optimally
pack, so the randomization isn't providing much.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/io-uring/b6f508ca-b1b2-5f40-7998-e4cff1cf7212@kernel.dk/
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9f131e5..daf69a6 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -339,17 +339,12 @@ enum rw_hint {
 
 struct kiocb {
        struct file             *ki_filp;
-
-       /* The 'ki_filp' pointer is shared in a union for aio */
-       randomized_struct_fields_start
-
        loff_t                  ki_pos;
        void (*ki_complete)(struct kiocb *iocb, long ret);
        void                    *private;
        int                     ki_flags;
        u16                     ki_ioprio; /* See linux/ioprio.h */
        struct wait_page_queue  *ki_waitq; /* for async buffered IO */
-       randomized_struct_fields_end
 };
 
 static inline bool is_sync_kiocb(struct kiocb *kiocb)