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Date:   Sun, 14 Aug 2022 11:35:35 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Keith Busch <kbusch@fb.com>
Cc:     axboe@kernel.dk, io-uring@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, Keith Busch <kbusch@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] fs: don't randomized kiocb fields
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On Fri, Aug 12, 2022 at 03:56:33PM -0700, Keith Busch wrote:
>  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
>  };

Now that I've read the thread ...

If we care about struct size on 32-bit, we should fit something into
the 32-bit hole before the 64-bit loff_t (assuming at least some 32-bit
arches want loff_t to be 64-bit aligned; I thik x86 doesn't?)
Easiest seems to be to put ki_complete before ki_pos?