Re: [PATCH 1/3] vfs: dedpue: return s64

[Matthew Wilcox]

On Mon, May 07, 2018 at 10:21:06AM +0200, Miklos Szeredi wrote:
> f_op->dedupe_file_range() gets a u64 length to dedup and returns an ssize_t
> actual length deduped.  This breaks badly on 32bit archs since the returned
> length will be truncated and possibly overflow into the sign bit (xfs and
> ocfs2 are affected, btrfs limits actual length to 16MiB).
> 
> Returning s64 should be good, since clone_verify_area() makes sure that the
> supplied length doesn't overflow.

Why s64 rather than loff_t?  Particularly since the next patch turns
the paramters into loff_t.