Re: [PATCH 3/3] f2fs: support clone_file_range

[Christoph Hellwig]

On Sat, Jul 16, 2016 at 11:24:27PM -0700, Jaegeuk Kim wrote:
> This patch implements clone_file_range in f2fs.

[...]

> +int f2fs_clone_file_range(struct file *file_in, loff_t pos_in,
> +		struct file *file_out, loff_t pos_out, u64 len)
> +{
> +	return f2fs_clone_files(file_in, pos_in, file_out, pos_out, len);
> +}
> +

Falling back from copy to clone should be done in the VFS.  I look into
implementing the fallback, and the code is trivial, but we don't seem
to have any useful coverage for copy_file_range yet, so I didn't dare
to add it yet.  How did you test copy and clone in f2fs?  And how did
you handle the difference in corner cases (e.g. the lacking 0 special
case in copy)?