Re: [GIT PULL] overlayfs update for 4.18

[Miklos Szeredi]

On Tue, May 29, 2018 at 4:12 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> On Tue, May 29, 2018 at 3:59 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:

>>>       vfs: export vfs_dedupe_file_range_one() to modules
>>
>> Please use EXPORT_SYMBOL_GPL for all these crazy low-level exports.

I'd argue with the "crazy" part.  This should have been the primary
interface from the start.  The batched dedupe interface is the crazy
one:

 - deduping is page size granularity at worst; performance would not
be horrible even if we had to do one syscall per page
 - vast majority of the time it will be file size granularity

Why was that batching invented in the first place?

Thanks,
Miklos