Re: [PATCH 1/4] [RESEND] Btrfs: btrfs_dedupe_file_range() ioctl, remove 16MiB restriction

[David Sterba <dsterba@suse.cz>]

On Wed, Apr 25, 2018 at 02:37:14AM +0300, Timofey Titovets wrote:
> At now btrfs_dedupe_file_range() restricted to 16MiB range for
> limit locking time and memory requirement for dedup ioctl()
> 
> For too big input range code silently set range to 16MiB
> 
> Let's remove that restriction by do iterating over dedup range.
> That's backward compatible and will not change anything for request
> less then 16MiB.
> 
> Changes:
>   v1 -> v2:
>     - Refactor btrfs_cmp_data_prepare and btrfs_extent_same
>     - Store memory of pages array between iterations
>     - Lock inodes once, not on each iteration
>     - Small inplace cleanups

I think this patch should be split into more, there are several logical
changes mixed together.

I can add the patch to for-next to see if there are any problems caught
by the existing test, but will expect more revisions of the patch. I
don't see any fundamental problems so far.

Suggested changes:
* factor out __btrfs_extent_same
* adjust parameters if needed by the followup patches
* add the chunk counting logic
* any other cleanups