Re: BTRFS file clone support for cp

[Jim Meyering]

Pádraig Brady wrote:
> Giuseppe Scrivano wrote:
>> Pádraig Brady <address@hidden> writes:
>>
>>>> +#expensive_
>>> That comment is just for testing I presume?
>>> Note you can run a single expensive test like:
>>> (cd tests && make check TESTS=cp/file-clone VERBOSE=yes 
>>> RUN_EXPENSIVE_TESTS=yes)
>>
>> sorry, yes I commented it out only for testing purpose.  If you think
>> the rest is fine and want to push it, can you please amend my commit?
>
> Sure I'll fix it up from here.
> I'll not push yet though, until the interface settles down.
> I.E. we'll probably need to be calling {cp,ln} --reflink instead.

I am now convinced that cp's new behavior belongs on
a separate option, --reflink (i.e., it should not be the default).
Giuseppe, do you feel like adding that option and adjusting your
test accordingly?

Things to adjust, other than copy.c and the test:
  NEWS
  cp --help
  doc/coreutils.texi

For now, let's continue to use the ioctl,
but eventually we'll use the reflinkat syscall.