Re: [PATCH 4/7] xfs: Implement fallocate query support mode

[Florian Weimer <fweimer@redhat.com>]

On 09/19/2017 05:55 PM, Christoph Hellwig wrote:
> On Tue, Sep 19, 2017 at 10:55:20AM -0400, Theodore Ts'o wrote:
>> Maybe the right answer is we should define a new pathconfat(2) system
>> call which can be used as part of a C library's implementation of
>> pathconf() and fpathconf()?  glibc probably won't use it for years, of
>> course.  But we can at least provide the information via an interface
>> which we can control, and which is capable of returning correct
>> results?
> 
> glibc is very fast at picking up new kernel interface these days
> as long as they aren't too controversial.  Implementing a syscall
> that backs a function they implement should not be in the controversial
> category I think.

We have a significant backlog, but I don't expect opposition to patches 
implementing syscall wrappers which are just slightly generic (and 
pathconfat should really be fine).

Technically, pathconfat might be tricky to maintain if it's expected to 
be a variadic dispatcher function, and the accompanying UAPI header 
isn't very clean.

Thanks,
Florian