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

Lukas Czerner
2017-09-22T08:40:43Z

On Thu, Sep 21, 2017 at 03:54:01PM +0200, Florian Weimer wrote:
> On 09/20/2017 01:17 AM, Theodore Ts'o wrote:
> > There might be some tricky bits will be if glibc feels it needs to
> > override the values returned by the kernel (if it believes it may
> > impose some limitations due to its implementation). Also, not all
> > file systems will implement some or all pathconf parameters initially
> > (or perhaps ever). So should the VFS be responsible for returning
> > some intelligent defaults, or glibc?
>
> I'd prefer if we could export pathconfat directly on the glibc side, without
> any emulation, and have the application deal with ENOSYS.
>
> We would use it to implement parts of pathconf/fpathconf if available, but I
> don't think we should copy the existing emulation for pathconfat because
> every time we add such emulation, it comes back to haunt us.

Fair enough, I'll get back with some kernel code.

Thanks!
-Lukas