[PATCH, RFC] xfs: batched discard support

[Jamie Lokier]

Christoph Hellwig wrote:
> > So i'm torn about the 'syscall versus ioctl' issue, i'd 
> > like to avoid making interface design mistakes and i'd 
> > like to solicit some opinions about this. I've attached 
> > the perfcounters ioctl patch below.
> 
> Only add a syscall if it has _one_ clear defined purpose,
> which has kernel-wide meaning.

One clear defined purpose which comes to mind is a "trim" or "punch"
system call, for making holes in files as well as trimming block
devices.  Several other OSes have that capability on files.

I don't remember - does TRIM guarantee the blocks read zeros afterwards?

It would be tidy if it does, as it could have the same meaning with files.

-- Jamie