Re: [PATCH v5.1 0/2] create BLKZEROOUT ioctl that invalidates page cache

[Arnd Bergmann]

On Wednesday 02 March 2016 01:44:16 Christoph Hellwig wrote:
> On Wed, Mar 02, 2016 at 10:15:02AM +0100, Arnd Bergmann wrote:
> > I'm missing the background on this, just saw the patch fly by,
> > so sorry if this has been asked before:
> > 
> > Why do you want to invalidate the cache? Is this to save RAM
> > or is something else going to write here and you have to invalidate
> > it for correctness?
> 
> BLKZEROOUT can be though as a direct I/O operation - it issues a 
> WRITE SAME (or similar) command straight to the device to zero
> the specified range.  If there was cached data for this range it would
> now be stale.

Ok, got it. Thanks,

	Arnd