On Wed, 03/09 08:43, Paolo Bonzini wrote:
> 
> 
> On 09/03/2016 04:35, Fam Zheng wrote:
> >> >  enum BdrvTrackedRequestType {
> >> >      BDRV_TRACKED_READ,
> >> >      BDRV_TRACKED_WRITE,
> >> > -    BDRV_TRACKED_FLUSH,
> >> > -    BDRV_TRACKED_IOCTL,
> >> >      BDRV_TRACKED_DISCARD,
> > Okay, so flush and ioctl are not needed, but why is discard different?
> 
> Discard can modify the contents of the device, so I think it's safer to
> serialize it against RMW and copy-on-read operations.

Okay, that makes sense, but ioctl like SG_IO can also modify content, no?

Fam

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