Re: zero out blocks of freed user data for operation a virtual machine environment

Theodore Tso
2009-05-25T12:03:44Z

On Sun, May 24, 2009 at 07:39:33PM +0200, Thomas Glanzmann wrote:
> Hello,
>
> > > tunable feature that zeroes our free data
>
> > wouldn't it be better if the VM's would just support the TRIM command?
>
> the resources available to me indicate that the TRIM command is a not
> yet standarized command targeted at SSD disks to indicate free disk
> space. Does ext3/4 trigger a block device layer call that could result
> in a TRIM command?

Yes, it does, sb_issue_discard(). So if you wanted to hook into this
routine with a function which issued calls to zero out blocks, it
would be easy to create a private patch.

- Ted