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Date: Mon, 25 May 2009 11:26:15 -0600 From: Chris Worley <worleys@...il.com> To: LKML <linux-kernel@...r.kernel.org>, linux-ext4@...r.kernel.org Subject: RE: zero out blocks of freed user data for operation a virtual machine environment On Mon, May 25, 2009 at 7:14 AM, Goswin von Brederlow <goswin-v-b@....de> wrote: > Thomas Glanzmann <thomas@...nzmann.de> writes: > > Hello Ted, > > > >> 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. > > > > that sounds good because it wouldn't only target the most used > > filesystem but every other filesystem that uses the interface as well. > > Do you think that a tunable or configurable patch has a chance to hit > > upstream as well? > > > > Thomas > > I could imagine a device mapper target that eats TRIM commands and > writes out zeroes instead. That should be easy to maintain outside or > inside the upstream kernel source. Why bother with a time-consuming performance-draining operation? There are devices that already support TRIM/discard commands today, and once you discard a block, it's completely irretrievable (you'll just get back zeros if you try to read that block w/o writing it after the discard). Chris > > > MfG > Goswin -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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