From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:48798) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SiHBY-0006pB-MT for qemu-devel@nongnu.org; Fri, 22 Jun 2012 23:38:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SiHBX-00038G-4j for qemu-devel@nongnu.org; Fri, 22 Jun 2012 23:38:56 -0400 Received: from parsec.stupidest.org ([71.6.196.126]:55285) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SiHBW-000387-Uz for qemu-devel@nongnu.org; Fri, 22 Jun 2012 23:38:55 -0400 Date: Fri, 22 Jun 2012 20:38:51 -0700 From: Chris Wedgwood Message-ID: <20120623033851.GA10913@puku.stupidest.org> References: <1340319857-28198-1-git-send-email-mdroth@linux.vnet.ibm.com> <1340319857-28198-3-git-send-email-mdroth@linux.vnet.ibm.com> <20120622174856.GA6505@puku.stupidest.org> <20120622211224.GA3020@illuin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120622211224.GA3020@illuin> Subject: Re: [Qemu-devel] [PATCH 2/2] qemu-ga: add guest-fstrim command List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Roth Cc: pbonzini@redhat.com, aliguori@us.ibm.com, qemu-devel@nongnu.org > I'm not sure I understand, wouldn't the filesystem need to be involved > at some level? How can the block layer differentiate lazilly discarded data > blocks from ones that are still in use without the aid of the > filesystem? It might be me that doesn't understand. Yes, the filesystem is involved. Current linux filesystems can trim on demand or using fstrim. That mechanism seems to be like it should suffice if exposed in the most common cases.