From: Lukas Czerner Subject: Re: Is it deliberate that the device mapper is not passing the DISCARD ioctls Date: Tue, 21 Sep 2010 12:42:25 +0200 (CEST) Message-ID: References: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: linux-ext4@vger.kernel.org, dm-devel@redhat.com To: "Theodore Ts'o" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:4277 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752522Ab0IUKmf (ORCPT ); Tue, 21 Sep 2010 06:42:35 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, 20 Sep 2010, Theodore Ts'o wrote: > Hi there, > > I was just testing discard support in mke2fs, and I was surprised that > although the dm layer appears to pass discard requests through to the > underlying block device driver when submitted through the bio layer > (i.e., from kernel file systems), apparently the discard ioctls (i.e., > BLKDISCARD, BLKDISCARDSEC, BLKDISCARDZEROES) are not currently wired up > in the dm layer. > > Is this deliberate, or an oversight? > > Thanks, regards, Hi Ted, I have tested this with 2.6.35 and it really did not work for me as well, but with 2.6.36-rc5 (latests kernel) it works just fine. Though, not sure when it was added. But according to the log it seems it was merged in with 8357422d4bf33bc2c35884d4016c3fc9efbbc1d2. -Lukas > > - Ted > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >