From: Theodore Ts'o Subject: Re: [PATCH] mke2fs: restore verbose message for BLKDISCARD Date: Fri, 8 Mar 2013 14:00:19 -0500 Message-ID: <20130308190019.GB12008@thunk.org> References: <1362515118-30344-1-git-send-email-swarren@wwwdotorg.org> <5138EEBD.5000705@wwwdotorg.org> <513A1D56.1010402@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: =?utf-8?B?THVrw6HFoQ==?= Czerner , Chris Ball , linux-ext4@vger.kernel.org, Stephen Warren To: Stephen Warren Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:52018 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751426Ab3CHTA0 (ORCPT ); Fri, 8 Mar 2013 14:00:26 -0500 Content-Disposition: inline In-Reply-To: <513A1D56.1010402@wwwdotorg.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: I hate to suggest this, but there's so many crappy devices out there that I'm wondering if we need to figure out some way of maintaining a black list of devices that don't handle discard properly. For example, the Sandisk U100 advertises a max discard granularity of 512 bytes, but I've been advised that if you don't use a discard granularity of 256k, aligned on 256k, you'll be very, very, sorry. It sounds like Stephen's device is probably an example of Yet Another Busted Trim implementation. The problem is that manufacturers will be releasing more broken products faster than we can update a blacklist in the kernel. So any blacklist would have to be maintained online on the web, and dynamically updated by distro installers. :-( - Ted