From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Re: [RFC 1/2] MD: raid5 trim support Date: Tue, 17 Apr 2012 11:16:12 -0700 Message-ID: References: <20120417083552.483324288@kernel.org> <20120417084632.306032602@kernel.org> <4F8D871E.2050403@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <4F8D871E.2050403@kernel.org> Sender: linux-raid-owner@vger.kernel.org To: Shaohua Li Cc: linux-raid@vger.kernel.org, neilb@suse.de, axboe@kernel.dk, Shaohua Li List-Id: linux-raid.ids On Tue, Apr 17, 2012 at 8:07 AM, Shaohua Li wrote: > Hi Dan, > > On 4/17/12 10:46 PM, Dan Williams wrote: >> >> On Tue, Apr 17, 2012 at 1:35 AM, Shaohua Li =A0wrot= e: >>> >>> Discard for raid4/5/6 has limitation. If discard request size is sm= all, >>> we do >>> discard for one disk, but we need calculate parity and write parity= disk. >>> =A0To >>> correctly calculate parity, zero_after_discard must be guaranteed. >> >> >> I'm wondering if we could use the new bad blocks facility to mark >> discarded ranges so we don't necessarily need determinate data after >> discard. > > > It would be great the limitation can be avoided and the code can be > simplified. I didn't follow linux-raid maillist, can you point me the= url > of the new bad blocks facility please? It came in at 3.1 starting with: commit 2230dfe4ccc3add340dc6d437965b2de1d269fde Author: NeilBrown Date: Thu Jul 28 11:31:46 2011 +1000 md: beginnings of bad block management. This the first step in allowing md to track bad-blocks per-device s= o that we can fail individual blocks rather than the whole device. This patch just adds a data structure for recording bad blocks, wit= h routines to add, remove, search the list. Signed-off-by: NeilBrown Reviewed-by: Namhyung Kim Here is a link to the patch set: http://marc.info/?l=3Dlinux-raid&m=3D131121721902900&w=3D2 -- Dan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html