From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from a.ns.miles-group.at ([95.130.255.143] helo=radon.swed.at) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aQ9rT-0001vp-9H for linux-mtd@lists.infradead.org; Mon, 01 Feb 2016 08:29:29 +0000 Subject: Re: [PATCH 1/1] fs:ubifs:recovery:fixup UBIFS cannot recover master node issue To: =?UTF-8?B?QmVhbiBIdW8g6ZyN5paM5paMIChiZWFuaHVvKQ==?= , Artem Bityutskiy , Adrian Hunter , Brian Norris References: <566A9378.4070900@nod.at> <566F03AC.90305@nod.at> <56A9E00E.1070706@nod.at> Cc: "linux-mtd@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Boris Brezillon , =?UTF-8?B?UGV0ZXIgUGFuIOa9mOagiyAocGV0ZXJwYW5kb25nKQ==?= , =?UTF-8?B?S2FybCBaaGFuZyDlvKDlj4zplKMgKGthcmx6?= =?UTF-8?Q?hang=29?= , =?UTF-8?B?SmFzb24gVGlhbiDnlLDmmZPlvLogKGphc29udGlhbik=?= From: Richard Weinberger Message-ID: <56AF1749.2010806@nod.at> Date: Mon, 1 Feb 2016 09:28:57 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 8bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Bean, Am 01.02.2016 um 08:17 schrieb Bean Huo »ô±ó±ó (beanhuo): >> If you can explain in detail why UBIFS' assumptions are wrong and how such >> corruptions can happen on SLC we can talk. >> But I think then we'd have to redo a lot of UBI and UBIFS code. > > I will hack my patch again, and double check these strict checks. > But I still insist on Master node should always be recovered by another good master, > even if two corrupted pages exist in one block. This is more reasonable and reliable. > Of course, so far, we did not meet this scenario on SLC NAND. > Current UBIFS master node recovery mechanism totally can handle with > Power loss no matter MLC or SLC, why not let UBIFS more reliable? Two master node blocks > Just for SLC NAND? Of course, I'm all for improvements. But if you talk about "more reliable" you have to define first what the issue is. As I said, we have this strict checks for reasons and they did a very good service so far. I've seen a lot UBIFS corruptions where the master node was damaged but not a single time it was UBIFS' fault. It was always a subtle MTD driver issue. Thanks, //richard