Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754890Ab3CNJNQ (ORCPT ); Thu, 14 Mar 2013 05:13:16 -0400 Received: from mga03.intel.com ([143.182.124.21]:1740 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751141Ab3CNJNO (ORCPT ); Thu, 14 Mar 2013 05:13:14 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,843,1355126400"; d="cfg'?sh'?scan'208,223";a="270604223" Message-ID: <1363252425.11441.94.camel@sauron.fi.intel.com> Subject: Re: MTD : Kernel oops when remounting ubifs as read/write From: Artem Bityutskiy Reply-To: dedekind1@gmail.com To: Mark Jackson Cc: "linux-mtd@lists.infradead.org" , "linux-omap@vger.kernel.org" , lkml , adrian.hunter@intel.com Date: Thu, 14 Mar 2013 11:13:45 +0200 In-Reply-To: <51405F3A.3090901@mimc.co.uk> References: <5134CEF9.5070502@mimc.co.uk> <1363087506.3348.62.camel@sauron.fi.intel.com> <51405F3A.3090901@mimc.co.uk> Content-Type: multipart/mixed; boundary="=-YlVgXk/tIznaGNfH/Lkm" X-Mailer: Evolution 3.6.3 (3.6.3-2.fc18) Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7097 Lines: 230 --=-YlVgXk/tIznaGNfH/Lkm Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit On Wed, 2013-03-13 at 11:12 +0000, Mark Jackson wrote: > Sorry ... this just locks up the unit. OK, I've reproduced the issue with 3.9-rc2 in nandsim, see the details below. The patch I proposed did not get the error path correctly, but it does fix the issue. I think what you treat as "lockup" is the fixup process. UBIFS basically reads the entire UBI volume and writes it back. And it uses the atomic change UBI service, which means it also calculates CRC of everything it writes. And this all just takes a lot of time. This has to be done only once on the first mount. I've attached the following: 1. The patch which fixes the issue when I use nandsim. It is also inlined in the end. Please, give it a try and be more patient - wait longer. Please, do report your results back. 2. 'reproduce.sh' - a quick and dirty shell script which reproduces the problem 3. ubinize.cfg - is needed for 'reproduce.sh'. Thanks! >From a173f8e9296562e5ece3dd2936d799001897d6c6 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Thu, 14 Mar 2013 10:49:23 +0200 Subject: [PATCH] UBIFS: make space fixup work in the remount case The UBIFS space fixup is a useful feature which allows to fixup the "broken" flash space at the time of the first mount. The "broken" space is usually the result of using a "dumb" industrial flasher which is not able to skip empty NAND pages and just writes all 0xFFs to the empty space, which has grave side-effects for UBIFS when UBIFS trise to write useful data to those empty pages. The fix-up feature works roughly like this: 1. mkfs.ubifs sets the fixup flag in UBIFS superblock when creating the image (see -F option) 2. when the file-system is mounted for the first time, UBIFS notices the fixup flag and re-writes the entire media atomically, which may take really a lot of time. 3. UBIFS clears the fixup flag in the superblock. This works fine when the file system is mounted R/W for the very first time. But it did not really work in the case when we first mount the file-system R/O, and then re-mount R/W. The reason was that we started the fixup procedure too late, which we cannot really do because we have to fixup the space before it starts being used. Signed-off-by: Artem Bityutskiy Reported-by: Mark Jackson Cc: stable@vger.kernel.org # 3.0+ --- fs/ubifs/super.c | 13 +++++++------ 1 files changed, 7 insertions(+), 6 deletions(-) diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index ac838b8..fa4aec6 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -1568,10 +1568,17 @@ static int ubifs_remount_rw(struct ubifs_info *c) c->remounting_rw = 1; c->ro_mount = 0; + if (c->space_fixup) { + err = ubifs_fixup_free_space(c); + if (err) + return err; + } + err = check_free_space(c); if (err) goto out; + if (c->old_leb_cnt != c->leb_cnt) { struct ubifs_sb_node *sup; @@ -1684,12 +1691,6 @@ static int ubifs_remount_rw(struct ubifs_info *c) err = dbg_check_space_info(c); } - if (c->space_fixup) { - err = ubifs_fixup_free_space(c); - if (err) - goto out; - } - mutex_unlock(&c->umount_mutex); return err; -- 1.7.7.6 -- Best Regards, Artem Bityutskiy --=-YlVgXk/tIznaGNfH/Lkm Content-Disposition: attachment; filename="0001-UBIFS-make-space-fixup-work-in-the-remount-case.patch" Content-Type: text/x-patch; name="0001-UBIFS-make-space-fixup-work-in-the-remount-case.patch"; charset="UTF-8" Content-Transfer-Encoding: 7bit >From a173f8e9296562e5ece3dd2936d799001897d6c6 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Thu, 14 Mar 2013 10:49:23 +0200 Subject: [PATCH] UBIFS: make space fixup work in the remount case The UBIFS space fixup is a useful feature which allows to fixup the "broken" flash space at the time of the first mount. The "broken" space is usually the result of using a "dumb" industrial flasher which is not able to skip empty NAND pages and just writes all 0xFFs to the empty space, which has grave side-effects for UBIFS when UBIFS trise to write useful data to those empty pages. The fix-up feature works roughly like this: 1. mkfs.ubifs sets the fixup flag in UBIFS superblock when creating the image (see -F option) 2. when the file-system is mounted for the first time, UBIFS notices the fixup flag and re-writes the entire media atomically, which may take really a lot of time. 3. UBIFS clears the fixup flag in the superblock. This works fine when the file system is mounted R/W for the very first time. But it did not really work in the case when we first mount the file-system R/O, and then re-mount R/W. The reason was that we started the fixup procedure too late, which we cannot really do because we have to fixup the space before it starts being used. Signed-off-by: Artem Bityutskiy Cc: stable@vger.kernel.org # 3.0+ --- fs/ubifs/super.c | 13 +++++++------ 1 files changed, 7 insertions(+), 6 deletions(-) diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index ac838b8..fa4aec6 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -1568,10 +1568,17 @@ static int ubifs_remount_rw(struct ubifs_info *c) c->remounting_rw = 1; c->ro_mount = 0; + if (c->space_fixup) { + err = ubifs_fixup_free_space(c); + if (err) + return err; + } + err = check_free_space(c); if (err) goto out; + if (c->old_leb_cnt != c->leb_cnt) { struct ubifs_sb_node *sup; @@ -1684,12 +1691,6 @@ static int ubifs_remount_rw(struct ubifs_info *c) err = dbg_check_space_info(c); } - if (c->space_fixup) { - err = ubifs_fixup_free_space(c); - if (err) - goto out; - } - mutex_unlock(&c->umount_mutex); return err; -- 1.7.7.6 --=-YlVgXk/tIznaGNfH/Lkm Content-Type: application/x-shellscript; name="reproduce.sh" Content-Disposition: attachment; filename="reproduce.sh" Content-Transfer-Encoding: 7bit #!/bin/sh -euf umount /mnt/ubifs ||: rmmod ubifs ||: rmmod ubi ||: rmmod nandsim ||: modprobe nandsim first_id_byte=0x20 second_id_byte=0xaa third_id_byte=0x00 fourth_id_byte=0x15 modprobe ubi modprobe ubifs mkfs.ubifs -F -r /home/dedekind/bin -m 2048 -e 129024 -c 2047 -o ubifs.img ubinize -o ubi.img -m 2048 -p 128KiB -s 512 ubinize.cfg dd if=ubi.img of=/dev/mtd0 sync ubiattach -p /dev/mtd0 mount -t ubifs -o ro ubi0_0 /mnt/ubifs mount -o remount ubi0_0 /mnt/ubifs --=-YlVgXk/tIznaGNfH/Lkm Content-Disposition: attachment; filename="ubinize.cfg" Content-Type: text/plain; name="ubinize.cfg"; charset="UTF-8" Content-Transfer-Encoding: 7bit [ubifs] mode=ubi image=ubifs.img vol_id=0 vol_size=200MiB vol_type=dynamic vol_name=rootfs vol_flags=autoresize --=-YlVgXk/tIznaGNfH/Lkm-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/