From nobody Sat Feb 7 17:09:41 2026 Received: from smtp-fw-52004.amazon.com (smtp-fw-52004.amazon.com [52.119.213.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ADBE012BF03; Thu, 15 Feb 2024 15:50:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.119.213.154 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708012224; cv=none; b=qwTuVPjAeHqU2ehFzWlY8vIMTcPirw1MlpVFAnNpsNtTG7AJ30RgN7UvDfKZX+bwe8yGAmW/byjIxH+R3JxNAUc7Yf9Ysz8LOkoeZ4t48vIHG8g2xh7dI2POjFBx3uIkz9gc/dRiNlCB+GVmP6DDDsOeDI7mEUAHwlzfQ0EzK6w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708012224; c=relaxed/simple; bh=nRsOhffUEUuRhmS+8HSepxdFjF49Sg5dDRzWq3AYXBE=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=JJYJ1uPq/keTl2HajSCH4zyigDxc6OQDqdKzwbqZmvqRPCkf7DSE4E4zTO2gvhiJwppqIago4jfeGPPyXlr/olTB1Chqq4xlRonziRru8yOYCIyXFDdFh+sh3ENXz4jdfM9xM4U26oFmGuXkapAR4eYM/rOaBePpphIwc/v8ezw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.de; spf=pass smtp.mailfrom=amazon.de; dkim=pass (1024-bit key) header.d=amazon.de header.i=@amazon.de header.b=O/EJRg6V; arc=none smtp.client-ip=52.119.213.154 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.de header.i=@amazon.de header.b="O/EJRg6V" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazon201209; t=1708012223; x=1739548223; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=GOmRYqtgssrc+Ztwxp13mDL5XOVk9YlZb1c27Zd3aaQ=; b=O/EJRg6VuRkk0gEkOELFMHYz8MUZ2/N/ODw/BoVaRuNI2L0h2CT6ocEw GCLEfS2bJqyFzXWyylqL6tU9dCt08gzUZOtMc2Wdd/9JipyQbvse0Punu OBuccVuL2f39HGPu59oC2gnSJHQn8YP0ik7i3+iCkCFR3x3I6V4u1YvqB Q=; X-IronPort-AV: E=Sophos;i="6.06,162,1705363200"; d="scan'208";a="185053725" Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.43.8.2]) by smtp-border-fw-52004.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Feb 2024 15:50:20 +0000 Received: from EX19MTAUWC002.ant.amazon.com [10.0.21.151:31897] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.60.209:2525] with esmtp (Farcaster) id 129ec688-a7b3-4980-8268-483dcdf08da3; Thu, 15 Feb 2024 15:50:18 +0000 (UTC) X-Farcaster-Flow-ID: 129ec688-a7b3-4980-8268-483dcdf08da3 Received: from EX19D001UWA002.ant.amazon.com (10.13.138.236) by EX19MTAUWC002.ant.amazon.com (10.250.64.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Thu, 15 Feb 2024 15:50:18 +0000 Received: from EX19MTAUWB001.ant.amazon.com (10.250.64.248) by EX19D001UWA002.ant.amazon.com (10.13.138.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Thu, 15 Feb 2024 15:50:18 +0000 Received: from dev-dsk-mheyne-1b-c1362c4d.eu-west-1.amazon.com (10.15.57.183) by mail-relay.amazon.com (10.250.64.254) with Microsoft SMTP Server id 15.2.1118.40 via Frontend Transport; Thu, 15 Feb 2024 15:50:18 +0000 Received: by dev-dsk-mheyne-1b-c1362c4d.eu-west-1.amazon.com (Postfix, from userid 5466572) id F14604266; Thu, 15 Feb 2024 15:50:17 +0000 (UTC) From: Maximilian Heyne To: CC: , Maximilian Heyne , , Theodore Ts'o , Andreas Dilger , Yongqiang Yang , , Subject: [PATCH v2] ext4: fix corruption during on-line resize Date: Thu, 15 Feb 2024 15:50:09 +0000 Message-ID: <20240215155009.94493-1-mheyne@amazon.de> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" We observed a corruption during on-line resize of a file system that is larger than 16 TiB with 4k block size. With having more then 2^32 blocks resize_inode is turned off by default by mke2fs. The issue can be reproduced on a smaller file system for convenience by explicitly turning off resize_inode. An on-line resize across an 8 GiB boundary (the size of a meta block group in this setup) then leads to a corruption: dev=3D/dev/ # should be >=3D 16 GiB mkdir -p /corruption /sbin/mke2fs -t ext4 -b 4096 -O ^resize_inode $dev $((2 * 2**21 - 2**15)) mount -t ext4 $dev /corruption dd if=3D/dev/zero bs=3D4096 of=3D/corruption/test count=3D$((2*2**21 - 4*= 2**15)) sha1sum /corruption/test # 79d2658b39dcfd77274e435b0934028adafaab11 /corruption/test /sbin/resize2fs $dev $((2*2**21)) # drop page cache to force reload the block from disk echo 1 > /proc/sys/vm/drop_caches sha1sum /corruption/test # 3c2abc63cbf1a94c9e6977e0fbd72cd832c4d5c3 /corruption/test 2^21 =3D 2^15*2^6 equals 8 GiB whereof 2^15 is the number of blocks per block group and 2^6 are the number of block groups that make a meta block group. The last checksum might be different depending on how the file is laid out across the physical blocks. The actual corruption occurs at physical block 63*2^15 =3D 2064384 which would be the location of the backup of the meta block group's block descriptor. During the on-line resize the file system will be converted to meta_bg starting at s_first_meta_bg which is 2 in the example - meaning all block groups after 16 GiB. However, in ext4_flex_group_add we might add block groups that are not part of the first meta block group yet. In the reproducer we achieved this by substracting the size of a whole block group from the point where the meta block group would start. This must be considered when updating the backup block group descriptors to follow the non-meta_bg layout. The fix is to add a test whether the group to add is already part of the meta block group or not. Fixes: 01f795f9e0d67 ("ext4: add online resizing support for meta_bg and 64= -bit file systems") Cc: stable@vger.kernel.org Signed-off-by: Maximilian Heyne --- fs/ext4/resize.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 4d4a5a32e310..3c0d12382e06 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -1602,7 +1602,8 @@ static int ext4_flex_group_add(struct super_block *sb, int gdb_num =3D group / EXT4_DESC_PER_BLOCK(sb); int gdb_num_end =3D ((group + flex_gd->count - 1) / EXT4_DESC_PER_BLOCK(sb)); - int meta_bg =3D ext4_has_feature_meta_bg(sb); + int meta_bg =3D ext4_has_feature_meta_bg(sb) && + gdb_num >=3D le32_to_cpu(es->s_first_meta_bg); sector_t padding_blocks =3D meta_bg ? 0 : sbi->s_sbh->b_blocknr - ext4_group_first_block_no(sb, 0); =20 --=20 2.40.1 Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879