From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 50F2A7F66 for ; Mon, 9 Jun 2014 16:31:04 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay1.corp.sgi.com (Postfix) with ESMTP id 3D1678F806F for ; Mon, 9 Jun 2014 14:31:00 -0700 (PDT) Received: from sandeen.net (sandeen.net [63.231.237.45]) by cuda.sgi.com with ESMTP id gVP7wGHvmIIbx9DQ for ; Mon, 09 Jun 2014 14:30:59 -0700 (PDT) Message-ID: <53962792.6040000@sandeen.net> Date: Mon, 09 Jun 2014 16:30:58 -0500 From: Eric Sandeen MIME-Version: 1.0 Subject: [PATCH V2] xfs: fix crc field handling in xfs_sb_to/from_disk References: <5390F89C.2050305@redhat.com> In-Reply-To: <5390F89C.2050305@redhat.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Eric Sandeen , xfs-oss I discovered this in userspace, but the same change applies to the kernel. If we xfs_mdrestore an image from a non-crc filesystem, lo and behold the restored image has gained a CRC: # db/xfs_metadump.sh -o /dev/sdc1 - | xfs_mdrestore - test.img # xfs_db -c "sb 0" -c "p crc" /dev/sdc1 crc = 0 (correct) # xfs_db -c "sb 0" -c "p crc" test.img crc = 0xb6f8d6a0 (correct) This is because xfs_sb_from_disk doesn't fill in sb_crc, but xfs_sb_to_disk(XFS_SB_ALL_BITS) does write the in-memory CRC to disk - so we get uninitialized memory on disk. Fix this by always initializing sb_crc to 0 when we read the superblock, and masking out the CRC bit from ALL_BITS when we write it. Signed-off-by: Eric Sandeen --- diff --git a/fs/xfs/xfs_sb.c b/fs/xfs/xfs_sb.c index 8baf61a..d2ccb2e 100644 --- a/fs/xfs/xfs_sb.c +++ b/fs/xfs/xfs_sb.c @@ -450,6 +450,8 @@ xfs_sb_from_disk( to->sb_features_incompat = be32_to_cpu(from->sb_features_incompat); to->sb_features_log_incompat = be32_to_cpu(from->sb_features_log_incompat); + /* crc is only used on disk, not in memory; just init to 0 here. */ + to->sb_crc = 0; to->sb_pad = 0; to->sb_pquotino = be64_to_cpu(from->sb_pquotino); to->sb_lsn = be64_to_cpu(from->sb_lsn); @@ -527,6 +529,9 @@ xfs_sb_to_disk( if (!fields) return; + /* We should never write the crc here, it's updated in the IO path */ + fields &= ~XFS_SB_CRC; + xfs_sb_quota_to_disk(to, from, &fields); while (fields) { f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields); _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs