From: "Darrick J. Wong" Subject: [PATCH 03/22] ext4: Record the checksum algorithm in use in the superblock Date: Mon, 28 Nov 2011 15:26:36 -0800 Message-ID: <20111128232636.19194.92115.stgit@elm3c44.beaverton.ibm.com> References: <20111128232615.19194.80081.stgit@elm3c44.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Sunil Mushran , Martin K Petersen , Greg Freemyer , Amir Goldstein , linux-kernel , Andi Kleen , Mingming Cao , Joel Becker , linux-fsdevel , linux-ext4@vger.kernel.org, Coly Li To: Andreas Dilger , Theodore Tso , "Darrick J. Wong" Return-path: Received: from e33.co.us.ibm.com ([32.97.110.151]:34386 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755253Ab1K1X05 (ORCPT ); Mon, 28 Nov 2011 18:26:57 -0500 Received: from /spool/local by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 28 Nov 2011 16:26:55 -0700 In-Reply-To: <20111128232615.19194.80081.stgit@elm3c44.beaverton.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Record the type of checksum algorithm we're using for metadata in the superblock, in case we ever want/need to change the algorithm. Signed-off-by: Darrick J. Wong --- fs/ext4/ext4.h | 5 ++++- fs/ext4/super.c | 18 ++++++++++++++++++ 2 files changed, 22 insertions(+), 1 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 414c2f8..e496e72 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -982,6 +982,9 @@ extern void ext4_set_bits(void *bm, int cur, int len); #define EXT4_ERRORS_PANIC 3 /* Panic */ #define EXT4_ERRORS_DEFAULT EXT4_ERRORS_CONTINUE +/* Metadata checksum algorithm codes */ +#define EXT4_CRC32C_CHKSUM 1 + /* * Structure of the super block */ @@ -1068,7 +1071,7 @@ struct ext4_super_block { __le64 s_mmp_block; /* Block for multi-mount protection */ __le32 s_raid_stripe_width; /* blocks on all data disks (N*stride)*/ __u8 s_log_groups_per_flex; /* FLEX_BG group size */ - __u8 s_reserved_char_pad; + __u8 s_checksum_type; /* metadata checksum algorithm used */ __le16 s_reserved_pad; __le64 s_kbytes_written; /* nr of lifetime kilobytes written */ __le32 s_snapshot_inum; /* Inode number of active snapshot */ diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 3858767..a56c14e 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -111,6 +111,16 @@ static struct file_system_type ext3_fs_type = { #define IS_EXT3_SB(sb) (0) #endif +static int ext4_verify_csum_type(struct super_block *sb, + struct ext4_super_block *es) +{ + if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) + return 1; + + return es->s_checksum_type == EXT4_CRC32C_CHKSUM; +} + void *ext4_kvmalloc(size_t size, gfp_t flags) { void *ret; @@ -3182,6 +3192,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) goto cantfind_ext4; sbi->s_kbytes_written = le64_to_cpu(es->s_kbytes_written); + /* Check for a known checksum algorithm */ + if (!ext4_verify_csum_type(sb, es)) { + ext4_msg(sb, KERN_ERR, "VFS: Found ext4 filesystem with " + "unknown checksum algorithm."); + silent = 1; + goto cantfind_ext4; + } + /* Set defaults before we parse the mount options */ def_mount_opts = le32_to_cpu(es->s_default_mount_opts); set_opt(sb, INIT_INODE_TABLE);