From: "Jose R. Santos" Subject: [PATCH 01/13][e2fsprogs] Add initial checksum support. Date: Thu, 11 Oct 2007 14:16:05 -0500 Message-ID: <20071011191605.4599.34407.stgit@gara> References: <20071011191559.4599.69332.stgit@gara> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit To: linux-ext4@vger.kernel.org Return-path: Received: from e34.co.us.ibm.com ([32.97.110.152]:41994 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751632AbXJKTP4 (ORCPT ); Thu, 11 Oct 2007 15:15:56 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e34.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id l9BJFqWT010832 for ; Thu, 11 Oct 2007 15:15:52 -0400 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id l9BJFqif478860 for ; Thu, 11 Oct 2007 13:15:52 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l9BJFqwj015937 for ; Thu, 11 Oct 2007 13:15:52 -0600 Received: from austin.ibm.com (netmail2.austin.ibm.com [9.41.248.176]) by d03av03.boulder.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id l9BJFpgW015916 for ; Thu, 11 Oct 2007 13:15:51 -0600 Received: from [127.0.1.1] (wecm-9-67-39-149.wecm.ibm.com [9.67.39.149]) by austin.ibm.com (8.13.8/8.12.10) with ESMTP id l9BJFolR040718 for ; Thu, 11 Oct 2007 14:15:51 -0500 In-Reply-To: <20071011191559.4599.69332.stgit@gara> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org From: Jose R. Santos Add initial checksum support. - Add support for computing CRC-16 value. - Add call to check/verify/set csum on block_groups. - Add a test program to verify csum operations. Signed-off-by: Jose R. Santos -- lib/ext2fs/Makefile.in | 23 ++++++- lib/ext2fs/crc16.c | 60 +++++++++++++++++++ lib/ext2fs/crc16.h | 29 +++++++++ lib/ext2fs/csum.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++++ lib/ext2fs/ext2fs.h | 7 ++ lib/ext2fs/tst_csum.c | 113 ++++++++++++++++++++++++++++++++++++ 6 files changed, 378 insertions(+), 3 deletions(-) diff --git a/lib/ext2fs/Makefile.in b/lib/ext2fs/Makefile.in index 03ce131..847fe23 100644 --- a/lib/ext2fs/Makefile.in +++ b/lib/ext2fs/Makefile.in @@ -66,7 +66,9 @@ OBJS= $(DEBUGFS_LIB_OBJS) $(RESIZE_LIB_OBJS) $(E2IMAGE_LIB_OBJS) \ unix_io.o \ unlink.o \ valid_blk.o \ - version.o + version.o \ + crc16.o \ + csum.o SRCS= ext2_err.c \ $(srcdir)/alloc.c \ @@ -132,7 +134,10 @@ SRCS= ext2_err.c \ $(srcdir)/tst_bitops.c \ $(srcdir)/tst_byteswap.c \ $(srcdir)/tst_getsize.c \ - $(srcdir)/tst_iscan.c + $(srcdir)/tst_iscan.c \ + $(srcdir)/tst_csum.c \ + $(srcdir)/crc16.c \ + $(srcdir)/csum.c HFILES= bitops.h ext2fs.h ext2_io.h ext2_fs.h ext2_ext_attr.h ext3_extents.h \ tdb.h @@ -239,17 +244,23 @@ ext2_tdbtool: tdbtool.o @echo " LD $@" @$(CC) -o ext2_tdbtool tdbtool.o tdb.o +tst_csum: tst_csum.o csum.o crc16.o $(STATIC_LIBEXT2FS) + @echo " LD $@" + @$(CC) -o tst_csum csum.o tst_csum.o crc16.o $(STATIC_LIBEXT2FS) \ + $(LIBCOM_ERR) + mkjournal: mkjournal.c $(STATIC_LIBEXT2FS) @echo " LD $@" @$(CC) -o mkjournal $(srcdir)/mkjournal.c -DDEBUG $(STATIC_LIBEXT2FS) $(LIBCOM_ERR) $(ALL_CFLAGS) -check:: tst_bitops tst_badblocks tst_iscan tst_types tst_icount tst_super_size +check:: tst_bitops tst_badblocks tst_iscan tst_types tst_icount tst_super_size tst_types tst_csum LD_LIBRARY_PATH=$(LIB) DYLD_LIBRARY_PATH=$(LIB) ./tst_bitops LD_LIBRARY_PATH=$(LIB) DYLD_LIBRARY_PATH=$(LIB) ./tst_badblocks LD_LIBRARY_PATH=$(LIB) DYLD_LIBRARY_PATH=$(LIB) ./tst_iscan LD_LIBRARY_PATH=$(LIB) DYLD_LIBRARY_PATH=$(LIB) ./tst_types LD_LIBRARY_PATH=$(LIB) DYLD_LIBRARY_PATH=$(LIB) ./tst_icount LD_LIBRARY_PATH=$(LIB) DYLD_LIBRARY_PATH=$(LIB) ./tst_super_size + LD_LIBRARY_PATH=$(LIB) DYLD_LIBRARY_PATH=$(LIB) ./tst_csum installdirs:: @echo " MKINSTALLDIRS $(libdir) $(includedir)/ext2fs" @@ -357,6 +368,10 @@ closefs.o: $(srcdir)/closefs.c $(srcdir)/ext2_fs.h \ $(srcdir)/ext2fs.h $(srcdir)/ext2_fs.h $(srcdir)/ext3_extents.h \ $(top_srcdir)/lib/et/com_err.h $(srcdir)/ext2_io.h \ $(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/bitops.h +crc16.o: $(srcdir)/crc16.c $(srcdir)/ext2_fs.h $(srcdir)/crc16.h \ + $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h $(srcdir)/ext2_fs.h +csum.o: $(srcdir)/csum.c $(srcdir)/ext2_fs.h \ + $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h $(srcdir)/ext2_fs.h dblist.o: $(srcdir)/dblist.c $(srcdir)/ext2_fs.h \ $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fsP.h \ $(srcdir)/ext2fs.h $(srcdir)/ext2_fs.h $(srcdir)/ext3_extents.h \ @@ -571,3 +586,5 @@ tst_iscan.o: $(srcdir)/tst_iscan.c $(srcdir)/ext2_fs.h \ $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h \ $(srcdir)/ext2_fs.h $(srcdir)/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \ $(srcdir)/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/bitops.h +tst_csum.o: $(srcdir)/tst_csum.c $(srcdir)/ext2_fs.h \ + $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h diff --git a/lib/ext2fs/crc16.c b/lib/ext2fs/crc16.c new file mode 100644 index 0000000..c3d07e1 --- /dev/null +++ b/lib/ext2fs/crc16.c @@ -0,0 +1,60 @@ +/* + * crc16.c + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + +#include +#include "crc16.h" + +/** CRC table for the CRC-16. The poly is 0x8005 (x16 + x15 + x2 + 1) */ +uint16_t const crc16_table[256] = { + 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, + 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440, + 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, + 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841, + 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, + 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41, + 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, + 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040, + 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, + 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441, + 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, + 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, + 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, + 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40, + 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, + 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041, + 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, + 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441, + 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, + 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840, + 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, + 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40, + 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, + 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041, + 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, + 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440, + 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, + 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, + 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, + 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, + 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, + 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040 +}; + +/** + * Compute the CRC-16 for the data buffer + * + * @param crc previous CRC value + * @param buffer data pointer + * @param len number of bytes in the buffer + * @return the updated CRC value + */ +uint16_t crc16(uint16_t crc, unsigned char const *buffer, size_t len) +{ + while (len--) + crc = crc16_byte(crc, *buffer++); + return crc; +} diff --git a/lib/ext2fs/crc16.h b/lib/ext2fs/crc16.h new file mode 100644 index 0000000..7f6913e --- /dev/null +++ b/lib/ext2fs/crc16.h @@ -0,0 +1,29 @@ +/* + * crc16.h - CRC-16 routine + * + * Implements the standard CRC-16: + * Width 16 + * Poly 0x8005 (x16 + x15 + x2 + 1) + * Init 0 + * + * Copyright (c) 2005 Ben Gardner + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + +#ifndef __CRC16_H +#define __CRC16_H + +#include + +extern uint16_t const crc16_table[256]; + +extern uint16_t crc16(uint16_t crc, const unsigned char *buffer, size_t len); + +static inline uint16_t crc16_byte(uint16_t crc, const unsigned char data) +{ + return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff]; +} + +#endif /* __CRC16_H */ diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c new file mode 100644 index 0000000..cba320c --- /dev/null +++ b/lib/ext2fs/csum.c @@ -0,0 +1,149 @@ +/* + * csum.c --- checksumming of ext3 structures + * + * Copyright (C) 2006 Cluster File Systems, Inc. + * + * %Begin-Header% + * This file may be redistributed under the terms of the GNU Public + * License. + * %End-Header% + */ + +#include "ext2_fs.h" +#include "ext2fs.h" +#include + +#ifndef offsetof +#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) +#endif + +__u16 ext2fs_group_desc_csum(struct ext2_super_block *sb, __u32 group, + struct ext2_group_desc *desc) +{ + __u16 crc = 0; + + if (sb->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) { + int offset = offsetof(struct ext2_group_desc, bg_checksum); + +#ifdef WORDS_BIGENDIAN + struct ext2_group_desc swabdesc = *desc; + + /* Have to swab back to little-endian to do the checksum */ + ext2fs_swab_group_desc(swabdesc); + desc = &swabdesc; + + group = ext2fs_swab32(group); +#endif + crc = crc16(~0, sb->s_uuid, sizeof(sb->s_uuid)); + crc = crc16(crc, &group, sizeof(group)); + crc = crc16(crc, desc, offset); + offset += sizeof(desc->bg_checksum); /* skip checksum */ + assert(offset == sizeof(*desc)); /* XXX handle s_desc_size */ + /* for checksum of struct ext4_group_desc do the rest...*/ + if (offset < sb->s_desc_size) { + crc = crc16(crc, (char *)desc + offset, + sb->s_desc_size - offset); + } + } + + return crc; +} + +int ext2fs_group_desc_csum_verify(struct ext2_super_block *sb, __u32 group, + struct ext2_group_desc *desc) +{ + if (desc->bg_checksum != ext2fs_group_desc_csum(sb, group, desc)) + return 0; + + return 1; +} + +static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap, + __u32 inodes_per_grp, dgrp_t grp_no) +{ + ext2_ino_t i, start_ino, end_ino; + + start_ino = grp_no * inodes_per_grp + 1; + end_ino = start_ino + inodes_per_grp - 1; + + for (i = end_ino; i >= start_ino; i--) { + if (ext2fs_fast_test_inode_bitmap(bitmap, i)) + return i - start_ino + 1; + } + return inodes_per_grp; +} + +/* update the bitmap flags, set the itable high watermark, and calculate + * checksums for the group descriptors */ +void ext2fs_set_gdt_csum(ext2_filsys fs) +{ + struct ext2_super_block *sb = fs->super; + struct ext2_group_desc *bg = fs->group_desc; + int blks, lazy_flag, csum_flag, dirty = 0; + dgrp_t i; + + csum_flag = EXT2_HAS_RO_COMPAT_FEATURE(fs->super, + EXT4_FEATURE_RO_COMPAT_GDT_CSUM); + if (!EXT2_HAS_COMPAT_FEATURE(fs->super, + EXT2_FEATURE_COMPAT_LAZY_BG) && !csum_flag) + return; + + for (i = 0; i < fs->group_desc_count; i++, bg++) { + int old_csum = bg->bg_checksum; + + /* Even if it wasn't zeroed, by the time this function is + * called by e2fsck we have already scanned and corrected + * the whole inode table so we may as well not overwrite it. + * This is just a hint to the kernel that it could do lazy + * zeroing of the inode table if mke2fs didn't do it, to help + * out if we need to do a full itable scan sometime later. */ + if (!(bg->bg_flags & (EXT2_BG_INODE_UNINIT | + EXT2_BG_INODE_ZEROED))) { + fs->group_desc[i].bg_flags |= EXT2_BG_INODE_ZEROED; + dirty = 1; + } + + if (bg->bg_free_inodes_count == sb->s_inodes_per_group && + i > 0 && (i < fs->group_desc_count - 1 || csum_flag)) { + if (!(bg->bg_flags & EXT2_BG_INODE_UNINIT)) { + bg->bg_flags |= EXT2_BG_INODE_UNINIT; + dirty = 1; + } + if (csum_flag) { + int old_unused = bg->bg_itable_unused; + bg->bg_itable_unused = sb->s_inodes_per_group; + if (old_unused != bg->bg_itable_unused) + dirty = 1; + } + } else if (csum_flag) { + int old_unused = bg->bg_itable_unused; + bg->bg_flags &= ~EXT2_BG_INODE_UNINIT; + bg->bg_itable_unused = sb->s_inodes_per_group - + find_last_inode_ingrp(fs->inode_map, + sb->s_inodes_per_group,i); + if (old_unused != bg->bg_itable_unused) + dirty = 1; + } + + /* skip first and last groups, or groups with GDT backups + * because the resize inode has blocks allocated in them. */ + if (i == 0 || (i == fs->group_desc_count - 1 && !csum_flag) || + (ext2fs_bg_has_super(fs, i) && sb->s_reserved_gdt_blocks)) + goto checksum; + + blks = ext2fs_super_and_bgd_loc(fs, i, 0, 0, 0, 0); + if (bg->bg_free_blocks_count == blks && + bg->bg_flags & EXT2_BG_INODE_UNINIT && + !(bg->bg_flags & EXT2_BG_BLOCK_UNINIT)) { + bg->bg_flags |= EXT2_BG_BLOCK_UNINIT; + dirty = 1; + } +checksum: + bg->bg_checksum = + ext2fs_group_desc_csum(fs->super, i, bg); + if (old_csum != bg->bg_checksum) + dirty = 1; + } + if (dirty) + ext2fs_mark_super_dirty(fs); +} diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h index 83a9091..1267ee8 100644 --- a/lib/ext2fs/ext2fs.h +++ b/lib/ext2fs/ext2fs.h @@ -627,6 +627,13 @@ extern int ext2fs_super_and_bgd_loc(ext2_filsys fs, int *ret_meta_bg); extern void ext2fs_update_dynamic_rev(ext2_filsys fs); +/* csum.c */ +extern __u16 ext2fs_group_desc_csum(struct ext2_super_block *sb, __u32 group, + struct ext2_group_desc *desc); +extern int ext2fs_group_desc_csum_verify(struct ext2_super_block *sb, + __u32 group, struct ext2_group_desc *desc); +extern void ext2fs_set_gdt_csum(ext2_filsys fs); + /* dblist.c */ extern errcode_t ext2fs_get_num_dirs(ext2_filsys fs, ext2_ino_t *ret_num_dirs); diff --git a/lib/ext2fs/tst_csum.c b/lib/ext2fs/tst_csum.c new file mode 100644 index 0000000..6a6d99d --- /dev/null +++ b/lib/ext2fs/tst_csum.c @@ -0,0 +1,113 @@ +/* + * This testing program verifies checksumming operations + * + * Copyright (C) 2006, 2007 by Andreas Dilger + * + * %Begin-Header% + * This file may be redistributed under the terms of the GNU Public + * License. + * %End-Header% + */ + +#include "ext2fs/ext2_fs.h" +#include "ext2fs/ext2fs.h" + +#ifndef offsetof +#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) +#endif + +void print_csum(const char *msg, struct ext2_super_block *sb, + __u32 group, struct ext2_group_desc *desc) +{ + __u16 crc1, crc2, crc3; + __u32 swabgroup; + +#ifdef WORDS_BIGENDIAN + struct ext2_group_desc swabdesc = *desc; + + /* Have to swab back to little-endian to do the checksum */ + ext2fs_swab_group_desc(swabdesc); + desc = &swabdesc; + + swabgroup = ext2fs_swab32(group); +#else + swabgroup = group; +#endif + + crc1 = crc16(~0, sb->s_uuid, sizeof(sb->s_uuid)); + crc2 = crc16(crc1, &swabgroup, sizeof(swabgroup)); + crc3 = crc16(crc2, desc, offsetof(struct ext2_group_desc, bg_checksum)); + printf("%s: UUID %016Lx%016Lx(%04x), grp %u(%04x): %04x=%04x\n", + msg, *(long long *)&sb->s_uuid, *(long long *)&sb->s_uuid[8], + crc1, group, crc2, crc3, ext2fs_group_desc_csum(sb, group,desc)); +} + +main(int argc, char **argv) +{ + struct ext2_group_desc desc = { .bg_block_bitmap = 124, + .bg_inode_bitmap = 125, + .bg_inode_table = 126, + .bg_free_blocks_count = 31119, + .bg_free_inodes_count = 15701, + .bg_used_dirs_count = 2, + .bg_flags = 0, + }; + struct ext2_super_block sb = { .s_feature_ro_compat = + EXT4_FEATURE_RO_COMPAT_GDT_CSUM, + .s_uuid = { 0x4f, 0x25, 0xe8, 0xcf, + 0xe7, 0x97, 0x48, 0x23, + 0xbe, 0xfa, 0xa7, 0x88, + 0x4b, 0xae, 0xec, 0xdb } }; + __u16 csum1, csum2, csum_known = 0xd3a4; + + csum1 = ext2fs_group_desc_csum(&sb, 0, &desc); + print_csum("csum0000", &sb, 0, &desc); + +#ifdef WORDS_BIGENDIAN + csum_known = ext2fs_swab16(known); +#endif + if (csum1 != csum_known) { + printf("checksum for group 0 should be %04x\n", csum_known); + exit(1); + } + csum2 = ext2fs_group_desc_csum(&sb, 1, &desc); + print_csum("csum0001", &sb, 1, &desc); + if (csum1 == csum2) { + printf("checksums for different groups shouldn't match\n"); + exit(1); + } + csum2 = ext2fs_group_desc_csum(&sb, 0xffff, &desc); + print_csum("csumffff", &sb, 0xffff, &desc); + if (csum1 == csum2) { + printf("checksums for different groups shouldn't match\n"); + exit(1); + } + desc.bg_checksum = csum1; + csum2 = ext2fs_group_desc_csum(&sb, 0, &desc); + print_csum("csum_set", &sb, 0, &desc); + if (csum1 != csum2) { + printf("checksums should not depend on checksum field\n"); + exit(1); + } + if (!ext2fs_group_desc_csum_verify(&sb, 0, &desc)) { + printf("checksums should verify against gd_checksum\n"); + exit(1); + } + memset(sb.s_uuid, 0x30, sizeof(sb.s_uuid)); + print_csum("new_uuid", &sb, 0, &desc); + if (ext2fs_group_desc_csum_verify(&sb, 0, &desc) != 0) { + printf("checksums for different filesystems shouldn't match\n"); + exit(1); + } + csum1 = desc.bg_checksum = ext2fs_group_desc_csum(&sb, 0, &desc); + print_csum("csum_new", &sb, 0, &desc); + desc.bg_free_blocks_count = 1; + csum2 = ext2fs_group_desc_csum(&sb, 0, &desc); + print_csum("csum_blk", &sb, 0, &desc); + if (csum1 == csum2) { + printf("checksums for different data shouldn't match\n"); + exit(1); + } + + return 0; +}