ext4: validate the debug_want_extra_isize mount option at parse time
Instead of setting s_want_extra_size and then making sure that it is a valid value afterwards, validate the field before we set it. This avoids races and other problems when remounting the file system. Link: https://lore.kernel.org/r/20191215063020.GA11512@mit.edu Cc: stable@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reported-and-tested-by: syzbot+4a39a025912b265cacef@syzkaller.appspotmail.com
This commit is contained in:
Theodore Ts'o
parent
a70fd5ac2e
commit
9803387c55
143
fs/ext4/super.c
143
fs/ext4/super.c
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@ -1886,6 +1886,13 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
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}
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sbi->s_commit_interval = HZ * arg;
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} else if (token == Opt_debug_want_extra_isize) {
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if ((arg & 1) ||
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(arg < 4) ||
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(arg > (sbi->s_inode_size - EXT4_GOOD_OLD_INODE_SIZE))) {
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ext4_msg(sb, KERN_ERR,
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"Invalid want_extra_isize %d", arg);
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return -1;
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}
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sbi->s_want_extra_isize = arg;
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} else if (token == Opt_max_batch_time) {
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sbi->s_max_batch_time = arg;
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@ -3540,40 +3547,6 @@ int ext4_calculate_overhead(struct super_block *sb)
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return 0;
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}
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static void ext4_clamp_want_extra_isize(struct super_block *sb)
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{
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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struct ext4_super_block *es = sbi->s_es;
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unsigned def_extra_isize = sizeof(struct ext4_inode) -
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EXT4_GOOD_OLD_INODE_SIZE;
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if (sbi->s_inode_size == EXT4_GOOD_OLD_INODE_SIZE) {
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sbi->s_want_extra_isize = 0;
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return;
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}
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if (sbi->s_want_extra_isize < 4) {
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sbi->s_want_extra_isize = def_extra_isize;
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if (ext4_has_feature_extra_isize(sb)) {
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if (sbi->s_want_extra_isize <
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le16_to_cpu(es->s_want_extra_isize))
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sbi->s_want_extra_isize =
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le16_to_cpu(es->s_want_extra_isize);
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if (sbi->s_want_extra_isize <
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le16_to_cpu(es->s_min_extra_isize))
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sbi->s_want_extra_isize =
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le16_to_cpu(es->s_min_extra_isize);
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}
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}
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/* Check if enough inode space is available */
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if ((sbi->s_want_extra_isize > sbi->s_inode_size) ||
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(EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >
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sbi->s_inode_size)) {
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sbi->s_want_extra_isize = def_extra_isize;
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ext4_msg(sb, KERN_INFO,
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"required extra inode space not available");
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}
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}
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static void ext4_set_resv_clusters(struct super_block *sb)
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{
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ext4_fsblk_t resv_clusters;
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@ -3781,6 +3754,68 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
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*/
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sbi->s_li_wait_mult = EXT4_DEF_LI_WAIT_MULT;
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if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
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sbi->s_inode_size = EXT4_GOOD_OLD_INODE_SIZE;
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sbi->s_first_ino = EXT4_GOOD_OLD_FIRST_INO;
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} else {
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sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
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sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
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if (sbi->s_first_ino < EXT4_GOOD_OLD_FIRST_INO) {
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ext4_msg(sb, KERN_ERR, "invalid first ino: %u",
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sbi->s_first_ino);
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goto failed_mount;
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}
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if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) ||
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(!is_power_of_2(sbi->s_inode_size)) ||
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(sbi->s_inode_size > blocksize)) {
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ext4_msg(sb, KERN_ERR,
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"unsupported inode size: %d",
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sbi->s_inode_size);
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goto failed_mount;
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}
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/*
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* i_atime_extra is the last extra field available for
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* [acm]times in struct ext4_inode. Checking for that
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* field should suffice to ensure we have extra space
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* for all three.
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*/
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if (sbi->s_inode_size >= offsetof(struct ext4_inode, i_atime_extra) +
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sizeof(((struct ext4_inode *)0)->i_atime_extra)) {
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sb->s_time_gran = 1;
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sb->s_time_max = EXT4_EXTRA_TIMESTAMP_MAX;
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} else {
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sb->s_time_gran = NSEC_PER_SEC;
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sb->s_time_max = EXT4_NON_EXTRA_TIMESTAMP_MAX;
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}
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sb->s_time_min = EXT4_TIMESTAMP_MIN;
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}
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if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
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sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
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EXT4_GOOD_OLD_INODE_SIZE;
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if (ext4_has_feature_extra_isize(sb)) {
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unsigned v, max = (sbi->s_inode_size -
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EXT4_GOOD_OLD_INODE_SIZE);
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v = le16_to_cpu(es->s_want_extra_isize);
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if (v > max) {
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ext4_msg(sb, KERN_ERR,
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"bad s_want_extra_isize: %d", v);
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goto failed_mount;
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}
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if (sbi->s_want_extra_isize < v)
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sbi->s_want_extra_isize = v;
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v = le16_to_cpu(es->s_min_extra_isize);
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if (v > max) {
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ext4_msg(sb, KERN_ERR,
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"bad s_min_extra_isize: %d", v);
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goto failed_mount;
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}
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if (sbi->s_want_extra_isize < v)
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sbi->s_want_extra_isize = v;
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}
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}
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if (sbi->s_es->s_mount_opts[0]) {
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char *s_mount_opts = kstrndup(sbi->s_es->s_mount_opts,
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sizeof(sbi->s_es->s_mount_opts),
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@ -4019,42 +4054,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
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has_huge_files);
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sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits, has_huge_files);
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if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
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sbi->s_inode_size = EXT4_GOOD_OLD_INODE_SIZE;
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sbi->s_first_ino = EXT4_GOOD_OLD_FIRST_INO;
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} else {
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sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
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sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
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if (sbi->s_first_ino < EXT4_GOOD_OLD_FIRST_INO) {
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ext4_msg(sb, KERN_ERR, "invalid first ino: %u",
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sbi->s_first_ino);
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goto failed_mount;
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}
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if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) ||
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(!is_power_of_2(sbi->s_inode_size)) ||
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(sbi->s_inode_size > blocksize)) {
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ext4_msg(sb, KERN_ERR,
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"unsupported inode size: %d",
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sbi->s_inode_size);
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goto failed_mount;
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}
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/*
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* i_atime_extra is the last extra field available for [acm]times in
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* struct ext4_inode. Checking for that field should suffice to ensure
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* we have extra space for all three.
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*/
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if (sbi->s_inode_size >= offsetof(struct ext4_inode, i_atime_extra) +
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sizeof(((struct ext4_inode *)0)->i_atime_extra)) {
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sb->s_time_gran = 1;
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sb->s_time_max = EXT4_EXTRA_TIMESTAMP_MAX;
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} else {
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sb->s_time_gran = NSEC_PER_SEC;
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sb->s_time_max = EXT4_NON_EXTRA_TIMESTAMP_MAX;
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}
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sb->s_time_min = EXT4_TIMESTAMP_MIN;
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}
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sbi->s_desc_size = le16_to_cpu(es->s_desc_size);
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if (ext4_has_feature_64bit(sb)) {
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if (sbi->s_desc_size < EXT4_MIN_DESC_SIZE_64BIT ||
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@ -4503,8 +4502,6 @@ no_journal:
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} else if (ret)
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goto failed_mount4a;
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ext4_clamp_want_extra_isize(sb);
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ext4_set_resv_clusters(sb);
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err = ext4_setup_system_zone(sb);
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@ -5292,8 +5289,6 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
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goto restore_opts;
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}
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ext4_clamp_want_extra_isize(sb);
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if ((old_opts.s_mount_opt & EXT4_MOUNT_JOURNAL_CHECKSUM) ^
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test_opt(sb, JOURNAL_CHECKSUM)) {
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ext4_msg(sb, KERN_ERR, "changing journal_checksum "
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