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| author | Darrick J. Wong <djwong@us.ibm.com> | 2012-04-29 18:47:10 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-04-29 18:47:10 -0400 |
| commit | 5c359a47e7d999a0ea7f397da2c15590d0a82815 (patch) | |
| tree | f104bbabd12d6ac422bf80a6c477b803102ed3c7 | |
| parent | feb0ab32a57e4e6c8b24f6fb68f0ce08efe4603c (diff) | |
| download | linux-5c359a47e7d999a0ea7f397da2c15590d0a82815.tar.bz2 | |
ext4: add checksums to the MMP block
Compute and verify a checksum for the MMP block.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/ext4.h | 3 | ||||
| -rw-r--r-- | fs/ext4/mmp.c | 44 |
2 files changed, 42 insertions, 5 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 84e76bb96070..0ee9669394f5 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2413,6 +2413,9 @@ extern int ext4_bio_write_page(struct ext4_io_submit *io, /* mmp.c */ extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t); +extern void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp); +extern int ext4_mmp_csum_verify(struct super_block *sb, + struct mmp_struct *mmp); /* BH_Uninit flag: blocks are allocated but uninitialized on disk */ enum ext4_state_bits { diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c index ed6548d89165..f99a1311e847 100644 --- a/fs/ext4/mmp.c +++ b/fs/ext4/mmp.c @@ -6,12 +6,45 @@ #include "ext4.h" +/* Checksumming functions */ +static __u32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp) +{ + struct ext4_sb_info *sbi = EXT4_SB(sb); + int offset = offsetof(struct mmp_struct, mmp_checksum); + __u32 csum; + + csum = ext4_chksum(sbi, sbi->s_csum_seed, (char *)mmp, offset); + + return cpu_to_le32(csum); +} + +int ext4_mmp_csum_verify(struct super_block *sb, struct mmp_struct *mmp) +{ + if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) + return 1; + + return mmp->mmp_checksum == ext4_mmp_csum(sb, mmp); +} + +void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp) +{ + if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) + return; + + mmp->mmp_checksum = ext4_mmp_csum(sb, mmp); +} + /* * Write the MMP block using WRITE_SYNC to try to get the block on-disk * faster. */ -static int write_mmp_block(struct buffer_head *bh) +static int write_mmp_block(struct super_block *sb, struct buffer_head *bh) { + struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data); + + ext4_mmp_csum_set(sb, mmp); mark_buffer_dirty(bh); lock_buffer(bh); bh->b_end_io = end_buffer_write_sync; @@ -59,7 +92,8 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh, } mmp = (struct mmp_struct *)((*bh)->b_data); - if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC) + if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC || + !ext4_mmp_csum_verify(sb, mmp)) return -EINVAL; return 0; @@ -120,7 +154,7 @@ static int kmmpd(void *data) mmp->mmp_time = cpu_to_le64(get_seconds()); last_update_time = jiffies; - retval = write_mmp_block(bh); + retval = write_mmp_block(sb, bh); /* * Don't spew too many error messages. Print one every * (s_mmp_update_interval * 60) seconds. @@ -200,7 +234,7 @@ static int kmmpd(void *data) mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN); mmp->mmp_time = cpu_to_le64(get_seconds()); - retval = write_mmp_block(bh); + retval = write_mmp_block(sb, bh); failed: kfree(data); @@ -299,7 +333,7 @@ skip: seq = mmp_new_seq(); mmp->mmp_seq = cpu_to_le32(seq); - retval = write_mmp_block(bh); + retval = write_mmp_block(sb, bh); if (retval) goto failed; |