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    Subject[PATCH 22/22] jbd2: Checksum data blocks that are stored in the journal
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    Calculate and verify checksums of each data block being stored in the journal.

    Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
    ---
    fs/jbd2/commit.c | 22 ++++++++++++++++++++++
    fs/jbd2/journal.c | 10 ++++++++--
    fs/jbd2/recovery.c | 30 ++++++++++++++++++++++++++++++
    include/linux/jbd2.h | 1 +
    4 files changed, 61 insertions(+), 2 deletions(-)


    diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
    index e083e55..231a02f 100644
    --- a/fs/jbd2/commit.c
    +++ b/fs/jbd2/commit.c
    @@ -339,6 +339,26 @@ static void jbd2_descr_block_csum_set(journal_t *j,
    tail->t_checksum = cpu_to_be32(csum);
    }

    +static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
    + struct buffer_head *bh, __u32 sequence)
    +{
    + struct page *page = bh->b_page;
    + __u8 *addr;
    + __u32 csum;
    +
    + if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
    + return;
    +
    + sequence = cpu_to_be32(sequence);
    + addr = kmap_atomic(page, KM_USER0);
    + csum = jbd2_chksum(j, j->j_uuid_csum, (__u8 *)&sequence,
    + sizeof(sequence));
    + csum = jbd2_chksum(j, csum, addr + offset_in_page(bh->b_data),
    + bh->b_size);
    + kunmap_atomic(addr, KM_USER0);
    +
    + tag->t_checksum = cpu_to_be32(csum);
    +}
    /*
    * jbd2_journal_commit_transaction
    *
    @@ -649,6 +669,8 @@ void jbd2_journal_commit_transaction(journal_t *journal)
    tag = (journal_block_tag_t *) tagp;
    write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr);
    tag->t_flags = cpu_to_be32(tag_flag);
    + jbd2_block_tag_csum_set(journal, tag, jh2bh(new_jh),
    + commit_transaction->t_tid);
    tagp += tag_bytes;
    space_left -= tag_bytes;

    diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
    index bea3c6e..e7e414f 100644
    --- a/fs/jbd2/journal.c
    +++ b/fs/jbd2/journal.c
    @@ -1989,10 +1989,16 @@ int jbd2_journal_blocks_per_page(struct inode *inode)
    */
    size_t journal_tag_bytes(journal_t *journal)
    {
    + journal_block_tag_t tag;
    + size_t x = 0;
    +
    + if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
    + x += sizeof(tag.t_checksum);
    +
    if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
    - return JBD2_TAG_SIZE64;
    + return x + JBD2_TAG_SIZE64;
    else
    - return JBD2_TAG_SIZE32;
    + return x + JBD2_TAG_SIZE32;
    }

    /*
    diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
    index 173e543..d4ad942 100644
    --- a/fs/jbd2/recovery.c
    +++ b/fs/jbd2/recovery.c
    @@ -390,6 +390,23 @@ static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
    return provided == calculated;
    }

    +static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
    + void *buf, __u32 sequence)
    +{
    + __u32 provided, calculated;
    +
    + if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
    + return 1;
    +
    + sequence = cpu_to_be32(sequence);
    + calculated = jbd2_chksum(j, j->j_uuid_csum, (__u8 *)&sequence,
    + sizeof(sequence));
    + calculated = jbd2_chksum(j, calculated, buf, j->j_blocksize);
    + provided = be32_to_cpu(tag->t_checksum);
    +
    + return provided == cpu_to_be32(calculated);
    +}
    +
    static int do_one_pass(journal_t *journal,
    struct recovery_info *info, enum passtype pass)
    {
    @@ -566,6 +583,19 @@ static int do_one_pass(journal_t *journal,
    goto skip_write;
    }

    + /* Look for block corruption */
    + if (!jbd2_block_tag_csum_verify(
    + journal, tag, obh->b_data,
    + be32_to_cpu(tmp->h_sequence))) {
    + brelse(obh);
    + success = -EIO;
    + printk(KERN_ERR "JBD: Invalid "
    + "checksum recovering "
    + "block %llu in log\n",
    + blocknr);
    + continue;
    + }
    +
    /* Find a buffer for the new
    * data being restored */
    nbh = __getblk(journal->j_fs_dev,
    diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
    index d948ddf..3ca096f 100644
    --- a/include/linux/jbd2.h
    +++ b/include/linux/jbd2.h
    @@ -190,6 +190,7 @@ typedef struct journal_block_tag_s
    __be32 t_blocknr; /* The on-disk block number */
    __be32 t_flags; /* See below */
    __be32 t_blocknr_high; /* most-significant high 32bits. */
    + __be32 t_checksum; /* crc32c(uuid+seq+block) */
    } journal_block_tag_t;

    #define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))


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