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    Subject[PATCH 19/23] jbd2: Checksum revocation blocks
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    Compute and verify revoke blocks inside the journal.

    Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
    ---
    fs/jbd2/recovery.c | 22 ++++++++++++++++++++++
    fs/jbd2/revoke.c | 27 ++++++++++++++++++++++++++-
    2 files changed, 48 insertions(+), 1 deletions(-)


    diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
    index da6d7ba..bfc52cd 100644
    --- a/fs/jbd2/recovery.c
    +++ b/fs/jbd2/recovery.c
    @@ -703,6 +703,25 @@ static int do_one_pass(journal_t *journal,
    return err;
    }

    +static int jbd2_revoke_block_csum_verify(journal_t *j,
    + void *buf)
    +{
    + struct jbd2_journal_revoke_tail *tail;
    + __u32 provided, calculated;
    +
    + if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
    + return 1;
    +
    + tail = (struct jbd2_journal_revoke_tail *)(buf + j->j_blocksize -
    + sizeof(struct jbd2_journal_revoke_tail));
    + provided = tail->r_checksum;
    + tail->r_checksum = 0;
    + calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
    + tail->r_checksum = provided;
    +
    + provided = be32_to_cpu(provided);
    + return provided == calculated;
    +}

    /* Scan a revoke record, marking all blocks mentioned as revoked. */

    @@ -717,6 +736,9 @@ static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
    offset = sizeof(jbd2_journal_revoke_header_t);
    max = be32_to_cpu(header->r_count);

    + if (!jbd2_revoke_block_csum_verify(journal, header))
    + return -EINVAL;
    +
    if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
    record_len = 8;

    diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
    index 69fd935..a197ba5 100644
    --- a/fs/jbd2/revoke.c
    +++ b/fs/jbd2/revoke.c
    @@ -548,6 +548,7 @@ static void write_one_revoke_record(journal_t *journal,
    struct jbd2_revoke_record_s *record,
    int write_op)
    {
    + int csum_size = 0;
    struct journal_head *descriptor;
    int offset;
    journal_header_t *header;
    @@ -562,9 +563,13 @@ static void write_one_revoke_record(journal_t *journal,
    descriptor = *descriptorp;
    offset = *offsetp;

    + /* Do we need to leave space at the end for a checksum? */
    + if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
    + csum_size = sizeof(struct jbd2_journal_revoke_tail);
    +
    /* Make sure we have a descriptor with space left for the record */
    if (descriptor) {
    - if (offset == journal->j_blocksize) {
    + if (offset >= journal->j_blocksize - csum_size) {
    flush_descriptor(journal, descriptor, offset, write_op);
    descriptor = NULL;
    }
    @@ -601,6 +606,24 @@ static void write_one_revoke_record(journal_t *journal,
    *offsetp = offset;
    }

    +static void jbd2_revoke_csum_set(journal_t *j,
    + struct journal_head *descriptor)
    +{
    + struct jbd2_journal_revoke_tail *tail;
    + __u32 csum;
    +
    + if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
    + return;
    +
    + tail = (struct jbd2_journal_revoke_tail *)
    + (jh2bh(descriptor)->b_data + j->j_blocksize -
    + sizeof(struct jbd2_journal_revoke_tail));
    + tail->r_checksum = 0;
    + csum = jbd2_chksum(j, j->j_csum_seed, jh2bh(descriptor)->b_data,
    + j->j_blocksize);
    + tail->r_checksum = cpu_to_be32(csum);
    +}
    +
    /*
    * Flush a revoke descriptor out to the journal. If we are aborting,
    * this is a noop; otherwise we are generating a buffer which needs to
    @@ -622,6 +645,8 @@ static void flush_descriptor(journal_t *journal,

    header = (jbd2_journal_revoke_header_t *) jh2bh(descriptor)->b_data;
    header->r_count = cpu_to_be32(offset);
    + jbd2_revoke_csum_set(journal, descriptor);
    +
    set_buffer_jwrite(bh);
    BUFFER_TRACE(bh, "write");
    set_buffer_dirty(bh);


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