On Thu, Jul 31, 2014 at 11:01:46AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> We recently had a bug where buffers were slipping through log
> recovery without any verifier attached to them. This was resulting
> in on-disk CRC mismatches for valid data. Add some warning code to
> catch this occurrence so that we catch such bugs during development
> rather than not being aware they exist.
>
> Note that we cannot do this verification unconditionally as non-CRC
> filesystems don't always attach verifiers to the buffers being
> written. e.g. during log recovery we cannot identify all the
> different types of buffers correctly on non-CRC filesystems, so we
> can't attach the correct verifiers in all cases and so we don't
> attach any. Hence we don't want on non-CRC filesystems to avoid
> spamming the logs with false indications.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_buf.c | 14 ++++++++++++++
> fs/xfs/xfs_log.c | 8 +++++++-
> 2 files changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index a6dc83e..cd7b8ca 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1330,6 +1330,20 @@ _xfs_buf_ioapply(
> SHUTDOWN_CORRUPT_INCORE);
> return;
> }
> + } else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
> + struct xfs_mount *mp = bp->b_target->bt_mount;
> +
> + /*
> + * non-crc filesystems don't attach verifiers during
> + * log recovery, so don't warn for such filesystems.
> + */
> + if (xfs_sb_version_hascrc(&mp->m_sb)) {
> + xfs_warn(mp,
> + "%s: no ops on block 0x%llx/0x%x",
> + __func__, bp->b_bn, bp->b_length);
> + xfs_hex_dump(bp->b_addr, 64);
> + dump_stack();
> + }
> }
> } else if (bp->b_flags & XBF_READ_AHEAD) {
> rw = READA;
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index 149a4a5..ca4fd5b 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -1378,8 +1378,14 @@ xlog_alloc_log(
>
> xlog_get_iclog_buffer_size(mp, log);
>
> + /*
> + * Use a NULL block for the extra log buffer used during splits so that
> + * it will trigger errors if we ever try to do IO on it without first
> + * having set it up properly.
> + */
> error = -ENOMEM;
> - bp = xfs_buf_alloc(mp->m_logdev_targp, 0, BTOBB(log->l_iclog_size), 0);
> + bp = xfs_buf_alloc(mp->m_logdev_targp, XFS_BUF_DADDR_NULL,
> + BTOBB(log->l_iclog_size), 0);
> if (!bp)
> goto out_free_log;
>
> --
> 2.0.0
>
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