Re: [PATCH 06/27] xfs: create helpers to record and deal with scrub problems

Dave Chinner
2017-09-22T07:16:11Z

On Wed, Sep 20, 2017 at 05:18:14PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> Create helper functions to record crc and corruption problems, and
> deal with any other runtime errors that arise.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> fs/xfs/scrub/common.c | 243 +++++++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/scrub/common.h | 39 ++++++++
> fs/xfs/scrub/trace.h | 193 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 475 insertions(+)
>
>
> diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
> index 13ccb36..cf3f1365 100644
> --- a/fs/xfs/scrub/common.c
> +++ b/fs/xfs/scrub/common.c
> @@ -47,6 +47,249 @@
>
> /* Common code for the metadata scrubbers. */
>
> +/* Check for operational errors. */
> +bool
> +xfs_scrub_op_ok(
> + struct xfs_scrub_context *sc,
> + xfs_agnumber_t agno,
> + xfs_agblock_t bno,
> + int *error)
> +{
> + switch (*error) {
> + case 0:
> + return true;
> + case -EDEADLOCK:
> + /* Used to restart an op with deadlock avoidance. */
> + trace_xfs_scrub_deadlock_retry(sc->ip, sc->sm, *error);
> + break;
> + case -EFSBADCRC:
> + case -EFSCORRUPTED:
> + /* Note the badness but don't abort. */
> + sc->sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
> + *error = 0;
> + /* fall through */
> + default:
> + trace_xfs_scrub_op_error(sc, agno, bno, *error,
> + __return_address);
> + break;
> + }
> + return false;
> +}

What are the semantics here w.r.t. *error? on some errors it's
cleared before we return, on others it's ignored. It's as clear as
mud what we should expect from these functions...

> +/* Check for metadata block optimization possibilities. */
> +bool
> +xfs_scrub_block_preen_ok(
> + struct xfs_scrub_context *sc,
> + struct xfs_buf *bp,
> + bool fs_ok)
> +{
> + struct xfs_mount *mp = sc->mp;
> + xfs_fsblock_t fsbno;
> + xfs_agnumber_t agno;
> + xfs_agblock_t bno;
> +
> + if (fs_ok)
> + return fs_ok;
> +
> + fsbno = XFS_DADDR_TO_FSB(mp, bp->b_bn);
> + agno = XFS_FSB_TO_AGNO(mp, fsbno);
> + bno = XFS_FSB_TO_AGBNO(mp, fsbno);
> +
> + sc->sm->sm_flags |= XFS_SCRUB_OFLAG_PREEN;
> + trace_xfs_scrub_block_preen(sc, agno, bno, __return_address);
> + return fs_ok;
> +}

Again, I'm not sure what the return value semantics of the functioon
are? Why does the fs_ok return shortcut exist?

Same for all the other functions...

> +
> +/* Check for inode metadata non-corruption problems. */
> +bool
> +xfs_scrub_ino_warn_ok(
> + struct xfs_scrub_context *sc,
> + struct xfs_buf *bp,
> + bool fs_ok)

Confusing. What's the difference between a corruption problem and a
"non-corruption problem" that requires a warning?

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com