Re: [PATCH 19/47] xfs: add tracepoints and error injection for deferred extent freeing

Brian Foster
2016-08-02T18:48:08Z

On Wed, Jul 20, 2016 at 09:58:10PM -0700, Darrick J. Wong wrote:
> Add a couple of tracepoints for the deferred extent free operation and
> a site for injecting errors while finishing the operation. This makes
> it easier to debug deferred ops and test log redo.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> fs/xfs/libxfs/xfs_alloc.c | 7 +++++++
> fs/xfs/libxfs/xfs_bmap.c | 2 ++
> fs/xfs/xfs_error.h | 4 +++-
> fs/xfs/xfs_trace.h | 5 ++++-
> 4 files changed, 16 insertions(+), 2 deletions(-)
>
>
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 5993f87..22ac3f1 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2702,6 +2702,13 @@ xfs_free_extent(
>
> ASSERT(len != 0);
>
> + trace_xfs_bmap_free_deferred(mp, agno, 0, agbno, len);
> +

Hmm, but the bmap code isn't the only caller here. I was thinking that
maybe we'd be better served by pushing these down into xfs_defer_add()
and friends, but I guess we don't necessarily have the extent
information at that layer.

How about we just rename these tracepoints to match the function names
so they don't confuse me in the future? :)

> + if (XFS_TEST_ERROR(false, mp,
> + XFS_ERRTAG_FREE_EXTENT,
> + XFS_RANDOM_FREE_EXTENT))
> + return -EIO;
> +
> error = xfs_free_extent_fix_freelist(tp, agno, &agbp);
> if (error)
> return error;
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 540a6b7..8e14ff4 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -596,6 +596,8 @@ xfs_bmap_add_free(
> new = kmem_zone_alloc(xfs_bmap_free_item_zone, KM_SLEEP);
> new->xefi_startblock = bno;
> new->xefi_blockcount = (xfs_extlen_t)len;
> + trace_xfs_bmap_free_defer(mp, XFS_FSB_TO_AGNO(mp, bno), 0,
> + XFS_FSB_TO_AGBNO(mp, bno), len);
> xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_FREE, &new->xefi_list);
> }
>
> diff --git a/fs/xfs/xfs_error.h b/fs/xfs/xfs_error.h
> index 2e4f67f..da6f951 100644
> --- a/fs/xfs/xfs_error.h
> +++ b/fs/xfs/xfs_error.h
> @@ -90,7 +90,8 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
> #define XFS_ERRTAG_STRATCMPL_IOERR 19
> #define XFS_ERRTAG_DIOWRITE_IOERR 20
> #define XFS_ERRTAG_BMAPIFORMAT 21
> -#define XFS_ERRTAG_MAX 22
> +#define XFS_ERRTAG_FREE_EXTENT 22
> +#define XFS_ERRTAG_MAX 23
>
> /*
> * Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
> @@ -117,6 +118,7 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
> #define XFS_RANDOM_STRATCMPL_IOERR (XFS_RANDOM_DEFAULT/10)
> #define XFS_RANDOM_DIOWRITE_IOERR (XFS_RANDOM_DEFAULT/10)
> #define XFS_RANDOM_BMAPIFORMAT XFS_RANDOM_DEFAULT
> +#define XFS_RANDOM_FREE_EXTENT 1
>

Why not XFS_RANDOM_DEFAULT?

Brian

> #ifdef DEBUG
> extern int xfs_error_test_active;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index a45b030..939caf5 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -2417,9 +2417,12 @@ DEFINE_DEFER_PENDING_EVENT(xfs_defer_pending_cancel);
> DEFINE_DEFER_PENDING_EVENT(xfs_defer_pending_finish);
> DEFINE_DEFER_PENDING_EVENT(xfs_defer_pending_abort);
>
> -DEFINE_PHYS_EXTENT_DEFERRED_EVENT(xfs_defer_phys_extent);
> DEFINE_MAP_EXTENT_DEFERRED_EVENT(xfs_defer_map_extent);
>
> +#define DEFINE_BMAP_FREE_DEFERRED_EVENT DEFINE_PHYS_EXTENT_DEFERRED_EVENT
> +DEFINE_BMAP_FREE_DEFERRED_EVENT(xfs_bmap_free_defer);
> +DEFINE_BMAP_FREE_DEFERRED_EVENT(xfs_bmap_free_deferred);
> +
> #endif /* _TRACE_XFS_H */
>
> #undef TRACE_INCLUDE_PATH
>
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