On Mon, Nov 28, 2022 at 02:34:05PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Add a new error injection knob so that we can arbitrarily slow down
> writeback to test for race conditions and aberrant reclaim behavior if
> the writeback mechanisms are slow to issue writeback. This will enable
> functional testing for the ifork sequence counters introduced in commit
> 745b3f76d1c8 ("xfs: maintain a sequence count for inode fork
> manipulations").
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_errortag.h | 4 +++-
> fs/xfs/xfs_aops.c | 12 ++++++++++--
> fs/xfs/xfs_error.c | 11 +++++++++++
> fs/xfs/xfs_error.h | 22 ++++++++++++++++++++++
> 4 files changed, 46 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_errortag.h b/fs/xfs/libxfs/xfs_errortag.h
> index 580ccbd5aadc..f5f629174eca 100644
> --- a/fs/xfs/libxfs/xfs_errortag.h
> +++ b/fs/xfs/libxfs/xfs_errortag.h
> @@ -61,7 +61,8 @@
> #define XFS_ERRTAG_LARP 39
> #define XFS_ERRTAG_DA_LEAF_SPLIT 40
> #define XFS_ERRTAG_ATTR_LEAF_TO_NODE 41
> -#define XFS_ERRTAG_MAX 42
> +#define XFS_ERRTAG_WB_DELAY_MS 42
> +#define XFS_ERRTAG_MAX 43
>
> /*
> * Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
> @@ -107,5 +108,6 @@
> #define XFS_RANDOM_LARP 1
> #define XFS_RANDOM_DA_LEAF_SPLIT 1
> #define XFS_RANDOM_ATTR_LEAF_TO_NODE 1
> +#define XFS_RANDOM_WB_DELAY_MS 3000
>
> #endif /* __XFS_ERRORTAG_H_ */
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index a22d90af40c8..4a13260527b9 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -17,6 +17,8 @@
> #include "xfs_bmap.h"
> #include "xfs_bmap_util.h"
> #include "xfs_reflink.h"
> +#include "xfs_errortag.h"
> +#include "xfs_error.h"
>
> struct xfs_writepage_ctx {
> struct iomap_writepage_ctx ctx;
> @@ -217,11 +219,15 @@ xfs_imap_valid(
> * checked (and found nothing at this offset) could have added
> * overlapping blocks.
> */
> - if (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq))
> + if (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq)) {
> + XFS_ERRORTAG_REPORT(ip->i_mount, XFS_ERRTAG_WB_DELAY_MS);
> return false;
> + }
> if (xfs_inode_has_cow_data(ip) &&
> - XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq))
> + XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) {
> + XFS_ERRORTAG_REPORT(ip->i_mount, XFS_ERRTAG_WB_DELAY_MS);
> return false;
These should be tracepoints, right?
Otherwise I don't see a problem with the delay code.
-Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
