On Fri, Dec 18, 2020 at 12:29:08AM -0700, Allison Henderson wrote:
> This is a quick patch to add a new tracepoint: xfs_das_state_return. We
> use this to track when ever a new state is set or -EAGAIN is returned
>
> Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_attr.c | 22 +++++++++++++++++++++-
> fs/xfs/libxfs/xfs_attr_remote.c | 1 +
> fs/xfs/xfs_trace.h | 20 ++++++++++++++++++++
> 3 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index cd72512..8ed00bc 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -263,6 +263,7 @@ xfs_attr_set_shortform(
> * We're still in XFS_DAS_UNINIT state here. We've converted the attr
> * fork to leaf format and will restart with the leaf add.
> */
> + trace_xfs_das_state_return(XFS_DAS_UNINIT);
It would help to record the inode number in the trace data. When
someone encounters an xattr problem involving things like fsstress,
it'll be /much/ easier to disentangle who's doing what.
> return -EAGAIN;
> }
>
> @@ -409,9 +410,11 @@ xfs_attr_set_iter(
> * down into the node handling code below
> */
> dac->flags |= XFS_DAC_DEFER_FINISH;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> case 0:
> dac->dela_state = XFS_DAS_FOUND_LBLK;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> }
> return error;
> @@ -841,6 +844,7 @@ xfs_attr_leaf_addname(
> return error;
>
> dac->flags |= XFS_DAC_DEFER_FINISH;
> + trace_xfs_das_state_return(dac->dela_state);
Also, please consider capturing more info about /which/ of these
xfs_das_state_return tracepoints fired, either by introducing more
variants (e.g. xfs_attr_leaf_addname_das_return) or by feeding
__this_address into the trace "call" and printing it in the TP_printk
output (formatting string '%pS').
Each declared tracepoint /does/ have a permanent memory cost, so I would
think hard about trying #2...
--D
> return -EAGAIN;
> }
>
> @@ -874,6 +878,7 @@ xfs_attr_leaf_addname(
> * Commit the flag value change and start the next trans in series.
> */
> dac->dela_state = XFS_DAS_FLIP_LFLAG;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> das_flip_flag:
> /*
> @@ -891,6 +896,8 @@ xfs_attr_leaf_addname(
> das_rm_lblk:
> if (args->rmtblkno) {
> error = __xfs_attr_rmtval_remove(dac);
> + if (error == -EAGAIN)
> + trace_xfs_das_state_return(dac->dela_state);
> if (error)
> return error;
> }
> @@ -1142,6 +1149,7 @@ xfs_attr_node_addname(
> * this point.
> */
> dac->flags |= XFS_DAC_DEFER_FINISH;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> }
>
> @@ -1175,6 +1183,7 @@ xfs_attr_node_addname(
> state = NULL;
>
> dac->dela_state = XFS_DAS_FOUND_NBLK;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> das_found_nblk:
>
> @@ -1202,6 +1211,7 @@ xfs_attr_node_addname(
> return error;
>
> dac->flags |= XFS_DAC_DEFER_FINISH;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> }
>
> @@ -1236,6 +1246,7 @@ xfs_attr_node_addname(
> * Commit the flag value change and start the next trans in series
> */
> dac->dela_state = XFS_DAS_FLIP_NFLAG;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> das_flip_flag:
> /*
> @@ -1253,6 +1264,10 @@ xfs_attr_node_addname(
> das_rm_nblk:
> if (args->rmtblkno) {
> error = __xfs_attr_rmtval_remove(dac);
> +
> + if (error == -EAGAIN)
> + trace_xfs_das_state_return(dac->dela_state);
> +
> if (error)
> return error;
> }
> @@ -1396,6 +1411,8 @@ xfs_attr_node_remove_rmt (
> * May return -EAGAIN to request that the caller recall this function
> */
> error = __xfs_attr_rmtval_remove(dac);
> + if (error == -EAGAIN)
> + trace_xfs_das_state_return(dac->dela_state);
> if (error)
> return error;
>
> @@ -1514,6 +1531,7 @@ xfs_attr_node_removename_iter(
>
> dac->flags |= XFS_DAC_DEFER_FINISH;
> dac->dela_state = XFS_DAS_RM_SHRINK;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> }
>
> @@ -1532,8 +1550,10 @@ xfs_attr_node_removename_iter(
> goto out;
> }
>
> - if (error == -EAGAIN)
> + if (error == -EAGAIN) {
> + trace_xfs_das_state_return(dac->dela_state);
> return error;
> + }
> out:
> if (state)
> xfs_da_state_free(state);
> diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
> index 6af86bf..4840de9 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.c
> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> @@ -763,6 +763,7 @@ __xfs_attr_rmtval_remove(
> */
> if (!done) {
> dac->flags |= XFS_DAC_DEFER_FINISH;
> + trace_xfs_das_state_return(dac->dela_state);
> return -EAGAIN;
> }
>
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 9074b8b..4f6939b4 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -3887,6 +3887,26 @@ DEFINE_EVENT(xfs_timestamp_range_class, name, \
> DEFINE_TIMESTAMP_RANGE_EVENT(xfs_inode_timestamp_range);
> DEFINE_TIMESTAMP_RANGE_EVENT(xfs_quota_expiry_range);
>
> +
> +DECLARE_EVENT_CLASS(xfs_das_state_class,
> + TP_PROTO(int das),
> + TP_ARGS(das),
> + TP_STRUCT__entry(
> + __field(int, das)
> + ),
> + TP_fast_assign(
> + __entry->das = das;
> + ),
> + TP_printk("state change %d",
> + __entry->das)
> +)
> +
> +#define DEFINE_DAS_STATE_EVENT(name) \
> +DEFINE_EVENT(xfs_das_state_class, name, \
> + TP_PROTO(int das), \
> + TP_ARGS(das))
> +DEFINE_DAS_STATE_EVENT(xfs_das_state_return);
> +
> #endif /* _TRACE_XFS_H */
>
> #undef TRACE_INCLUDE_PATH
> --
> 2.7.4
>
