Re: [PATCH v22 05/16] xfs: Add state machine tracepoints

Allison Henderson
2021-07-30T09:17:57Z

On 7/28/21 6:42 AM, Chandan Babu R wrote:
> On 27 Jul 2021 at 11:50, Allison Henderson wrote:
>> This is a quick patch to add a new xfs_attr_*_return tracepoints. We
>> use these to track when ever a new state is set or -EAGAIN is returned
>>
>> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
>> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
>> ---
>> fs/xfs/libxfs/xfs_attr.c | 28 ++++++++++++++++++++++++++--
>> fs/xfs/libxfs/xfs_attr_remote.c | 1 +
>> fs/xfs/xfs_trace.h | 24 ++++++++++++++++++++++++
>> 3 files changed, 51 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index 5040fc1..b0c6c62 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -335,6 +335,7 @@ xfs_attr_sf_addname(
>> * the attr fork to leaf format and will restart with the leaf
>> * add.
>> */
>> + trace_xfs_attr_sf_addname_return(XFS_DAS_UNINIT, args->dp);
>> dac->flags |= XFS_DAC_DEFER_FINISH;
>> return -EAGAIN;
>> }
>> @@ -394,6 +395,8 @@ xfs_attr_set_iter(
>> * handling code below
>> */
>> dac->flags |= XFS_DAC_DEFER_FINISH;
>> + trace_xfs_attr_set_iter_return(
>> + dac->dela_state, args->dp);
>> return -EAGAIN;
>> } else if (error) {
>> return error;
>> @@ -418,6 +421,7 @@ xfs_attr_set_iter(
>>
>> dac->dela_state = XFS_DAS_FOUND_NBLK;
>> }
>> + trace_xfs_attr_set_iter_return(dac->dela_state, args->dp);
>> return -EAGAIN;
>> case XFS_DAS_FOUND_LBLK:
>> /*
>> @@ -445,6 +449,8 @@ xfs_attr_set_iter(
>> error = xfs_attr_rmtval_set_blk(dac);
>> if (error)
>> return error;
>> + trace_xfs_attr_set_iter_return(dac->dela_state,
>> + args->dp);
>> return -EAGAIN;
>> }
>>
>> @@ -479,6 +485,7 @@ xfs_attr_set_iter(
>> * series.
>> */
>> dac->dela_state = XFS_DAS_FLIP_LFLAG;
>> + trace_xfs_attr_set_iter_return(dac->dela_state, args->dp);
>> return -EAGAIN;
>> case XFS_DAS_FLIP_LFLAG:
>> /*
>> @@ -496,6 +503,9 @@ xfs_attr_set_iter(
>> dac->dela_state = XFS_DAS_RM_LBLK;
>> if (args->rmtblkno) {
>> error = __xfs_attr_rmtval_remove(dac);
>> + if (error == -EAGAIN)
>> + trace_xfs_attr_set_iter_return(
>> + dac->dela_state, args->dp);
>> if (error)
>> return error;
>
> if __xfs_attr_rmtval_remove() successfully removes all the remote blocks, we
> transition over to XFS_DAS_RD_LEAF state and return -EAGAIN. A tracepoint
> is probably required for this as well?
>
>>
>> @@ -549,6 +559,8 @@ xfs_attr_set_iter(
>> error = xfs_attr_rmtval_set_blk(dac);
>> if (error)
>> return error;
>> + trace_xfs_attr_set_iter_return(
>> + dac->dela_state, args->dp);
>> return -EAGAIN;
>> }
>>
>> @@ -584,6 +596,7 @@ xfs_attr_set_iter(
>> * series
>> */
>> dac->dela_state = XFS_DAS_FLIP_NFLAG;
>> + trace_xfs_attr_set_iter_return(dac->dela_state, args->dp);
>> return -EAGAIN;
>>
>> case XFS_DAS_FLIP_NFLAG:
>> @@ -603,6 +616,10 @@ xfs_attr_set_iter(
>> dac->dela_state = XFS_DAS_RM_NBLK;
>> if (args->rmtblkno) {
>> error = __xfs_attr_rmtval_remove(dac);
>> + if (error == -EAGAIN)
>> + trace_xfs_attr_set_iter_return(
>> + dac->dela_state, args->dp);
>> +
>> if (error)
>> return error;
>
> A transition to XFS_DAS_CLR_FLAG state probably requires a tracepoint call.
>
>>
>> @@ -1183,6 +1200,8 @@ xfs_attr_node_addname(
>> * this point.
>> */
>> dac->flags |= XFS_DAC_DEFER_FINISH;
>> + trace_xfs_attr_node_addname_return(
>> + dac->dela_state, args->dp);
>> return -EAGAIN;
>> }
>>
>> @@ -1429,10 +1448,13 @@ xfs_attr_remove_iter(
>> * blocks are removed.
>> */
>> error = __xfs_attr_rmtval_remove(dac);
>> - if (error == -EAGAIN)
>> + if (error == -EAGAIN) {
>> + trace_xfs_attr_remove_iter_return(
>> + dac->dela_state, args->dp);
>> return error;
>> - else if (error)
>> + } else if (error) {
>> goto out;
>> + }
>>
>
> if the call to __xfs_attr_rmtval_remove() is successful, we transition over to
> XFS_DAS_RM_NAME state and return -EAGAIN. Maybe tracepoint is required here as
> well?
Yes, I think these three are good additions. I think this patch was
written before those extra states were added, and likley forgot to add
the corresponding traces. Will update. Thanks for the review!

Allison

>
>> /*
>> * Refill the state structure with buffers (the prior
>> @@ -1473,6 +1495,8 @@ xfs_attr_remove_iter(
>>
>> dac->flags |= XFS_DAC_DEFER_FINISH;
>> dac->dela_state = XFS_DAS_RM_SHRINK;
>> + trace_xfs_attr_remove_iter_return(
>> + dac->dela_state, args->dp);
>> return -EAGAIN;
>> }
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
>> index 0c8bee3..70f880d 100644
>> --- a/fs/xfs/libxfs/xfs_attr_remote.c
>> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
>> @@ -696,6 +696,7 @@ __xfs_attr_rmtval_remove(
>> */
>> if (!done) {
>> dac->flags |= XFS_DAC_DEFER_FINISH;
>> + trace_xfs_attr_rmtval_remove_return(dac->dela_state, args->dp);
>> return -EAGAIN;
>> }
>>
>> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
>> index f9d8d60..f9840dd 100644
>> --- a/fs/xfs/xfs_trace.h
>> +++ b/fs/xfs/xfs_trace.h
>> @@ -3987,6 +3987,30 @@ DEFINE_ICLOG_EVENT(xlog_iclog_want_sync);
>> DEFINE_ICLOG_EVENT(xlog_iclog_wait_on);
>> DEFINE_ICLOG_EVENT(xlog_iclog_write);
>>
>> +DECLARE_EVENT_CLASS(xfs_das_state_class,
>> + TP_PROTO(int das, struct xfs_inode *ip),
>> + TP_ARGS(das, ip),
>> + TP_STRUCT__entry(
>> + __field(int, das)
>> + __field(xfs_ino_t, ino)
>> + ),
>> + TP_fast_assign(
>> + __entry->das = das;
>> + __entry->ino = ip->i_ino;
>> + ),
>> + TP_printk("state change %d ino 0x%llx",
>> + __entry->das, __entry->ino)
>> +)
>> +
>> +#define DEFINE_DAS_STATE_EVENT(name) \
>> +DEFINE_EVENT(xfs_das_state_class, name, \
>> + TP_PROTO(int das, struct xfs_inode *ip), \
>> + TP_ARGS(das, ip))
>> +DEFINE_DAS_STATE_EVENT(xfs_attr_sf_addname_return);
>> +DEFINE_DAS_STATE_EVENT(xfs_attr_set_iter_return);
>> +DEFINE_DAS_STATE_EVENT(xfs_attr_node_addname_return);
>> +DEFINE_DAS_STATE_EVENT(xfs_attr_remove_iter_return);
>> +DEFINE_DAS_STATE_EVENT(xfs_attr_rmtval_remove_return);
>> #endif /* _TRACE_XFS_H */
>>
>> #undef TRACE_INCLUDE_PATH
>
>