Re: [PATCH v2 1/4] NFSD: refactor nfsd_read_vector_dio to EVENT_CLASS useful for READ and WRITE

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2025-07-31 at 15:44 -0400, Mike Snitzer wrote:
> Transform nfsd_read_vector_dio trace event into nfsd_analyze_dio_class
> and use it to create nfsd_analyze_read_dio and nfsd_analyze_write_dio
> trace events.
> 
> This prepares for nfsd_vfs_write() to also make use of it when
> handling misaligned WRITEs.
> 
> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
> ---
>  fs/nfsd/trace.h | 52 ++++++++++++++++++++++++++++++++++++-------------
>  fs/nfsd/vfs.c   | 11 ++++++-----
>  2 files changed, 44 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
> index 55055482f8a84..4173bd9344b6b 100644
> --- a/fs/nfsd/trace.h
> +++ b/fs/nfsd/trace.h
> @@ -473,25 +473,29 @@ DEFINE_NFSD_IO_EVENT(write_done);
>  DEFINE_NFSD_IO_EVENT(commit_start);
>  DEFINE_NFSD_IO_EVENT(commit_done);
>  
> -TRACE_EVENT(nfsd_read_vector_dio,
> +DECLARE_EVENT_CLASS(nfsd_analyze_dio_class,
>  	TP_PROTO(struct svc_rqst *rqstp,
>  		 struct svc_fh	*fhp,
>  		 u64		offset,
>  		 u32		len,
> -		 loff_t         start,
> -		 loff_t         start_extra,
> -		 loff_t         end,
> -		 loff_t         end_extra),
> -	TP_ARGS(rqstp, fhp, offset, len, start, start_extra, end, end_extra),
> +		 loff_t		start,
> +		 ssize_t	start_len,
> +		 loff_t		middle,
> +		 ssize_t	middle_len,
> +		 loff_t		end,
> +		 ssize_t	end_len),
> +	TP_ARGS(rqstp, fhp, offset, len, start, start_len, middle, middle_len, end, end_len),
>  	TP_STRUCT__entry(
>  		__field(u32, xid)
>  		__field(u32, fh_hash)
>  		__field(u64, offset)
>  		__field(u32, len)
>  		__field(loff_t, start)
> -		__field(loff_t, start_extra)
> +		__field(ssize_t, start_len)
> +		__field(loff_t, middle)
> +		__field(ssize_t, middle_len)
>  		__field(loff_t, end)
> -		__field(loff_t, end_extra)
> +		__field(ssize_t, end_len)
>  	),
>  	TP_fast_assign(
>  		__entry->xid = be32_to_cpu(rqstp->rq_xid);
> @@ -499,16 +503,36 @@ TRACE_EVENT(nfsd_read_vector_dio,
>  		__entry->offset = offset;
>  		__entry->len = len;
>  		__entry->start = start;
> -		__entry->start_extra = start_extra;
> +		__entry->start_len = start_len;
> +		__entry->middle = middle;
> +		__entry->middle_len = middle_len;
>  		__entry->end = end;
> -		__entry->end_extra = end_extra;
> +		__entry->end_len = end_len;
>  	),
> -	TP_printk("xid=0x%08x fh_hash=0x%08x offset=%llu len=%u start=%llu+%llu end=%llu-%llu",
> +	TP_printk("xid=0x%08x fh_hash=0x%08x offset=%llu len=%u start=%llu+%lu middle=%llu+%lu end=%llu+%lu",
>  		  __entry->xid, __entry->fh_hash,
>  		  __entry->offset, __entry->len,
> -		  __entry->start, __entry->start_extra,
> -		  __entry->end, __entry->end_extra)
> -);
> +		  __entry->start, __entry->start_len,
> +		  __entry->middle, __entry->middle_len,
> +		  __entry->end, __entry->end_len)
> +)
> +
> +#define DEFINE_NFSD_ANALYZE_DIO_EVENT(name)			\
> +DEFINE_EVENT(nfsd_analyze_dio_class, nfsd_analyze_##name##_dio,	\
> +	TP_PROTO(struct svc_rqst *rqstp,			\
> +		 struct svc_fh	*fhp,				\
> +		 u64		offset,				\
> +		 u32		len,				\
> +		 loff_t		start,				\
> +		 ssize_t	start_len,			\
> +		 loff_t		middle,				\
> +		 ssize_t	middle_len,			\
> +		 loff_t		end,				\
> +		 ssize_t	end_len),			\
> +	TP_ARGS(rqstp, fhp, offset, len, start, start_len, middle, middle_len, end, end_len))
> +
> +DEFINE_NFSD_ANALYZE_DIO_EVENT(read);
> +DEFINE_NFSD_ANALYZE_DIO_EVENT(write);
>  
>  DECLARE_EVENT_CLASS(nfsd_err_class,
>  	TP_PROTO(struct svc_rqst *rqstp,
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 46189020172fb..35c29b8ade9c3 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -1094,7 +1094,7 @@ static bool nfsd_analyze_read_dio(struct svc_rqst *rqstp, struct svc_fh *fhp,
>  				  struct nfsd_read_dio *read_dio)
>  {
>  	const u32 dio_blocksize = nf->nf_dio_read_offset_align;
> -	loff_t orig_end = offset + len;
> +	loff_t middle_end, orig_end = offset + len;
>  
>  	if (WARN_ONCE(!nf->nf_dio_mem_align || !nf->nf_dio_read_offset_align,
>  		      "%s: underlying filesystem has not provided DIO alignment info\n",
> @@ -1133,10 +1133,11 @@ static bool nfsd_analyze_read_dio(struct svc_rqst *rqstp, struct svc_fh *fhp,
>  	}
>  
>  	/* Show original offset and count, and how it was expanded for DIO */
> -	trace_nfsd_read_vector_dio(rqstp, fhp, offset, len,
> -				   read_dio->start, read_dio->start_extra,
> -				   read_dio->end, read_dio->end_extra);
> -
> +	middle_end = read_dio->end - read_dio->end_extra;
> +	trace_nfsd_analyze_read_dio(rqstp, fhp, offset, len,
> +				    read_dio->start, read_dio->start_extra,
> +				    offset, (middle_end - offset),
> +				    middle_end, read_dio->end_extra);
>  	return true;
>  }
>  

Reviewed-by: Jeff Layton <jlayton@kernel.org>