Re: [PATCH v6 2/9] fs: tracepoints around multigrain timestamp events

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jul 15, 2024 at 08:48:53AM -0400, Jeff Layton wrote:
> Add some tracepoints around various multigrain timestamp events.
> 
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>

Woot!
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/inode.c                       |   9 ++-
>  fs/stat.c                        |   3 +
>  include/trace/events/timestamp.h | 124 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 135 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index 417acbeabef3..869994285e87 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -22,6 +22,9 @@
>  #include <linux/iversion.h>
>  #include <linux/rw_hint.h>
>  #include <trace/events/writeback.h>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/timestamp.h>
> +
>  #include "internal.h"
>  
>  /*
> @@ -2569,6 +2572,7 @@ EXPORT_SYMBOL(inode_nohighmem);
>  
>  struct timespec64 inode_set_ctime_to_ts(struct inode *inode, struct timespec64 ts)
>  {
> +	trace_inode_set_ctime_to_ts(inode, &ts);
>  	set_normalized_timespec64(&ts, ts.tv_sec, ts.tv_nsec);
>  	inode->i_ctime_sec = ts.tv_sec;
>  	inode->i_ctime_nsec = ts.tv_nsec;
> @@ -2668,13 +2672,16 @@ struct timespec64 inode_set_ctime_current(struct inode *inode)
>  	cur = cns;
>  
>  	/* No need to cmpxchg if it's exactly the same */
> -	if (cns == now_ts.tv_nsec && inode->i_ctime_sec == now_ts.tv_sec)
> +	if (cns == now_ts.tv_nsec && inode->i_ctime_sec == now_ts.tv_sec) {
> +		trace_ctime_xchg_skip(inode, &now_ts);
>  		goto out;
> +	}
>  retry:
>  	/* Try to swap the nsec value into place. */
>  	if (try_cmpxchg(&inode->i_ctime_nsec, &cur, now_ts.tv_nsec)) {
>  		/* If swap occurred, then we're (mostly) done */
>  		inode->i_ctime_sec = now_ts.tv_sec;
> +		trace_ctime_ns_xchg(inode, cns, now_ts.tv_nsec, cur);
>  	} else {
>  		/*
>  		 * Was the change due to someone marking the old ctime QUERIED?
> diff --git a/fs/stat.c b/fs/stat.c
> index df7fdd3afed9..552dfd67688b 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -23,6 +23,8 @@
>  #include <linux/uaccess.h>
>  #include <asm/unistd.h>
>  
> +#include <trace/events/timestamp.h>
> +
>  #include "internal.h"
>  #include "mount.h"
>  
> @@ -49,6 +51,7 @@ void fill_mg_cmtime(struct kstat *stat, u32 request_mask, struct inode *inode)
>  	stat->mtime = inode_get_mtime(inode);
>  	stat->ctime.tv_sec = inode->i_ctime_sec;
>  	stat->ctime.tv_nsec = ((u32)atomic_fetch_or(I_CTIME_QUERIED, pcn)) & ~I_CTIME_QUERIED;
> +	trace_fill_mg_cmtime(inode, &stat->ctime, &stat->mtime);
>  }
>  EXPORT_SYMBOL(fill_mg_cmtime);
>  
> diff --git a/include/trace/events/timestamp.h b/include/trace/events/timestamp.h
> new file mode 100644
> index 000000000000..c9e5ec930054
> --- /dev/null
> +++ b/include/trace/events/timestamp.h
> @@ -0,0 +1,124 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM timestamp
> +
> +#if !defined(_TRACE_TIMESTAMP_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_TIMESTAMP_H
> +
> +#include <linux/tracepoint.h>
> +#include <linux/fs.h>
> +
> +#define CTIME_QUERIED_FLAGS \
> +	{ I_CTIME_QUERIED, "Q" }
> +
> +DECLARE_EVENT_CLASS(ctime,
> +	TP_PROTO(struct inode *inode,
> +		 struct timespec64 *ctime),
> +
> +	TP_ARGS(inode, ctime),
> +
> +	TP_STRUCT__entry(
> +		__field(dev_t,		dev)
> +		__field(ino_t,		ino)
> +		__field(time64_t,	ctime_s)
> +		__field(u32,		ctime_ns)
> +		__field(u32,		gen)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->dev		= inode->i_sb->s_dev;
> +		__entry->ino		= inode->i_ino;
> +		__entry->gen		= inode->i_generation;
> +		__entry->ctime_s	= ctime->tv_sec;
> +		__entry->ctime_ns	= ctime->tv_nsec;
> +	),
> +
> +	TP_printk("ino=%d:%d:%ld:%u ctime=%lld.%u",
> +		MAJOR(__entry->dev), MINOR(__entry->dev), __entry->ino, __entry->gen,
> +		__entry->ctime_s, __entry->ctime_ns
> +	)
> +);
> +
> +DEFINE_EVENT(ctime, inode_set_ctime_to_ts,
> +		TP_PROTO(struct inode *inode,
> +			 struct timespec64 *ctime),
> +		TP_ARGS(inode, ctime));
> +
> +DEFINE_EVENT(ctime, ctime_xchg_skip,
> +		TP_PROTO(struct inode *inode,
> +			 struct timespec64 *ctime),
> +		TP_ARGS(inode, ctime));
> +
> +TRACE_EVENT(ctime_ns_xchg,
> +	TP_PROTO(struct inode *inode,
> +		 u32 old,
> +		 u32 new,
> +		 u32 cur),
> +
> +	TP_ARGS(inode, old, new, cur),
> +
> +	TP_STRUCT__entry(
> +		__field(dev_t,		dev)
> +		__field(ino_t,		ino)
> +		__field(u32,		gen)
> +		__field(u32,		old)
> +		__field(u32,		new)
> +		__field(u32,		cur)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->dev		= inode->i_sb->s_dev;
> +		__entry->ino		= inode->i_ino;
> +		__entry->gen		= inode->i_generation;
> +		__entry->old		= old;
> +		__entry->new		= new;
> +		__entry->cur		= cur;
> +	),
> +
> +	TP_printk("ino=%d:%d:%ld:%u old=%u:%s new=%u cur=%u:%s",
> +		MAJOR(__entry->dev), MINOR(__entry->dev), __entry->ino, __entry->gen,
> +		__entry->old & ~I_CTIME_QUERIED,
> +		__print_flags(__entry->old & I_CTIME_QUERIED, "|", CTIME_QUERIED_FLAGS),
> +		__entry->new,
> +		__entry->cur & ~I_CTIME_QUERIED,
> +		__print_flags(__entry->cur & I_CTIME_QUERIED, "|", CTIME_QUERIED_FLAGS)
> +	)
> +);
> +
> +TRACE_EVENT(fill_mg_cmtime,
> +	TP_PROTO(struct inode *inode,
> +		 struct timespec64 *ctime,
> +		 struct timespec64 *mtime),
> +
> +	TP_ARGS(inode, ctime, mtime),
> +
> +	TP_STRUCT__entry(
> +		__field(dev_t,		dev)
> +		__field(ino_t,		ino)
> +		__field(time64_t,	ctime_s)
> +		__field(time64_t,	mtime_s)
> +		__field(u32,		ctime_ns)
> +		__field(u32,		mtime_ns)
> +		__field(u32,		gen)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->dev		= inode->i_sb->s_dev;
> +		__entry->ino		= inode->i_ino;
> +		__entry->gen		= inode->i_generation;
> +		__entry->ctime_s	= ctime->tv_sec;
> +		__entry->mtime_s	= mtime->tv_sec;
> +		__entry->ctime_ns	= ctime->tv_nsec;
> +		__entry->mtime_ns	= mtime->tv_nsec;
> +	),
> +
> +	TP_printk("ino=%d:%d:%ld:%u ctime=%lld.%u mtime=%lld.%u",
> +		MAJOR(__entry->dev), MINOR(__entry->dev), __entry->ino, __entry->gen,
> +		__entry->ctime_s, __entry->ctime_ns,
> +		__entry->mtime_s, __entry->mtime_ns
> +	)
> +);
> +#endif /* _TRACE_TIMESTAMP_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> 
> -- 
> 2.45.2
> 
>