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Subject: Re: [PATCH RFC 01/10] fs/locks: Add trace_leases_conflict
From:   Jeff Layton <jlayton@kernel.org>
To:     ira.weiny@intel.com, Dan Williams <dan.j.williams@intel.com>,
        Jan Kara <jack@suse.cz>, Theodore Ts'o <tytso@mit.edu>,
        Dave Chinner <david@fromorbit.com>
Cc:     Matthew Wilcox <willy@infradead.org>, linux-xfs@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        John Hubbard <jhubbard@nvidia.com>,
        =?ISO-8859-1?Q?J=E9r=F4me?= Glisse <jglisse@redhat.com>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org, linux-ext4@vger.kernel.org,
        linux-mm@kvack.org
Date:   Sun, 09 Jun 2019 08:52:20 -0400
In-Reply-To: <20190606014544.8339-2-ira.weiny@intel.com>
References: <20190606014544.8339-1-ira.weiny@intel.com>
         <20190606014544.8339-2-ira.weiny@intel.com>
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On Wed, 2019-06-05 at 18:45 -0700, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
>  fs/locks.c                      | 20 ++++++++++++++-----
>  include/trace/events/filelock.h | 35 +++++++++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/locks.c b/fs/locks.c
> index ec1e4a5df629..0cc2b9f30e22 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1534,11 +1534,21 @@ static void time_out_leases(struct inode *inode, struct list_head *dispose)
>  
>  static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
>  {
> -	if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT))
> -		return false;
> -	if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))
> -		return false;
> -	return locks_conflict(breaker, lease);
> +	bool rc;
> +
> +	if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) {
> +		rc = false;
> +		goto trace;
> +	}
> +	if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) {
> +		rc = false;
> +		goto trace;
> +	}
> +
> +	rc = locks_conflict(breaker, lease);
> +trace:
> +	trace_leases_conflict(rc, lease, breaker);
> +	return rc;
>  }
>  
>  static bool
> diff --git a/include/trace/events/filelock.h b/include/trace/events/filelock.h
> index fad7befa612d..4b735923f2ff 100644
> --- a/include/trace/events/filelock.h
> +++ b/include/trace/events/filelock.h
> @@ -203,6 +203,41 @@ TRACE_EVENT(generic_add_lease,
>  		show_fl_type(__entry->fl_type))
>  );
>  
> +TRACE_EVENT(leases_conflict,
> +	TP_PROTO(bool conflict, struct file_lock *lease, struct file_lock *breaker),
> +
> +	TP_ARGS(conflict, lease, breaker),
> +
> +	TP_STRUCT__entry(
> +		__field(void *, lease)
> +		__field(void *, breaker)
> +		__field(unsigned int, l_fl_flags)
> +		__field(unsigned int, b_fl_flags)
> +		__field(unsigned char, l_fl_type)
> +		__field(unsigned char, b_fl_type)
> +		__field(bool, conflict)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->lease = lease;
> +		__entry->l_fl_flags = lease->fl_flags;
> +		__entry->l_fl_type = lease->fl_type;
> +		__entry->breaker = breaker;
> +		__entry->b_fl_flags = breaker->fl_flags;
> +		__entry->b_fl_type = breaker->fl_type;
> +		__entry->conflict = conflict;
> +	),
> +
> +	TP_printk("conflict %d: lease=0x%p fl_flags=%s fl_type=%s; breaker=0x%p fl_flags=%s fl_type=%s",
> +		__entry->conflict,
> +		__entry->lease,
> +		show_fl_flags(__entry->l_fl_flags),
> +		show_fl_type(__entry->l_fl_type),
> +		__entry->breaker,
> +		show_fl_flags(__entry->b_fl_flags),
> +		show_fl_type(__entry->b_fl_type))
> +);
> +
>  #endif /* _TRACE_FILELOCK_H */
>  
>  /* This part must be outside protection */

This looks useful. I'll plan to merge this one for v5.3 unless there
are objections.

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