Re: [PATCH] locks: add some tracepoints in the lease handling code

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, May 01, 2014 at 07:45:45AM -0400, Jeff Layton wrote:
> Recently, I needed these to help track down a softlockup when recalling a
> delegation, but they might be helpful in other situations as well.

Looks fine to me, though the block/unblock tracepoints seem very
specific to the problem you were seeing.

Something that also triggered e.g. in the nonblocking case might also be
handy?

--b.

> 
> Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
> ---
>  fs/locks.c                      |  9 +++++
>  include/trace/events/filelock.h | 90 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 99 insertions(+)
>  create mode 100644 include/trace/events/filelock.h
> 
> diff --git a/fs/locks.c b/fs/locks.c
> index 2129ba8ac062..5453ac1b9b64 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -130,6 +130,9 @@
>  #include <linux/percpu.h>
>  #include <linux/lglock.h>
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/filelock.h>
> +
>  #include <asm/uaccess.h>
>  
>  #define IS_POSIX(fl)	(fl->fl_flags & FL_POSIX)
> @@ -1397,10 +1400,12 @@ restart:
>  	if (break_time == 0)
>  		break_time++;
>  	locks_insert_block(flock, new_fl);
> +	trace_break_lease_block(inode, new_fl);
>  	spin_unlock(&inode->i_lock);
>  	error = wait_event_interruptible_timeout(new_fl->fl_wait,
>  						!new_fl->fl_next, break_time);
>  	spin_lock(&inode->i_lock);
> +	trace_break_lease_unblock(inode, new_fl);
>  	locks_delete_block(new_fl);
>  	if (error >= 0) {
>  		if (error == 0)
> @@ -1522,6 +1527,8 @@ static int generic_add_lease(struct file *filp, long arg, struct file_lock **flp
>  	int error;
>  
>  	lease = *flp;
> +	trace_generic_add_lease(inode, lease);
> +
>  	/*
>  	 * In the delegation case we need mutual exclusion with
>  	 * a number of operations that take the i_mutex.  We trylock
> @@ -1611,6 +1618,8 @@ static int generic_delete_lease(struct file *filp, struct file_lock **flp)
>  	struct dentry *dentry = filp->f_path.dentry;
>  	struct inode *inode = dentry->d_inode;
>  
> +	trace_generic_delete_lease(inode, *flp);
> +
>  	for (before = &inode->i_flock;
>  			((fl = *before) != NULL) && IS_LEASE(fl);
>  			before = &fl->fl_next) {
> diff --git a/include/trace/events/filelock.h b/include/trace/events/filelock.h
> new file mode 100644
> index 000000000000..e2f77ff30a9c
> --- /dev/null
> +++ b/include/trace/events/filelock.h
> @@ -0,0 +1,90 @@
> +/*
> + * Events for filesystem locks
> + *
> + * Copyright 2013 Jeff Layton <jlayton@poochiereds.net>
> + */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM filelock
> +
> +#if !defined(_TRACE_FILELOCK_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_FILELOCK_H
> +
> +#include <linux/tracepoint.h>
> +#include <linux/fs.h>
> +#include <linux/device.h>
> +#include <linux/kdev_t.h>
> +
> +#define show_fl_flags(val)				\
> +	__print_flags(val, "|", 			\
> +		{    1, "FL_POSIX" },			\
> +		{    2, "FL_FLOCK" },			\
> +		{    4, "FL_DELEG" },			\
> +		{    8, "FL_ACCESS" },			\
> +		{   16, "FL_EXISTS" },			\
> +		{   32, "FL_LEASE" },			\
> +		{   64, "FL_CLOSE" },			\
> +		{  128, "FL_SLEEP" },			\
> +		{  256, "FL_DOWNGRADE_PENDING" },	\
> +		{  512, "FL_UNLOCK_PENDING" },		\
> +		{ 1024, "FL_FILE_PVT" })
> +
> +#define show_fl_type(val)				\
> +	__print_symbolic(val,				\
> +			{ F_RDLCK, "F_RDLCK" },		\
> +			{ F_WRLCK, "F_WRLCK" },		\
> +			{ F_UNLCK, "F_UNLCK" })
> +
> +DECLARE_EVENT_CLASS(filelock_lease,
> +
> +	TP_PROTO(struct inode *inode, struct file_lock *fl),
> +
> +	TP_ARGS(inode, fl),
> +
> +	TP_STRUCT__entry(
> +		__field(struct file_lock *, fl)
> +		__field(unsigned long, i_ino)
> +		__field(dev_t, s_dev)
> +		__field(struct file_lock *, fl_next)
> +		__field(fl_owner_t, fl_owner)
> +		__field(unsigned int, fl_flags)
> +		__field(unsigned char, fl_type)
> +		__field(unsigned long, fl_break_time)
> +		__field(unsigned long, fl_downgrade_time)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->fl = fl;
> +		__entry->s_dev = inode->i_sb->s_dev;
> +		__entry->i_ino = inode->i_ino;
> +		__entry->fl_next = fl->fl_next;
> +		__entry->fl_owner = fl->fl_owner;
> +		__entry->fl_flags = fl->fl_flags;
> +		__entry->fl_type = fl->fl_type;
> +		__entry->fl_break_time = fl->fl_break_time;
> +		__entry->fl_downgrade_time = fl->fl_downgrade_time;
> +	),
> +
> +	TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_next=0x%p fl_owner=0x%p fl_flags=%s fl_type=%s fl_break_time=%lu fl_downgrade_time=%lu",
> +		__entry->fl, MAJOR(__entry->s_dev), MINOR(__entry->s_dev),
> +		__entry->i_ino, __entry->fl_next, __entry->fl_owner,
> +		show_fl_flags(__entry->fl_flags),
> +		show_fl_type(__entry->fl_type),
> +		__entry->fl_break_time, __entry->fl_downgrade_time)
> +);
> +
> +DEFINE_EVENT(filelock_lease, break_lease_block, TP_PROTO(struct inode *inode, struct file_lock *fl),
> +		TP_ARGS(inode, fl));
> +
> +DEFINE_EVENT(filelock_lease, break_lease_unblock, TP_PROTO(struct inode *inode, struct file_lock *fl),
> +		TP_ARGS(inode, fl));
> +
> +DEFINE_EVENT(filelock_lease, generic_add_lease, TP_PROTO(struct inode *inode, struct file_lock *fl),
> +		TP_ARGS(inode, fl));
> +
> +DEFINE_EVENT(filelock_lease, generic_delete_lease, TP_PROTO(struct inode *inode, struct file_lock *fl),
> +		TP_ARGS(inode, fl));
> +
> +#endif /* _TRACE_FILELOCK_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> -- 
> 1.9.0
>