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

From: J. Bruce Fields
Date: Tue May 06 2014 - 12:31:59 EST

On Mon, May 05, 2014 at 07:57:55AM -0400, Jeff Layton wrote:
> v2: add a __break_lease tracepoint for non-blocking case
>
> Recently, I needed these to help track down a softlockup when recalling a
> delegation, but they might be helpful in other situations as well.

Still feels a little ad-hoc, but I don't have another proposal, so, ACK.

The forced-unlock/downgrade case in time_out_leases might be another
good spot for a tracepoint.

--b.

>
> Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
> ---
> fs/locks.c | 10 +++++
> include/trace/events/filelock.h | 93 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 103 insertions(+)
> create mode 100644 include/trace/events/filelock.h
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 6b01d5a1de4a..2367f3118662 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)
> @@ -1386,6 +1389,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
> }
>
> if (i_have_this_lease || (mode & O_NONBLOCK)) {
> + trace_break_lease_noblock(inode, new_fl);
> error = -EWOULDBLOCK;
> goto out;
> }
> @@ -1397,10 +1401,12 @@ 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 +1528,8 @@ 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 +1619,8 @@ 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..d1e9d3eaa8ce
> --- /dev/null
> +++ b/include/trace/events/filelock.h
> @@ -0,0 +1,93 @@
> +/*
> + * Events for filesystem locks
> + *
> + * Copyright 2013 Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
> + */
> +#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, "|", \
> + { FL_POSIX, "FL_POSIX" }, \
> + { FL_FLOCK, "FL_FLOCK" }, \
> + { FL_DELEG, "FL_DELEG" }, \
> + { FL_ACCESS, "FL_ACCESS" }, \
> + { FL_EXISTS, "FL_EXISTS" }, \
> + { FL_LEASE, "FL_LEASE" }, \
> + { FL_CLOSE, "FL_CLOSE" }, \
> + { FL_SLEEP, "FL_SLEEP" }, \
> + { FL_DOWNGRADE_PENDING, "FL_DOWNGRADE_PENDING" }, \
> + { FL_UNLOCK_PENDING, "FL_UNLOCK_PENDING" }, \
> + { FL_OFDLCK, "FL_OFDLCK" })
> +
> +#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_noblock, TP_PROTO(struct inode *inode, struct file_lock *fl),
> + TP_ARGS(inode, fl));
> +
> +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
>
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