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locks: add some tracepoints in the lease handling code
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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.

Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
Change-Id: Ic6309053c6edeef4da644d349122a60afac0fb04
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@jtlayton @rlawoehd187
jtlayton authored and rlawoehd187 committed Mar 9, 2023
1 parent 4c337c4 commit 6d1a063
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11 changes: 11 additions & 0 deletions fs/locks.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -1287,6 +1290,7 @@ static void time_out_leases(struct inode *inode)

before = &inode->i_flock;
while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
trace_time_out_leases(inode, fl);
if (past_time(fl->fl_downgrade_time))
lease_modify(before, F_RDLCK);
if (past_time(fl->fl_break_time))
Expand Down Expand Up @@ -1374,6 +1378,7 @@ 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;
}
Expand All @@ -1385,10 +1390,12 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
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)
Expand Down Expand Up @@ -1510,6 +1517,8 @@ 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
Expand Down Expand Up @@ -1599,6 +1608,8 @@ 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) {
Expand Down
96 changes: 96 additions & 0 deletions include/trace/events/filelock.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,96 @@
/*
* 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, "|", \
{ 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));

DEFINE_EVENT(filelock_lease, time_out_leases, 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>

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