[PATCH 08/42] xfs: rework the perag trace points to be perag centric

Dave Chinner
2023-01-18T22:45:27Z

So that they all output the same information in the traces to make
debugging refcount issues easier.

This means that all the lookup/drop functions no longer need to use
the full memory barrier atomic operations (atomic*_return()) so
will have less overhead when tracing is off. The set/clear tag
tracepoints no longer abuse the reference count to pass the tag -
the tag being cleared is obvious from the _RET_IP_ that is recorded
in the trace point.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/libxfs/xfs_ag.c | 25 +++++++++----------------
fs/xfs/xfs_icache.c | 4 ++--
fs/xfs/xfs_trace.h | 21 +++++++++++----------
3 files changed, 22 insertions(+), 28 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 46e25c682bf4..7cff61875340 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -44,16 +44,15 @@ xfs_perag_get(
xfs_agnumber_t agno)
{
struct xfs_perag *pag;
- int ref = 0;

rcu_read_lock();
pag = radix_tree_lookup(&mp->m_perag_tree, agno);
if (pag) {
+ trace_xfs_perag_get(pag, _RET_IP_);
ASSERT(atomic_read(&pag->pag_ref) >= 0);
- ref = atomic_inc_return(&pag->pag_ref);
+ atomic_inc(&pag->pag_ref);
}
rcu_read_unlock();
- trace_xfs_perag_get(mp, agno, ref, _RET_IP_);
return pag;
}

@@ -68,7 +67,6 @@ xfs_perag_get_tag(
{
struct xfs_perag *pag;
int found;
- int ref;

rcu_read_lock();
found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
@@ -77,9 +75,9 @@ xfs_perag_get_tag(
rcu_read_unlock();
return NULL;
}
- ref = atomic_inc_return(&pag->pag_ref);
+ trace_xfs_perag_get_tag(pag, _RET_IP_);
+ atomic_inc(&pag->pag_ref);
rcu_read_unlock();
- trace_xfs_perag_get_tag(mp, pag->pag_agno, ref, _RET_IP_);
return pag;
}

@@ -87,11 +85,9 @@ void
xfs_perag_put(
struct xfs_perag *pag)
{
- int ref;
-
+ trace_xfs_perag_put(pag, _RET_IP_);
ASSERT(atomic_read(&pag->pag_ref) > 0);
- ref = atomic_dec_return(&pag->pag_ref);
- trace_xfs_perag_put(pag->pag_mount, pag->pag_agno, ref, _RET_IP_);
+ atomic_dec(&pag->pag_ref);
}

/*
@@ -110,8 +106,7 @@ xfs_perag_grab(
rcu_read_lock();
pag = radix_tree_lookup(&mp->m_perag_tree, agno);
if (pag) {
- trace_xfs_perag_grab(mp, pag->pag_agno,
- atomic_read(&pag->pag_active_ref), _RET_IP_);
+ trace_xfs_perag_grab(pag, _RET_IP_);
if (!atomic_inc_not_zero(&pag->pag_active_ref))
pag = NULL;
}
@@ -138,8 +133,7 @@ xfs_perag_grab_tag(
rcu_read_unlock();
return NULL;
}
- trace_xfs_perag_grab_tag(mp, pag->pag_agno,
- atomic_read(&pag->pag_active_ref), _RET_IP_);
+ trace_xfs_perag_grab_tag(pag, _RET_IP_);
if (!atomic_inc_not_zero(&pag->pag_active_ref))
pag = NULL;
rcu_read_unlock();
@@ -150,8 +144,7 @@ void
xfs_perag_rele(
struct xfs_perag *pag)
{
- trace_xfs_perag_rele(pag->pag_mount, pag->pag_agno,
- atomic_read(&pag->pag_active_ref), _RET_IP_);
+ trace_xfs_perag_rele(pag, _RET_IP_);
if (atomic_dec_and_test(&pag->pag_active_ref))
wake_up(&pag->pag_active_wq);
}
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 0f4a014dded3..8b2823d85a68 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -255,7 +255,7 @@ xfs_perag_set_inode_tag(
break;
}

- trace_xfs_perag_set_inode_tag(mp, pag->pag_agno, tag, _RET_IP_);
+ trace_xfs_perag_set_inode_tag(pag, _RET_IP_);
}

/* Clear a tag on both the AG incore inode tree and the AG radix tree. */
@@ -289,7 +289,7 @@ xfs_perag_clear_inode_tag(
radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno, tag);
spin_unlock(&mp->m_perag_lock);

- trace_xfs_perag_clear_inode_tag(mp, pag->pag_agno, tag, _RET_IP_);
+ trace_xfs_perag_clear_inode_tag(pag, _RET_IP_);
}

/*
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index f0b62054ea68..c921e9a5256d 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -159,33 +159,34 @@ TRACE_EVENT(xlog_intent_recovery_failed,
);

DECLARE_EVENT_CLASS(xfs_perag_class,
- TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, int refcount,
- unsigned long caller_ip),
- TP_ARGS(mp, agno, refcount, caller_ip),
+ TP_PROTO(struct xfs_perag *pag, unsigned long caller_ip),
+ TP_ARGS(pag, caller_ip),
TP_STRUCT__entry(
__field(dev_t, dev)
__field(xfs_agnumber_t, agno)
__field(int, refcount)
+ __field(int, active_refcount)
__field(unsigned long, caller_ip)
),
TP_fast_assign(
- __entry->dev = mp->m_super->s_dev;
- __entry->agno = agno;
- __entry->refcount = refcount;
+ __entry->dev = pag->pag_mount->m_super->s_dev;
+ __entry->agno = pag->pag_agno;
+ __entry->refcount = atomic_read(&pag->pag_ref);
+ __entry->active_refcount = atomic_read(&pag->pag_active_ref);
__entry->caller_ip = caller_ip;
),
- TP_printk("dev %d:%d agno 0x%x refcount %d caller %pS",
+ TP_printk("dev %d:%d agno 0x%x passive refs %d active refs %d caller %pS",
MAJOR(__entry->dev), MINOR(__entry->dev),
__entry->agno,
__entry->refcount,
+ __entry->active_refcount,
(char *)__entry->caller_ip)
);

#define DEFINE_PERAG_REF_EVENT(name) \
DEFINE_EVENT(xfs_perag_class, name, \
- TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, int refcount, \
- unsigned long caller_ip), \
- TP_ARGS(mp, agno, refcount, caller_ip))
+ TP_PROTO(struct xfs_perag *pag, unsigned long caller_ip), \
+ TP_ARGS(pag, caller_ip))
DEFINE_PERAG_REF_EVENT(xfs_perag_get);
DEFINE_PERAG_REF_EVENT(xfs_perag_get_tag);
DEFINE_PERAG_REF_EVENT(xfs_perag_put);
--
2.39.0