xfs: Add trace points for per-ag refcount debugging.

Uninline xfs_perag_{get,put} so that tracepoints can be inserted
into them to speed debugging of reference count problems.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

fs/xfs/linux-2.6/xfs_trace.h

@@ -78,6 +78,33 @@ DECLARE_EVENT_CLASS(xfs_attr_list_class,
 	)
 )
 
+#define DEFINE_PERAG_REF_EVENT(name) \
+TRACE_EVENT(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_STRUCT__entry( \
+		__field(dev_t, dev) \
+		__field(xfs_agnumber_t, agno) \
+		__field(int, refcount) \
+		__field(unsigned long, caller_ip) \
+	), \
+	TP_fast_assign( \
+		__entry->dev = mp->m_super->s_dev; \
+		__entry->agno = agno; \
+		__entry->refcount = refcount; \
+		__entry->caller_ip = caller_ip; \
+	), \
+	TP_printk("dev %d:%d agno %u refcount %d caller %pf", \
+		  MAJOR(__entry->dev), MINOR(__entry->dev), \
+		  __entry->agno, \
+		  __entry->refcount, \
+		  (char *)__entry->caller_ip) \
+);
+
+DEFINE_PERAG_REF_EVENT(xfs_perag_get)
+DEFINE_PERAG_REF_EVENT(xfs_perag_put)
+
 #define DEFINE_ATTR_LIST_EVENT(name) \
 DEFINE_EVENT(xfs_attr_list_class, name, \
 	TP_PROTO(struct xfs_attr_list_context *ctx), \

fs/xfs/xfs_ag.h

@@ -197,6 +197,8 @@ typedef struct xfs_perag_busy {
 #endif
 
 typedef struct xfs_perag {
+	struct xfs_mount *pag_mount;	/* owner filesystem */
+	xfs_agnumber_t	pag_agno;	/* AG this structure belongs to */
 	atomic_t	pag_ref;	/* perag reference count */
 	char		pagf_init;	/* this agf's entry is initialized */
 	char		pagi_init;	/* this agi's entry is initialized */

fs/xfs/xfs_mount.c

@@ -200,6 +200,38 @@ xfs_uuid_unmount(
 }
 
 
+/*
+ * Reference counting access wrappers to the perag structures.
+ */
+struct xfs_perag *
+xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
+{
+	struct xfs_perag	*pag;
+	int			ref = 0;
+
+	spin_lock(&mp->m_perag_lock);
+	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
+	if (pag) {
+		ASSERT(atomic_read(&pag->pag_ref) >= 0);
+		/* catch leaks in the positive direction during testing */
+		ASSERT(atomic_read(&pag->pag_ref) < 1000);
+		ref = atomic_inc_return(&pag->pag_ref);
+	}
+	spin_unlock(&mp->m_perag_lock);
+	trace_xfs_perag_get(mp, agno, ref, _RET_IP_);
+	return pag;
+}
+
+void
+xfs_perag_put(struct xfs_perag *pag)
+{
+	int	ref;
+
+	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_);
+}
+
 /*
  * Free up the resources associated with a mount structure.  Assume that
  * the structure was initially zeroed, so we can tell which fields got
@@ -433,6 +465,8 @@ xfs_initialize_perag(
 			kmem_free(pag);
 			return -EEXIST;
 		}
+		pag->pag_agno = index;
+		pag->pag_mount = mp;
 		spin_unlock(&mp->m_perag_lock);
 		radix_tree_preload_end();
 	}

fs/xfs/xfs_mount.h

@@ -386,29 +386,8 @@ xfs_daddr_to_agbno(struct xfs_mount *mp, xfs_daddr_t d)
 /*
  * perag get/put wrappers for ref counting
  */
-static inline struct xfs_perag *
+struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
-xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
+void	xfs_perag_put(struct xfs_perag *pag);
-{
-	struct xfs_perag	*pag;
-
-	spin_lock(&mp->m_perag_lock);
-	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
-	if (pag) {
-		ASSERT(atomic_read(&pag->pag_ref) >= 0);
-		/* catch leaks in the positive direction during testing */
-		ASSERT(atomic_read(&pag->pag_ref) < 1000);
-		atomic_inc(&pag->pag_ref);
-	}
-	spin_unlock(&mp->m_perag_lock);
-	return pag;
-}
-
-static inline void
-xfs_perag_put(struct xfs_perag *pag)
-{
-	ASSERT(atomic_read(&pag->pag_ref) > 0);
-	atomic_dec(&pag->pag_ref);
-}
 
 /*
  * Per-cpu superblock locking functions