[PATCH 7/6] XFS: Add trace points for per-ag refcount debugging.

[Alex Elder]

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

Looks good.

> Signed-off-by: Dave Chinner <david at fromorbit.com>

Reviewed-by: Alex Elder <aelder at sgi.com>

> ---
>  fs/xfs/linux-2.6/xfs_trace.h |   27 +++++++++++++++++++++++++++
>  fs/xfs/xfs_ag.h              |    2 ++
>  fs/xfs/xfs_mount.c           |   34 ++++++++++++++++++++++++++++++++++
>  fs/xfs/xfs_mount.h           |   25 ++-----------------------
>  4 files changed, 65 insertions(+), 23 deletions(-)
> 
> diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h
> index d4ded59..5ec1475 100644
> --- a/fs/xfs/linux-2.6/xfs_trace.h
> +++ b/fs/xfs/linux-2.6/xfs_trace.h
> @@ -33,6 +33,33 @@ struct xfs_dquot;
>  struct xlog_ticket;
>  struct log;
> 
> +#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) \
>  TRACE_EVENT(name, \
>  	TP_PROTO(struct xfs_attr_list_context *ctx), \
> diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
> index 18ae43f..963bc27 100644
> --- a/fs/xfs/xfs_ag.h
> +++ b/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 */
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 1d00f7f..223d9c3 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -201,6 +201,38 @@ 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
>   * initialized.
> @@ -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();
>  	}
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 16b2212..e62fd1c 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/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 *
> -xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
> -{
> -	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);
> -}
> +struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
> +void	xfs_perag_put(struct xfs_perag *pag);
> 
>  /*
>   * Per-cpu superblock locking functions
> 
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