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>

1 files changed, 34 insertions, 0 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index f241fec26070..049dbc71c28e 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();
         }