xfs: add tracepoints to AGF/AGI read operations

To help track down AGI/AGF lock ordering issues, I added these
tracepoints to tell us when an AGI or AGF is read and locked.  With
these we can now determine if the lock ordering goes wrong from
tracing captures.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>

3 files changed, 34 insertions, 2 deletions

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index bcf16528bac5..9eab2dfdcbb5 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -2294,6 +2294,8 @@ xfs_read_agf(
 {
         int             error;
 
+        trace_xfs_read_agf(mp, agno);
+
         ASSERT(agno != NULLAGNUMBER);
         error = xfs_trans_read_buf(
                         mp, tp, mp->m_ddev_targp,
@@ -2324,8 +2326,9 @@ xfs_alloc_read_agf(
         struct xfs_perag        *pag;           /* per allocation group data */
         int                     error;
 
-        ASSERT(agno != NULLAGNUMBER);
+        trace_xfs_alloc_read_agf(mp, agno);
 
+        ASSERT(agno != NULLAGNUMBER);
         error = xfs_read_agf(mp, tp, agno,
                         (flags & XFS_ALLOC_FLAG_TRYLOCK) ? XBF_TRYLOCK : 0,
                         bpp);
diff --git a/fs/xfs/xfs_ialloc.c b/fs/xfs/xfs_ialloc.c
index 14d732f61a41..e87719c5bebe 100644
--- a/fs/xfs/xfs_ialloc.c
+++ b/fs/xfs/xfs_ialloc.c
@@ -40,6 +40,7 @@
 #include "xfs_icreate_item.h"
 #include "xfs_icache.h"
 #include "xfs_dinode.h"
+#include "xfs_trace.h"
 
 
 /*
@@ -1627,8 +1628,9 @@ xfs_read_agi(
 {
         int                     error;
 
-        ASSERT(agno != NULLAGNUMBER);
+        trace_xfs_read_agi(mp, agno);
 
+        ASSERT(agno != NULLAGNUMBER);
         error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
                         XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
                         XFS_FSS_TO_BB(mp, 1), 0, bpp, &xfs_agi_buf_ops);
@@ -1651,6 +1653,8 @@ xfs_ialloc_read_agi(
         struct xfs_perag        *pag;   /* per allocation group data */
         int                     error;
 
+        trace_xfs_ialloc_read_agi(mp, agno);
+
         error = xfs_read_agi(mp, tp, agno, bpp);
         if (error)
                 return error;
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index f195476a037c..425dfa45b9a0 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -135,6 +135,31 @@ DEFINE_PERAG_REF_EVENT(xfs_perag_clear_reclaim);
 DEFINE_PERAG_REF_EVENT(xfs_perag_set_eofblocks);
 DEFINE_PERAG_REF_EVENT(xfs_perag_clear_eofblocks);
 
+DECLARE_EVENT_CLASS(xfs_ag_class,
+        TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno),
+        TP_ARGS(mp, agno),
+        TP_STRUCT__entry(
+                __field(dev_t, dev)
+                __field(xfs_agnumber_t, agno)
+        ),
+        TP_fast_assign(
+                __entry->dev = mp->m_super->s_dev;
+                __entry->agno = agno;
+        ),
+        TP_printk("dev %d:%d agno %u",
+                  MAJOR(__entry->dev), MINOR(__entry->dev),
+                  __entry->agno)
+);
+#define DEFINE_AG_EVENT(name)   \
+DEFINE_EVENT(xfs_ag_class, name,        \
+        TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno),    \
+        TP_ARGS(mp, agno))
+
+DEFINE_AG_EVENT(xfs_read_agf);
+DEFINE_AG_EVENT(xfs_alloc_read_agf);
+DEFINE_AG_EVENT(xfs_read_agi);
+DEFINE_AG_EVENT(xfs_ialloc_read_agi);
+
 TRACE_EVENT(xfs_attr_list_node_descend,
         TP_PROTO(struct xfs_attr_list_context *ctx,
                  struct xfs_da_node_entry *btree),