Bug#35500304 NdbFS debugging output for wrong requests

As part of debugging problem situations, NdbFS can output a list
of in-flight file system requests, including how long they have
been stalled.
This is useful to understand the circumstances leading to an issue.

The implementation of this functionality was incorrect and could
return the wrong set of requests, leading to the wrong conclusions
being reached in analysis.

Change-Id: Icf6cab79aa604ddfec356c1d1935eeade8749796

Author: frazerclement

storage/ndb/src/kernel/blocks/ndbfs/AsyncIoThread.hpp

@@ -1,4 +1,5 @@
-/* Copyright (c) 2008, 2021, Oracle and/or its affiliates.
+/*
+   Copyright (c) 2008, 2023, Oracle and/or its affiliates.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2.0,
@@ -142,6 +143,10 @@ class Request
 
   /* More debugging info */
   NDB_TICKS m_startTime;
+
+  /* Pool members */
+  Request* listNext;
+  Request* listPrev;
 };
 
 NdbOut& operator <<(NdbOut&, const Request&);

storage/ndb/src/kernel/blocks/ndbfs/Ndbfs.cpp

@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2003, 2022, Oracle and/or its affiliates.
+   Copyright (c) 2003, 2023, Oracle and/or its affiliates.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2.0,
@@ -1828,21 +1828,20 @@ Ndbfs::execDUMP_STATE_ORD(Signal* signal)
   {
     g_eventLogger->info("NDBFS: Dump requests: %u",
                         theRequestPool->inuse());
-    for (unsigned ridx=0; ridx < theRequestPool->inuse(); ridx++)
+    const Request* req = NULL;
+    while((req = theRequestPool->getNextInUseItem(req)))
     {
-      const Request* req = theRequestPool->peekInuseItem(ridx);
       Uint64 duration = 0;
 
       if (NdbTick_IsValid(req->m_startTime))
       {
         duration = NdbTick_Elapsed(req->m_startTime,
-                                   getHighResTimer()).milliSec();
+                                   getHighResTimer()).microSec();
       }
 
-      g_eventLogger->info("Request %u action %u %s userRef 0x%x "
+      g_eventLogger->info("Request action %u %s userRef 0x%x "
                           "userPtr %u filePtr %u bind %u "
-                          "duration(ms) %llu filename %s",
-                          ridx,
+                          "duration(us) %llu filename %s",
                           req->action,
                           Request::actionName(req->action),
                           req->theUserReference,

storage/ndb/src/kernel/blocks/ndbfs/Pool.hpp

@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2003, 2021, Oracle and/or its affiliates.
+   Copyright (c) 2003, 2023, Oracle and/or its affiliates.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2.0,
@@ -202,7 +202,8 @@ class Pool
     theIncSize(anIncSize),
     theTop(0),
     theCurrentSize(0),   
-    theList(0)
+    theList(0),
+    theInUseList(NULL)
   {
     allocate(anInitSize);
   }
@@ -224,7 +225,7 @@ class Pool
   // inuse() : Return number items taken from pool
   unsigned inuse() const { return theCurrentSize - theTop; };
 
-  const T* peekInuseItem(unsigned idx) const;
+  const T* getNextInUseItem(const T*) const;
 
 protected:
   void allocate(int aSize)
@@ -252,6 +253,7 @@ class Pool
   int theCurrentSize;
 
   T** theList;
+  T*  theInUseList;
 };
 
 //******************************************************************************
@@ -264,6 +266,18 @@ template <class T> inline T* Pool<T>::get()
    }
    --theTop;
    tmp = theList[theTop];
+
+   /* Maintain inuse list */
+   /* Add to head */
+   if (theInUseList)
+   {
+     assert(theInUseList->listPrev == NULL);
+     theInUseList->listPrev = tmp;
+   }
+   tmp->listNext = theInUseList;
+   tmp->listPrev = NULL;
+   theInUseList = tmp;
+
    tmp->atGet();
    return tmp;
 }
@@ -274,13 +288,33 @@ template <class T> inline void Pool<T>::put(T* aT)
 {
    theList[theTop]= aT;
    ++theTop;
+
+   /* Remove item from InUse list */
+   T* next = aT->listNext;
+   T* prev = aT->listPrev;
+
+   if (next)
+   {
+     next->listPrev = prev;
+   }
+   if (prev)
+   {
+     prev->listNext = next;
+   }
+   else
+   {
+     theInUseList = next;
+   }
+   aT->listNext = aT->listPrev = NULL;
 }
 
-template <class T> const T* Pool<T>::peekInuseItem(unsigned idx) const
+template <class T> const T* Pool<T>::getNextInUseItem(const T* item) const
 {
-  assert(idx <= inuse());
-  // theTop is index of the first item in use
-  return theList[theTop + idx];
+  if (item)
+  {
+    return item->listNext;
+  }
+  return theInUseList;
 }