From 4b1b378cd7d3b1c3f0366ccda0f1092de833774e Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Wed, 1 Jul 2020 19:06:45 -0700
Subject: [PATCH v4 02/15] Add some error checking around pinning

---
 src/include/storage/bufmgr.h        |  1 +
 src/backend/storage/buffer/bufmgr.c | 42 ++++++++++++++++++++---------
 2 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index b8a18b8081f..973547a8baf 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -134,6 +134,7 @@ extern void ReleaseBuffer(Buffer buffer);
 extern void UnlockReleaseBuffer(Buffer buffer);
 extern void MarkBufferDirty(Buffer buffer);
 extern void IncrBufferRefCount(Buffer buffer);
+extern void BufferCheckOneLocalPin(Buffer buffer);
 extern Buffer ReleaseAndReadBuffer(Buffer buffer, Relation relation,
 								   BlockNumber blockNum);
 
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 0a05577b68d..55df6a76c9c 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1755,6 +1755,8 @@ PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy)
 	bool		result;
 	PrivateRefCountEntry *ref;
 
+	Assert(!BufferIsLocal(b));
+
 	ref = GetPrivateRefCountEntry(b, true);
 
 	if (ref == NULL)
@@ -1900,6 +1902,8 @@ UnpinBuffer(BufferDesc *buf)
 	PrivateRefCountEntry *ref;
 	Buffer		b = BufferDescriptorGetBuffer(buf);
 
+	Assert(!BufferIsLocal(b));
+
 	/* not moving as we're likely deleting it soon anyway */
 	ref = GetPrivateRefCountEntry(b, false);
 	Assert(ref != NULL);
@@ -4282,6 +4286,25 @@ ConditionalLockBuffer(Buffer buffer)
 									LW_EXCLUSIVE);
 }
 
+void
+BufferCheckOneLocalPin(Buffer buffer)
+{
+	if (BufferIsLocal(buffer))
+	{
+		/* There should be exactly one pin */
+		if (LocalRefCount[-buffer - 1] != 1)
+			elog(ERROR, "incorrect local pin count: %d",
+				 LocalRefCount[-buffer - 1]);
+	}
+	else
+	{
+		/* There should be exactly one local pin */
+		if (GetPrivateRefCount(buffer) != 1)
+			elog(ERROR, "incorrect local pin count: %d",
+				 GetPrivateRefCount(buffer));
+	}
+}
+
 /*
  * LockBufferForCleanup - lock a buffer in preparation for deleting items
  *
@@ -4309,20 +4332,11 @@ LockBufferForCleanup(Buffer buffer)
 	Assert(BufferIsPinned(buffer));
 	Assert(PinCountWaitBuf == NULL);
 
-	if (BufferIsLocal(buffer))
-	{
-		/* There should be exactly one pin */
-		if (LocalRefCount[-buffer - 1] != 1)
-			elog(ERROR, "incorrect local pin count: %d",
-				 LocalRefCount[-buffer - 1]);
-		/* Nobody else to wait for */
-		return;
-	}
+	BufferCheckOneLocalPin(buffer);
 
-	/* There should be exactly one local pin */
-	if (GetPrivateRefCount(buffer) != 1)
-		elog(ERROR, "incorrect local pin count: %d",
-			 GetPrivateRefCount(buffer));
+	/* Nobody else to wait for */
+	if (BufferIsLocal(buffer))
+		return;
 
 	bufHdr = GetBufferDescriptor(buffer - 1);
 
@@ -4823,6 +4837,8 @@ LockBufHdr(BufferDesc *desc)
 	SpinDelayStatus delayStatus;
 	uint32		old_buf_state;
 
+	Assert(!BufferIsLocal(BufferDescriptorGetBuffer(desc)));
+
 	init_local_spin_delay(&delayStatus);
 
 	while (true)
-- 
2.38.0