From: Andres Freund <andres@anarazel.de>
Date: Wed, 26 Oct 2022 12:05:07 -0700
Subject: [PATCH v5 05/15] bufmgr: Add Pin/UnpinLocalBuffer()

diff --git a/src/backend/storage/buffer/bufmgr.c
b/src/backend/storage/buffer/bufmgr.c
index fa20fab5a2..6f50dbd212 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -4288,18 +4268,16 @@ ConditionalLockBuffer(Buffer buffer)
 }

 void
-BufferCheckOneLocalPin(Buffer buffer)
+BufferCheckWePinOnce(Buffer buffer)

This name is weird. Who is we?

diff --git a/src/backend/storage/buffer/localbuf.c
b/src/backend/storage/buffer/localbuf.c
index 5325ddb663..798c5b93a8 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
+bool
+PinLocalBuffer(BufferDesc *buf_hdr, bool adjust_usagecount)
+{
+    uint32        buf_state;
+    Buffer        buffer = BufferDescriptorGetBuffer(buf_hdr);
+    int            bufid = -(buffer + 1);

You do
  int            buffid = -buffer - 1;
in UnpinLocalBuffer()
They should be consistent.

  int            bufid = -(buffer + 1);

I think this version is better:

  int            buffid = -buffer - 1;

Since if buffer is INT_MAX, then the -(buffer + 1) version invokes
undefined behavior while the -buffer - 1 version doesn't.