Properly access a buffer's LSN using existing access macros instead of abusing

knowledge of page layout.

Stolen from Jonah Harris' CRC patch

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 53d7819c01ecab0d0b3077773f5cb438035569a6..560293d3723eee95a8bbe2651086880009d52609 100644 (file)
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -48,7 +48,7 @@
 
 /* Note: these two macros only work on shared buffers, not local ones! */
 #define BufHdrGetBlock(bufHdr) ((Block) (BufferBlocks + ((Size) (bufHdr)->buf_id) * BLCKSZ))
-#define BufferGetLSN(bufHdr)   (*((XLogRecPtr*) BufHdrGetBlock(bufHdr)))
+#define BufferGetLSN(bufHdr)   (PageGetLSN(BufHdrGetBlock(bufHdr)))
 
 /* Note: this macro only works on local buffers, not shared ones! */
 #define LocalBufHdrGetBlock(bufHdr) \