For wal_consistency_checking, mask page checksum as well as page LSN.

If the LSN is different, the checksum will be different, too.

Ashwin Agrawal, reviewed by Michael Paquier and Kuntal Ghosh

Discussion: http://postgr.es/m/CALfoeis5iqrAU-+JAN+ZzXkpPr7+-0OAGv7QUHwFn=-wDy4o4Q@mail.gmail.com

src/backend/access/brin/brin_xlog.c

@@ -332,7 +332,7 @@ brin_mask(char *pagedata, BlockNumber blkno)
 {
 	Page		page = (Page) pagedata;
 
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_page_hint_bits(page);
 

src/backend/access/common/bufmask.c

@@ -23,15 +23,17 @@
  * mask_page_lsn
  *
  * In consistency checks, the LSN of the two pages compared will likely be
- * different because of concurrent operations when the WAL is generated
- * and the state of the page when WAL is applied.
+ * different because of concurrent operations when the WAL is generated and
+ * the state of the page when WAL is applied. Also, mask out checksum as
+ * masking anything else on page means checksum is not going to match as well.
  */
 void
-mask_page_lsn(Page page)
+mask_page_lsn_and_checksum(Page page)
 {
 	PageHeader	phdr = (PageHeader) page;
 
 	PageXLogRecPtrSet(phdr->pd_lsn, (uint64) MASK_MARKER);
+	phdr->pd_checksum = MASK_MARKER;
 }
 
 /*

src/backend/access/gin/ginxlog.c

@@ -770,7 +770,7 @@ gin_mask(char *pagedata, BlockNumber blkno)
 	Page		page = (Page) pagedata;
 	GinPageOpaque opaque;
 
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 	opaque = GinPageGetOpaque(page);
 
 	mask_page_hint_bits(page);

src/backend/access/gist/gistxlog.c

@@ -352,14 +352,14 @@ gist_mask(char *pagedata, BlockNumber blkno)
 {
 	Page		page = (Page) pagedata;
 
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_page_hint_bits(page);
 	mask_unused_space(page);
 
 	/*
 	 * NSN is nothing but a special purpose LSN. Hence, mask it for the same
-	 * reason as mask_page_lsn.
+	 * reason as mask_page_lsn_and_checksum.
 	 */
 	GistPageSetNSN(page, (uint64) MASK_MARKER);
 

src/backend/access/hash/hash_xlog.c

@@ -1263,7 +1263,7 @@ hash_mask(char *pagedata, BlockNumber blkno)
 	HashPageOpaque opaque;
 	int			pagetype;
 
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_page_hint_bits(page);
 	mask_unused_space(page);

src/backend/access/heap/heapam.c

@@ -9149,7 +9149,7 @@ heap_mask(char *pagedata, BlockNumber blkno)
 	Page		page = (Page) pagedata;
 	OffsetNumber off;
 
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_page_hint_bits(page);
 	mask_unused_space(page);

src/backend/access/nbtree/nbtxlog.c

@@ -1040,7 +1040,7 @@ btree_mask(char *pagedata, BlockNumber blkno)
 	Page		page = (Page) pagedata;
 	BTPageOpaque maskopaq;
 
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_page_hint_bits(page);
 	mask_unused_space(page);

src/backend/access/spgist/spgxlog.c

@@ -1034,7 +1034,7 @@ spg_mask(char *pagedata, BlockNumber blkno)
 {
 	Page		page = (Page) pagedata;
 
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_page_hint_bits(page);
 

src/backend/access/transam/generic_xlog.c

@@ -541,7 +541,7 @@ generic_redo(XLogReaderState *record)
 void
 generic_mask(char *page, BlockNumber blkno)
 {
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_unused_space(page);
 }

src/backend/commands/sequence.c

@@ -1941,7 +1941,7 @@ ResetSequenceCaches(void)
 void
 seq_mask(char *page, BlockNumber blkno)
 {
-	mask_page_lsn(page);
+	mask_page_lsn_and_checksum(page);
 
 	mask_unused_space(page);
 }

src/include/access/bufmask.h

@@ -23,7 +23,7 @@
 /* Marker used to mask pages consistently */
 #define MASK_MARKER		0
 
-extern void mask_page_lsn(Page page);
+extern void mask_page_lsn_and_checksum(Page page);
 extern void mask_page_hint_bits(Page page);
 extern void mask_unused_space(Page page);
 extern void mask_lp_flags(Page page);