Let caller of PageIsVerified() control ignore_checksum_failure

For AIO the completion of a read into shared buffers (i.e. verifying the page
including the checksum, updating the BufferDesc to reflect the IO) can happen
in a different backend than the backend that started the IO. As
ignore_checksum_failure can differ between backends, we need to allow the
caller of PageIsVerified() control whether to ignore checksum failures.

The commit leaves a gap in the PIV_* values, as an upcoming commit, which
depends on this commit, will add PIV_LOG_LOG, which better fits just after
PIV_LOG_WARNING.

Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/20250329212929.a6.nmisch@google.com

src/backend/catalog/storage.c

@@ -508,6 +508,7 @@ RelationCopyStorage(SMgrRelation src, SMgrRelation dst,
 	for (blkno = 0; blkno < nblocks; blkno++)
 	{
 		BulkWriteBuffer buf;
+		int			piv_flags;
 		bool		checksum_failure;
 		bool		verified;
 
@@ -517,9 +518,11 @@ RelationCopyStorage(SMgrRelation src, SMgrRelation dst,
 		buf = smgr_bulk_get_buf(bulkstate);
 		smgrread(src, forkNum, blkno, (Page) buf);
 
-		verified = PageIsVerified((Page) buf, blkno, PIV_LOG_WARNING,
+		piv_flags = PIV_LOG_WARNING;
+		if (ignore_checksum_failure)
+			piv_flags |= PIV_IGNORE_CHECKSUM_FAILURE;
+		verified = PageIsVerified((Page) buf, blkno, piv_flags,
 								  &checksum_failure);
-
 		if (checksum_failure)
 		{
 			RelFileLocatorBackend rloc = src->smgr_rlocator;

src/backend/storage/buffer/bufmgr.c

@@ -1569,6 +1569,7 @@ WaitReadBuffers(ReadBuffersOperation *operation)
 		{
 			BufferDesc *bufHdr;
 			Block		bufBlock;
+			int			piv_flags;
 			bool		verified;
 			bool		checksum_failure;
 
@@ -1584,8 +1585,11 @@ WaitReadBuffers(ReadBuffersOperation *operation)
 			}
 
 			/* check for garbage data */
+			piv_flags = PIV_LOG_WARNING;
+			if (ignore_checksum_failure)
+				piv_flags |= PIV_IGNORE_CHECKSUM_FAILURE;
 			verified = PageIsVerified((Page) bufBlock, io_first_block + j,
-									  PIV_LOG_WARNING, &checksum_failure);
+									  piv_flags, &checksum_failure);
 			if (checksum_failure)
 			{
 				RelFileLocatorBackend rloc = operation->smgr->smgr_rlocator;

src/backend/storage/page/bufpage.c

@@ -81,10 +81,14 @@ PageInit(Page page, Size pageSize, Size specialSize)
  * If flag PIV_LOG_WARNING is set, a WARNING is logged in the event of
  * a checksum failure.
  *
+ * If flag PIV_IGNORE_CHECKSUM_FAILURE is set, checksum failures will cause a
+ * message about the failure to be emitted, but will not cause
+ * PageIsVerified() to return false.
+ *
  * To allow the caller to report statistics about checksum failures,
  * *checksum_failure_p can be passed in. Note that there may be checksum
  * failures even if this function returns true, due to
- * ignore_checksum_failure.
+ * IGNORE_CHECKSUM_FAILURE.
  */
 bool
 PageIsVerified(PageData *page, BlockNumber blkno, int flags, bool *checksum_failure_p)
@@ -150,7 +154,7 @@ PageIsVerified(PageData *page, BlockNumber blkno, int flags, bool *checksum_fail
 					 errmsg("page verification failed, calculated checksum %u but expected %u",
 							checksum, p->pd_checksum)));
 
-		if (header_sane && ignore_checksum_failure)
+		if (header_sane && (flags & PIV_IGNORE_CHECKSUM_FAILURE))
 			return true;
 	}
 

src/include/storage/bufpage.h

@@ -467,6 +467,7 @@ do { \
 
 /* flags for PageIsVerified() */
 #define PIV_LOG_WARNING			(1 << 0)
+#define PIV_IGNORE_CHECKSUM_FAILURE (1 << 2)
 
 #define PageAddItem(page, item, size, offsetNumber, overwrite, is_heap) \
 	PageAddItemExtended(page, item, size, offsetNumber, \