Extend PageIsVerified() to handle more custom options

michaelpq · michaelpq · commit 0a593bc4674f · 2020-11-02T10:41:34.000+09:00
This is useful for checks of relation pages without having to load the pages into the shared buffers, and two cases can make use of that: page verification in base backups and the online, lock-safe, flavor. Compatibility is kept with past versions using a routine that calls the new extended routine with the set of options compatible with the original version. Contrary to d401c57, a macro cannot be used as there may be external code relying on the presence of the original routine. This is applied down to 11, where this will be used by a follow-up commit addressing a set of issues with page verification in base backups. Extracted from a larger patch by the same author. Author: Anastasia Lubennikova Reviewed-by: Michael Paquier, Julien Rouhaud Discussion: https://postgr.es/m/608f3476-0598-2514-2c03-e05c7d2b0cbd@postgrespro.ru Backpatch-through: 11
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
@@ -612,7 +612,8 @@ ReadBuffer(Relation reln, BlockNumber blockNum)
  *
  * In RBM_NORMAL mode, the page is read from disk, and the page header is
  * validated.  An error is thrown if the page header is not valid.  (But
- * note that an all-zero page is considered "valid"; see PageIsVerified().)
+ * note that an all-zero page is considered "valid"; see
+ * PageIsVerifiedExtended().)
  *
  * RBM_ZERO_ON_ERROR is like the normal mode, but if the page header is not
  * valid, the page is zeroed instead of throwing an error. This is intended
@@ -898,7 +899,8 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
 			}
 
 			/* check for garbage data */
-			if (!PageIsVerified((Page) bufBlock, blockNum))
+			if (!PageIsVerifiedExtended((Page) bufBlock, blockNum,
+										PIV_LOG_WARNING))
 			{
 				if (mode == RBM_ZERO_ON_ERROR || zero_damaged_pages)
 				{
diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c
@@ -61,6 +61,17 @@ PageInit(Page page, Size pageSize, Size specialSize)
 
 /*
  * PageIsVerified
+ *		Utility wrapper for PageIsVerifiedExtended().
+ */
+bool
+PageIsVerified(Page page, BlockNumber blkno)
+{
+	return PageIsVerifiedExtended(page, blkno, PIV_LOG_WARNING);
+}
+
+
+/*
+ * PageIsVerifiedExtended
  *		Check that the page header and checksum (if any) appear valid.
  *
  * This is called when a page has just been read in from disk.  The idea is
@@ -76,9 +87,12 @@ PageInit(Page page, Size pageSize, Size specialSize)
  * allow zeroed pages here, and are careful that the page access macros
  * treat such a page as empty and without free space.  Eventually, VACUUM
  * will clean up such a page and make it usable.
+ *
+ * If flag PIV_LOG_WARNING is set, a WARNING is logged in the event of
+ * a checksum failure.
  */
 bool
-PageIsVerified(Page page, BlockNumber blkno)
+PageIsVerifiedExtended(Page page, BlockNumber blkno, int flags)
 {
 	PageHeader	p = (PageHeader) page;
 	size_t	   *pagebytes;
@@ -146,10 +160,11 @@ PageIsVerified(Page page, BlockNumber blkno)
 	 */
 	if (checksum_failure)
 	{
-		ereport(WARNING,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg("page verification failed, calculated checksum %u but expected %u",
-						checksum, p->pd_checksum)));
+		if ((flags & PIV_LOG_WARNING) != 0)
+			ereport(WARNING,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg("page verification failed, calculated checksum %u but expected %u",
+							checksum, p->pd_checksum)));
 
 		if (header_sane && ignore_checksum_failure)
 			return true;
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
@@ -406,16 +406,22 @@ do { \
  *		extern declarations
  * ----------------------------------------------------------------
  */
+
+/* flags for PageAddItemExtended() */
 #define PAI_OVERWRITE			(1 << 0)
 #define PAI_IS_HEAP				(1 << 1)
 
+/* flags for PageIsVerifiedExtended() */
+#define PIV_LOG_WARNING			(1 << 0)
+
 #define PageAddItem(page, item, size, offsetNumber, overwrite, is_heap) \
 	PageAddItemExtended(page, item, size, offsetNumber, \
 						((overwrite) ? PAI_OVERWRITE : 0) | \
 						((is_heap) ? PAI_IS_HEAP : 0))
 
 extern void PageInit(Page page, Size pageSize, Size specialSize);
 extern bool PageIsVerified(Page page, BlockNumber blkno);
+extern bool PageIsVerifiedExtended(Page page, BlockNumber blkno, int flags);
 extern OffsetNumber PageAddItemExtended(Page page, Item item, Size size,
 					OffsetNumber offsetNumber, int flags);
 extern Page PageGetTempPage(Page page);

Original file line number	Diff line number	Diff line change
`@@ -612,7 +612,8 @@ ReadBuffer(Relation reln, BlockNumber blockNum)`
`612`	`612`	`*`
`613`	`613`	`* In RBM_NORMAL mode, the page is read from disk, and the page header is`
`614`	`614`	`* validated. An error is thrown if the page header is not valid. (But`
`615`		`- * note that an all-zero page is considered "valid"; see PageIsVerified().)`
	`615`	`+ * note that an all-zero page is considered "valid"; see`
	`616`	`+ * PageIsVerifiedExtended().)`
`616`	`617`	`*`
`617`	`618`	`* RBM_ZERO_ON_ERROR is like the normal mode, but if the page header is not`
`618`	`619`	`* valid, the page is zeroed instead of throwing an error. This is intended`
`@@ -898,7 +899,8 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,`
`898`	`899`	`}`
`899`	`900`
`900`	`901`	`/* check for garbage data */`
`901`		`- if (!PageIsVerified((Page) bufBlock, blockNum))`
	`902`	`+ if (!PageIsVerifiedExtended((Page) bufBlock, blockNum,`
	`903`	`+ PIV_LOG_WARNING))`
`902`	`904`	`{`
`903`	`905`	`if (mode == RBM_ZERO_ON_ERROR \|\| zero_damaged_pages)`
`904`	`906`	`{`