Fix masking of SP-GiST pages during xlog consistency check

akorotkov · akorotkov · commit 396a44a01536 · 2020-06-20T17:35:55.000+03:00
spg_mask() didn't take into account that pd_lower equal to SizeOfPageHeaderData is still valid value. This commit fixes that. Backpatch to 11, where spg_mask() pg_lower check was introduced. Reported-by: Michael Paquier Discussion: https://postgr.es/m/20200615131405.GM52676%40paquier.xyz Backpatch-through: 11
diff --git a/src/backend/access/spgist/spgxlog.c b/src/backend/access/spgist/spgxlog.c
@@ -1008,6 +1008,6 @@ spg_mask(char *pagedata, BlockNumber blkno)
 	 * Mask the unused space, but only if the page's pd_lower appears to have
 	 * been set correctly.
 	 */
-	if (pagehdr->pd_lower > SizeOfPageHeaderData)
+	if (pagehdr->pd_lower >= SizeOfPageHeaderData)
 		mask_unused_space(page);
 }

Original file line number	Diff line number	Diff line change
`@@ -1008,6 +1008,6 @@ spg_mask(char *pagedata, BlockNumber blkno)`
`1008`	`1008`	`* Mask the unused space, but only if the page's pd_lower appears to have`
`1009`	`1009`	`* been set correctly.`
`1010`	`1010`	`*/`
`1011`		`- if (pagehdr->pd_lower > SizeOfPageHeaderData)`
	`1011`	`+ if (pagehdr->pd_lower >= SizeOfPageHeaderData)`
`1012`	`1012`	`mask_unused_space(page);`
`1013`	`1013`	`}`