Invalidate smgr_targblock in smgrrelease().

macdice · macdice · commit 81e36d3e0df8 · 2023-08-17T15:45:13.000+12:00
In rare circumstances involving relfilenode reuse, it might have been possible for smgr_targblock to finish up pointing past the end. Oversight in b74e94d. Back-patch to 15. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Discussion: https://postgr.es/m/CA%2BhUKGJ8NTvqLHz6dqbQnt2c8XCki4r2QvXjBQcXpVwxTY_pvA%40mail.gmail.com
diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
@@ -296,6 +296,7 @@ smgrrelease(SMgrRelation reln)
 		smgrsw[reln->smgr_which].smgr_close(reln, forknum);
 		reln->smgr_cached_nblocks[forknum] = InvalidBlockNumber;
 	}
+	reln->smgr_targblock = InvalidBlockNumber;
 }
 
 /*

Original file line number	Diff line number	Diff line change
`@@ -296,6 +296,7 @@ smgrrelease(SMgrRelation reln)`
`296`	`296`	`smgrsw[reln->smgr_which].smgr_close(reln, forknum);`
`297`	`297`	`reln->smgr_cached_nblocks[forknum] = InvalidBlockNumber;`
`298`	`298`	`}`
	`299`	`+ reln->smgr_targblock = InvalidBlockNumber;`
`299`	`300`	`}`
`300`	`301`
`301`	`302`	`/*`