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In REASSIGN OWNED of a database, lock the tuple as mandated.

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Commit aac2c9b4fd mandated such locking
and attempted to fulfill that mandate, but it missed REASSIGN OWNED.
Hence, it remained possible to lose VACUUM's inplace update of
datfrozenxid if a REASSIGN OWNED processed that database at the same
time.  This didn't affect the other inplace-updated catalog, pg_class.
For pg_class, REASSIGN OWNED calls ATExecChangeOwner() instead of the
generic AlterObjectOwner_internal(), and ATExecChangeOwner() fulfills
the locking mandate.

Like in GRANT, implement this by following the locking protocol for any
catalog subject to the generic AlterObjectOwner_internal().  It would
suffice to do this for IsInplaceUpdateOid() catalogs only.  Back-patch
to v13 (all supported versions).

Kirill Reshke.  Reported by Alexander Kukushkin.

Discussion: https://postgr.es/m/CAFh8B=mpKjAy4Cuun-HP-f_vRzh2HSvYFG3rhVfYbfEBUhBAGg@mail.gmail.com
This commit is contained in:
Noah Misch
2024-12-28 07:16:22 -08:00
parent 58a359e585
commit ff90ee6145
5 changed files with 51 additions and 2 deletions
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9
src/backend/commands/alter.c
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@@ -59,6 +59,7 @@
#include "miscadmin.h"
#include "replication/logicalworker.h"
#include "rewrite/rewriteDefine.h"
#include "storage/lmgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
@@ -924,7 +925,9 @@ AlterObjectOwner_internal(Oid classId, Oid objectId, Oid new_ownerId)
rel = table_open(catalogId, RowExclusiveLock);
oldtup = get_catalog_object_by_oid(rel, Anum_oid, objectId);
/* Search tuple and lock it. */
oldtup =
get_catalog_object_by_oid_extended(rel, Anum_oid, objectId, true);
if (oldtup == NULL)
elog(ERROR, "cache lookup failed for object %u of catalog \"%s\"",
objectId, RelationGetRelationName(rel));
@@ -1024,6 +1027,8 @@ AlterObjectOwner_internal(Oid classId, Oid objectId, Oid new_ownerId)
/* Perform actual update */
CatalogTupleUpdate(rel, &newtup->t_self, newtup);
UnlockTuple(rel, &oldtup->t_self, InplaceUpdateTupleLock);
/* Update owner dependency reference */
changeDependencyOnOwner(classId, objectId, new_ownerId);
@@ -1032,6 +1037,8 @@ AlterObjectOwner_internal(Oid classId, Oid objectId, Oid new_ownerId)
pfree(nulls);
pfree(replaces);
}
else
UnlockTuple(rel, &oldtup->t_self, InplaceUpdateTupleLock);
/* Note the post-alter hook gets classId not catalogId */
InvokeObjectPostAlterHook(classId, objectId, 0);