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

Commit aac2c9b4fde889d13f859c233c2523345e72d32b 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

diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index be7e4a5dd01d43e42e709cd05028f156d3303dc4..87af58fac3a62b34cdcbc6e36d55067ee222ea08 100644 (file)
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -2784,6 +2784,22 @@ get_object_property_data(Oid class_id)
  */
 HeapTuple
 get_catalog_object_by_oid(Relation catalog, AttrNumber oidcol, Oid objectId)
+{
+       return
+               get_catalog_object_by_oid_extended(catalog, oidcol, objectId, false);
+}
+
+/*
+ * Same as get_catalog_object_by_oid(), but with an additional "locktup"
+ * argument controlling whether to acquire a LOCKTAG_TUPLE at mode
+ * InplaceUpdateTupleLock.  See README.tuplock section "Locking to write
+ * inplace-updated tables".
+ */
+HeapTuple
+get_catalog_object_by_oid_extended(Relation catalog,
+                                                                  AttrNumber oidcol,
+                                                                  Oid objectId,
+                                                                  bool locktup)
 {
        HeapTuple       tuple;
        Oid                     classId = RelationGetRelid(catalog);
@@ -2791,7 +2807,12 @@ get_catalog_object_by_oid(Relation catalog, AttrNumber oidcol, Oid objectId)
 
        if (oidCacheId > 0)
        {
-               tuple = SearchSysCacheCopy1(oidCacheId, ObjectIdGetDatum(objectId));
+               if (locktup)
+                       tuple = SearchSysCacheLockedCopy1(oidCacheId,
+                                                                                         ObjectIdGetDatum(objectId));
+               else
+                       tuple = SearchSysCacheCopy1(oidCacheId,
+                                                                               ObjectIdGetDatum(objectId));
                if (!HeapTupleIsValid(tuple))   /* should not happen */
                        return NULL;
        }
@@ -2816,6 +2837,10 @@ get_catalog_object_by_oid(Relation catalog, AttrNumber oidcol, Oid objectId)
                        systable_endscan(scan);
                        return NULL;
                }
+
+               if (locktup)
+                       LockTuple(catalog, &tuple->t_self, InplaceUpdateTupleLock);
+
                tuple = heap_copytuple(tuple);
 
                systable_endscan(scan);

diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index a45f3bb6b8347924d14d2497fadbe21fe6f50907..abb80fd1224a26ec14d6604222b7c9fa5cc5f7a8 100644 (file)
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -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);

diff --git a/src/include/catalog/objectaddress.h b/src/include/catalog/objectaddress.h
index 3a70d80e3201ee89273ed9da16b8b8a27543f107..c4ba1cb2b32933aa52516ce9906ab1e053e49f07 100644 (file)
--- a/src/include/catalog/objectaddress.h
+++ b/src/include/catalog/objectaddress.h
@@ -69,6 +69,10 @@ extern bool get_object_namensp_unique(Oid class_id);
 
 extern HeapTuple get_catalog_object_by_oid(Relation catalog,
                                                                                   AttrNumber oidcol, Oid objectId);
+extern HeapTuple get_catalog_object_by_oid_extended(Relation catalog,
+                                                                                                       AttrNumber oidcol,
+                                                                                                       Oid objectId,
+                                                                                                       bool locktup);
 
 extern char *getObjectDescription(const ObjectAddress *object,
                                                                  bool missing_ok);

diff --git a/src/test/regress/expected/database.out b/src/test/regress/expected/database.out
index 454db91ec090bc93cffd39a21cd8a36de0ddee2a..4cbdbdf84d0c55f9eb5f43a49adc4f60cd040765 100644 (file)
--- a/src/test/regress/expected/database.out
+++ b/src/test/regress/expected/database.out
@@ -12,4 +12,10 @@ WHERE datname = 'regression_utf8';
 -- load catcache entry, if nothing else does
 ALTER DATABASE regression_utf8 RESET TABLESPACE;
 ROLLBACK;
+CREATE ROLE regress_datdba_before;
+CREATE ROLE regress_datdba_after;
+ALTER DATABASE regression_utf8 OWNER TO regress_datdba_before;
+REASSIGN OWNED BY regress_datdba_before TO regress_datdba_after;
 DROP DATABASE regression_utf8;
+DROP ROLE regress_datdba_before;
+DROP ROLE regress_datdba_after;

diff --git a/src/test/regress/sql/database.sql b/src/test/regress/sql/database.sql
index 0367c0e37ab1fe85673355d182ac4c94627d739c..46ad2634781ea61fc1686bf987733f942fd552e2 100644 (file)
--- a/src/test/regress/sql/database.sql
+++ b/src/test/regress/sql/database.sql
@@ -14,4 +14,11 @@ WHERE datname = 'regression_utf8';
 ALTER DATABASE regression_utf8 RESET TABLESPACE;
 ROLLBACK;
 
+CREATE ROLE regress_datdba_before;
+CREATE ROLE regress_datdba_after;
+ALTER DATABASE regression_utf8 OWNER TO regress_datdba_before;
+REASSIGN OWNED BY regress_datdba_before TO regress_datdba_after;
+
 DROP DATABASE regression_utf8;
+DROP ROLE regress_datdba_before;
+DROP ROLE regress_datdba_after;