postgres.git / summary / log / commit / refs

commit    fbbc48995d056d54a7feb701a77707a6202b267a
Author:   Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:     Thu Jun 24 08:19:03 2021 +0000
First released in: 14.0, 9.6.23, 10.18, 11.13, 12.8, 13.4

    Another fix to relmapper race condition.
    
    In previous commit, I missed that relmap_redo() was also not acquiring the
    RelationMappingLock. Thanks to Thomas Munro for pointing that out.
    
    Backpatch-through: 9.6, like previous commit.
    Discussion: https://www.postgresql.org/message-id/CA%2BhUKGLev%3DPpOSaL3WRZgOvgk217et%2BbxeJcRr4eR-NttP1F6Q%40mail.gmail.com


 src/backend/utils/cache/relmapper.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/backend/utils/cache/relmapper.c b/src/backend/utils/cache/relmapper.c
index e837c409e4c..5ff8dfd1143 100644
--- a/src/backend/utils/cache/relmapper.c
+++ b/src/backend/utils/cache/relmapper.c
@@ -948,12 +948,13 @@ relmap_redo(XLogReaderState *record)
 		 * preserve files, either.
 		 *
 		 * There shouldn't be anyone else updating relmaps during WAL replay,
-		 * so we don't bother to take the RelationMappingLock.  We would need
-		 * to do so if load_relmap_file needed to interlock against writers.
+		 * but grab the lock to interlock against load_relmap_file().
 		 */
+		LWLockAcquire(RelationMappingLock, LW_EXCLUSIVE);
 		write_relmap_file((xlrec->dbid == InvalidOid), &newmap,
 						  false, true, false,
 						  xlrec->dbid, xlrec->tsid, dbpath);
+		LWLockRelease(RelationMappingLock);
 
 		pfree(dbpath);
 	}


[parent: a5eacd86b715]