Fix wrong backpatching of ginRedoDeletePage() deadlock fix

19cf52e6cc changes lock order in ginRedoDeletePage().  But did it in a wrong
way due to oversight during backpatching.  This commit fixes that.

Reported-by: Bruce Momjian
Discussion: https://postgr.es/m/20181213153232.GA10664%40momjian.us

diff --git a/src/backend/access/gin/ginxlog.c b/src/backend/access/gin/ginxlog.c
index 091268175e5983b2cff37b0bae6da4da4a9cdbbc..76dabf19736cb574a10a8b92ba5542bca875f61f 100644 (file)
--- a/src/backend/access/gin/ginxlog.c
+++ b/src/backend/access/gin/ginxlog.c
@@ -690,7 +690,7 @@ ginRedoDeletePage(XLogRecPtr lsn, XLogRecord *record)
    ginxlogDeletePage *data = (ginxlogDeletePage *) XLogRecGetData(record);
    Buffer      dbuffer;
    Buffer      pbuffer;
-   Buffer      lbuffer;
+   Buffer      lbuffer = InvalidBlockNumber;
    Page        page;
 
    /*
@@ -698,7 +698,7 @@ ginRedoDeletePage(XLogRecPtr lsn, XLogRecord *record)
     * ginStepRight().
     */
    if (record->xl_info & XLR_BKP_BLOCK(2))
-       (void) RestoreBackupBlock(lsn, record, 2, false, false);
+       lbuffer = RestoreBackupBlock(lsn, record, 2, false, true);
    else if (data->leftBlkno != InvalidBlockNumber)
    {
        lbuffer = XLogReadBuffer(data->node, data->leftBlkno, false);
@@ -712,7 +712,6 @@ ginRedoDeletePage(XLogRecPtr lsn, XLogRecord *record)
                PageSetLSN(page, lsn);
                MarkBufferDirty(lbuffer);
            }
-           UnlockReleaseBuffer(lbuffer);
        }
    }
 
@@ -735,7 +734,7 @@ ginRedoDeletePage(XLogRecPtr lsn, XLogRecord *record)
    }
 
    if (record->xl_info & XLR_BKP_BLOCK(1))
-       pbuffer = RestoreBackupBlock(lsn, record, 1, false, true);
+       (void) RestoreBackupBlock(lsn, record, 1, false, false);
    else
    {
        pbuffer = XLogReadBuffer(data->node, data->parentBlkno, false);
@@ -750,13 +749,12 @@ ginRedoDeletePage(XLogRecPtr lsn, XLogRecord *record)
                PageSetLSN(page, lsn);
                MarkBufferDirty(pbuffer);
            }
+           UnlockReleaseBuffer(pbuffer);
        }
    }
 
    if (BufferIsValid(lbuffer))
        UnlockReleaseBuffer(lbuffer);
-   if (BufferIsValid(pbuffer))
-       UnlockReleaseBuffer(pbuffer);
    if (BufferIsValid(dbuffer))
        UnlockReleaseBuffer(dbuffer);
 }