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);
 }