Be careful to get share lock on each page before computing its free space.

ITAGAKI Takahiro

diff --git a/contrib/pgstattuple/pgstattuple.c b/contrib/pgstattuple/pgstattuple.c
index 83546d57c38c7df53928cf94db599c830af30884..176f517c52001b35762d31551ee28c95517f036d 100644 (file)
--- a/contrib/pgstattuple/pgstattuple.c
+++ b/contrib/pgstattuple/pgstattuple.c
@@ -291,8 +291,7 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
                        buffer = ReadBuffer(rel, block);
                        LockBuffer(buffer, BUFFER_LOCK_SHARE);
                        stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
-                       LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-                       ReleaseBuffer(buffer);
+                       UnlockReleaseBuffer(buffer);
                        block++;
                }
        }
@@ -301,8 +300,9 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
        while (block < nblocks)
        {
                buffer = ReadBuffer(rel, block);
+               LockBuffer(buffer, BUFFER_LOCK_SHARE);
                stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
-               ReleaseBuffer(buffer);
+               UnlockReleaseBuffer(buffer);
                block++;
        }