Fix two violations of the ResourceOwnerEnlarge/Remember protocol.

The point of having separate ResourceOwnerEnlargeFoo and
ResourceOwnerRememberFoo functions is so that resource allocation
can happen in between.  Doing it in some other order is just wrong.

OpenTemporaryFile() did open(), enlarge, remember, which would leak the
open file if the enlarge step ran out of memory.  Because fd.c has its own
layer of resource-remembering, the consequences look like they'd be limited
to an intratransaction FD leak, but it's still not good.

IncrBufferRefCount() did enlarge, remember, incr-refcount, which would blow
up if the incr-refcount step ever failed.  It was safe enough when written,
but since the introduction of PrivateRefCountHash, I think the assumption
that no error could happen there is pretty shaky.

The odds of real problems from either bug are probably small, but still,
back-patch to supported branches.

Thomas Munro and Tom Lane, per a comment from Andres Freund

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 3a300305ecd63a74fdfd27f31c9b7384cfa1412a..9cc2470de872e60715102057f1482e198017963e 100644 (file)
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -3348,7 +3348,6 @@ IncrBufferRefCount(Buffer buffer)
 {
        Assert(BufferIsPinned(buffer));
        ResourceOwnerEnlargeBuffers(CurrentResourceOwner);
-       ResourceOwnerRememberBuffer(CurrentResourceOwner, buffer);
        if (BufferIsLocal(buffer))
                LocalRefCount[-buffer - 1]++;
        else
@@ -3359,6 +3358,7 @@ IncrBufferRefCount(Buffer buffer)
                Assert(ref != NULL);
                ref->refcount++;
        }
+       ResourceOwnerRememberBuffer(CurrentResourceOwner, buffer);
 }
 
 /*

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index b07628fd7b2f57cbd7e5ecab6968772fb852c95d..b3020b11c5d344e3fb56fd79bc65380c7c7a58f1 100644 (file)
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -1335,6 +1335,13 @@ OpenTemporaryFile(bool interXact)
 {
        File            file = 0;
 
+       /*
+        * Make sure the current resource owner has space for this File before we
+        * open it, if we'll be registering it below.
+        */
+       if (!interXact)
+               ResourceOwnerEnlargeFiles(CurrentResourceOwner);
+
        /*
         * If some temp tablespace(s) have been given to us, try to use the next
         * one.  If a given tablespace can't be found, we silently fall back to
@@ -1371,9 +1378,8 @@ OpenTemporaryFile(bool interXact)
        {
                VfdCache[file].fdstate |= FD_XACT_TEMPORARY;
 
-               ResourceOwnerEnlargeFiles(CurrentResourceOwner);
-               ResourceOwnerRememberFile(CurrentResourceOwner, file);
                VfdCache[file].resowner = CurrentResourceOwner;
+               ResourceOwnerRememberFile(CurrentResourceOwner, file);
 
                /* ensure cleanup happens at eoxact */
                have_xact_temporary_files = true;