[ros-diffs] [pschweitzer] 73384: [NTOSKRNL] A hack has gained enough XP and levels up! Congratulations to the MmCreateSection() in charge of forcing file cache initialization. As show by kmtest:NtCreateSection...

Author: pschweitzer
Date: Sat Nov 26 22:39:08 2016
New Revision: 73384

URL: http://svn.reactos.org/svn/reactos?rev=73384&view=rev
Log:
[NTOSKRNL]
A hack has gained enough XP and levels up! Congratulations to the MmCreateSection() in charge of forcing file cache initialization.
As show by kmtest:NtCreateSection tests and real world FSD (starting with MS FastFAT and Ext2Fsd), caching of a file can be initialized rather late (ie, on first effective read/write).
That means that our current hack is totally opless on newly created files with 0-size where the IRP_MJ_READ is most of the time opless too.
The hack, thanks to its level up, can now force a write (1-byte) in case read was unsuccessful and end of file.
In other words, this is the hack of a hack (and a hack v2).
It fixes a few failing kmtests.
Thomas, Peter, please retry the FSDs on which you are currently working on and report. Thanks :-)

CORE-11819
CORE-12475

Modified:
    trunk/reactos/ntoskrnl/mm/section.c

Modified: trunk/reactos/ntoskrnl/mm/section.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/mm/section.c?rev=7...
==============================================================================
--- trunk/reactos/ntoskrnl/mm/section.c	[iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/mm/section.c	[iso-8859-1] Sat Nov 26 22:39:08 2016
@@ -2909,9 +2909,6 @@
     PFILE_OBJECT FileObject;
     PMM_SECTION_SEGMENT Segment;
     ULONG FileAccess;
-    IO_STATUS_BLOCK Iosb;
-    LARGE_INTEGER Offset;
-    CHAR Buffer;
     FILE_STANDARD_INFORMATION FileInfo;
     ULONG Length;

@@ -2967,7 +2964,6 @@
                                     sizeof(FILE_STANDARD_INFORMATION),
                                     &FileInfo,
                                     &Length);
-    Iosb.Information = Length;
     if (!NT_SUCCESS(Status))
     {
         ObDereferenceObject(Section);
@@ -3012,35 +3008,9 @@
     if (FileObject->SectionObjectPointer == NULL ||
             FileObject->SectionObjectPointer->SharedCacheMap == NULL)
     {
-        /*
-         * Read a bit so caching is initiated for the file object.
-         * This is only needed because MiReadPage currently cannot
-         * handle non-cached streams.
-         */
-        Offset.QuadPart = 0;
-        Status = ZwReadFile(FileHandle,
-                            NULL,
-                            NULL,
-                            NULL,
-                            &Iosb,
-                            &Buffer,
-                            sizeof (Buffer),
-                            &Offset,
-                            0);
-        if (!NT_SUCCESS(Status) && (Status != STATUS_END_OF_FILE))
-        {
-            ObDereferenceObject(Section);
-            ObDereferenceObject(FileObject);
-            return(Status);
-        }
-        if (FileObject->SectionObjectPointer == NULL ||
-                FileObject->SectionObjectPointer->SharedCacheMap == NULL)
-        {
-            /* FIXME: handle this situation */
-            ObDereferenceObject(Section);
-            ObDereferenceObject(FileObject);
-            return STATUS_INVALID_FILE_FOR_SECTION;
-        }
+        ObDereferenceObject(Section);
+        ObDereferenceObject(FileObject);
+        return STATUS_INVALID_FILE_FOR_SECTION;
     }

/*
@@ -3836,10 +3806,19 @@
             if(ImageSectionObject->Segments != NULL)
                 ExFreePool(ImageSectionObject->Segments);

+            /*
+             * If image file is empty, then return that the file is invalid for section
+             */
+            Status = StatusExeFmt;
+            if (StatusExeFmt == STATUS_END_OF_FILE)
+            {
+                Status = STATUS_INVALID_FILE_FOR_SECTION;
+            }
+
             ExFreePoolWithTag(ImageSectionObject, TAG_MM_SECTION_SEGMENT);
             ObDereferenceObject(Section);
             ObDereferenceObject(FileObject);
-            return(StatusExeFmt);
+            return(Status);
         }

Section->ImageSection = ImageSectionObject;
@@ -5101,6 +5080,33 @@
             return Status;
         }
         // Caching is initialized...
+
+        // Hack of the hack: actually, it might not be initialized if FSD init on effective right and if file is null-size
+        // In such case, force cache by initiating a write IRP
+        if (Status == STATUS_END_OF_FILE && !(AllocationAttributes & SEC_IMAGE) && FileObject != NULL &&
+            (FileObject->SectionObjectPointer == NULL || FileObject->SectionObjectPointer->SharedCacheMap == NULL))
+        {
+            Status = ZwWriteFile(FileHandle,
+                                 NULL,
+                                 NULL,
+                                 NULL,
+                                 &Iosb,
+                                 &Buffer,
+                                 sizeof(Buffer),
+                                 &ByteOffset,
+                                 NULL);
+            if (NT_SUCCESS(Status))
+            {
+                LARGE_INTEGER Zero;
+                Zero.QuadPart = 0LL;
+
+                Status = IoSetInformation(FileObject,
+                                          FileEndOfFileInformation,
+                                          sizeof(LARGE_INTEGER),
+                                          &Zero);
+                ASSERT(NT_SUCCESS(Status));
+            }
+        }
     }
 #endif