sys: fileinfo: call MmCanFileBeTruncated only when truncating (allows file mappings to be created)

sys: util.c: FspGetMdlAddress()

src/sys/file.c

@@ -472,6 +472,10 @@ VOID FspFileNodeCleanupComplete(FSP_FILE_NODE *FileNode, PFILE_OBJECT FileObject
         }
         else if (FileNode->TruncateOnClose && FlagOn(FileObject->Flags, FO_CACHE_SUPPORTED))
         {
+            /*
+             * Even when the FileInfo is expired, this is the best guess for a file size
+             * without asking the user-mode file system.
+             */
             TruncateSize = FileNode->Header.FileSize;
             PTruncateSize = &TruncateSize;
         }

src/sys/fileinfo.c

@@ -573,21 +573,34 @@ static NTSTATUS FspFsvolSetAllocationInformation(PFILE_OBJECT FileObject,
     {
         PFILE_ALLOCATION_INFORMATION Info = (PFILE_ALLOCATION_INFORMATION)Buffer;
         FSP_FILE_NODE *FileNode = FileObject->FsContext;
+        FSP_FSCTL_FILE_INFO FileInfo;
         FSP_FSVOL_DEVICE_EXTENSION *FsvolDeviceExtension =
             FspFsvolDeviceExtension(FileNode->FsvolDeviceObject);
-        UINT64 AllocationSize = Info->AllocationSize.QuadPart;
+        LARGE_INTEGER AllocationSize = Info->AllocationSize;
         UINT64 AllocationUnit;
         BOOLEAN Success;
 
         AllocationUnit = FsvolDeviceExtension->VolumeParams.SectorSize *
             FsvolDeviceExtension->VolumeParams.SectorsPerAllocationUnit;
-        AllocationSize = (AllocationSize + AllocationUnit - 1) / AllocationUnit * AllocationUnit;
+        AllocationSize.QuadPart = (AllocationSize.QuadPart + AllocationUnit - 1) /
-        Request->Req.SetInformation.Info.Allocation.AllocationSize = AllocationSize;
+            AllocationUnit * AllocationUnit;
+        Request->Req.SetInformation.Info.Allocation.AllocationSize = AllocationSize.QuadPart;
 
-        Success = MmCanFileBeTruncated(FileObject->SectionObjectPointer, &Info->AllocationSize);
+        /*
+         * Even when the FileInfo is expired, this is the best guess for a file size
+         * without asking the user-mode file system.
+         */
+        FspFileNodeGetFileInfo(FileNode, &FileInfo);
+
+        /* are we truncating? */
+        if ((UINT64)AllocationSize.QuadPart < FileInfo.FileSize)
+        {
+            /* see what the MM thinks about all this */
+            Success = MmCanFileBeTruncated(FileObject->SectionObjectPointer, &AllocationSize);
             if (!Success)
                 return STATUS_USER_MAPPED_FILE;
         }
+    }
     else
     {
         FSP_FILE_NODE *FileNode = FileObject->FsContext;
@@ -654,14 +667,27 @@ static NTSTATUS FspFsvolSetEndOfFileInformation(PFILE_OBJECT FileObject,
     else if (0 == Response)
     {
         PFILE_END_OF_FILE_INFORMATION Info = (PFILE_END_OF_FILE_INFORMATION)Buffer;
+        FSP_FILE_NODE *FileNode = FileObject->FsContext;
+        FSP_FSCTL_FILE_INFO FileInfo;
         BOOLEAN Success;
 
         Request->Req.SetInformation.Info.EndOfFile.FileSize = Info->EndOfFile.QuadPart;
 
+        /*
+         * Even when the FileInfo is expired, this is the best guess for a file size
+         * without asking the user-mode file system.
+         */
+        FspFileNodeGetFileInfo(FileNode, &FileInfo);
+
+        /* are we truncating? */
+        if ((UINT64)Info->EndOfFile.QuadPart < FileInfo.FileSize)
+        {
+            /* see what the MM thinks about all this */
             Success = MmCanFileBeTruncated(FileObject->SectionObjectPointer, &Info->EndOfFile);
             if (!Success)
                 return STATUS_USER_MAPPED_FILE;
         }
+    }
     else
     {
         FSP_FILE_NODE *FileNode = FileObject->FsContext;

src/sys/util.c

@@ -539,11 +539,21 @@ static VOID FspQueueDelayedWorkItemDPC(PKDPC Dpc,
     ExQueueWorkItem(&DelayedWorkItem->WorkQueueItem, DelayedWorkQueue);
 }
 
+static inline PVOID FspGetMdlAddress(PMDL Mdl)
+{
+    PVOID VirtualAddress = MmGetMdlVirtualAddress(Mdl);
+
+    if (0 == VirtualAddress)
+        VirtualAddress = MmGetSystemAddressForMdlSafe(Mdl, NormalPagePriority);
+
+    return VirtualAddress;
+}
+
 BOOLEAN FspSafeMdlCheck(PMDL Mdl)
 {
     PAGED_CODE();
 
-    PVOID VirtualAddress = MmGetMdlVirtualAddress(Mdl);
+    PVOID VirtualAddress = FspGetMdlAddress(Mdl);
     ULONG ByteCount = MmGetMdlByteCount(Mdl);
 
     return 0 == BYTE_OFFSET(VirtualAddress) && 0 == BYTE_OFFSET(ByteCount);
@@ -554,7 +564,7 @@ NTSTATUS FspSafeMdlCreate(PMDL UserMdl, LOCK_OPERATION Operation, FSP_SAFE_MDL *
     PAGED_CODE();
 
     NTSTATUS Result;
-    PVOID VirtualAddress = MmGetMdlVirtualAddress(UserMdl);
+    PVOID VirtualAddress = FspGetMdlAddress(UserMdl);
     ULONG ByteCount = MmGetMdlByteCount(UserMdl);
     ULONG PageCount = ADDRESS_AND_SIZE_TO_SPAN_PAGES(VirtualAddress, ByteCount);
     FSP_SAFE_MDL *SafeMdl;
@@ -696,7 +706,7 @@ VOID FspSafeMdlCopyBack(FSP_SAFE_MDL *SafeMdl)
     if (IoReadAccess == SafeMdl->Operation)
         return;
 
-    PVOID VirtualAddress = MmGetMdlVirtualAddress(SafeMdl->UserMdl);
+    PVOID VirtualAddress = FspGetMdlAddress(SafeMdl->UserMdl);
     ULONG ByteCount = MmGetMdlByteCount(SafeMdl->UserMdl);
     ULONG PageCount = ADDRESS_AND_SIZE_TO_SPAN_PAGES(VirtualAddress, ByteCount);
     ULONG ByteOffsetBgn0, ByteOffsetEnd0, ByteOffsetEnd1;