I am confused - once upon a time, there would have been only a sysmem surface on the wined3d side, and wined3d does the clear directly on its system memory and reads the data from the source's system memory in the Blt() call.
Nowadays we have a video memory draw texture for sysmem surfaces because one can use them for texturing on native ddraw.
Is the issue here that ddraw accidentally made wined3d perform stuff on the vidmem draw texture rather than the 'original' system wiend3d_texture?