switch aio and shm to do_mmap_pgoff(), make do_mmap() static

after all, 0 bytes and 0 pages is the same thing...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/aio.c

@@ -134,9 +134,9 @@ static int aio_setup_ring(struct kioctx *ctx)
 	info->mmap_size = nr_pages * PAGE_SIZE;
 	dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
 	down_write(&ctx->mm->mmap_sem);
-	info->mmap_base = do_mmap(NULL, 0, info->mmap_size, 
-				  PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE,
-				  0);
+	info->mmap_base = do_mmap_pgoff(NULL, 0, info->mmap_size, 
+					PROT_READ|PROT_WRITE,
+					MAP_ANONYMOUS|MAP_PRIVATE, 0);
 	if (IS_ERR((void *)info->mmap_base)) {
 		up_write(&ctx->mm->mmap_sem);
 		info->mmap_size = 0;