make get_file() return its argument

simplifies a bunch of callers...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index 79826c1..ff5d4e4 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -2306,7 +2306,7 @@
 	 * partially initialize the vma for the sampling buffer
 	 */
 	vma->vm_mm	     = mm;
-	vma->vm_file	     = filp;
+	vma->vm_file	     = get_file(filp);
 	vma->vm_flags	     = VM_READ| VM_MAYREAD |VM_RESERVED;
 	vma->vm_page_prot    = PAGE_READONLY; /* XXX may need to change */
 
@@ -2345,8 +2345,6 @@
 		goto error;
 	}
 
-	get_file(filp);
-
 	/*
 	 * now insert the vma in the vm list for the process, must be
 	 * done with mmap lock held