mm/vmalloc: extend __find_vmap_area() with one more argument

__find_vmap_area() finds a "vmap_area" based on passed address.  It scan
the specific "vmap_area_root" rb-tree.  Extend the function with one extra
argument, so any tree can be specified where the search has to be done.

There is no functional change as a result of this patch.

Link: https://lkml.kernel.org/r/20220607093449.3100-5-urezki@gmail.comSigned-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc.c

@@ -815,9 +815,9 @@ static struct vmap_area *find_vmap_area_exceed_addr(unsigned long addr)
 	return va;
 }
 
-static struct vmap_area *__find_vmap_area(unsigned long addr)
+static struct vmap_area *__find_vmap_area(unsigned long addr, struct rb_root *root)
 {
-	struct rb_node *n = vmap_area_root.rb_node;
+	struct rb_node *n = root->rb_node;
 
 	addr = (unsigned long)kasan_reset_tag((void *)addr);
 
@@ -1834,7 +1834,7 @@ struct vmap_area *find_vmap_area(unsigned long addr)
 	struct vmap_area *va;
 
 	spin_lock(&vmap_area_lock);
-	va = __find_vmap_area(addr);
+	va = __find_vmap_area(addr, &vmap_area_root);
 	spin_unlock(&vmap_area_lock);
 
 	return va;
@@ -2577,7 +2577,7 @@ struct vm_struct *remove_vm_area(const void *addr)
 	might_sleep();
 
 	spin_lock(&vmap_area_lock);
-	va = __find_vmap_area((unsigned long)addr);
+	va = __find_vmap_area((unsigned long)addr, &vmap_area_root);
 	if (va && va->vm) {
 		struct vm_struct *vm = va->vm;