[PATCH 1/2] mm/mmap: not necessary to check mapping separately

[Wei Yang]

*root* with type of struct rb_root_cached is an element of *mapping*
with type of struct address_space. This implies when we have a valid
*root* it must be a part of valid *mapping*.

So we can merge these two checks together to make the code more easy to
read and to save some cpu cycles.

Signed-off-by: Wei Yang <richard.weiy...@linux.alibaba.com>
---
 mm/mmap.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 1922e6fce9e7..30b155098606 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -895,10 +895,9 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long 
start,
                        anon_vma_interval_tree_post_update_vma(next);
                anon_vma_unlock_write(anon_vma);
        }
-       if (mapping)
-               i_mmap_unlock_write(mapping);
 
        if (root) {
+               i_mmap_unlock_write(mapping);
                uprobe_mmap(vma);
 
                if (adjust_next)
-- 
2.20.1 (Apple Git-117)