From: Wei Yang <richard.weiyang@linux.alibaba.com>
Date: Tue, 13 Oct 2020 23:54:04 +0000 (-0700)
Subject: mm/mmap: not necessary to check mapping separately
X-Git-Tag: howlett/maple_spf/20210104~841^2~77
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=808fbdbea05f1e965da5b887d808025ba22c1946;p=users%2Fjedix%2Flinux-maple.git

mm/mmap: not necessary to check mapping separately

*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.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200913133631.37781-1-richard.weiyang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/mmap.c b/mm/mmap.c
index 57de816e2614..295197b75cb0 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -895,10 +895,9 @@ again:
 			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)