[104/181] mm/mmap: not necessary to check mapping separately

Commit Message

Andrew Morton Oct. 13, 2020, 11:54 p.m. UTC

From: Wei Yang <[e-mail]>
Subject: 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.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Wei Yang <[e-mail]>
Reviewed-by: Andrew Morton <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/mmap.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Patch

--- a/mm/mmap.c~mm-mmap-not-necessary-to-check-mapping-separately
+++ a/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)