linux-kernel - [PATCH] mm: Use helper function put_write

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Date:   Thu, 24 Sep 2020 07:52:35 -0400
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <christian.brauner@...ntu.com>,
        <mingo@...nel.org>, <peterz@...radead.org>,
        <ebiederm@...ssion.com>, <christian@...lner.me>,
        <surenb@...gle.com>, <areber@...hat.com>, <shakeelb@...gle.com>,
        <cyphar@...har.com>, <tglx@...utronix.de>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH] mm: Use helper function put_write_access()

In commit 1da177e4c3f4 ("Linux-2.6.12-rc2"), the helper put_write_access()
came with the atomic_dec operation of the i_writecount field. But it forgot
to use this helper in __vma_link_file() and dup_mmap().

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 kernel/fork.c | 2 +-
 mm/mmap.c     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index b9164b75b20c..c92bbbdcc6ad 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -555,7 +555,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 
 			get_file(file);
 			if (tmp->vm_flags & VM_DENYWRITE)
-				atomic_dec(&inode->i_writecount);
+				put_write_access(inode);
 			i_mmap_lock_write(mapping);
 			if (tmp->vm_flags & VM_SHARED)
 				mapping_allow_writable(mapping);
diff --git a/mm/mmap.c b/mm/mmap.c
index fc1bd8264407..9b211e8b267d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -663,7 +663,7 @@ static void __vma_link_file(struct vm_area_struct *vma)
 		struct address_space *mapping = file->f_mapping;
 
 		if (vma->vm_flags & VM_DENYWRITE)
-			atomic_dec(&file_inode(file)->i_writecount);
+			put_write_access(file_inode(file));
 		if (vma->vm_flags & VM_SHARED)
 			mapping_allow_writable(mapping);
 
-- 
2.19.1