mm: use helper function mapping_allow_writable()

Commit 4bb5f5d9395b ("mm: allow drivers to prevent new writable mappings")
changed i_mmap_writable from unsigned int to atomic_t and add the helper
function mapping_allow_writable() to atomic_inc i_mmap_writable.  But it
forgot to use this helper function in dup_mmap() and __vma_link_file().

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Christian Kellner <christian@kellner.me>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Adrian Reber <areber@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200917112736.7789-1-linmiaohe@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/fork.c b/kernel/fork.c
index a3795aaaab5c580598aacd1299820d9a76b3aad0..2dcb19a30650d1d02dbfd379a44853e017ea942d 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -559,7 +559,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
                                atomic_dec(&inode->i_writecount);
                        i_mmap_lock_write(mapping);
                        if (tmp->vm_flags & VM_SHARED)
-                               atomic_inc(&mapping->i_mmap_writable);
+                               mapping_allow_writable(mapping);
                        flush_dcache_mmap_lock(mapping);
                        /* insert tmp into the share list, just after mpnt */
                        vma_interval_tree_insert_after(tmp, mpnt,

diff --git a/mm/mmap.c b/mm/mmap.c
index 19cd69524837d8492f428b9cf8062f3ccffb508b..7799a3f2e48385b8257b12d8ce06f694095bc138 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -621,7 +621,7 @@ static void __vma_link_file(struct vm_area_struct *vma)
                if (vma->vm_flags & VM_DENYWRITE)
                        atomic_dec(&file_inode(file)->i_writecount);
                if (vma->vm_flags & VM_SHARED)
-                       atomic_inc(&mapping->i_mmap_writable);
+                       mapping_allow_writable(mapping);
 
                flush_dcache_mmap_lock(mapping);
                vma_interval_tree_insert(vma, &mapping->i_mmap);