kernfs: fix barrier usage in __kernfs_new_node()

BugLink: https://bugs.launchpad.net/bugs/1838576
commit 998267900cee901c5d1dfa029a6304d00acbc29f upstream.

smp_mb__before_atomic() can not be applied to atomic_set().  Remove the
barrier and rely on RELEASE synchronization.

Fixes: ba16b2846a8c6 ("kernfs: add an API to get kernfs node from inode number")
Cc: stable@vger.kernel.org
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 79db13fff3f07c002707a03736c14182eaf5b510..c95490e9b2258e0ef63b3052fdce5fc32af877f9 100644 (file)
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -650,11 +650,10 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
        kn->id.generation = gen;
 
        /*
-        * set ino first. This barrier is paired with atomic_inc_not_zero in
+        * set ino first. This RELEASE is paired with atomic_inc_not_zero in
         * kernfs_find_and_get_node_by_ino
         */
-       smp_mb__before_atomic();
-       atomic_set(&kn->count, 1);
+       atomic_set_release(&kn->count, 1);
        atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
        RB_CLEAR_NODE(&kn->rb);