md: initialize percpu refcounters using PERCU_REF_ALLOW_REINIT

Percpu reference counters should now be initialized with the
PERCPU_REF_ALLOW_REINIT in order to allow switching them to the
percpu mode from the atomic mode.
To make percpu_ref_switch_to_percpu() call in set_in_sync()
succeed,let's initialize percpu refcounters with the
PERCU_REF_ALLOW_REINIT flag.

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Dennis Zhou <dennis@kernel.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 05ffffb8b7694ac8583f2285d483d4997a06aaec..16e034747a86dd64e94274d7902b4fcd702c93e6 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5249,7 +5249,8 @@ int mddev_init_writes_pending(struct mddev *mddev)
 {
        if (mddev->writes_pending.percpu_count_ptr)
                return 0;
-       if (percpu_ref_init(&mddev->writes_pending, no_op, 0, GFP_KERNEL) < 0)
+       if (percpu_ref_init(&mddev->writes_pending, no_op,
+                           PERCPU_REF_ALLOW_REINIT, GFP_KERNEL) < 0)
                return -ENOMEM;
        /* We want to start with the refcount at zero */
        percpu_ref_put(&mddev->writes_pending);