LU-3316 obdclass: fix wrong device put in case of race

The ls_device_put() might be called from local_oid_storage_fini()
wrongly if mutex-protected check failed due to race

This patch is back-ported from the following one:
Lustre-commit: 458804418f3c24706db7ad9a46f791e59f008a7d
Lustre-change: http://review.whamcloud.com/6334

Signed-off-by: Mikhail Pershin <mike.pershin@intel.com>
Change-Id: I386597e431ded0dd2b63b078200571a00bc5fe96
Signed-off-by: Jian Yu <jian.yu@intel.com>
Reviewed-on: http://review.whamcloud.com/8461
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/obdclass/local_storage.c b/lustre/obdclass/local_storage.c
index 26a3137..962da44 100644 (file)
--- a/lustre/obdclass/local_storage.c
+++ b/lustre/obdclass/local_storage.c
@@ -891,12 +891,15 @@ void local_oid_storage_fini(const struct lu_env *env,
        ls = dt2ls_dev(los->los_dev);
 
        mutex_lock(&ls->ls_los_mutex);
-       if (cfs_atomic_read(&los->los_refcount) == 0) {
-               if (los->los_obj)
-                       lu_object_put_nocache(env, &los->los_obj->do_lu);
-               cfs_list_del(&los->los_list);
-               OBD_FREE_PTR(los);
+       if (cfs_atomic_read(&los->los_refcount) > 0) {
+               mutex_unlock(&ls->ls_los_mutex);
+               return;
        }
+
+       if (los->los_obj)
+               lu_object_put_nocache(env, &los->los_obj->do_lu);
+       cfs_list_del(&los->los_list);
+       OBD_FREE_PTR(los);
        mutex_unlock(&ls->ls_los_mutex);
        ls_device_put(env, ls);
 }