[PATCH 24/39] staging/lustre/obdclass: fix wrong device put in case of race

[Peng Tao]

From: Mikhail Pershin <mike.pershin@xxxxxxxxx>

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

Lustre-change: http://review.whamcloud.com/6334
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3316
Signed-off-by: Mikhail Pershin <mike.pershin@xxxxxxxxx>
Reviewed-by: Fan Yong <fan.yong@xxxxxxxxx>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@xxxxxxxxx>
Reviewed-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Signed-off-by: Peng Tao <bergwolf@xxxxxxxxx>
Signed-off-by: Andreas Dilger <andreas.dilger@xxxxxxxxx>
---
 .../staging/lustre/lustre/obdclass/local_storage.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/lustre/lustre/obdclass/local_storage.c b/drivers/staging/lustre/lustre/obdclass/local_storage.c
index 295bb7c..367d3fd 100644
--- a/drivers/staging/lustre/lustre/obdclass/local_storage.c
+++ b/drivers/staging/lustre/lustre/obdclass/local_storage.c
@@ -882,12 +882,15 @@ void local_oid_storage_fini(const struct lu_env *env,
 	ls = dt2ls_dev(los->los_dev);
 
 	mutex_lock(&ls->ls_los_mutex);
-	if (atomic_read(&los->los_refcount) == 0) {
-		if (los->los_obj)
-			lu_object_put_nocache(env, &los->los_obj->do_lu);
-		list_del(&los->los_list);
-		OBD_FREE_PTR(los);
+	if (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);
+	list_del(&los->los_list);
+	OBD_FREE_PTR(los);
 	mutex_unlock(&ls->ls_los_mutex);
 	ls_device_put(env, ls);
 }
-- 
1.7.9.5

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