[PATCH] Use proper lock in fscache_objlist_config.

[Artem Savkov]

fscache_objlist_config doesn't hold rkey->sem when calling user_key_payload,
that can result in a "suspicious RCU usage" warning. It does hold
rcu_read_lock,  so it either needs to use unprotected rcu_dereference,
or take rkey->sem instead of rcu_read_lock.

Signed-off-by: Artem Savkov <asav...@redhat.com>
---
 fs/fscache/object-list.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/fscache/object-list.c b/fs/fscache/object-list.c
index 5d5ddaa..26c20e9 100644
--- a/fs/fscache/object-list.c
+++ b/fs/fscache/object-list.c
@@ -327,7 +327,7 @@ static void fscache_objlist_config(struct 
fscache_objlist_data *data)
                goto no_config;
 
        config = 0;
-       rcu_read_lock();
+       down_read(&key->sem);
 
        confkey = user_key_payload(key);
        buf = confkey->data;
@@ -349,7 +349,7 @@ static void fscache_objlist_config(struct 
fscache_objlist_data *data)
                }
        }
 
-       rcu_read_unlock();
+       up_read(&key->sem);
        key_put(key);
 
        if (!(config & (FSCACHE_OBJLIST_CONFIG_COOKIE | 
FSCACHE_OBJLIST_CONFIG_NOCOOKIE)))
-- 
2.7.4