NFS: get module in idmap PipeFS notifier callback

This is bug fix.
Notifier callback is called from SUNRPC module. So before dereferencing NFS
module we have to make sure, that it's alive.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index b7f348bb618b8d8864f7a5e2569aff8f4ef4e3a7..ba3019f5934c21a610a96569b1d239b90eca0459 100644 (file)
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -554,12 +554,16 @@ static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
        struct nfs_client *clp;
        int error = 0;
 
+       if (!try_module_get(THIS_MODULE))
+               return 0;
+
        while ((clp = nfs_get_client_for_event(sb->s_fs_info, event))) {
                error = __rpc_pipefs_event(clp, event, sb);
                nfs_put_client(clp);
                if (error)
                        break;
        }
+       module_put(THIS_MODULE);
        return error;
 }