pnfs/blocklayout: serialize GETDEVICEINFO calls

The rpc_pipefs code isn't thread safe, leading to occasional use after
frees when running xfstests generic/241 (dbench).

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/1411740170-18611-2-git-send-email-hch@lst.de
Cc: stable@vger.kernel.org # 3.17.x
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
index ef221fb8a183..f0e06e4acbef 100644
--- a/fs/nfs/netns.h
+++ b/fs/nfs/netns.h
@@ -19,6 +19,7 @@ struct nfs_net {
         struct rpc_pipe *bl_device_pipe;
         struct bl_dev_msg bl_mount_reply;
         wait_queue_head_t bl_wq;
+        struct mutex bl_mutex;
         struct list_head nfs_client_list;
         struct list_head nfs_volume_list;
 #if IS_ENABLED(CONFIG_NFS_V4)