Make nfs_file_cred more robust.

As not all files have an associated open_context (e.g. device special
files), it is safest to test for the existence of the open context
before de-referencing it.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index ac8d0233b05c..4eaa8347a0d9 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -367,8 +367,12 @@ static inline struct nfs_open_context *nfs_file_open_context(struct file *filp)
 
 static inline struct rpc_cred *nfs_file_cred(struct file *file)
 {
-        if (file != NULL)
-                return nfs_file_open_context(file)->cred;
+        if (file != NULL) {
+                struct nfs_open_context *ctx =
+                        nfs_file_open_context(file);
+                if (ctx)
+                        return ctx->cred;
+        }
         return NULL;
 }