nfs: handle lock context allocation failures in nfs_create_request

nfs_get_lock_context can return NULL on an allocation failure.
Regression introduced by commit f11ac8db.

Reported-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 919490232e17..137b549e63db 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -65,6 +65,13 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
         if (req == NULL)
                 return ERR_PTR(-ENOMEM);
 
+        /* get lock context early so we can deal with alloc failures */
+        req->wb_lock_context = nfs_get_lock_context(ctx);
+        if (req->wb_lock_context == NULL) {
+                nfs_page_free(req);
+                return ERR_PTR(-ENOMEM);
+        }
+
         /* Initialize the request struct. Initially, we assume a
          * long write-back delay. This will be adjusted in
          * update_nfs_request below if the region is not locked. */
@@ -79,7 +86,6 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
         req->wb_pgbase  = offset;
         req->wb_bytes   = count;
         req->wb_context = get_nfs_open_context(ctx);
-        req->wb_lock_context = nfs_get_lock_context(ctx);
         kref_init(&req->wb_kref);
         return req;
 }