NFSv4: Avoid unnecessary credential references in layoutget

Layoutget is just using the credential attached to the open context.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs4proc.c

@@ -9177,7 +9177,7 @@ nfs4_proc_layoutget(struct nfs4_layoutget *lgp, long *timeout)
 		.rpc_message = &msg,
 		.callback_ops = &nfs4_layoutget_call_ops,
 		.callback_data = lgp,
-		.flags = RPC_TASK_ASYNC,
+		.flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
 	};
 	struct pnfs_layout_segment *lseg = NULL;
 	struct nfs4_exception exception = {

fs/nfs/pnfs.c

@@ -1073,7 +1073,7 @@ pnfs_alloc_init_layoutget_args(struct inode *ino,
 	lgp->args.ctx = get_nfs_open_context(ctx);
 	nfs4_stateid_copy(&lgp->args.stateid, stateid);
 	lgp->gfp_flags = gfp_flags;
-	lgp->cred = get_cred(ctx->cred);
+	lgp->cred = ctx->cred;
 	return lgp;
 }
 
@@ -1084,7 +1084,6 @@ void pnfs_layoutget_free(struct nfs4_layoutget *lgp)
 	nfs4_free_pages(lgp->args.layout.pages, max_pages);
 	if (lgp->args.inode)
 		pnfs_put_layout_hdr(NFS_I(lgp->args.inode)->layout);
-	put_cred(lgp->cred);
 	put_nfs_open_context(lgp->args.ctx);
 	kfree(lgp);
 }