From patchwork Thu Nov 30 20:56:38 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 10085645 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id EC6E5602B9 for ; Thu, 30 Nov 2017 20:56:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D801E2A322 for ; Thu, 30 Nov 2017 20:56:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CCE7B2A325; Thu, 30 Nov 2017 20:56:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_TVD_MIME_EPI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 505D02A323 for ; Thu, 30 Nov 2017 20:56:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750995AbdK3U4u (ORCPT ); Thu, 30 Nov 2017 15:56:50 -0500 Received: from mx2.suse.de ([195.135.220.15]:51187 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750842AbdK3U4t (ORCPT ); Thu, 30 Nov 2017 15:56:49 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de X-Amavis-Alert: BAD HEADER SECTION, Header field occurs more than once: "To" occurs 3 times Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 59FD4AF11; Thu, 30 Nov 2017 20:56:47 +0000 (UTC) From: NeilBrown To: Trond Myklebust , Anna.Schumaker@Netapp.com To: Al Viro , Andrew Morton To: Linus Torvalds Date: Fri, 01 Dec 2017 07:56:38 +1100 Cc: lkml , "linux-nfs\@vger.kernel.org" , linux-fsdevel Cc: Lennart Poettering Subject: [PATCH] NFS: allow name_to_handle_at() to work for Amazon EFS. Message-ID: <87po7zv62h.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Amazon EFS provides an NFSv4.1 filesystem which appears to use (close to) full length (128 byte) file handles. This causes the handle reported by name_to_handle_at() to exceed MAX_HANDLE_SZ, resulting in EOVERFLOW if 128 bytes were requested, or EINVAL if the size reported by the previous call was requested. To fix this, increase MAX_HANDLE_SIZE a little, and add a BUILD_BUG so that this sort of inconsistent error reporting won't happen again. Link: https://github.com/systemd/systemd/issues/7082#issuecomment-347380436 Signed-off-by: NeilBrown --- Sorry for the scatter-gun To: list. This is really more of a VFS patch than an NFS patch and sending patches in either direction has been a bit hit-and-miss lately, so I'm hoping Andrew will take it unless someone else objects or beats him to it... Thanks, NeilBrown fs/nfs/export.c | 2 ++ include/linux/exportfs.h | 7 +++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/nfs/export.c b/fs/nfs/export.c index 83fd09fc8f77..23b2fc3ab2bb 100644 --- a/fs/nfs/export.c +++ b/fs/nfs/export.c @@ -39,6 +39,8 @@ nfs_encode_fh(struct inode *inode, __u32 *p, int *max_len, struct inode *parent) size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size; int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size); + BUILD_BUG_ON_MSG(EMBED_FH_OFF + NFS_MAXFHSIZE > MAX_HANDLE_SZ, + "MAX_HANDLE_SZ is too small"); dprintk("%s: max fh len %d inode %p parent %p", __func__, *max_len, inode, parent); diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index 0d3037419bc7..e7ab1b071c5e 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -11,8 +11,11 @@ struct iomap; struct super_block; struct vfsmount; -/* limit the handle size to NFSv4 handle size now */ -#define MAX_HANDLE_SZ 128 +/* Must be larger than NFSv4 file handle, but small + * enough for an on-stack allocation. overlayfs doesn't + * want this too close to 255. + */ +#define MAX_HANDLE_SZ 200 /* * The fileid_type identifies how the file within the filesystem is encoded.