Return-Path: Received: from mail-pa0-f47.google.com ([209.85.220.47]:33718 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211AbbFBB0A (ORCPT ); Mon, 1 Jun 2015 21:26:00 -0400 Message-ID: <556D0613.4000201@gmail.com> Date: Tue, 02 Jun 2015 09:25:39 +0800 From: Kinglong Mee MIME-Version: 1.0 To: "J. Bruce Fields" , linux-fsdevel@vger.kernel.org, "linux-nfs@vger.kernel.org" , Al Viro CC: NeilBrown , Trond Myklebust , kinglongmee@gmail.com Subject: [PATCH 0/4 v3] NFSD: Pin to vfsmount for nfsd exports cache Content-Type: text/plain; charset=utf-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: If there are some mount points(not exported for nfs) under pseudo root, after client's operation of those entry under the root, anyone *can't* unmount those mount points until export cache expired. # cat /etc/exports /nfs/xfs *(rw,insecure,no_subtree_check,no_root_squash) /nfs/pnfs *(rw,insecure,no_subtree_check,no_root_squash) # ll /nfs/ total 0 drwxr-xr-x. 3 root root 84 Apr 21 22:27 pnfs drwxr-xr-x. 3 root root 84 Apr 21 22:27 test drwxr-xr-x. 2 root root 6 Apr 20 22:01 xfs # mount /dev/sde /nfs/test # df Filesystem 1K-blocks Used Available Use% Mounted on ...... /dev/sdd 1038336 32944 1005392 4% /nfs/pnfs /dev/sdc 10475520 32928 10442592 1% /nfs/xfs /dev/sde 999320 1284 929224 1% /nfs/test # mount -t nfs 127.0.0.1:/nfs/ /mnt # ll /mnt/*/ /mnt/pnfs/: total 0 -rw-r--r--. 1 root root 0 Apr 21 22:23 attr drwxr-xr-x. 2 root root 6 Apr 21 22:19 tmp /mnt/xfs/: total 0 # umount /nfs/test/ umount: /nfs/test/: target is busy (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1).) It's caused by exports cache of nfsd holds the reference of the path (here is /nfs/test/), so, it can't be umounted. I don't think that's user expect, they want umount /nfs/test/. Bruce think user can also umount /nfs/pnfs/ and /nfs/xfs. This patch site lets nfsd exports pinning to vfsmount, not using mntget, so user can umount any exports mountpoint now. v1 --> v3, 1. New helpers path_get_pin/path_put_unpin for path pin. 2. Use kzalloc for allocating memory. Kinglong Mee (5): fs_pin: Fix uninitialized value in fs_pin fs_pin: Export functions for specific filesystem path: New helpers path_get_pin/path_put_unpin for path pin sunrpc: New helper cache_force_expire for cache cleanup nfsd: Allows user un-mounting filesystem where nfsd exports base on fs/fs_pin.c | 3 +++ fs/namei.c | 26 ++++++++++++++++++++++++++ fs/nfsd/export.c | 38 ++++++++++++++++++++++++++++---------- fs/nfsd/export.h | 10 +++++++++- include/linux/fs_pin.h | 6 ++++++ include/linux/path.h | 4 ++++ include/linux/sunrpc/cache.h | 11 +++++++++++ 7 files changed, 87 insertions(+), 11 deletions(-) -- 2.4.2