Return-Path: Received: from mail-pd0-f171.google.com ([209.85.192.171]:33070 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751145AbbEXPCJ (ORCPT ); Sun, 24 May 2015 11:02:09 -0400 Message-ID: <5561E7E4.50604@gmail.com> Date: Sun, 24 May 2015 23:01:56 +0800 From: Kinglong Mee MIME-Version: 1.0 To: "J. Bruce Fields" , Al Viro , linux-fsdevel@vger.kernel.org, "linux-nfs@vger.kernel.org" , NeilBrown CC: Trond Myklebust , Steve Dickson , kinglongmee@gmail.com Subject: [PATCH 0/4 v2] NFSD: Pin to vfsmount for some 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).) I don't think that's user expect, they want umount /nfs/test/. It's caused by exports cache of nfsd holds the reference of the path (here is /nfs/test/), so, it can't be umounted. v1 --> v2, 1. Adds an option named "allow_umount" for exports allowing user un-mounting the filesystem where nfsd exports base on. 2. New helpers path_get_pin/path_put_unpin for path pin. 3. Update exports according to the "allow_umount" option. 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 | 52 ++++++++++++++++++++++++++++++++-------- fs/nfsd/export.h | 11 ++++++++- include/linux/fs_pin.h | 6 +++++ include/linux/path.h | 4 ++++ include/linux/sunrpc/cache.h | 11 +++++++++ include/uapi/linux/nfsd/export.h | 3 ++- 8 files changed, 104 insertions(+), 12 deletions(-) -- 2.4.1