Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754267AbbEBTQd (ORCPT ); Sat, 2 May 2015 15:16:33 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44757 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1945923AbbEBTQ2 (ORCPT ); Sat, 2 May 2015 15:16:28 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Eric W. Biederman" Subject: [PATCH 4.0 116/220] mnt: Honor MNT_LOCKED when detaching mounts Date: Sat, 2 May 2015 21:00:31 +0200 Message-Id: <20150502185859.336354853@linuxfoundation.org> X-Mailer: git-send-email 2.3.7 In-Reply-To: <20150502185854.333748961@linuxfoundation.org> References: <20150502185854.333748961@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3572 Lines: 107 4.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" commit ce07d891a0891d3c0d0c2d73d577490486b809e1 upstream. Modify umount(MNT_DETACH) to keep mounts in the hash table that are locked to their parent mounts, when the parent is lazily unmounted. In mntput_no_expire detach the children from the hash table, depending on mnt_pin_kill in cleanup_mnt to decrement the mnt_count of the children. In __detach_mounts if there are any mounts that have been unmounted but still are on the list of mounts of a mountpoint, remove their children from the mount hash table and those children to the unmounted list so they won't linger potentially indefinitely waiting for their final mntput, now that the mounts serve no purpose. Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman --- fs/namespace.c | 29 ++++++++++++++++++++++++++--- fs/pnode.h | 2 ++ 2 files changed, 28 insertions(+), 3 deletions(-) --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1099,6 +1099,13 @@ static void mntput_no_expire(struct moun rcu_read_unlock(); list_del(&mnt->mnt_instance); + + if (unlikely(!list_empty(&mnt->mnt_mounts))) { + struct mount *p, *tmp; + list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { + umount_mnt(p); + } + } unlock_mount_hash(); if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { @@ -1372,6 +1379,7 @@ static void umount_tree(struct mount *mn propagate_umount(&tmp_list); while (!list_empty(&tmp_list)) { + bool disconnect; p = list_first_entry(&tmp_list, struct mount, mnt_list); list_del_init(&p->mnt_expire); list_del_init(&p->mnt_list); @@ -1380,10 +1388,18 @@ static void umount_tree(struct mount *mn if (how & UMOUNT_SYNC) p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; - pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted); + disconnect = !IS_MNT_LOCKED_AND_LAZY(p); + + pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, + disconnect ? &unmounted : NULL); if (mnt_has_parent(p)) { mnt_add_count(p->mnt_parent, -1); - umount_mnt(p); + if (!disconnect) { + /* Don't forget about p */ + list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); + } else { + umount_mnt(p); + } } change_mnt_propagation(p, MS_PRIVATE); } @@ -1508,7 +1524,14 @@ void __detach_mounts(struct dentry *dent lock_mount_hash(); while (!hlist_empty(&mp->m_list)) { mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); - umount_tree(mnt, 0); + if (mnt->mnt.mnt_flags & MNT_UMOUNT) { + struct mount *p, *tmp; + list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { + hlist_add_head(&p->mnt_umount.s_list, &unmounted); + umount_mnt(p); + } + } + else umount_tree(mnt, 0); } unlock_mount_hash(); put_mountpoint(mp); --- a/fs/pnode.h +++ b/fs/pnode.h @@ -20,6 +20,8 @@ #define SET_MNT_MARK(m) ((m)->mnt.mnt_flags |= MNT_MARKED) #define CLEAR_MNT_MARK(m) ((m)->mnt.mnt_flags &= ~MNT_MARKED) #define IS_MNT_LOCKED(m) ((m)->mnt.mnt_flags & MNT_LOCKED) +#define IS_MNT_LOCKED_AND_LAZY(m) \ + (((m)->mnt.mnt_flags & (MNT_LOCKED|MNT_SYNC_UMOUNT)) == MNT_LOCKED) #define CL_EXPIRE 0x01 #define CL_SLAVE 0x02 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/