Return-Path: Received: from mail-pa0-f50.google.com ([209.85.220.50]:36858 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755260AbbG0DIm (ORCPT ); Sun, 26 Jul 2015 23:08:42 -0400 Message-ID: <55B5A0B0.7060604@gmail.com> Date: Mon, 27 Jul 2015 11:08:32 +0800 From: Kinglong Mee MIME-Version: 1.0 To: "J. Bruce Fields" , Al Viro CC: "linux-nfs@vger.kernel.org" , linux-fsdevel@vger.kernel.org, NeilBrown , Trond Myklebust , kinglongmee@gmail.com Subject: [PATCH 4/9 v8] fs: New helper legitimize_mntget() for getting a legitimize mnt References: <55B5A012.1030006@gmail.com> In-Reply-To: <55B5A012.1030006@gmail.com> Content-Type: text/plain; charset=utf-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: New helper legitimize_mntget for getting a mnt without setting MNT_SYNC_UMOUNT | MNT_UMOUNT | MNT_DOOMED, otherwise return NULL. v8, same as v6 Signed-off-by: Kinglong Mee --- fs/namespace.c | 19 +++++++++++++++++++ include/linux/mount.h | 1 + 2 files changed, 20 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index 2b8aa15..842cf57 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1153,6 +1153,25 @@ struct vfsmount *mntget(struct vfsmount *mnt) } EXPORT_SYMBOL(mntget); +struct vfsmount *legitimize_mntget(struct vfsmount *vfsmnt) +{ + struct mount *mnt; + + if (vfsmnt == NULL) + return NULL; + + read_seqlock_excl(&mount_lock); + mnt = real_mount(vfsmnt); + if (vfsmnt->mnt_flags & (MNT_SYNC_UMOUNT | MNT_UMOUNT | MNT_DOOMED)) + vfsmnt = NULL; + else + mnt_add_count(mnt, 1); + read_sequnlock_excl(&mount_lock); + + return vfsmnt; +} +EXPORT_SYMBOL(legitimize_mntget); + struct vfsmount *mnt_clone_internal(struct path *path) { struct mount *p; diff --git a/include/linux/mount.h b/include/linux/mount.h index f822c3c..8ae9dc0 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -79,6 +79,7 @@ extern void mnt_drop_write(struct vfsmount *mnt); extern void mnt_drop_write_file(struct file *file); extern void mntput(struct vfsmount *mnt); extern struct vfsmount *mntget(struct vfsmount *mnt); +extern struct vfsmount *legitimize_mntget(struct vfsmount *vfsmnt); extern struct vfsmount *mnt_clone_internal(struct path *path); extern int __mnt_is_readonly(struct vfsmount *mnt); -- 2.4.3