From 8271242be97498b40f49ece9202bf392df21ac29 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 30 Aug 2012 16:13:49 +0200 Subject: [PATCH 03/13] vfs: introduce clone_private_mount() Patch-mainline: not yet Overlayfs needs a private clone of the mount, so create a function for this and export to modules. Signed-off-by: Miklos Szeredi --- fs/namespace.c | 18 ++++++++++++++++++ include/linux/mount.h | 3 +++ 2 files changed, 21 insertions(+) Index: linux-3.6-rc7-master/fs/namespace.c =================================================================== --- linux-3.6-rc7-master.orig/fs/namespace.c 2012-09-24 03:10:57.000000000 +0200 +++ linux-3.6-rc7-master/fs/namespace.c 2012-09-28 13:36:51.000000000 +0200 @@ -1387,6 +1387,24 @@ void drop_collected_mounts(struct vfsmou release_mounts(&umount_list); } +struct vfsmount *clone_private_mount(struct path *path) +{ + struct mount *old_mnt = real_mount(path->mnt); + struct mount *new_mnt; + + if (IS_MNT_UNBINDABLE(old_mnt)) + return ERR_PTR(-EINVAL); + + down_read(&namespace_sem); + new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); + up_read(&namespace_sem); + if (!new_mnt) + return ERR_PTR(-ENOMEM); + + return &new_mnt->mnt; +} +EXPORT_SYMBOL_GPL(clone_private_mount); + int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, struct vfsmount *root) { Index: linux-3.6-rc7-master/include/linux/mount.h =================================================================== --- linux-3.6-rc7-master.orig/include/linux/mount.h 2012-09-24 03:10:57.000000000 +0200 +++ linux-3.6-rc7-master/include/linux/mount.h 2012-09-28 13:36:51.000000000 +0200 @@ -66,6 +66,9 @@ extern void mnt_pin(struct vfsmount *mnt extern void mnt_unpin(struct vfsmount *mnt); extern int __mnt_is_readonly(struct vfsmount *mnt); +struct path; +extern struct vfsmount *clone_private_mount(struct path *path); + struct file_system_type; extern struct vfsmount *vfs_kern_mount(struct file_system_type *type, int flags, const char *name,