[Devel] [PATCH rh7 3/6] Revert "devtmpfs: containerize it with new obj ns operation"

[Vladimir Davydov]

This reverts commit 53343c3b231ed36d973e6d3ac2ab9ad7b7c87e25.

The whole point of devtmpfs is simplifying the system bootup logic.
There is absolutely no point in virtualizing it, because on container
start we create devices from a hardcoded list (these are ttys, which I'd
prefer not to create at all using ptys instead, but we have to live with
it for compatibility reasons for now). This means that it is enough to
provide the userspace with per VE tmpfs mount called "devtmpfs" and
teach it to make device nodes from a hardcoded list on container start
instead of implementing devtmpfs virtualization in the kernel. The
kernel part will be done by the following patches.

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
 drivers/base/devtmpfs.c    | 37 ++-----------------------------------
 fs/sysfs/ve.c              |  9 ---------
 include/linux/kobject_ns.h |  2 --
 3 files changed, 2 insertions(+), 46 deletions(-)

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 0448af8195f3..349d6eb88bde 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -366,46 +366,13 @@ int devtmpfs_mount(const char *mntdir)
 
 static DECLARE_COMPLETION(setup_done);
 
-static struct path set_dev_pwd(struct device *dev)
-{
-	const struct kobj_ns_type_operations *ops;
-	struct path pwd = current->fs->pwd;
-
-	ops = kobj_ns_ops(&dev->kobj);
-	path_get(&pwd);
-
-	if (ops && ops->devtmpfs) {
-		const struct path *devtmpfs_root;
-
-		devtmpfs_root = ops->devtmpfs(&dev->kobj);
-		BUG_ON(!devtmpfs_root);
-		set_fs_pwd(current->fs, devtmpfs_root);
-	}
-	return pwd;
-}
-
-static void drop_dev_pwd(struct path *pwd)
-{
-	set_fs_pwd(current->fs, pwd);
-	path_put(pwd);
-}
-
 static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
 		  struct device *dev)
 {
-	struct path pwd;
-	int err;
-
-	pwd = set_dev_pwd(dev);
-
 	if (mode)
-		err = handle_create(name, mode, uid, gid, dev);
+		return handle_create(name, mode, uid, gid, dev);
 	else
-		err = handle_remove(name, dev);
-
-	/* Restore kthread pwd */
-	drop_dev_pwd(&pwd);
-	return err;
+		return handle_remove(name, dev);
 }
 
 static int devtmpfsd(void *p)
diff --git a/fs/sysfs/ve.c b/fs/sysfs/ve.c
index 79ad6d596e26..bb28a4bbce45 100644
--- a/fs/sysfs/ve.c
+++ b/fs/sysfs/ve.c
@@ -43,21 +43,12 @@ const void *ve_namespace(struct device *dev)
 	return (!dev->groups && dev_get_drvdata(dev)) ? dev_get_drvdata(dev) : get_ve0();
 }
 
-static const struct path *ve_devtmpfs(const struct kobject *kobj)
-{
-	struct device *dev = container_of(kobj, struct device, kobj);
-	const struct ve_struct *ve = dev->class->namespace(dev);
-
-	return &ve->devtmpfs_root;
-}
-
 struct kobj_ns_type_operations ve_ns_type_operations = {
 	.type = KOBJ_NS_TYPE_VE,
 	.grab_current_ns = ve_grab_current_ns,
 	.netlink_ns = ve_netlink_ns,
 	.initial_ns = ve_initial_ns,
 	.drop_ns = ve_drop_ns,
-	.devtmpfs = ve_devtmpfs,
 };
 
 static bool sysfs_perms_shown(struct ve_struct *ve, struct sysfs_dirent *sd)
diff --git a/include/linux/kobject_ns.h b/include/linux/kobject_ns.h
index ebc2e2d89aa0..b1395aa7bef5 100644
--- a/include/linux/kobject_ns.h
+++ b/include/linux/kobject_ns.h
@@ -19,7 +19,6 @@
 
 struct sock;
 struct kobject;
-struct path;
 
 /*
  * Namespace types which are used to tag kobjects and sysfs entries.
@@ -45,7 +44,6 @@ struct kobj_ns_type_operations {
 	const void *(*netlink_ns)(struct sock *sk);
 	const void *(*initial_ns)(void);
 	void (*drop_ns)(void *);
-	const struct path *(*devtmpfs)(const struct kobject *);
 };
 
 int kobj_ns_type_register(const struct kobj_ns_type_operations *ops);
-- 
2.1.4