driver core: Introduce device_move(): move a device to a new parent.

Provide a function device_move() to move a device to a new parent device. Add
auxilliary functions kobject_move() and sysfs_move_dir().
kobject_move() generates a new uevent of type KOBJ_MOVE, containing the
previous path (DEVPATH_OLD) in addition to the usual values. For this, a new
interface kobject_uevent_env() is created that allows to add further
environmental data to the uevent at the kobject layer.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 45 insertions, 0 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 3aa3434621ca..a5782e8c7f07 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -372,6 +372,51 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
         return error;
 }
 
+int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
+{
+        struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
+        struct sysfs_dirent *new_parent_sd, *sd;
+        int error;
+
+        if (!new_parent)
+                return -EINVAL;
+
+        old_parent_dentry = kobj->parent ?
+                kobj->parent->dentry : sysfs_mount->mnt_sb->s_root;
+        new_parent_dentry = new_parent->dentry;
+
+again:
+        mutex_lock(&old_parent_dentry->d_inode->i_mutex);
+        if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
+                mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+                goto again;
+        }
+
+        new_parent_sd = new_parent_dentry->d_fsdata;
+        sd = kobj->dentry->d_fsdata;
+
+        new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
+                                    strlen(kobj->name));
+        if (IS_ERR(new_dentry)) {
+                error = PTR_ERR(new_dentry);
+                goto out;
+        } else
+                error = 0;
+        d_add(new_dentry, NULL);
+        d_move(kobj->dentry, new_dentry);
+        dput(new_dentry);
+
+        /* Remove from old parent's list and insert into new parent's list. */
+        list_del_init(&sd->s_sibling);
+        list_add(&sd->s_sibling, &new_parent_sd->s_children);
+
+out:
+        mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
+        mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+
+        return error;
+}
+
 static int sysfs_dir_open(struct inode *inode, struct file *file)
 {
         struct dentry * dentry = file->f_dentry;