kernfs: implement kernfs_node_from_dentry(), kernfs_root_from_sb() and kernfs_rename()

Implement helpers to determine node from dentry and root from
super_block.  Also add a kernfs_rename_ns() wrapper which assumes NULL
namespace.  These generally make sense and will be used by cgroup.

v2: Some dummy implementations for !CONFIG_SYSFS was missing.  Fixed.
    Reported by kbuild test robot.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo
2014-02-03 14:09:15 -05:00
committed by Greg Kroah-Hartman
parent 2536390da0
commit 0c23b2259a
3 changed files with 48 additions and 0 deletions
+18
View File
@@ -350,6 +350,24 @@ const struct dentry_operations kernfs_dops = {
.d_release = kernfs_dop_release,
};
/**
* kernfs_node_from_dentry - determine kernfs_node associated with a dentry
* @dentry: the dentry in question
*
* Return the kernfs_node associated with @dentry. If @dentry is not a
* kernfs one, %NULL is returned.
*
* While the returned kernfs_node will stay accessible as long as @dentry
* is accessible, the returned node can be in any state and the caller is
* fully responsible for determining what's accessible.
*/
struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
{
if (dentry->d_op == &kernfs_dops)
return dentry->d_fsdata;
return NULL;
}
static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
const char *name, umode_t mode,
unsigned flags)