sysfs: add sysfs_dirent->s_parent
Add sysfs_dirent->s_parent. With this patch, each sd points to and
holds a reference to its parent. This allows walking sysfs tree
without referencing sd->s_dentry which can go away anytime if the user
doesn't control when it's deleted.
sd->s_parent is initialized and parent is referenced in
sysfs_attach_dirent(). Reference to parent is released when the sd is
released, so as long as reference to a sd is held, s_parent can be
followed.
dentry walk in sysfs_readdir() is convereted to s_parent walk.
This will be used to reimplement symlink such that it uses only
sysfs_dirent tree.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index f8f49cc..ce05d6f 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -1,5 +1,6 @@
struct sysfs_dirent {
atomic_t s_count;
+ struct sysfs_dirent * s_parent;
struct list_head s_sibling;
struct list_head s_children;
void * s_element;