sysfs: make sysfs_dirent->s_element a union

Make sd->s_element a union of sysfs_elem_{dir|symlink|attr|bin_attr}
and rename it to s_elem.  This is to achieve...

* some level of type checking : changing symlink to point to
  sysfs_dirent instead of kobject is much safer and less painful now.
* easier / standardized dereferencing
* allow sysfs_elem_* to contain more than one entry

Where possible, pointer is obtained by directly deferencing from sd
instead of going through other entities.  This reduces dependencies to
dentry, inode and kobject.  to_attr() and to_bin_attr() are unused now
and removed.

This is in preparation of object reference simplification.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 0 insertions, 1 deletions

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 31c1fc67f604..8f6d8b1b211f 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -31,7 +31,6 @@ static struct sysfs_dirent sysfs_root = {
         .s_count        = ATOMIC_INIT(1),
         .s_sibling      = LIST_HEAD_INIT(sysfs_root.s_sibling),
         .s_children     = LIST_HEAD_INIT(sysfs_root.s_children),
-        .s_element      = NULL,
         .s_type         = SYSFS_ROOT,
         .s_iattr        = NULL,
         .s_ino          = 1,