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, 1 insertions, 1 deletions

diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 5c605b0003a8..617d10cea07d 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -272,7 +272,7 @@ int sysfs_hash_and_remove(struct dentry * dir, const char * name)
         parent_sd = dir->d_fsdata;
         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
-                if (!sd->s_element)
+                if (!sd->s_type)
                         continue;
                 if (!strcmp(sd->s_name, name)) {
                         list_del_init(&sd->s_sibling);