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, 4 insertions, 19 deletions

diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index c72820450e7c..27df635b786a 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -48,30 +48,15 @@ static void fill_object_path(struct kobject * kobj, char * buffer, int length)
 static int sysfs_add_link(struct dentry * parent, const char * name, struct kobject * target)
 {
         struct sysfs_dirent * parent_sd = parent->d_fsdata;
-        struct sysfs_symlink * sl;
         struct sysfs_dirent * sd;
-        int error;
 
-        error = -ENOMEM;
-        sl = kzalloc(sizeof(*sl), GFP_KERNEL);
-        if (!sl)
-                goto err_out;
-
-        sl->target_kobj = kobject_get(target);
-
-        sd = sysfs_new_dirent(name, sl, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+        sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
         if (!sd)
-                goto err_out;
-        sysfs_attach_dirent(sd, parent_sd, NULL);
+                return -ENOMEM;
 
+        sd->s_elem.symlink.target_kobj = kobject_get(target);
+        sysfs_attach_dirent(sd, parent_sd, NULL);
         return 0;
-
- err_out:
-        if (sl) {
-                kobject_put(sl->target_kobj);
-                kfree(sl);
-        }
-        return error;
 }
 
 /**