sysfs: Implement sysfs_getattr & sysfs_permission

With the implementation of sysfs_getattr and sysfs_permission
sysfs becomes able to lazily propogate inode attribute changes
from the sysfs_dirents to the vfs inodes.   This paves the way
for deleting significant chunks of now unnecessary code.

While doing this we did not reference sysfs_setattr from
sysfs_symlink_inode_operations so I added along with
sysfs_getattr and sysfs_permission.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 36ee6d8..e319379 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -800,7 +800,9 @@
 
 const struct inode_operations sysfs_dir_inode_operations = {
 	.lookup		= sysfs_lookup,
+	.permission	= sysfs_permission,
 	.setattr	= sysfs_setattr,
+	.getattr	= sysfs_getattr,
 	.setxattr	= sysfs_setxattr,
 };