sysfs: implement SYSFS_FLAG_REMOVED flag

Implement SYSFS_FLAG_REMOVED flag which currently is used only to
improve sanity check in sysfs_deactivate().  The flag will be used to
make directory entries reclamiable.

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

diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index ee3a5d9..e2f6ef1 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -296,6 +296,7 @@
 		if (!sysfs_type(sd))
 			continue;
 		if (!strcmp(sd->s_name, name)) {
+			sd->s_flags |= SYSFS_FLAG_REMOVED;
 			*pos = sd->s_sibling;
 			sd->s_sibling = NULL;
 			found = 1;