xfs: xfs_kset should be static

As it is accessed through the struct xfs_mount and can be set up
entirely from fs/xfs/xfs_super.c

Signed-off-by: Dave Chinner <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Dave Chinner <[e-mail]>

fs/xfs/xfs_mount.c

···
 static int xfs_uuid_table_size;
 static uuid_t *xfs_uuid_table;
 
-extern struct kset *xfs_kset;
-
 /*
  * See if the UUID is unique among mounted XFS filesystems.
  * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
···
 
 	xfs_set_maxicount(mp);
 
-	mp->m_kobj.kobject.kset = xfs_kset;
 	error = xfs_sysfs_init(&mp->m_kobj, &xfs_mp_ktype, NULL, mp->m_fsname);
 	if (error)
 		goto out;

fs/xfs/xfs_super.c

···
 static kmem_zone_t *xfs_ioend_zone;
 mempool_t *xfs_ioend_pool;
 
-struct kset *xfs_kset;			/* top-level xfs sysfs dir */
+static struct kset *xfs_kset;		/* top-level xfs sysfs dir */
 #ifdef DEBUG
 static struct xfs_kobj xfs_dbg_kobj;	/* global debug sysfs attrs */
 #endif
···
 	atomic_set(&mp->m_active_trans, 0);
 	INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker);
 	INIT_DELAYED_WORK(&mp->m_eofblocks_work, xfs_eofblocks_worker);
+	mp->m_kobj.kobject.kset = xfs_kset;
 
 	mp->m_super = sb;
 	sb->s_fs_info = mp;