xfs: #ifdef out perag code for userspace

The xfs_perag structure and initialization is unused in userspace,
so #ifdef it out with __KERNEL__ to facilitate the xfsprogs sync
and build.
Signed-off-by: Eric Sandeen <esandeen@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/xfs/libxfs/xfs_ag.c

@@ -248,6 +248,7 @@ xfs_initialize_perag(
 		spin_unlock(&mp->m_perag_lock);
 		radix_tree_preload_end();
 
+#ifdef __KERNEL__
 		/* Place kernel structure only init below this point. */
 		spin_lock_init(&pag->pag_ici_lock);
 		spin_lock_init(&pag->pagb_lock);
@@ -257,6 +258,7 @@ xfs_initialize_perag(
 		init_waitqueue_head(&pag->pagb_wait);
 		pag->pagb_count = 0;
 		pag->pagb_tree = RB_ROOT;
+#endif /* __KERNEL__ */
 
 		error = xfs_buf_hash_init(pag);
 		if (error)

fs/xfs/libxfs/xfs_ag.h

@@ -64,6 +64,10 @@ struct xfs_perag {
 	/* Blocks reserved for the reverse mapping btree. */
 	struct xfs_ag_resv	pag_rmapbt_resv;
 
+	/* for rcu-safe freeing */
+	struct rcu_head	rcu_head;
+
+#ifdef __KERNEL__
 	/* -- kernel only structures below this line -- */
 
 	/*
@@ -90,9 +94,6 @@ struct xfs_perag {
 	spinlock_t	pag_buf_lock;	/* lock for pag_buf_hash */
 	struct rhashtable pag_buf_hash;
 
-	/* for rcu-safe freeing */
-	struct rcu_head	rcu_head;
-
 	/* background prealloc block trimming */
 	struct delayed_work	pag_blockgc_work;
 
@@ -102,6 +103,7 @@ struct xfs_perag {
 	 * or have some other means to control concurrency.
 	 */
 	struct rhashtable	pagi_unlinked_hash;
+#endif /* __KERNEL__ */
 };
 
 int xfs_initialize_perag(struct xfs_mount *mp, xfs_agnumber_t agcount,