nilfs2: remove useless b_low and b_high fields from nilfs_bmap struct

This will cut off 16 bytes from the nilfs_bmap struct which is
embedded in the on-memory inode of nilfs.

The b_high field was never used, and the b_low field stores a constant
value which can be determined by whether the inode uses btree for
block mapping or not.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/direct.c b/fs/nilfs2/direct.c
index eaeccb0..8e8095c 100644
--- a/fs/nilfs2/direct.c
+++ b/fs/nilfs2/direct.c
@@ -242,8 +242,7 @@
 }
 
 int nilfs_direct_delete_and_convert(struct nilfs_bmap *bmap,
-				    __u64 key, __u64 *keys, __u64 *ptrs,
-				    int n, __u64 low, __u64 high)
+				    __u64 key, __u64 *keys, __u64 *ptrs, int n)
 {
 	struct nilfs_direct *direct;
 	__le64 *dptrs;
@@ -273,8 +272,7 @@
 			dptrs[i] = NILFS_BMAP_INVALID_PTR;
 	}
 
-	nilfs_direct_init(bmap, low, high);
-
+	nilfs_direct_init(bmap);
 	return 0;
 }
 
@@ -410,14 +408,11 @@
 	.dop_assign		=	nilfs_direct_assign_p,
 };
 
-int nilfs_direct_init(struct nilfs_bmap *bmap, __u64 low, __u64 high)
+int nilfs_direct_init(struct nilfs_bmap *bmap)
 {
-	struct nilfs_direct *direct;
+	struct nilfs_direct *direct = (struct nilfs_direct *)bmap;
 
-	direct = (struct nilfs_direct *)bmap;
 	bmap->b_ops = &nilfs_direct_ops;
-	bmap->b_low = low;
-	bmap->b_high = high;
 	switch (bmap->b_inode->i_ino) {
 	case NILFS_DAT_INO:
 		direct->d_ops = &nilfs_direct_ops_p;