nilfs2: remove own inode allocator and destructor for metadata files

This finally removes own inode allocator and destructor functions for
metadata files.  Several routines, nilfs_mdt_new(),
nilfs_mdt_new_common(), nilfs_mdt_clear(), nilfs_mdt_destroy(), and
nilfs_alloc_inode_common() will be gone.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index ab96d26..d92ebd5 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -146,7 +146,7 @@
 }
 
 
-struct inode *nilfs_alloc_inode_common(struct the_nilfs *nilfs)
+struct inode *nilfs_alloc_inode(struct super_block *sb)
 {
 	struct nilfs_inode_info *ii;
 
@@ -157,15 +157,10 @@
 	ii->i_state = 0;
 	ii->i_cno = 0;
 	ii->vfs_inode.i_version = 1;
-	nilfs_btnode_cache_init(&ii->i_btnode_cache, nilfs->ns_bdi);
+	nilfs_btnode_cache_init(&ii->i_btnode_cache, sb->s_bdi);
 	return &ii->vfs_inode;
 }
 
-struct inode *nilfs_alloc_inode(struct super_block *sb)
-{
-	return nilfs_alloc_inode_common(NILFS_SB(sb)->s_nilfs);
-}
-
 void nilfs_destroy_inode(struct inode *inode)
 {
 	struct nilfs_mdt_info *mdi = NILFS_MDT(inode);