nilfs2: use iget for all metadata files

This makes use of iget5_locked to allocate or get inode for metadata
files to stop using own inode allocator.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/mdt.h b/fs/nilfs2/mdt.h
index 1e0901c..73ff7c0 100644
--- a/fs/nilfs2/mdt.h
+++ b/fs/nilfs2/mdt.h
@@ -85,8 +85,7 @@
 int nilfs_mdt_mark_block_dirty(struct inode *, unsigned long);
 int nilfs_mdt_fetch_dirty(struct inode *);
 
-int nilfs_mdt_init(struct inode *inode, struct the_nilfs *nilfs,
-		   gfp_t gfp_mask, size_t objsz);
+int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz);
 struct inode *nilfs_mdt_new(struct the_nilfs *, struct super_block *, ino_t,
 			    size_t);
 struct inode *nilfs_mdt_new_common(struct the_nilfs *, struct super_block *,