f2fs: introduce f2fs_do_tmpfile for code consistency

This patch adds f2fs_do_tmpfile to eliminate the redundant init_inode_metadata
flow.
Throught this, we can provide the consistent lock usage, e.g., fi->i_sem,  and
this will enable better debugging stuffs.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 3677f41..fb7e01e 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -337,8 +337,7 @@
 	struct page *page;
 	int err;
 
-	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE) &&
-			inode->i_nlink) {
+	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
 		page = new_inode_page(inode, name);
 		if (IS_ERR(page))
 			return page;
@@ -364,7 +363,8 @@
 		set_cold_node(inode, page);
 	}
 
-	init_dent_inode(name, page);
+	if (name)
+		init_dent_inode(name, page);
 
 	/*
 	 * This file should be checkpointed during fsync.
@@ -537,6 +537,27 @@
 	return err;
 }
 
+int f2fs_do_tmpfile(struct inode *inode, struct inode *dir)
+{
+	struct page *page;
+	int err = 0;
+
+	down_write(&F2FS_I(inode)->i_sem);
+	page = init_inode_metadata(inode, dir, NULL);
+	if (IS_ERR(page)) {
+		err = PTR_ERR(page);
+		goto fail;
+	}
+	/* we don't need to mark_inode_dirty now */
+	update_inode(inode, page);
+	f2fs_put_page(page, 1);
+
+	clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
+fail:
+	up_write(&F2FS_I(inode)->i_sem);
+	return err;
+}
+
 /*
  * It only removes the dentry from the dentry page,corresponding name
  * entry in name page does not need to be touched during deletion.