filesystems: add missing nlink wrappers

Replace direct i_nlink updates with the respective updater function
(inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count).

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

fs/ext4/ialloc.c

@@ -1084,7 +1084,7 @@ fail_free_drop:
 fail_drop:
 	dquot_drop(inode);
 	inode->i_flags |= S_NOQUOTA;
-	inode->i_nlink = 0;
+	clear_nlink(inode);
 	unlock_new_inode(inode);
 	iput(inode);
 	brelse(inode_bitmap_bh);

fs/ext4/migrate.c

@@ -507,7 +507,7 @@ int ext4_ext_migrate(struct inode *inode)
 	 * Set the i_nlink to zero so it will be deleted later
 	 * when we drop inode reference.
 	 */
-	tmp_inode->i_nlink = 0;
+	clear_nlink(tmp_inode);
 
 	ext4_ext_tree_init(handle, tmp_inode);
 	ext4_orphan_add(handle, tmp_inode);

fs/ext4/namei.c

@@ -2539,7 +2539,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 		if (new_inode) {
 			/* checked empty_dir above, can't have another parent,
 			 * ext4_dec_count() won't work for many-linked dirs */
-			new_inode->i_nlink = 0;
+			clear_nlink(new_inode);
 		} else {
 			ext4_inc_count(handle, new_dir);
 			ext4_update_dx_flag(new_dir);