[Ocfs2-devel] [PATCH 04/15] Make extend allocation generic.

[Tao Ma]

Joel Becker wrote:
> On Fri, Aug 15, 2008 at 03:14:38PM +0800, Tao Ma wrote:
>> Joel Becker wrote:
>>> On Thu, Aug 07, 2008 at 06:31:26AM +0800, Tao Ma wrote:
>>>> The old ocfs2_do_extend_allocation is restrictly to be used in file
>>>> extension. Now a new function named ocfs2_do_cluster_allocation will
>>>> handle the issue of generic extend allocation and it is created in
>>>> suballoc.c.
>>> <snip> 
>>>
>>>> +int ocfs2_add_clusters_in_btree(struct ocfs2_super *osb,
>>>> +				struct inode *inode,
>>>> +				u32 *logical_offset,
>>>> +				u32 clusters_to_add,
>>>> +				int mark_unwritten,
>>>> +				struct buffer_head *root_bh,
>>>> +				struct ocfs2_extent_list *root_el,
>>>> +				handle_t *handle,
>>>> +				struct ocfs2_alloc_context *data_ac,
>>>> +				struct ocfs2_alloc_context *meta_ac,
>>>> +				enum ocfs2_alloc_restarted *reason_ret,
>>>> +				enum ocfs2_extent_tree_type type)
>>> 	It seems to me that if you have root_bh and type, you can create
>>> an ocfs2_extent_tree and calculate root_el from that.  So you don't need
>>> root_el in this function's arguments, and callers don't need to know how
>>> to compute it.
>> No we can't. For a ocfs2_xattr_value_root. It can be stored in any place 
>> of a buffer_head, so we have to give it to this function.
> 
> 	But don't you later turn a private pointer into that thing?
I think I know your meaning now.
I have gone through the function and it doesn't create 
ocfs2_extent_tree. So I don't think it is worth for us to just erase a 
"parameter" in kernel stack while doing kmalloc+kfree, right?

Regards,
Tao