[Ocfs2-devel] [PATCH 1/1] ocfs2: Add extended attribute support v3

[Mark Fasheh]

On Wed, Aug 06, 2008 at 10:34:53AM +0800, Tiger Yang wrote:
> 
> Mark Fasheh wrote:
> >In order to protect against mmap changing the inline data state, you should
> >hold a write lock on ip_alloc_sem across the call to 
> >ocfs2_xattr_ibody_find()
> >and until the return from ocfs2_xattr_set_entry.
> >
> >So basically, ocfs2_xattr_set() should look like:
> >
> >...
> >down_write(&oi->ip_alloc_sem);
> >ocfs2_ibody_find();
> >...
> >ocfs2_xattr_set_entry();
> >up_write(&oi->ip_alloc_sem);
> >...
> >
> >This way mmap can't change inline data state in between the calls to
> >ibody_find and xattr_set_entry.
> 
> Thanks the guide. I think I have done what your said.
> In ocfs2_ibody_find(), I checked the l_count/id_count with readable 
> semaphore. And in ocfs2_xattr_set_ibody, I checked it again and follow 
> by ocfs2_xattr_set_entry() with writable semaphore. If mmap change 
> l_count/id_count between those two function, I still have chance to know 
> it. And data in struct ocfs2_xattr_search which filled in 
> ocfs2_ibody_find() are not affected by mmap operations.

Ok, sounds good to me.
	--Mark

--
Mark Fasheh