Re: [RFC 0/8] Cpuset aware writeback

[Christoph Lameter]

On Wed, 17 Jan 2007, Andrew Morton wrote:

> > The problem there is that we do a GFP_ATOMIC allocation (no allocation 
> > context) that may fail when the first page is dirtied. We must therefore 
> > be able to subsequently allocate the nodemask_t in set_page_dirty(). 
> > Otherwise the first failure will mean that there will never be a dirty 
> > map for the inode/mapping.
> 
> True.  But it's pretty simple to change __mark_inode_dirty() to fix this.

Ok I tried it but this wont work unless I also pass the page struct pointer to 
__mark_inode_dirty() since the dirty_node pointer could be freed 
when the inode_lock is droppped. So I cannot dereference the 
dirty_nodes pointer outside of __mark_inode_dirty. 

If I expand __mark_inode_dirty then all variations of mark_inode_dirty() 
need to be changed and we need to pass a page struct everywhere. This 
result in extensive changes.

I think I need to stick with the tree_lock. This also makes more sense 
since we modify dirty information in the address_space structure and the 
radix tree is already protected by that lock.


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