Re: [RFC] vfs/inode: For none-block-based filesystems default to sb->s_bdi

[Boaz Harrosh <bharrosh@panasas.com>]

On 10/05/2010 09:53 AM, Boaz Harrosh wrote:
> On 10/05/2010 04:32 AM, Jan Kara wrote:
>>   Hi Boaz,
>>
>> On Mon 04-10-10 18:02:13, Boaz Harrosh wrote:
>>> Sorry I've just seen Jan's patch:
>>> From: Jan Kara <jack@suse.cz>
>>> Date: Mon, 27 Sep 2010 23:56:48 +0200
>>> Subject: [PATCH] bdi: Initialize inode->i_mapping.backing_dev_info to sb->s_bdi
>> ...
>>> That works for me as well. Was it decided how to solve this? Other wise
>>> I'll need to patch exofs, ASAP for this -rc
>>   In the end, we'll use Christoph's patch
>> (http://lkml.org/lkml/2010/9/29/76) changing inode_to_bdi() to be
>> more conservative and also the warning will be gone. So you don't have to
>> patch anything...
>>
>> 								Honza
> 
> I would still like to fix it. Currently each inode->mapping.backing_dev_info in my
> none-block-filesystem is set to &default_backing_dev_info. This sounds scary!
> what about the future patches that will schedule a wakup on set_inode_dirty ?
> Will they not need my proper sb->s_bdi on each ->mapping?
> 
> I could do it in the filesystem, but the way the code is now I'll need to
> set it in 5 different places, or clean up the code with more common code.
> 
> That said, I think your (or my) patch makes much more sense. The sb->s_bdi
> is a much better common default then &default_backing_dev_info. By now
> is &default_backing_dev_info really needed at all?
> 
> I guess I'll have to go head and do it in FS code.
> 

BTW: I liked that WARN_ON it exposed a real problem.

> Thanks
> Boaz