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

[Jan Kara <jack@suse.cz>]

On Tue 05-10-10 09:54:49, Boaz Harrosh wrote:
> 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.
  In fact, it exposed too many of them for being so late in the -rc cycle
;). Luckily they were all harmless (at least currently). So for now we are
better off without the warning so that we don't scare users.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR