Re: [PATCH v1 0/9] do not use s_dirt in ext4

From: Jan Kara
Date: Tue Mar 27 2012 - 16:14:16 EST

On Tue 27-03-12 16:29:58, Artem Bityutskiy wrote:
> On Thu, 2012-03-22 at 11:33 +0100, Jan Kara wrote:
> > Then we have ext4_mark_super_dirty() call from 4 places - I forgot about
> > these originally... I kind of miss their purpose. Originally they were used
> > so that we write total number of free blocks and inodes in the superblock
> > but when we do not maintain them in the journal mode I don't see a reason
> > to periodically sync them in no-journal mode. Ted, what is the purpose of
> > these calls?
> I do not understand what's the fundamental difference between journal
> and non-journal mode. Why when we do have the journal we do not mark the
> super-block as dirty in many places (e.g., in 'ext4_file_open()' - if we
> do have the journal, when do we make sure we save the mount point path
> change?).
We write it at least during ext4_put_super().

> May be it has something to do with behaving like the ext2 driver when
> mounting ext2-formatted media with the the ext4 driver?
I'm not really sure about this...

> Jan, since Ted did not answer, may be you can figure out the reasons
> from this commit message, which actually introduced the
> 'ext4_mark_super_dirty()' function?
Anyway, attached are two patches which you can include in your series
and which should make your cleanups simpler.

Jan Kara <jack@xxxxxxx>