Re: [PATCH 3/3] md: separate flags for superblock changes

[Shaohua Li <shli@kernel.org>]

On Fri, Dec 09, 2016 at 03:43:58PM +1100, Neil Brown wrote:
> On Fri, Dec 09 2016, Shaohua Li wrote:
> 
> > The mddev->flags are used for different purposes. There are a lot of
> > places we check/change the flags without masking unrelated flags, we
> > could check/change unrelated flags. These usage are most for superblock
> > write, so spearate superblock related flags. This should make the code
> > clearer and also fix real bugs.
> >
> > Signed-off-by: Shaohua Li <shli@fb.com>
> 
> That real bug would be:
> 
> >  		md_wakeup_thread(mddev->thread);
> > -		wait_event(mddev->sb_wait, mddev->flags == 0 ||
> > +		wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
> >  			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));

Yes, for the reshape hang.

> 
> mddev->flags used to be called mddev->sb_dirty, before
> Commit: 850b2b420cd5 ("[PATCH] md: replace magic numbers in sb_dirty with well defined bit flags")
> 
> Then we added lots of other flags.  Now we are going back to the same
> idea :-)
> 
> Reviewed-by: NeilBrown <neilb@suse.com>
> 
> Thanks,
> NeilBrown