Re: [PATCH v3 2/2] writeback: Fix false warning in inode_to_wb()

[Jan Kara]

Hi Andrew!

Can you please take this patch through MM tree? Thanks! Andreas is already
taking the first patch in the series through GFS2 tree.

								Honza

On Sat 12-04-25 18:39:12, Andreas Gruenbacher wrote:
> From: Jan Kara <jack@xxxxxxx>
> 
> inode_to_wb() is used also for filesystems that don't support cgroup
> writeback. For these filesystems inode->i_wb is stable during the
> lifetime of the inode (it points to bdi->wb) and there's no need to hold
> locks protecting the inode->i_wb dereference. Improve the warning in
> inode_to_wb() to not trigger for these filesystems.
> 
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> Reviewed-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> ---
>  include/linux/backing-dev.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
> index 8e7af9a03b41..e721148c95d0 100644
> --- a/include/linux/backing-dev.h
> +++ b/include/linux/backing-dev.h
> @@ -249,6 +249,7 @@ static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
>  {
>  #ifdef CONFIG_LOCKDEP
>  	WARN_ON_ONCE(debug_locks &&
> +		     (inode->i_sb->s_iflags & SB_I_CGROUPWB) &&
>  		     (!lockdep_is_held(&inode->i_lock) &&
>  		      !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
>  		      !lockdep_is_held(&inode->i_wb->list_lock)));
> -- 
> 2.48.1
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR