Re: [PATCH 11/12] xfs: drop s_umount over opening the log and RT devices

[Christian Brauner <brauner@kernel.org>]

On Sat, Aug 05, 2023 at 09:19:04AM -0700, Darrick J. Wong wrote:
> On Sat, Aug 05, 2023 at 10:32:39AM +0200, Christoph Hellwig wrote:
> > On Wed, Aug 02, 2023 at 09:32:19AM -0700, Darrick J. Wong wrote:
> > > > +	/* see get_tree_bdev why this is needed and safe */
> > > 
> > > Which part of get_tree_bdev?  Is it this?
> > > 
> > > 		/*
> > > 		 * s_umount nests inside open_mutex during
> > > 		 * __invalidate_device().  blkdev_put() acquires
> > > 		 * open_mutex and can't be called under s_umount.  Drop
> > > 		 * s_umount temporarily.  This is safe as we're
> > > 		 * holding an active reference.
> > > 		 */
> > > 		up_write(&s->s_umount);
> > > 		blkdev_put(bdev, fc->fs_type);
> > > 		down_write(&s->s_umount);
> > 
> > Yes.  With the refactoring earlier in the series get_tree_bdev should
> > be trivial enough to not need a more specific reference.  If you
> > think there's a better way to refer to it I can update the comment,
> > though.
> 
> How about:
> 
> 	/*
> 	 * blkdev_put can't be called under s_umount, see the comment in
> 	 * get_tree_bdev for more details
> 	 */
> 
> with that and the label name change,
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>

Added that comment and you rvb in-tree.