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

Christoph Hellwig
2023-08-05T08:32:47Z

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.

> > mp->m_logdev_targp = mp->m_ddev_targp;
> > }
> >
> > - return 0;
> > + error = 0;
> > +out_unlock:
> > + down_write(&sb->s_umount);
>
> Isn't down_write taking s_umount? I think the label should be
> out_relock or something less misleading.

Agreed. Christian, can you just change this in your branch, or should
I send an incremental patch?