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

Christian Brauner
2023-08-05T10:39:31Z

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.
>
> > > 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?

No need to send an incremental patch. I just s/out_unlock/out_relock/g
in-tree. Thanks!