Re: [PATCH v2 08/15] xfs: mount-api - add xfs_get_tree()

[Ian Kent <raven@themaw.net>]

On Wed, 2019-08-28 at 09:27 -0400, Brian Foster wrote:
> On Fri, Aug 23, 2019 at 08:59:59AM +0800, Ian Kent wrote:
> > Add the fs_context_operations method .get_tree that validates
> > mount options and fills the super block as previously done
> > by the file_system_type .mount method.
> > 
> > Signed-off-by: Ian Kent <raven@themaw.net>
> > ---
> >  fs/xfs/xfs_super.c |   47
> > +++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> > 
> > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> > index d3fc9938987d..7de64808eb00 100644
> > --- a/fs/xfs/xfs_super.c
> > +++ b/fs/xfs/xfs_super.c
> > @@ -1904,6 +1904,52 @@ xfs_fs_fill_super(
> >  	return error;
> >  }
> >  
> > +STATIC int
> > +xfs_fill_super(
> > +	struct super_block	*sb,
> > +	struct fs_context	*fc)
> > +{
> > +	struct xfs_fs_context	*ctx = fc->fs_private;
> > +	struct xfs_mount	*mp = sb->s_fs_info;
> > +	int			silent = fc->sb_flags & SB_SILENT;
> > +	int			error = -ENOMEM;
> > +
> > +	mp->m_super = sb;
> > +
> > +	/*
> > +	 * set up the mount name first so all the errors will refer to
> > the
> > +	 * correct device.
> > +	 */
> > +	mp->m_fsname = kstrndup(sb->s_id, MAXNAMELEN, GFP_KERNEL);
> > +	if (!mp->m_fsname)
> > +		return -ENOMEM;
> > +	mp->m_fsname_len = strlen(mp->m_fsname) + 1;
> > +
> > +	error = xfs_validate_params(mp, ctx, false);
> > +	if (error)
> > +		goto out_free_fsname;
> > +
> > +	error = __xfs_fs_fill_super(mp, silent);
> > +	if (error)
> > +		goto out_free_fsname;
> > +
> > +	return 0;
> > +
> > + out_free_fsname:
> > +	sb->s_fs_info = NULL;
> > +	xfs_free_fsname(mp);
> > +	kfree(mp);
> 
> So where is mp allocated in the updated mount sequence? Has that code
> been added yet or does this tie into the existing fill_super
> sequence?
> It's hard to tell because xfs_context_ops is still unused. It looks a
> little strange to free mp here when it's presumably been allocated
> somewhere else. If that is separate code, perhaps some of the patches
> should be combined (i.e. even if just setup/teardown bits) for easier
> review.

Umm, good question, and good suggestion.

I haven't looked at what I'm doing there so I'll keep your
suggestion in mind when I'm working through it.

> 
> Brian
> 
> > +
> > +	return error;
> > +}
> > +
> > +STATIC int
> > +xfs_get_tree(
> > +	struct fs_context	*fc)
> > +{
> > +	return vfs_get_block_super(fc, xfs_fill_super);
> > +}
> > +
> >  STATIC void
> >  xfs_fs_put_super(
> >  	struct super_block	*sb)
> > @@ -1976,6 +2022,7 @@ static const struct super_operations
> > xfs_super_operations = {
> >  
> >  static const struct fs_context_operations xfs_context_ops = {
> >  	.parse_param = xfs_parse_param,
> > +	.get_tree    = xfs_get_tree,
> >  };
> >  
> >  static struct file_system_type xfs_fs_type = {
> >