linux-kernel - Re: [RFC PATCH 17/20] famfs: Add module stuff

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Date: Tue, 27 Feb 2024 16:15:21 -0600
From: John Groves <John@...ves.net>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: John Groves <jgroves@...ron.com>, Jonathan Corbet <corbet@....net>, 
	Dan Williams <dan.j.williams@...el.com>, Vishal Verma <vishal.l.verma@...el.com>, 
	Dave Jiang <dave.jiang@...el.com>, Alexander Viro <viro@...iv.linux.org.uk>, 
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, Matthew Wilcox <willy@...radead.org>, 
	linux-cxl@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, nvdimm@...ts.linux.dev, john@...alactic.com, 
	Dave Chinner <david@...morbit.com>, Christoph Hellwig <hch@...radead.org>, 
	dave.hansen@...ux.intel.com, gregory.price@...verge.com
Subject: Re: [RFC PATCH 17/20] famfs: Add module stuff

On 24/02/26 01:47PM, Jonathan Cameron wrote:
> On Fri, 23 Feb 2024 11:42:01 -0600
> John Groves <John@...ves.net> wrote:
> 
> > This commit introduces the module init and exit machinery for famfs.
> > 
> > Signed-off-by: John Groves <john@...ves.net>
> I'd prefer to see this from the start with the functionality of the module
> built up as you go + build logic in place.  Makes it easy to spot places
> where the patches aren't appropriately self constrained. 
> > ---
> >  fs/famfs/famfs_inode.c | 44 ++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 44 insertions(+)
> > 
> > diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c
> > index ab46ec50b70d..0d659820e8ff 100644
> > --- a/fs/famfs/famfs_inode.c
> > +++ b/fs/famfs/famfs_inode.c
> > @@ -462,4 +462,48 @@ static struct file_system_type famfs_fs_type = {
> >  	.fs_flags	  = FS_USERNS_MOUNT,
> >  };
> >  
> > +/*****************************************************************************************
> > + * Module stuff
> 
> I'd drop these drivers structure comments. They add little beyond
> a high possibility of being wrong after the code has evolved a bit.

Probably will do with the module-ops-up refactor for v2

> 
> > + */
> > +static struct kobject *famfs_kobj;
> > +
> > +static int __init init_famfs_fs(void)
> > +{
> > +	int rc;
> > +
> > +#if defined(CONFIG_DEV_DAX_IOMAP)
> > +	pr_notice("%s: Your kernel supports famfs on /dev/dax\n", __func__);
> > +#else
> > +	pr_notice("%s: Your kernel does not support famfs on /dev/dax\n", __func__);
> > +#endif
> > +	famfs_kobj = kobject_create_and_add(MODULE_NAME, fs_kobj);
> > +	if (!famfs_kobj) {
> > +		pr_warn("Failed to create kobject\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	rc = sysfs_create_group(famfs_kobj, &famfs_attr_group);
> > +	if (rc) {
> > +		kobject_put(famfs_kobj);
> > +		pr_warn("%s: Failed to create sysfs group\n", __func__);
> > +		return rc;
> > +	}
> > +
> > +	return register_filesystem(&famfs_fs_type);
> 
> If this fails, do we not leak the kobj and sysfs groups?

Good catch, thanks! Fixed for now- but the kobj is also likely to go away. Will
endeavor to get it right...

Thanks,
John