linux-kernel - Re: [RFC PATCH 09/20] famfs: Add super

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Message-ID: <20240226125136.00002e64@Huawei.com>
Date: Mon, 26 Feb 2024 12:51:36 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: John Groves <John@...ves.net>
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 09/20] famfs: Add super_operations

On Fri, 23 Feb 2024 11:41:53 -0600
John Groves <John@...ves.net> wrote:

> Introduce the famfs superblock operations
> 
> Signed-off-by: John Groves <john@...ves.net>
> ---
>  fs/famfs/famfs_inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 72 insertions(+)
>  create mode 100644 fs/famfs/famfs_inode.c
> 
> diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c
> new file mode 100644
> index 000000000000..3329aff000d1
> --- /dev/null
> +++ b/fs/famfs/famfs_inode.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * famfs - dax file system for shared fabric-attached memory
> + *
> + * Copyright 2023-2024 Micron Technology, inc
> + *
> + * This file system, originally based on ramfs the dax support from xfs,
> + * is intended to allow multiple host systems to mount a common file system
> + * view of dax files that map to shared memory.
> + */
> +
> +#include <linux/fs.h>
> +#include <linux/pagemap.h>
> +#include <linux/highmem.h>
> +#include <linux/time.h>
> +#include <linux/init.h>
> +#include <linux/string.h>
> +#include <linux/backing-dev.h>
> +#include <linux/sched.h>
> +#include <linux/parser.h>
> +#include <linux/magic.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <linux/fs_context.h>
> +#include <linux/fs_parser.h>
> +#include <linux/seq_file.h>
> +#include <linux/dax.h>
> +#include <linux/hugetlb.h>
> +#include <linux/uio.h>
> +#include <linux/iomap.h>
> +#include <linux/path.h>
> +#include <linux/namei.h>
> +#include <linux/pfn_t.h>
> +#include <linux/blkdev.h>

That's a lot of header for such a small patch.. I'm going to guess
they aren't all used - bring them in as you need them - I hope
you never need some of these!


> +
> +#include "famfs_internal.h"
> +
> +#define FAMFS_DEFAULT_MODE	0755
> +
> +static const struct super_operations famfs_ops;
> +static const struct inode_operations famfs_file_inode_operations;
> +static const struct inode_operations famfs_dir_inode_operations;

Why are these all up here?

> +
> +/**********************************************************************************
> + * famfs super_operations
> + *
> + * TODO: implement a famfs_statfs() that shows size, free and available space, etc.
> + */
> +
> +/**
> + * famfs_show_options() - Display the mount options in /proc/mounts.
Run kernel doc script + fix all warnings.

> + */
> +static int famfs_show_options(
> +	struct seq_file *m,
> +	struct dentry   *root)
Not that familiar with fs code, but this unusual kernel style. I'd go with 
something more common

static int famfs_show_options(struct seq_file *m, struct dentry *root)

> +{
> +	struct famfs_fs_info *fsi = root->d_sb->s_fs_info;
> +
> +	if (fsi->mount_opts.mode != FAMFS_DEFAULT_MODE)
> +		seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
> +
> +	return 0;
> +}
> +
> +static const struct super_operations famfs_ops = {
> +	.statfs		= simple_statfs,
> +	.drop_inode	= generic_delete_inode,
> +	.show_options	= famfs_show_options,
> +};
> +
> +
One blank line probably fine.


Add the rest of the stuff a module normally has, author etc in this
patch.

> +MODULE_LICENSE("GPL");