Re: [RFC PATCH 09/20] famfs: Add super_operations

Jonathan Cameron
2024-02-26T12:51:40Z

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

> Introduce the famfs superblock operations
>
> Signed-off-by: John Groves <john@groves.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");