linux-kernel - Re: [RFC PATCH 12/20] famfs: Add inode_operations and file_system

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Message-ID: <20240226132538.00002656@Huawei.com>
Date: Mon, 26 Feb 2024 13:25:38 +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 12/20] famfs: Add inode_operations and
 file_system_type

On Fri, 23 Feb 2024 11:41:56 -0600
John Groves <John@...ves.net> wrote:

> This commit introduces the famfs inode_operations. There is nothing really
> unique to famfs here in the inode_operations..
> 
> This commit also introduces the famfs_file_system_type struct and the
> famfs_kill_sb() function.
> 
> Signed-off-by: John Groves <john@...ves.net>

Trivial comments only.

> +
> +/*
> + * File creation. Allocate an inode, and we're done..
> + */
> +/* SMP-safe */
> +static int
> +famfs_mknod(
> +	struct mnt_idmap *idmap,
> +	struct inode     *dir,
> +	struct dentry    *dentry,
> +	umode_t           mode,
> +	dev_t             dev)
> +{
> +	struct inode *inode = famfs_get_inode(dir->i_sb, dir, mode, dev);
> +	int error           = -ENOSPC;
> +
> +	if (inode) {

As below. I would flip it for cleaner code/ shorter indent etc.

> +		struct timespec64       tv;
> +
> +		d_instantiate(dentry, inode);
> +		dget(dentry);	/* Extra count - pin the dentry in core */
> +		error = 0;
> +		tv = inode_set_ctime_current(inode);
> +		inode_set_mtime_to_ts(inode, tv);
> +		inode_set_atime_to_ts(inode, tv);
> +	}
> +	return error;
> +}
> +
> +static int famfs_mkdir(
> +	struct mnt_idmap *idmap,
> +	struct inode     *dir,
> +	struct dentry    *dentry,
> +	umode_t           mode)
> +{
> +	int retval = famfs_mknod(&nop_mnt_idmap, dir, dentry, mode | S_IFDIR, 0);
> +
> +	if (!retval)
> +		inc_nlink(dir);

Copy local style, so fine if this is common pattern, otherwise I'd go for
consistent error cases out of line as easier for us sleepy caffeine 
deprived reviewers.


	if (retval)
		return retval;

	inc_nlink(dir);

	return 0;
> +
> +	return retval;
> +}
> +
> +static int famfs_create(
> +	struct mnt_idmap *idmap,
> +	struct inode     *dir,
> +	struct dentry    *dentry,
> +	umode_t           mode,
> +	bool              excl)
> +{
> +	return famfs_mknod(&nop_mnt_idmap, dir, dentry, mode | S_IFREG, 0);
> +}
> +
> +static int famfs_symlink(
> +	struct mnt_idmap *idmap,
> +	struct inode     *dir,
> +	struct dentry    *dentry,
> +	const char       *symname)
> +{
> +	struct inode *inode;
> +	int error = -ENOSPC;
> +
> +	inode = famfs_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0);
	if (!inode)
		return -ENOSPC;

> +	if (inode) {
> +		int l = strlen(symname)+1;
> +
> +		error = page_symlink(inode, symname, l);
	if (error) {
		iput(inode);
		return error;
	}
	
	...

> +		if (!error) {
> +			struct timespec64       tv;
> +
> +			d_instantiate(dentry, inode);
> +			dget(dentry);
> +			tv = inode_set_ctime_current(inode);
> +			inode_set_mtime_to_ts(inode, tv);
> +			inode_set_atime_to_ts(inode, tv);
> +		} else
> +			iput(inode);
> +	}
> +	return error;
> +}