linux-kernel - Re: [for-next][PATCH 7/7] tracing: Have mkdir and rmdir be part of tracefs

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Date:	Mon, 9 Feb 2015 10:07:58 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Al Viro <viro@...IV.linux.org.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [for-next][PATCH 7/7] tracing: Have mkdir and rmdir be part of
 tracefs

On Mon, 9 Feb 2015 15:07:22 +0900
Namhyung Kim <namhyung@...nel.org> wrote:

> On Wed, Feb 04, 2015 at 09:34:27AM -0500, Steven Rostedt wrote:
> > +static int tracefs_syscall_mkdir(struct inode *inode, struct dentry *dentry, umode_t mode)
> > +{
> > +	char *name;
> > +	int ret;
> > +
> > +	name = get_dname(dentry);
> > +	if (!name)
> > +		return -ENOMEM;
> > +
> > +	/*
> > +	 * The mkdir call can call the generic functions that create
> 
> 	   The mkdir can call ... ?

Actually, that wasn't a typo. "mkdir call" is the subject.

> 
> 
> > +	 * the files within the tracefs system. It is up to the individual
> > +	 * mkdir routine to handle races.
> > +	 */
> > +	mutex_unlock(&inode->i_mutex);
> > +	ret = tracefs_ops.mkdir(name);
> > +	mutex_lock(&inode->i_mutex);
> > +
> > +	kfree(name);
> > +
> > +	return ret;
> > +}
> > +
> > +static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry)
> > +{
> > +	char *name;
> > +	int ret;
> > +
> > +	name = get_dname(dentry);
> > +	if (!name)
> > +		return -ENOMEM;
> > +
> > +	/*
> > +	 * The rmdir call can call the generic functions that create
> 
> Ditto.
> 

"rmdir call" is also the subject.

> 
> > +	 * the files within the tracefs system. It is up to the individual
> > +	 * rmdir routine to handle races.
> > +	 * This time we need to unlock not only the parent (inode) but
> > +	 * also the directory that is being deleted.
> > +	 */
> > +	mutex_unlock(&inode->i_mutex);
> > +	mutex_unlock(&dentry->d_inode->i_mutex);
> > +
> > +	ret = tracefs_ops.rmdir(name);
> > +
> > +	mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
> > +	mutex_lock(&dentry->d_inode->i_mutex);
> > +
> > +	kfree(name);
> > +
> > +	return ret;
> > +}
> > +
> 
> [SNIP]
> > +/**
> > + * tracefs_create_instance_dir - create the tracing instances directory
> > + * @name: The name of the instances directory to create
> > + * @parent: The parent directory that the instances directory will exist
> > + * @mkdir: The function to call when a mkdir is performed.
> > + * @rmdir: The function to call when a rmdir is performed.
> > + *
> > + * Only one instances directory is allowed.
> > + *
> > + * The instances directory is special as it allows for mkdir and rmdir to
> > + * to be done by userspace. When a mkdir or rmdir is performed, the inode
> > + * locks are released and the methhods passed in (@mkdir and @rmdir) are
> 
> s/methhods/methods/

I must have been on meth ;-)

Thanks.

-- Steve
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