Re: [PATCH 1/8] apparmor: just use vfs_kern_mount to make .null

[Luis Chamberlain <mcgrof@kernel.org>]

On Tue, Apr 14, 2020 at 02:42:55PM +0200, Emanuele Giuseppe Esposito wrote:
> aa_mk_null_file is using simple_pin_fs/simple_release_fs with local
> variables as arguments, for what would amount to a simple
> vfs_kern_mount/mntput pair if everything was inlined.  Just use
> the normal filesystem API since the reference counting is not needed
> here.

*Why* is refcounting not needed here?

   Luis

> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> ---
>  security/apparmor/apparmorfs.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
> index 280741fc0f5f..828bb1eb77ea 100644
> --- a/security/apparmor/apparmorfs.c
> +++ b/security/apparmor/apparmorfs.c
> @@ -2525,14 +2525,14 @@ struct path aa_null;
>  
>  static int aa_mk_null_file(struct dentry *parent)
>  {
> -	struct vfsmount *mount = NULL;
> +	struct file_system_type *type = parent->d_sb->s_type;
> +	struct vfsmount *mount;
>  	struct dentry *dentry;
>  	struct inode *inode;
> -	int count = 0;
> -	int error = simple_pin_fs(parent->d_sb->s_type, &mount, &count);
>  
> -	if (error)
> -		return error;
> +	mount = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
> +	if (IS_ERR(mount))
> +		return PTR_ERR(mount);
>  
>  	inode_lock(d_inode(parent));
>  	dentry = lookup_one_len(NULL_FILE_NAME, parent, strlen(NULL_FILE_NAME));
> @@ -2561,7 +2561,7 @@ static int aa_mk_null_file(struct dentry *parent)
>  	dput(dentry);
>  out:
>  	inode_unlock(d_inode(parent));
> -	simple_release_fs(&mount, &count);
> +	mntput(mount);
>  	return error;
>  }
>  
> -- 
> 2.25.2
>