[PATCH] apparmor: use per file locks for transactional queries

[John Johansen]

On 7/29/21 10:23 PM, Hamza Mahfooz wrote:
> As made mention of in commit 1dea3b41e84c5 ("apparmor: speed up
> transactional queries"), a single lock is currently used to synchronize
> transactional queries. We can, use the lock allocated for each file by
> VFS instead.
> 
> Signed-off-by: Hamza Mahfooz <someguy at effective-light.com>

Acked-by: John Johansen <john.johansen at canonical.com>

I'll pull this into my tree asap

> ---
>  security/apparmor/apparmorfs.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
> index 2ee3b3d29f10..c0b626a271a0 100644
> --- a/security/apparmor/apparmorfs.c
> +++ b/security/apparmor/apparmorfs.c
> @@ -812,8 +812,6 @@ struct multi_transaction {
>  };
>  
>  #define MULTI_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct multi_transaction))
> -/* TODO: replace with per file lock */
> -static DEFINE_SPINLOCK(multi_transaction_lock);
>  
>  static void multi_transaction_kref(struct kref *kref)
>  {
> @@ -847,10 +845,10 @@ static void multi_transaction_set(struct file *file,
>  	AA_BUG(n > MULTI_TRANSACTION_LIMIT);
>  
>  	new->size = n;
> -	spin_lock(&multi_transaction_lock);
> +	spin_lock(&file->f_lock);
>  	old = (struct multi_transaction *) file->private_data;
>  	file->private_data = new;
> -	spin_unlock(&multi_transaction_lock);
> +	spin_unlock(&file->f_lock);
>  	put_multi_transaction(old);
>  }
>  
> @@ -879,9 +877,10 @@ static ssize_t multi_transaction_read(struct file *file, char __user *buf,
>  	struct multi_transaction *t;
>  	ssize_t ret;
>  
> -	spin_lock(&multi_transaction_lock);
> +	spin_lock(&file->f_lock);
>  	t = get_multi_transaction(file->private_data);
> -	spin_unlock(&multi_transaction_lock);
> +	spin_unlock(&file->f_lock);
> +
>  	if (!t)
>  		return 0;
>  
>