On Wed 28-06-23 21:21:50, Baokun Li wrote:
> Add a new global dquot list that obeys the following rules:
>
> 1). A dquot is added to this list when its last reference count is about
> to be dropped.
> 2). The reference count of the dquot in the list is greater than or equal
> to 1 ( due to possible race with dqget()).
> 3). When a dquot is removed from this list, a reference count is always
> subtracted, and if the reference count is then 0, the dquot is added
> to the free_dquots list.
>
> This list is used to safely perform the final cleanup before releasing
> the last reference count, to avoid various contention issues caused by
> performing cleanup directly in dqput(), and to avoid the performance impact
> caused by calling synchronize_srcu(&dquot_srcu) directly in dqput(). Here
> it is just defining the list and implementing the corresponding operation
> function, which we will use later.
>
> Suggested-by: Jan Kara <jack@xxxxxxx>
> Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
I think you can merge this patch with patch 5. It is not like separating
this bit helps in review or anything...
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index 108ba9f1e420..a8b43b5b5623 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -226,12 +226,21 @@ static void put_quota_format(struct quota_format_type *fmt)
> /*
> * Dquot List Management:
> * The quota code uses four lists for dquot management: the inuse_list,
^^^ five now :)
> - * free_dquots, dqi_dirty_list, and dquot_hash[] array. A single dquot
> - * structure may be on some of those lists, depending on its current state.
> + * releasing_dquots, free_dquots, dqi_dirty_list, and dquot_hash[] array.
> + * A single dquot structure may be on some of those lists, depending on
> + * its current state.
> *
> * All dquots are placed to the end of inuse_list when first created, and this
> * list is used for invalidate operation, which must look at every dquot.
> *
> + * When the last reference of a dquot will be dropped, the dquot will be
> + * added to releasing_dquots. We'd then queue work item which would call
> + * synchronize_srcu() and after that perform the final cleanup of all the
> + * dquots on the list. Both releasing_dquots and free_dquots use the
> + * dq_free list_head in the dquot struct. when a dquot is removed from
^^^ Capital W please
> + * releasing_dquots, a reference count is always subtracted, and if
> + * dq_count == 0 at that point, the dquot will be added to the free_dquots.
> + *
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
