s/AE_SHUTDOWN/1/
Reviewed-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
On Thu, Sep 8, 2016 at 4:25 PM, Jan Kara <jack@xxxxxxx> wrote:
> Implement a function that can be called when a group is being shutdown
> to stop queueing new events to the group. Fanotify will use this.
>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/notify/group.c | 19 +++++++++++++++++++
> fs/notify/notification.c | 5 +++++
> include/linux/fsnotify_backend.h | 4 ++++
> 3 files changed, 28 insertions(+)
>
> diff --git a/fs/notify/group.c b/fs/notify/group.c
> index 3e2dd85be5dd..b47f7cfdcaa4 100644
> --- a/fs/notify/group.c
> +++ b/fs/notify/group.c
> @@ -40,6 +40,17 @@ static void fsnotify_final_destroy_group(struct fsnotify_group *group)
> }
>
> /*
> + * Stop queueing new events for this group. Once this function returns
> + * fsnotify_add_event() will not add any new events to the group's queue.
> + */
> +void fsnotify_group_stop_queueing(struct fsnotify_group *group)
> +{
> + mutex_lock(&group->notification_mutex);
> + group->shutdown = true;
> + mutex_unlock(&group->notification_mutex);
> +}
> +
> +/*
> * Trying to get rid of a group. Remove all marks, flush all events and release
> * the group reference.
> * Note that another thread calling fsnotify_clear_marks_by_group() may still
> @@ -47,6 +58,14 @@ static void fsnotify_final_destroy_group(struct fsnotify_group *group)
> */
> void fsnotify_destroy_group(struct fsnotify_group *group)
> {
> + /*
> + * Stop queueing new events. The code below is careful enough to not
> + * require this but fanotify needs to stop queuing events even before
> + * fsnotify_destroy_group() is called and this makes the other callers
> + * of fsnotify_destroy_group() to see the same behavior.
> + */
> + fsnotify_group_stop_queueing(group);
> +
> /* clear all inode marks for this group, attach them to destroy_list */
> fsnotify_detach_group_marks(group);
>
> diff --git a/fs/notify/notification.c b/fs/notify/notification.c
> index 12bfd6790fc4..af0497cac06c 100644
> --- a/fs/notify/notification.c
> +++ b/fs/notify/notification.c
> @@ -96,6 +96,11 @@ enum fsn_add_event_ret fsnotify_add_event(
>
> mutex_lock(&group->notification_mutex);
>
> + if (group->shutdown) {
> + mutex_unlock(&group->notification_mutex);
> + return AE_SHUTDOWN;
> + }
> +
> if (group->q_len >= group->max_events) {
> ret = AE_OVERFLOW;
> /* Queue overflow event only if it isn't already queued */
> diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> index b948a52ce65f..bcba826a99fc 100644
> --- a/include/linux/fsnotify_backend.h
> +++ b/include/linux/fsnotify_backend.h
> @@ -148,6 +148,7 @@ struct fsnotify_group {
> #define FS_PRIO_1 1 /* fanotify content based access control */
> #define FS_PRIO_2 2 /* fanotify pre-content access */
> unsigned int priority;
> + bool shutdown; /* group is being shut down, don't queue more events */
>
> /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
> struct mutex mark_mutex; /* protect marks_list */
> @@ -292,6 +293,8 @@ extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *op
> extern void fsnotify_get_group(struct fsnotify_group *group);
> /* drop reference on a group from fsnotify_alloc_group */
> extern void fsnotify_put_group(struct fsnotify_group *group);
> +/* group destruction begins, stop queuing new events */
> +extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
> /* destroy group */
> extern void fsnotify_destroy_group(struct fsnotify_group *group);
> /* fasync handler function */
> @@ -304,6 +307,7 @@ enum fsn_add_event_ret {
> AE_INSERTED, /* Event was added in the queue */
> AE_MERGED, /* Event was merged with another event, passed event unused */
> AE_OVERFLOW, /* Queue overflow, passed event unused */
> + AE_SHUTDOWN, /* Group is being released, passed event unused */
> };
> /* attach the event to the group notification queue */
> extern enum fsn_add_event_ret fsnotify_add_event(
> --
> 2.6.6
>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
