Splice off the notification list while processing read events, which allows it to be processed without taking and releasing the spinlock for each event.
Signed-off-by: Jes Sorensen <[email protected]> Reviewed-by: Josef Bacik <[email protected]> --- fs/notify/inotify/inotify_user.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c index 4a93750..45b1f69 100644 --- a/fs/notify/inotify/inotify_user.c +++ b/fs/notify/inotify/inotify_user.c @@ -224,22 +224,27 @@ static ssize_t inotify_read(struct file *file, char __user *buf, struct fsnotify_group *group; struct fsnotify_event *kevent; char __user *start; - int ret; + int ret, consumed = 0; DEFINE_WAIT_FUNC(wait, woken_wake_function); + LIST_HEAD(tmp_list); start = buf; group = file->private_data; mutex_lock(&group->inotify_data.consumer_mutex); add_wait_queue(&group->notification_waitq, &wait); + + spin_lock(&group->notification_lock); + list_splice_init(&group->notification_list, &tmp_list); + spin_unlock(&group->notification_lock); + while (1) { - spin_lock(&group->notification_lock); - kevent = get_one_event(&group->notification_list, count); - spin_unlock(&group->notification_lock); + kevent = get_one_event(&tmp_list, count); pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent); if (kevent) { + consumed++; ret = PTR_ERR(kevent); if (IS_ERR(kevent)) break; @@ -262,8 +267,23 @@ static ssize_t inotify_read(struct file *file, char __user *buf, if (start != buf) break; + spin_lock(&group->notification_lock); + list_splice_init(&tmp_list, &group->notification_list); + group->q_len -= consumed; + consumed = 0; + spin_unlock(&group->notification_lock); + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + + spin_lock(&group->notification_lock); + list_splice_init(&group->notification_list, &tmp_list); + spin_unlock(&group->notification_lock); } + spin_lock(&group->notification_lock); + list_splice(&tmp_list, &group->notification_list); + group->q_len -= consumed; + spin_unlock(&group->notification_lock); + remove_wait_queue(&group->notification_waitq, &wait); mutex_unlock(&group->inotify_data.consumer_mutex); -- 2.9.3
