From 6f73171e192366ff7c98af9fb50615ef9615f8a7 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 4 Mar 2021 12:48:22 +0200 Subject: fsnotify: allow fsnotify_{peek,remove}_first_event with empty queue Current code has an assumtion that fsnotify_notify_queue_is_empty() is called to verify that queue is not empty before trying to peek or remove an event from queue. Remove this assumption by moving the fsnotify_notify_queue_is_empty() into the functions, allow them to return NULL value and check return value by all callers. This is a prep patch for multi event queues. Link: https://lore.kernel.org/r/20210304104826.3993892-2-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- fs/notify/fanotify/fanotify_user.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'fs/notify/fanotify') diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 9e0c1afac8bd..16162207e886 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -100,24 +100,30 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group, { size_t event_size = FAN_EVENT_METADATA_LEN; struct fanotify_event *event = NULL; + struct fsnotify_event *fsn_event; unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); pr_debug("%s: group=%p count=%zd\n", __func__, group, count); spin_lock(&group->notification_lock); - if (fsnotify_notify_queue_is_empty(group)) + fsn_event = fsnotify_peek_first_event(group); + if (!fsn_event) goto out; - if (fid_mode) { - event_size += fanotify_event_info_len(fid_mode, - FANOTIFY_E(fsnotify_peek_first_event(group))); - } + event = FANOTIFY_E(fsn_event); + if (fid_mode) + event_size += fanotify_event_info_len(fid_mode, event); if (event_size > count) { event = ERR_PTR(-EINVAL); goto out; } - event = FANOTIFY_E(fsnotify_remove_first_event(group)); + + /* + * Held the notification_lock the whole time, so this is the + * same event we peeked above. + */ + fsnotify_remove_first_event(group); if (fanotify_is_perm_event(event->mask)) FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED; out: @@ -573,6 +579,7 @@ static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t static int fanotify_release(struct inode *ignored, struct file *file) { struct fsnotify_group *group = file->private_data; + struct fsnotify_event *fsn_event; /* * Stop new events from arriving in the notification queue. since @@ -601,13 +608,12 @@ static int fanotify_release(struct inode *ignored, struct file *file) * dequeue them and set the response. They will be freed once the * response is consumed and fanotify_get_response() returns. */ - while (!fsnotify_notify_queue_is_empty(group)) { - struct fanotify_event *event; + while ((fsn_event = fsnotify_remove_first_event(group))) { + struct fanotify_event *event = FANOTIFY_E(fsn_event); - event = FANOTIFY_E(fsnotify_remove_first_event(group)); if (!(event->mask & FANOTIFY_PERM_EVENTS)) { spin_unlock(&group->notification_lock); - fsnotify_destroy_event(group, &event->fse); + fsnotify_destroy_event(group, fsn_event); } else { finish_permission_event(group, FANOTIFY_PERM(event), FAN_ALLOW); -- cgit v1.2.3