From 767cd46c332d1360cdbe46ef18d80c3ade06fdc1 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 17 Dec 2009 21:24:25 -0500 Subject: [PATCH] fanotify:drop notification if they exist in the outgoing queue fanotify listeners get an open file descriptor to the object in question so the ordering of operations is not as important as in other notification systems. inotify will drop events if the last event in the event FIFO is the same as the current event. This patch will drop fanotify events if they are the same as another event anywhere in the event FIFO. Signed-off-by: Eric Paris --- fs/notify/fanotify/fanotify.c | 45 +++++++++++++++++++++++++++++++++-- 1 file changed, 43 insertions(+), 2 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 3ffb9dbcab0..c35c1175c4c 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -6,6 +6,45 @@ #include "fanotify.h" +static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new) +{ + pr_debug("%s: old=%p new=%p\n", __func__, old, new); + + if ((old->mask == new->mask) && + (old->to_tell == new->to_tell) && + (old->data_type == new->data_type)) { + switch (old->data_type) { + case (FSNOTIFY_EVENT_PATH): + if ((old->path.mnt == new->path.mnt) && + (old->path.dentry == new->path.dentry)) + return true; + case (FSNOTIFY_EVENT_NONE): + return true; + default: + BUG(); + }; + } + return false; +} + +static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) +{ + struct fsnotify_event_holder *holder; + struct fsnotify_event *test_event; + + pr_debug("%s: list=%p event=%p\n", __func__, list, event); + + /* and the list better be locked by something too! */ + + list_for_each_entry_reverse(holder, list, event_list) { + test_event = holder->event; + if (should_merge(test_event, event)) + return -EEXIST; + } + + return 0; +} + static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event) { int ret; @@ -21,8 +60,10 @@ static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_e pr_debug("%s: group=%p event=%p\n", __func__, group, event); - ret = fsnotify_add_notify_event(group, event, NULL, NULL); - + ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge); + /* -EEXIST means this event was merged with another, not that it was an error */ + if (ret == -EEXIST) + ret = 0; return ret; } -- 2.41.0