[PATCH 4/8] fanotify:drop notification if they exist in the outgoing queue
From: Eric Paris <eparis@redhat.com>
Date: 2009-09-11 05:26:20
Also in:
linux-fsdevel, lkml
Subsystem:
fanotify, filesystems (vfs and infrastructure), fsnotify: filesystem notification infrastructure, the rest · Maintainers:
Jan Kara, Alexander Viro, Christian Brauner, Linus Torvalds
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 <eparis@redhat.com> --- fs/notify/fanotify/fanotify.c | 40 ++++++++++++++++++++++++++++++++++++++-- 1 files changed, 38 insertions(+), 2 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index b5c2e32..f054300 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c@@ -8,6 +8,40 @@ #include "fanotify.h" +static bool try_merge(struct fsnotify_event *old, struct fsnotify_event *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; + + /* and the list better be locked by something too! */ + + list_for_each_entry_reverse(holder, list, event_list) { + test_event = holder->event; + if (try_merge(test_event, event)) + return -EEXIST; + } + + return 0; +} static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event) { int ret;
@@ -20,8 +54,10 @@ static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_e BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); - 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; }