With inotify, when a watch is set on a directory and on its child, an event on the child is reported twice, once with wd of the parent watch and once with wd of the child watch without the filename. With fanotify, when a watch is set on a directory and on its child, an event on the child is reported twice, but it has the exact same information - either an open file descriptor of the child or an encoded fid of the child. The reason that the two identical events are not merged is because the tag used for merging events in the queue is the child inode in one event and parent inode in the other. For events with path or dentry data, use the dentry instead of inode as the tag for event merging, so that the event reported on parent will be merged with the event reported on the child. Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> --- fs/notify/fanotify/fanotify.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 98c3cbf29003..dab7e9895e02 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -282,6 +282,7 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, gfp_t gfp = GFP_KERNEL_ACCOUNT; struct inode *id = fanotify_fid_inode(inode, mask, data, data_type); const struct path *path = fsnotify_data_path(data, data_type); + struct dentry *dentry = fsnotify_data_dentry(data, data_type); /* * For queues with unlimited length lost events are not expected and @@ -312,7 +313,12 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, if (!event) goto out; init: __maybe_unused - fsnotify_init_event(&event->fse, inode); + /* + * Use the dentry instead of inode as tag for event queue, so event + * reported on parent is merged with event reported on child when both + * directory and child watches exist. + */ + fsnotify_init_event(&event->fse, (void *)dentry ?: inode); event->mask = mask; if (FAN_GROUP_FLAG(group, FAN_REPORT_TID)) event->pid = get_pid(task_pid(current)); -- 2.17.1
