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Message-ID: <CAE8kqZJkmWzNtvYiqoFH3j9qRo2PTo58MtVON5try9vjLNsQ_Q@mail.gmail.com>
Date: Thu, 13 Oct 2011 21:27:51 +0800
From: boyd yang <boyd.yang@...il.com>
To: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: eparis@...hat.com
Subject: Re: [PATCH] fanotify: to differ file access event from different threads
Does anybody review my patch and integrate into kernel?
On Thu, Oct 13, 2011 at 4:56 PM, boyd yang <boyd.yang@...il.com> wrote:
> This patch fixes a hang problem of Eric Paris's fs Notification/fanotify.
>
> Fanotify brings a way to intercept file access events.
> When multiple threadsiterate the same direcotry, some thread will hang.
> This patch let fanotify to differ access events from different
> threads, prevent fanotify from merging access events from different
> threads.
>
> =============================================================
>
> diff -r -u linux-3.1-rc4_orig/fs/notify/fanotify/fanotify.c
> linux-3.1-rc4/fs/notify/fanotify/fanotify.c
> --- linux-3.1-rc4_orig/fs/notify/fanotify/fanotify.c 2011-08-29
> 12:16:01.000000000 +0800
> +++ linux-3.1-rc4/fs/notify/fanotify/fanotify.c 2011-10-10
> 12:28:23.276847000 +0800
> @@ -15,7 +15,8 @@
>
> if (old->to_tell == new->to_tell &&
> old->data_type == new->data_type &&
> - old->tgid == new->tgid) {
> + old->tgid == new->tgid &&
> + old->pid == new->pid) {
> switch (old->data_type) {
> case (FSNOTIFY_EVENT_PATH):
> if ((old->path.mnt == new->path.mnt) &&
> @@ -144,11 +145,19 @@
> return PTR_ERR(notify_event);
>
> #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
> - if (event->mask & FAN_ALL_PERM_EVENTS) {
> - /* if we merged we need to wait on the new event */
> - if (notify_event)
> - event = notify_event;
> - ret = fanotify_get_response_from_access(group, event);
> + //if overflow, do not wait for response
> + if(fsnotify_isoverflow(event))
> + {
> + pr_debug("fanotify overflow!\n");
> + }
> + else
> + {
> + if (event->mask & FAN_ALL_PERM_EVENTS) {
> + /* if we merged we need to wait on the new event */
> + if (notify_event)
> + event = notify_event;
> + ret = fanotify_get_response_from_access(group, event);
> + }
> }
> #endif
>
> diff -r -u linux-3.1-rc4_orig/fs/notify/notification.c
> linux-3.1-rc4/fs/notify/notification.c
> --- linux-3.1-rc4_orig/fs/notify/notification.c 2011-08-29
> 12:16:01.000000000 +0800
> +++ linux-3.1-rc4/fs/notify/notification.c 2011-10-10 12:27:09.331787000 +0800
> @@ -95,6 +95,7 @@
> BUG_ON(!list_empty(&event->private_data_list));
>
> kfree(event->file_name);
> + put_pid(event->pid);
> put_pid(event->tgid);
> kmem_cache_free(fsnotify_event_cachep, event);
> }
> @@ -132,6 +133,14 @@
> return priv;
> }
>
> +bool fsnotify_isoverflow(struct fsnotify_event *event)
> +{
> + if(event==q_overflow_event)
> + {
> + return true;
> + }
> + return false;
> +}
> /*
> * Add an event to the group notification queue. The group can later pull this
> * event off the queue to deal with. If the event is successfully added to the
> @@ -374,6 +383,7 @@
> return NULL;
> }
> }
> + event->pid = get_pid(old_event->pid);
> event->tgid = get_pid(old_event->tgid);
> if (event->data_type == FSNOTIFY_EVENT_PATH)
> path_get(&event->path);
> @@ -417,6 +427,7 @@
> event->name_len = strlen(event->file_name);
> }
>
> + event->pid = get_pid(task_pid(current));
> event->tgid = get_pid(task_tgid(current));
> event->sync_cookie = cookie;
> event->to_tell = to_tell;
> diff -r -u linux-3.1-rc4_orig/include/linux/fsnotify_backend.h
> linux-3.1-rc4/include/linux/fsnotify_backend.h
> --- linux-3.1-rc4_orig/include/linux/fsnotify_backend.h 2011-08-29
> 12:16:01.000000000 +0800
> +++ linux-3.1-rc4/include/linux/fsnotify_backend.h 2011-10-10
> 12:27:48.587369000 +0800
> @@ -238,6 +238,7 @@
> u32 sync_cookie; /* used to corrolate events, namely inotify mv events */
> const unsigned char *file_name;
> size_t name_len;
> + struct pid *pid;
> struct pid *tgid;
>
> #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
> @@ -378,6 +379,8 @@
> struct fsnotify_event_private_data *priv,
> struct fsnotify_event *(*merge)(struct list_head *,
> struct fsnotify_event *));
> +/*true if the event is an overflow event*/
> +extern bool fsnotify_isoverflow(struct fsnotify_event *event);
> /* true if the group notification queue is empty */
> extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
> /* return, but do not dequeue the first event on the notification queue */
>
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