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Message-ID: <CAE8kqZ+GV3CoxWMV=4GXgc6YYCcnAk_jnBxzwRubgccZL8VstA@mail.gmail.com>
Date: Thu, 17 Nov 2011 18:21:26 +0800
From: boyd yang <boyd.yang@...il.com>
To: Josef Bacik <josef@...hat.com>, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: eparis@...hat.com, xiyou.wangcong@...il.com
Subject: Re: [PATCH] fanotify: to differ file access event from different threads
How can this patch get merged?
Who is responsible for this?
We are developing some real-time antivirus software, the fanotify can make
it work without dirver/kenel-modues( like RedirFS).
But the bug costs a lot trouble.
If we used the patch, our software works great!
I think other antivirus or file-motoring softwares are influnced by the bug
too.
On Fri, Oct 14, 2011 at 2:56 PM, boyd yang <boyd.yang@...il.com> wrote:
>
> Thanks, I updated the patch.
> Now it passed checkpatch.pl.
>
> I used the flag you mentioned.
>
> fanotify: to differ file access event from different threads
> When fanotify is monitoring the whole mount point "/", and multiple
> threads iterate 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.
> It also hide overflow events to reach user space.
> Signed-off-by: Boyd Yang <boyd.yang@...il.com>
>
> 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 2011-10-14
> 14:17:53.055958000 +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 +145,16 @@
> 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 (event->mask&FS_Q_OVERFLOW) {
> + 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 2011-10-14 13:52:36.946608000 +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);
> }
> @@ -374,6 +375,7 @@
> 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 +419,7 @@
> 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 2011-10-14
> 13:51:50.380168000 +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
>
>
>
>
>
> On Thu, Oct 13, 2011 at 9:38 PM, Josef Bacik <josef@...hat.com> wrote:
> > On Thu, Oct 13, 2011 at 04:56:43PM +0800, boyd yang 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.
> >>
> >
> > You need to run this through checkpatch.pl, you have a ton of formatting
> > problems. Also your email client seems to have word-wrapped parts of this, so
> > use a email client that doesn't word wrap.
> >
> >> =============================================================
> >>
> >> 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);
> >> + }
> >> }
> >
> > The overflow event should only have FS_Q_OVERFLOW set in it's mask right? So
> > why is this test needed at all? Thanks,
> >
> > Josef
> >
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