Linux-2.6.31-rc8 inotify hangs samba clients

Linux-2.6.31-rc8 inotify hangs samba clients

[Jeff Chua]

The first part of commit 0db501bd0610ee0c0aca84d927f90bcccd09e2bd hangs 
WinXP clients browsing Linux samba folders ... trying to add a 
terminating byte to name_len. Reverting this solves the problem.

The second part of adding zeros is fine.

If we don't revert here, then Samba 3.3.7 will have to change to work with 
Linux 2.6.31-rc8, and perhaps other codes as well.

Thanks,
Jeff




commit 0db501bd0610ee0c0aca84d927f90bcccd09e2bd
Author: Eric W. Biederman <ebiederm@xmission.com>
Date:   Thu Aug 27 03:20:04 2009 -0700

     inotify: Ensure we alwasy write the terminating NULL.

     Before the rewrite copy_event_to_user always wrote a terqminating '\0'
     byte to user space after the filename.  Since the rewrite that
     terminating byte was skipped if your filename is exactly a multiple of
     event_size.  Ouch!

     So add one byte to name_size before we round up.

     Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
     Signed-off-by: Eric Paris <eparis@redhat.com>

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index ce1f582..0e781bc 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -199,8 +196,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
  		inotify_free_event_priv(fsn_priv);
  	}

-	/* round up event->name_len so it is a multiple of event_size */
-	name_len = roundup(event->name_len, event_size);
+	/* round up event->name_len so it is a multiple of event_size
+	 * plus an extra byte for the terminating '\0'.
+	 */
+	name_len = roundup(event->name_len, event_size) + 1;
  	inotify_event.len = name_len;

  	inotify_event.mask = inotify_mask_to_arg(event->mask);

Re: Linux-2.6.31-rc8 inotify hangs samba clients

[Eric Paris]

On Sat, 2009-08-29 at 00:13 +0800, Jeff Chua wrote:
> 
> The first part of commit 0db501bd0610ee0c0aca84d927f90bcccd09e2bd hangs 
> WinXP clients browsing Linux samba folders ... trying to add a 
> terminating byte to name_len. Reverting this solves the problem.
> 
> The second part of adding zeros is fine.
> 
> If we don't revert here, then Samba 3.3.7 will have to change to work with 
> Linux 2.6.31-rc8, and perhaps other codes as well.

Deffinitly not Samba's fault.  I should have 2 patches to fix inotify
at:

http://git.infradead.org/users/eparis/notify.git/shortlog/refs/heads/for-linus

-Eric

Re: Linux-2.6.31-rc8 inotify hangs samba clients

[Jeff Chua]

On Sat, Aug 29, 2009 at 12:20 AM, Eric Paris<eparis@redhat.com> wrote:

> Deffinitly not Samba's fault.  I should have 2 patches to fix inotify
> at:
>
> http://git.infradead.org/users/eparis/notify.git/shortlog/refs/heads/for-linus

Eric, didn't expect instantaneous response as I was sending out the
wrong patch and had to correct it.

Thanks again for the pointer and fixes. Will wait to pull from Linus's git.

Jeff.

Re: Linux-2.6.31-rc8 inotify hangs samba clients

[Linus Torvalds]

On Sat, 29 Aug 2009, Jeff Chua wrote:
> 
> Thanks again for the pointer and fixes. Will wait to pull from Linus's 
> git.

Ok, I've merged the inotify things (along with a few others changes). 
Please do give it a good test. I'm going to be online only to a _very_ 
limited degree (four-tank dive day tomorrow! Yeehaa), so I really hope 
that this solves it all.

			Linus

Re: Linux-2.6.31-rc8 inotify hangs samba clients

[Jeff Chua]

On Sat, Aug 29, 2009 at 1:48 PM, Linus
Torvalds<torvalds@linux-foundation.org> wrote:
> On Sat, 29 Aug 2009, Jeff Chua wrote:
>>
>> Thanks again for the pointer and fixes. Will wait to pull from Linus's
>> git.
>
> Ok, I've merged the inotify things (along with a few others changes).
> Please do give it a good test. I'm going to be online only to a _very_
> limited degree (four-tank dive day tomorrow! Yeehaa), so I really hope
> that this solves it all.

Looks solved. Seems faster than before "introducing the bad fix".

Have a great dive!

Thanks,
Jeff

Re: Linux-2.6.31-rc8 inotify hangs samba clients

[walt]

On 08/28/2009 09:13 AM, Jeff Chua wrote:
>
>
> The first part of commit 0db501bd0610ee0c0aca84d927f90bcccd09e2bd hangs
> WinXP clients browsing Linux samba folders ... trying to add a
> terminating byte to name_len. Reverting this solves the problem.

As another data point, the same commit also prevents udev from creating
the /dev/vboxdrv device when the vboxdrv kernel module gets loaded.

Haven't tried Eric's patches yet, but I'm betting the problem will be
cured.  Thanks for the quick fix, Eric.