On Fri, Jul 22, 2016 at 5:36 AM, Thomas Gambier
<thomas.gambier@xxxxxxxxx> wrote:
> Hello,
>
> when doing more tests with TCL, I found a more critical problem.
>
> If I create a directory and just after I create a read only file (mode
> 0444) inside it, I got a permission denied error. See the attached C
> source code. As the previous error, it is random but I always have it
> fail before the 10th execution.
>
> I attach the network traffic but it seems that the problem is again in
> the client.
>
> Olga, could you test this new testcase on the newest kernel ?
Works fine for me on the RHEL7.2 and upstream.
>
> Regards.
>
> Thomas.
>
> On Thu, Jul 21, 2016 at 8:10 PM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote:
>> On Thu, Jul 21, 2016 at 1:14 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>>> On Thu, Jul 21, 2016 at 04:54:36PM +0200, Thomas Gambier wrote:
>>>> On Mon, Jul 18, 2016 at 4:09 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>>>> > On Mon, Jul 18, 2016 at 03:44:48PM +0200, Thomas Gambier wrote:
>>>> >> Hello,
>>>> >>
>>>> >> thanks for your answer. See my comments below.
>>>> >>
>>>> >> On Wed, Jul 13, 2016 at 3:26 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>>>> >> > On Mon, Jul 11, 2016 at 07:40:11PM +0200, Thomas Gambier wrote:
>>>> >> >> Hello,
>>>> >> >>
>>>> >> >> I just discovered a problem with NFSv4 file system. I was using TCL
>>>> >> >> scripts that were doing some file manipulation (mkdir, copy, ...) on
>>>> >> >> my NFSv4 file system and sometimes the scripts failed with "permission
>>>> >> >> denied" error.
>>>> >> >>
>>>> >> >> I ran strace and I found that the system call returning the error was:
>>>> >> >> open("d1/in.txt", O_WRONLY|O_CREAT|O_TRUNC, 0100444) = -1 EACCES
>>>> >> >> (Permission denied)
>>>> >> >
>>>> >> > Is that even allowed? The open(2) man page says posix leaves behavior
>>>> >> > in that case unspecified, and doesn't say anything I can find about
>>>> >> > Linux behavior in this case.
>>>> >> >
>>>> >> You're right. I will send a mail to TCL mailing list to know why they
>>>> >> put this flag in the open call.
>>>> >>
>>>> >> > I guess it would be nicer for client or server to do something
>>>> >> > predictable, though. First steps might be to confirm what happens other
>>>> >> > filesystems, then do a network trace (watch the traffic in wireshark) to
>>>> >> > see if it's the client rejecting this open, or the client passing
>>>> >> > through that bit in the mode and the server returning the error.
>>>> >>
>>>> >> I agree. For other filesystem, I only tested with ext4 which works
>>>> >> fine. Let me know if you want me to test specific filesystems.
>>>> >>
>>>> >> I attach the wireshark capture of a test with 8 open call working fine
>>>> >> and the 9th one failing. For me, it seems the activity on the network
>>>> >> is exactly the same for the failing case (same call from client to
>>>> >> server and same answer from server to client). It would mean that the
>>>> >> client itself is messing things up...
>>>> >
>>>> > Agreed, sounds like the client's only deciding to fail the open after
>>>> > the OPEN call to the server succeeds.
>>>> >
>>>> > Unfortunately, the client open logic is (necessarily) pretty
>>>> > complicated--a few minutes digging around wasn't enough for me to figure
>>>> > uot where the error's coming from.
>>>> >
>>>>
>>>> I'm not sure if I can help... I don't know the NFS source code at all.
>>>> I can do more tests if you need, though.
>>>
>>> It doesn't look like a high priority based just on what we know
>>> (slightly odd behavior in an undefined case), so I think we'll just have
>>> to leave it at that until somebody gets curious. Thanks for the report.
>>>
>>
>> Hi Thomas,
>>
>> I don't know exactly what was fixed or when but I thought I'd note
>> that I don't see the problem on the upstream 4.7-rc7 but I can
>> reproduce the problem on RHEL7.2 kernel.
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