[Samba] problem when writing to a deleted file

[Simon Weatherill]

I take that back. I get a "Text file busy" first, and then each 
subsequent FileOutputStream.write() gets a "Bad file descriptor" 
IOException.

I have some java source that I've used to create these errors.

Simon

Simon Weatherill wrote:

> I just tested it without using the PDF library and (luckily) got 
> similar results. This time, however, I got a "Text file busy" 
> Exception (java) while the first thread was writing. The second thread 
> continued writing to the new file.
>
> Simon
>
> Simon Weatherill wrote:
>
>> I've got a weird situation. I have an RMI application that is 
>> creating PDF's for a web server. A request comes in to the web 
>> server, the web server deletes the PDF if it exists and then requests 
>> an RMI server to create the PDF. The PDF is written directly to the 
>> web server's disk via a Samba mount (both systems are Linux and are 
>> running Samba 3.0.10). The problem occurs when the web server serves 
>> 2 almost simultaneous requests for the same PDF. The first request 
>> deletes (if necessary) the existing PDF and calls the RMI server to 
>> create a new PDF. The next request deletes the PDF (that is now being 
>> created by the RMI server) and calls the RMI server to create a new 
>> PDF. The first RMI process can no longer write to the PDF and the 
>> second process can't write to it either. It's very much a timing 
>> issue. If the requests are spread out just enough, then no one's the 
>> wiser.
>>
>> Samba generates the following error (from messages). I believe that 
>> means that Samba is getting an EBADF error (bad file number).
>>
>>    kernel: smb_writepage_sync: failed write, wsize=4096, result=-9
>>
>> What exactly is going on in the file system during this? I know what 
>> happens in a normal UNIX file system (and the problem does not occur 
>> there). I am going to write a test application that creates just 
>> plain files without using the PDF library to see if perhaps they do 
>> something funny or if it's just how Samba handles deleted files. I 
>> have a call into the writers of the PDF library as well.
>>
>> This seems like a silly problem and we'll probably have to code 
>> around it anyway, but something is not working correctly (in my eye).
>>
>> Thanks,
>> Simon
>
>
>

-- 
Simon Weatherill