[Samba] problem when writing to a deleted file

[Simon Weatherill]

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
office phone: 603-863-4111
cell phone: 603-359-1071

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