On Tue, 3 Dec 2013 14:16:08 +0100 (CET)
mail654@xxxxxx wrote:
> Hello,
>
> write() from cifs kernel driver blocks when disconnecting the cifs server. The blocking call didn't return after 30 minutes. Client and server are connected via a switch and server's LAN cable is unplugged during the write call. I use kernel 3.11.8 and mounted without "hard" option.
>
> Is there a possibility for an non-blocking write() without using O_SYNC or "directio" mount option?
>
> Way to reproduce the scenario: Below is a sample program which calls write() in a loop. The error messages appear when unplugging the cable during this loop.
>
> Kind regards,
> Hagen
>
> CIFS VFS: sends on sock ffff88003710c280 stuck for 15 seconds
> CIFS VFS: Error -11 sending data on socket to server
>
> #include <fstream>
> #include <iostream>
> int main () {
> const int size = 100000;
> char buffer[size];
> std::ofstream outfile("/mnt/new.bin",std::ofstream::binary);
> if (!outfile.is_open())
> {
> return 1;
> }
> for (int idx=0; idx<10000 && outfile.good(); idx++)
> {
> outfile.write(buffer,size);
> std::cout << "written, size=" << size << std::endl;
> }
> std::cout << "finished " << outfile.good() << std::endl;
> outfile.close();
> return 0;
> }
A hang of that length is unexpected. If you're able to reproduce this,
can you get the stack from the task issuing the write at the time?
$ cat /proc/<pid>/stack
That might give us a clue as to what it's doing.
--
Jeff Layton <jlayton@xxxxxxxxx>
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