truncate() syscall against EFBIG errno issue over nfs filesystem

[Shuang Qiu <shuang.qiu@oracle.com>]

Hi guys,

In LTP truncate03 testcase 
(https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/truncate/truncate03.c),the 
sub-test which test the EFBUG errno will fail.
The test want to truncate the testfile to twice of the RLIMIT_FSIZE size.

According to the man page:
RLIMIT_FSIZE
               The  maximum  size of files that the process may create.  
Attempts to extend a file beyond this limit result in delivery of a
               SIGXFSZ signal.  By default, this signal terminates a 
process, but a process can catch this signal instead, in which case the
               relevant system call (e.g., write(2), truncate(2)) fails 
with the error EFBIG.

We can get EFBIG on some other filesystem such like ext4,xfs.
But truncate will succeed unexpectedly if the testfile on nfs filesystem 
after catch the SIGXFSZ signal.
I'm not sure if it is a bug for truncate(2) on nfs,or expected behavior?
Could someone help to have a look?

Thanks
Shuang