ceph/qa/workunits/fs/misc/filelock_interrupt.py

   1 #!/usr/bin/python3
   2
   3 from contextlib import contextmanager
   4 import errno
   5 import fcntl
   6 import signal
   7 import struct
   8
   9 @contextmanager
  10 def timeout(seconds):
  11     def timeout_handler(signum, frame):
  12         raise InterruptedError
  13
  14     orig_handler = signal.signal(signal.SIGALRM, timeout_handler)
  15     try:
  16         signal.alarm(seconds)
  17         yield
  18     finally:
  19         signal.alarm(0)
  20         signal.signal(signal.SIGALRM, orig_handler)
  21
  22
  23 """
  24 introduced by Linux 3.15
  25 """
  26 setattr(fcntl, "F_OFD_GETLK", 36)
  27 setattr(fcntl, "F_OFD_SETLK", 37)
  28 setattr(fcntl, "F_OFD_SETLKW", 38)
  29
  30
  31 def main():
  32     f1 = open("testfile", 'w')
  33     f2 = open("testfile", 'w')
  34
  35     fcntl.flock(f1, fcntl.LOCK_SH | fcntl.LOCK_NB)
  36
  37     """
  38     is flock interruptible?
  39     """
  40     with timeout(5):
  41         try:
  42             fcntl.flock(f2, fcntl.LOCK_EX)
  43         except InterruptedError:
  44             pass
  45         else:
  46             raise RuntimeError("expect flock to block")
  47
  48     fcntl.flock(f1, fcntl.LOCK_UN)
  49
  50     lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 10, 0, 0)
  51     try:
  52         fcntl.fcntl(f1, fcntl.F_OFD_SETLK, lockdata)
  53     except IOError as e:
  54         if e.errno != errno.EINVAL:
  55             raise
  56         else:
  57             print('kernel does not support fcntl.F_OFD_SETLK')
  58             return
  59
  60     lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 10, 10, 0, 0)
  61     fcntl.fcntl(f2, fcntl.F_OFD_SETLK, lockdata)
  62
  63     """
  64     is posix lock interruptible?
  65     """
  66     with timeout(5):
  67         try:
  68             lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
  69             fcntl.fcntl(f2, fcntl.F_OFD_SETLKW, lockdata)
  70         except InterruptedError:
  71             pass
  72         else:
  73             raise RuntimeError("expect posix lock to block")
  74
  75     """
  76     file handler 2 should still hold lock on 10~10
  77     """
  78     try:
  79         lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 10, 10, 0, 0)
  80         fcntl.fcntl(f1, fcntl.F_OFD_SETLK, lockdata)
  81     except IOError as e:
  82         if e.errno == errno.EAGAIN:
  83             pass
  84     else:
  85         raise RuntimeError("expect file handler 2 to hold lock on 10~10")
  86
  87     lockdata = struct.pack('hhllhh', fcntl.F_UNLCK, 0, 0, 0, 0, 0)
  88     fcntl.fcntl(f1, fcntl.F_OFD_SETLK, lockdata)
  89     fcntl.fcntl(f2, fcntl.F_OFD_SETLK, lockdata)
  90
  91     print('ok')
  92
  93
  94 main()