config/kernel-bio-rw-barrier.m4

   1 dnl #
   2 dnl # Interface for issuing a discard bio:
   3 dnl # 2.6.28-2.6.35: BIO_RW_BARRIER
   4 dnl # 2.6.36-3.x:    REQ_BARRIER
   5 dnl #
   6
   7 dnl # Since REQ_BARRIER is a preprocessor definition, there is no need for an
   8 dnl # autotools check for it. Also, REQ_BARRIER existed in the request layer
   9 dnl # until torvalds/linux@7b6d91daee5cac6402186ff224c3af39d79f4a0e unified the
  10 dnl # request layer and bio layer flags, so it would be wrong to assume that
  11 dnl # the APIs are mutually exclusive contrary to the typical case.
  12 AC_DEFUN([ZFS_AC_KERNEL_BIO_RW_BARRIER], [
  13         AC_MSG_CHECKING([whether BIO_RW_BARRIER is defined])
  14         ZFS_LINUX_TRY_COMPILE([
  15                 #include <linux/bio.h>
  16         ],[
  17                 int flags __attribute__ ((unused));
  18                 flags = BIO_RW_BARRIER;
  19         ],[
  20                 AC_MSG_RESULT(yes)
  21                 AC_DEFINE(HAVE_BIO_RW_BARRIER, 1, [BIO_RW_BARRIER is defined])
  22         ],[
  23                 AC_MSG_RESULT(no)
  24         ])
  25 ])