25 lines
844 B
Text
25 lines
844 B
Text
dnl #
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dnl # Interface for issuing a discard bio:
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dnl # 2.6.28-2.6.35: BIO_RW_BARRIER
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dnl # 2.6.36-3.x: REQ_BARRIER
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dnl #
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dnl # Since REQ_BARRIER is a preprocessor definition, there is no need for an
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dnl # autotools check for it. Also, REQ_BARRIER existed in the request layer
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dnl # until torvalds/linux@7b6d91daee5cac6402186ff224c3af39d79f4a0e unified the
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dnl # request layer and bio layer flags, so it would be wrong to assume that
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dnl # the APIs are mutually exclusive contrary to the typical case.
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AC_DEFUN([ZFS_AC_KERNEL_BIO_RW_BARRIER], [
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AC_MSG_CHECKING([whether BIO_RW_BARRIER is defined])
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ZFS_LINUX_TRY_COMPILE([
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#include <linux/bio.h>
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],[
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int flags __attribute__ ((unused));
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flags = BIO_RW_BARRIER;
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],[
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AC_MSG_RESULT(yes)
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AC_DEFINE(HAVE_BIO_RW_BARRIER, 1, [BIO_RW_BARRIER is defined])
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],[
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AC_MSG_RESULT(no)
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])
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])
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