mirror_zfs/config/kernel-clear-inode.m4
Brian Behlendorf ff3e2e3c70 Perform KABI checks in parallel
Reduce the time required for ./configure to perform the needed
KABI checks by allowing kbuild to compile multiple test cases in
parallel.  This was accomplished by splitting each test's source
code from the logic handling whether that code could be compiled
or not.

By introducing this split it's possible to minimize the number of
times kbuild needs to be invoked.  As importantly, it means all of
the tests can be built in parallel.  This does require a little extra
care since we expect some tests to fail, so the --keep-going (-k)
option must be provided otherwise some tests may not get compiled.
Furthermore, since a failure during the kbuild modpost phase will
result in an early exit; the final linking phase is limited to tests
which passed the initial compilation and produced an object file.

Once everything has been built the configure script proceeds as
previously.  The only significant difference is that it now merely
needs to test for the existence of a .ko file to determine the
result of a given test.  This vastly speeds up the entire process.

New test cases should use ZFS_LINUX_TEST_SRC to declare their test
source code and ZFS_LINUX_TEST_RESULT to check the result.  All of
the existing kernel-*.m4 files have been updated accordingly, see
config/kernel-current-time.m4 for a basic example.  The legacy
ZFS_LINUX_TRY_COMPILE macro has been kept to handle special cases
but it's use is not encouraged.

                  master (secs)   patched (secs)
                  -------------   ----------------
autogen.sh        61              68
configure         137             24  (~17% of current run time)
make -j $(nproc)  44              44
make rpms         287             150

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8547
Closes #9132
Closes #9341
Conflicts:
	Makefile.am
	config/kernel-fpu.m4
2020-01-22 13:49:01 -08:00

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dnl #
dnl # 3.5.0 API change
dnl # torvalds/linux@dbd5768f87ff6fb0a4fe09c4d7b6c4a24de99430 and
dnl # torvalds/linux@7994e6f7254354e03028a11f98a27bd67dace9f1 reworked
dnl # where inode_sync_wait() is called.
dnl #
dnl # Prior to these changes it would occur in end_writeback() but due
dnl # to various issues (described in the above commits) it has been
dnl # moved to evict(). This changes the ordering is which sync occurs
dnl # but otherwise doesn't impact the zpl implementation.
dnl #
dnl # The major impact here is the renaming of end_writeback() to
dnl # clear_inode(). However, care must be taken when detecting this
dnl # API change because as recently as 2.6.35 there was a clear_inode()
dnl # function. However, it was made obsolete by the evict_inode() API
dnl # change at the same time.
dnl #
dnl # Therefore, to ensure we have the correct API we only allow the
dnl # clear_inode() compatibility code to be defined iff the evict_inode()
dnl # functionality is also detected.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_CLEAR_INODE], [
ZFS_LINUX_TEST_SRC([clear_inode], [
#include <linux/fs.h>
], [
clear_inode(NULL);
])
])
AC_DEFUN([ZFS_AC_KERNEL_CLEAR_INODE], [
AC_MSG_CHECKING([whether clear_inode() is available])
ZFS_LINUX_TEST_RESULT_SYMBOL([clear_inode],
[clear_inode], [fs/inode.c], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_CLEAR_INODE, 1, [clear_inode() is available])
], [
AC_MSG_RESULT(no)
])
])