zfs 0.7.12 dkms build failure against fedora 29 kernel-4.20.6

[glbyers]

System information

Type | Version/Name
--- | ---
Distribution Name | Fedora
Distribution Version | 29
Linux Kernel | 4.20.6-200.fc29.x86_64
Architecture | x86_64
ZFS Version | 0.7.12-1
SPL Version | 0.7.12-1

Describe the problem you're observing

Unable to build zfs module via dkms with 4.20.6-200.fc29.x86_64 from fedora official updates-testing repository (this particular version is required because recent stable kernel packages have a serious regression that prevents some machines from booting). The dkms build log doesn't give much to go on. Note that spl/0.7.12 and other dkms modules (nvidia) are building fine.

Describe how to reproduce the problem

dkms build zfs/0.7.12

Include any warning/errors/backtraces from the system logs

  CC [M]  /var/lib/dkms/zfs/0.7.12/build/module/zfs/vdev_raidz_math_avx512bw.o
  LD [M]  /var/lib/dkms/zfs/0.7.12/build/module/zfs/zfs.o
make[3]: *** [Makefile:1566: _module_/var/lib/dkms/zfs/0.7.12/build/module] Error 2
make[3]: Leaving directory '/usr/src/kernels/4.20.6-200.fc29.x86_64'
make[2]: *** [Makefile:27: modules] Error 2
make[2]: Leaving directory '/var/lib/dkms/zfs/0.7.12/build/module'
make[1]: *** [Makefile:739: all-recursive] Error 1
make[1]: Leaving directory '/var/lib/dkms/zfs/0.7.12/build'
make: *** [Makefile:608: all] Error 2

[glbyers]

OK. I've set `MAKE[0]="make -j1" which yields the following;

  CC [M]  /var/lib/dkms/zfs/0.7.12/build/module/zpios/pios.o
In file included from /var/lib/dkms/zfs/0.7.12/build/include/zpios-internal.h:39,
                 from /var/lib/dkms/zfs/0.7.12/build/module/zpios/pios.c:42:
/var/lib/dkms/zfs/0.7.12/build/include/zpios-ctl.h: In function ‘zpios_timespec_now’:
/var/lib/dkms/zfs/0.7.12/build/include/zpios-ctl.h:186:11: error: implicit declaration of function ‘current_kernel_time’; did you mean ‘current_kernel_time64’? [-Werror=implicit-function-declaration]
  ts_now = current_kernel_time();
           ^~~~~~~~~~~~~~~~~~~
           current_kernel_time64
/var/lib/dkms/zfs/0.7.12/build/include/zpios-ctl.h:186:9: error: incompatible types when assigning to type ‘struct timespec’ from type ‘int’
  ts_now = current_kernel_time();
         ^
cc1: some warnings being treated as errors
make[5]: *** [scripts/Makefile.build:292: /var/lib/dkms/zfs/0.7.12/build/module/zpios/pios.o] Error 1
make[4]: *** [scripts/Makefile.build:516: /var/lib/dkms/zfs/0.7.12/build/module/zpios] Error 2

[glbyers]

Closing this one. Have found other bug reports to say this is wip for 0.7.13. Applying the following patch - https://github.com/zfsonlinux/zfs/commit/4f981f6ab614a908f912f7dc147b248f96b498a2.patch