Build error on Ubuntu 24.04 with Kernel 6.8.0-88

[JensErat]

We get build errors when building on Ubuntu 24.04 with Kernel 6.8.0-88.

I did not fully triage to the commit. Last known working is 6e8ccad, first known bad is bf5d41b.

+ export KERNELPATH=/usr/src/linux-headers-6.8.0-88-generic
+ KERNELPATH=/usr/src/linux-headers-6.8.0-88-generic
+ make
Kernel version 6.8 supports fastpath.
Kernel version 6.8 supports blkmq driver model.
make  -C /usr/src/linux-headers-6.8.0-88-generic  M=/builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse modules
make[1]: Entering directory '/usr/src/linux-headers-6.8.0-88-generic'
warning: the compiler differs from the one used to build the kernel
  The kernel was built by: x86_64-linux-gnu-gcc-13 (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
  You are using:           gcc-13 (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
Kernel version 6.8 supports fastpath.
Kernel version 6.8 supports blkmq driver model.
  CC [M]  /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/pxd.o
  CC [M]  /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/dev.o
  CC [M]  /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/iov_iter.o
  CC [M]  /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/px_version.o
  CC [M]  /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/kiolib.o
  CC [M]  /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/pxd_bio_blkmq.o
/builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/pxd_bio_blkmq.c: In function 'clone_root':
/builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/pxd_bio_blkmq.c:429:57: error: 'blkcg_root' undeclared (first use in this function)
  429 |                 bio_associate_blkg_from_css(clone_bio, &blkcg_root.css);
      |                                                         ^~~~~~~~~~
/builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/pxd_bio_blkmq.c:429:57: note: each undeclared identifier is reported only once for each function it appears in
make[3]: *** [scripts/Makefile.build:243: /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse/pxd_bio_blkmq.o] Error 1
make[2]: *** [/usr/src/linux-headers-6.8.0-88-generic/Makefile:1927: /builds/cit/t-caas/image-building/custom-patches/px-fuse/fuse/px-fuse] Error 2
make[1]: *** [Makefile:240: __sub-make] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-6.8.0-88-generic'
make: *** [Makefile:177: all] Error 2