Hi Emanuele,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on char-misc/char-misc-testing]
[also build test ERROR on driver-core/driver-core-testing linus/master v5.7-rc1 next-20200414]
[cannot apply to security/next-testing]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Emanuele-Giuseppe-Esposito/Simplefs-group-and-simplify-linux-fs-code/20200415-030834
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git 885a64715fd81e6af6d94a038556e0b2e6deb19c
config: arm-mvebu_v7_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=9.3.0 make.cross ARCH=arm 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: fs/tracefs/inode.o: in function `remove_one':
>> inode.c:(.text+0x1c): undefined reference to `simple_release_fs'
   arm-linux-gnueabi-ld: fs/tracefs/inode.o: in function `start_creating.part.0':
   inode.c:(.text+0x454): undefined reference to `simple_release_fs'
   arm-linux-gnueabi-ld: fs/tracefs/inode.o: in function `__create_dir':
>> inode.c:(.text+0x55c): undefined reference to `simple_pin_fs'
>> arm-linux-gnueabi-ld: inode.c:(.text+0x640): undefined reference to `simple_release_fs'
   arm-linux-gnueabi-ld: fs/tracefs/inode.o: in function `tracefs_create_file':
   inode.c:(.text+0x690): undefined reference to `simple_pin_fs'
   arm-linux-gnueabi-ld: inode.c:(.text+0x75c): undefined reference to `simple_release_fs'
   arm-linux-gnueabi-ld: fs/tracefs/inode.o: in function `tracefs_remove':
   inode.c:(.text+0x79c): undefined reference to `simple_pin_fs'
   arm-linux-gnueabi-ld: inode.c:(.text+0x7c0): undefined reference to `simple_release_fs'

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org