[bcachefs:bcachefs-testing 143/145] fs/bcachefs/fs-ioctl.c:504:5: warning: ignoring return value of function declared with 'warn_unused_result' attribute

[bcachefs:bcachefs-testing 143/145] fs/bcachefs/fs-ioctl.c:504:5: warning: ignoring return value of function declared with 'warn_unused_result' attribute

[kernel test robot]

tree:   https://evilpiepirate.org/git/bcachefs.git bcachefs-testing
head:   964337312db426db662cde052d6a56c96657f7fb
commit: 57c6ac42e14b4593a73133062c2d7b63a0d6d776 [143/145] bcachefs: new subvol ioctls
config: s390-defconfig (https://download.01.org/0day-ci/archive/20240311/202403112348.VdoxraGn-lkp@intel.com/config)
compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project 503c55e17037436dcd45ac69dea8967e67e3f5e8)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240311/202403112348.VdoxraGn-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202403112348.VdoxraGn-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from fs/bcachefs/fs-ioctl.c:4:
   In file included from fs/bcachefs/bcachefs.h:188:
   In file included from include/linux/bio.h:10:
   In file included from include/linux/blk_types.h:10:
   In file included from include/linux/bvec.h:10:
   In file included from include/linux/highmem.h:10:
   In file included from include/linux/mm.h:2188:
   include/linux/vmstat.h:508:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
     508 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~ ^
     509 |                            item];
         |                            ~~~~
   include/linux/vmstat.h:515:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
     515 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~ ^
     516 |                            NR_VM_NUMA_EVENT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~~
   include/linux/vmstat.h:522:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     522 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
   include/linux/vmstat.h:527:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
     527 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~ ^
     528 |                            NR_VM_NUMA_EVENT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~~
   include/linux/vmstat.h:536:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
     536 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~ ^
     537 |                            NR_VM_NUMA_EVENT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~~
>> fs/bcachefs/fs-ioctl.c:504:5: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
     504 |                   copy_to_user_errcode(&user_arg->buf, path.data, path.nr);
         |                   ^~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   6 warnings generated.


vim +/warn_unused_result +504 fs/bcachefs/fs-ioctl.c

   492	
   493	static long bch2_ioctl_subvolume_path(struct bch_fs *c, struct file *file,
   494					      struct bch_ioctl_subvolume_path __user *user_arg)
   495	{
   496		struct bch_ioctl_subvolume_path arg;
   497		darray_char path = {};
   498	
   499		int ret = copy_from_user_errcode(&arg, user_arg, sizeof(arg)) ?:
   500			  bch2_subvol_to_path_checked(c, file->f_path.mnt, arg.subvolid, &path);
   501			  (path.nr > arg.buflen ? -ERANGE : 0) ?:
   502			  (arg.buflen = path.nr, 0) ?:
   503			  copy_to_user_errcode(user_arg, &arg, sizeof(arg)) ?:
 > 504			  copy_to_user_errcode(&user_arg->buf, path.data, path.nr);
   505	
   506		darray_exit(&path);
   507		return ret;
   508	}
   509	

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