Re: [btrfs:ci-kvm-misc-next 143/160] fs/btrfs/ioctl.c:4179:6: warning: unused variable 'ret'

[David Sterba <dsterba@suse.cz>]

On Thu, Apr 16, 2026 at 09:27:45PM +0200, kernel test robot wrote:
> tree:   https://github.com/btrfs/linux.git ci-kvm-misc-next
> head:   8e37b8ffd9d4e4c1e43f45dd91f5c53e19520811
> commit: ef0c33ef0f4020b31bca106645340968f1a497bb [143/160] btrfs: convert ioctl handlers to AUTO_KFREE
> config: x86_64-kexec (https://download.01.org/0day-ci/archive/20260416/202604162130.a7ymx66r-lkp@intel.com/config)
> compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260416/202604162130.a7ymx66r-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/202604162130.a7ymx66r-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> fs/btrfs/ioctl.c:4179:6: warning: unused variable 'ret' [-Wunused-variable]
>     4179 |         int ret;
>          |             ^~~
>    1 warning generated.
> 
> 
> vim +/ret +4179 fs/btrfs/ioctl.c
> 
> 2eaa055fab4e31 Jeff Mahoney   2013-11-15  4175  
> 4e043cd196c85b David Sterba   2025-03-03  4176  static int _btrfs_ioctl_send(struct btrfs_root *root, void __user *argp, bool compat)
> 2351f431f72722 Josef Bacik    2017-09-27  4177  {
> ef0c33ef0f4020 David Sterba   2026-04-14  4178  	struct btrfs_ioctl_send_args AUTO_KFREE(arg);
> 2351f431f72722 Josef Bacik    2017-09-27 @4179  	int ret;
> 2351f431f72722 Josef Bacik    2017-09-27  4180  
> 2351f431f72722 Josef Bacik    2017-09-27  4181  	if (compat) {
> 2351f431f72722 Josef Bacik    2017-09-27  4182  #if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)

CONFIG_COMPAT is not defined so 'ret' is indeed not used.

> 9147b9ded499d9 Josef Bacik    2023-09-26  4183  		struct btrfs_ioctl_send_args_32 args32 = { 0 };
> 2351f431f72722 Josef Bacik    2017-09-27  4184  
> 2351f431f72722 Josef Bacik    2017-09-27  4185  		ret = copy_from_user(&args32, argp, sizeof(args32));
> 2351f431f72722 Josef Bacik    2017-09-27  4186  		if (ret)
> 2351f431f72722 Josef Bacik    2017-09-27  4187  			return -EFAULT;
> bf4afc53b77aea Linus Torvalds 2026-02-21  4188  		arg = kzalloc_obj(*arg);
> 2351f431f72722 Josef Bacik    2017-09-27  4189  		if (!arg)
> 2351f431f72722 Josef Bacik    2017-09-27  4190  			return -ENOMEM;
> 2351f431f72722 Josef Bacik    2017-09-27  4191  		arg->send_fd = args32.send_fd;
> 2351f431f72722 Josef Bacik    2017-09-27  4192  		arg->clone_sources_count = args32.clone_sources_count;
> 2351f431f72722 Josef Bacik    2017-09-27  4193  		arg->clone_sources = compat_ptr(args32.clone_sources);
> 2351f431f72722 Josef Bacik    2017-09-27  4194  		arg->parent_root = args32.parent_root;
> 2351f431f72722 Josef Bacik    2017-09-27  4195  		arg->flags = args32.flags;
> 5de0434bc06460 David Sterba   2023-11-14  4196  		arg->version = args32.version;
> 2351f431f72722 Josef Bacik    2017-09-27  4197  		memcpy(arg->reserved, args32.reserved,
> 2351f431f72722 Josef Bacik    2017-09-27  4198  		       sizeof(args32.reserved));
> 2351f431f72722 Josef Bacik    2017-09-27  4199  #else
> 2351f431f72722 Josef Bacik    2017-09-27  4200  		return -ENOTTY;
> 2351f431f72722 Josef Bacik    2017-09-27  4201  #endif
> 2351f431f72722 Josef Bacik    2017-09-27  4202  	} else {
> 2351f431f72722 Josef Bacik    2017-09-27  4203  		arg = memdup_user(argp, sizeof(*arg));
> 2351f431f72722 Josef Bacik    2017-09-27  4204  		if (IS_ERR(arg))
> 2351f431f72722 Josef Bacik    2017-09-27  4205  			return PTR_ERR(arg);
> 2351f431f72722 Josef Bacik    2017-09-27  4206  	}
> ef0c33ef0f4020 David Sterba   2026-04-14  4207  	return btrfs_ioctl_send(root, arg);
> 2351f431f72722 Josef Bacik    2017-09-27  4208  }
> 2351f431f72722 Josef Bacik    2017-09-27  4209  
> 
> :::::: The code at line 4179 was first introduced by commit
> :::::: 2351f431f727223b4d82851ee8fc045bf51edd34 btrfs: fix send ioctl on 32bit with 64bit kernel
> 
> :::::: TO: Josef Bacik <josef@toxicpanda.com>
> :::::: CC: David Sterba <dsterba@suse.com>
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki