Re: [PATCH v3] Add ioctls to get/set the ext4 superblock uuid.

[kernel test robot <lkp@intel.com>]

Hi Jeremy,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tytso-ext4/dev]
[also build test WARNING on linus/master v5.19-rc7 next-20220718]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jeremy-Bongio/Add-ioctls-to-get-set-the-ext4-superblock-uuid/20220719-145724
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: i386-defconfig (https://download.01.org/0day-ci/archive/20220719/202207191835.R8aDmooK-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/d53b0a271606a7f5c7b0f1a1f3fec9a34e771205
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Jeremy-Bongio/Add-ioctls-to-get-set-the-ext4-superblock-uuid/20220719-145724
        git checkout d53b0a271606a7f5c7b0f1a1f3fec9a34e771205
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash fs/ext4/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   fs/ext4/ioctl.c: In function 'ext4_ioctl_getuuid':
>> fs/ext4/ioctl.c:1149:13: warning: unused variable 'ret' [-Wunused-variable]
    1149 |         int ret = 0;
         |             ^~~


vim +/ret +1149 fs/ext4/ioctl.c

  1145	
  1146	static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi,
  1147				struct fsuuid __user *ufsuuid)
  1148	{
> 1149		int ret = 0;
  1150		struct fsuuid fsuuid;
  1151		__u8 uuid[UUID_SIZE];
  1152	
  1153		if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid)))
  1154			return -EFAULT;
  1155	
  1156		if (fsuuid.fsu_len != UUID_SIZE || fsuuid.fsu_flags != 0)
  1157			return -EINVAL;
  1158	
  1159		lock_buffer(sbi->s_sbh);
  1160		memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE);
  1161		unlock_buffer(sbi->s_sbh);
  1162	
  1163		if (copy_to_user(&ufsuuid->fsu_uuid[0], uuid, UUID_SIZE))
  1164			return -EFAULT;
  1165		return 0;
  1166	}
  1167	

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