Re: [PATCH 1/4] fs: add blockdev parser for filesystem mount option.

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

Hi Hongbo,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tytso-ext4/dev]
[also build test WARNING on brauner-vfs/vfs.all linus/master v6.10-rc1 next-20240523]
[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/Hongbo-Li/fs-add-blockdev-parser-for-filesystem-mount-option/20240527-094930
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
patch link:    https://lore.kernel.org/r/20240527014717.690140-2-lihongbo22%40huawei.com
patch subject: [PATCH 1/4] fs: add blockdev parser for filesystem mount option.
config: x86_64-allnoconfig (https://download.01.org/0day-ci/archive/20240527/202405271100.aGNNnrKK-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240527/202405271100.aGNNnrKK-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/202405271100.aGNNnrKK-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> fs/fs_parser.c:324:8: warning: variable 'f' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     324 |                         if (p->flags & fs_param_can_be_empty)
         |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   fs/fs_parser.c:343:29: note: uninitialized use occurs here
     343 |         ret = filename_lookup(dfd, f, LOOKUP_FOLLOW, &path, NULL);
         |                                    ^
   fs/fs_parser.c:324:4: note: remove the 'if' if its condition is always true
     324 |                         if (p->flags & fs_param_can_be_empty)
         |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     325 |                                 return 0;
   fs/fs_parser.c:316:20: note: initialize the variable 'f' to silence this warning
     316 |         struct filename *f;
         |                           ^
         |                            = NULL
>> fs/fs_parser.c:324:8: warning: variable 'put_f' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     324 |                         if (p->flags & fs_param_can_be_empty)
         |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   fs/fs_parser.c:360:6: note: uninitialized use occurs here
     360 |         if (put_f)
         |             ^~~~~
   fs/fs_parser.c:324:4: note: remove the 'if' if its condition is always true
     324 |                         if (p->flags & fs_param_can_be_empty)
         |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     325 |                                 return 0;
   fs/fs_parser.c:319:12: note: initialize the variable 'put_f' to silence this warning
     319 |         bool put_f;
         |                   ^
         |                    = 0
>> fs/fs_parser.c:324:8: warning: variable 'dfd' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     324 |                         if (p->flags & fs_param_can_be_empty)
         |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   fs/fs_parser.c:343:24: note: uninitialized use occurs here
     343 |         ret = filename_lookup(dfd, f, LOOKUP_FOLLOW, &path, NULL);
         |                               ^~~
   fs/fs_parser.c:324:4: note: remove the 'if' if its condition is always true
     324 |                         if (p->flags & fs_param_can_be_empty)
         |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     325 |                                 return 0;
   fs/fs_parser.c:315:9: note: initialize the variable 'dfd' to silence this warning
     315 |         int dfd;
         |                ^
         |                 = 0
   3 warnings generated.


vim +324 fs/fs_parser.c

   310	
   311	int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,
   312			  struct fs_parameter *param, struct fs_parse_result *result)
   313	{
   314		int ret;
   315		int dfd;
   316		struct filename *f;
   317		struct inode *dev_inode;
   318		struct path path;
   319		bool put_f;
   320	
   321		switch (param->type) {
   322		case fs_value_is_string:
   323			if (!*param->string) {
 > 324				if (p->flags & fs_param_can_be_empty)
   325					return 0;
   326				break;
   327			}
   328			f = getname_kernel(param->string);
   329			if (IS_ERR(f))
   330				return fs_param_bad_value(log, param);
   331			dfd = AT_FDCWD;
   332			put_f = true;
   333			break;
   334		case fs_value_is_filename:
   335			f = param->name;
   336			dfd = param->dirfd;
   337			put_f = false;
   338			break;
   339		default:
   340			return fs_param_bad_value(log, param);
   341		}
   342	
   343		ret = filename_lookup(dfd, f, LOOKUP_FOLLOW, &path, NULL);
   344		if (ret < 0) {
   345			error_plog(log, "%s: Lookup failure for '%s'", param->key, f->name);
   346			goto out_putname;
   347		}
   348	
   349		dev_inode = d_backing_inode(path.dentry);
   350		if (!S_ISBLK(dev_inode->i_mode)) {
   351			error_plog(log, "%s: Non-blockdev passed as '%s'", param->key, f->name);
   352			ret = -1;
   353			goto out_putpath;
   354		}
   355		result->uint_32 = new_encode_dev(dev_inode->i_rdev);
   356	
   357	out_putpath:
   358		path_put(&path);
   359	out_putname:
   360		if (put_f)
   361			putname(f);
   362	
   363		return (ret < 0) ? fs_param_bad_value(log, param) : 0;
   364	}
   365	EXPORT_SYMBOL(fs_param_is_blockdev);
   366	

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