[dhowells-fs:fscache-rewrite-indexing 75/75] fs/cachefiles/io.c:477:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git fscache-rewrite-indexing
head:   96d4e1af98c26988d3c1b3cf688974c24de90fa9
commit: 96d4e1af98c26988d3c1b3cf688974c24de90fa9 [75/75] cachefiles: Add error injection support
config: hexagon-randconfig-r041-20211014 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 6c76d0101193aa4eb891a6954ff047eda2f9cf71)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?id=96d4e1af98c26988d3c1b3cf688974c24de90fa9
        git remote add dhowells-fs https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
        git fetch --no-tags dhowells-fs fscache-rewrite-indexing
        git checkout 96d4e1af98c26988d3c1b3cf688974c24de90fa9
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=hexagon 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> fs/cachefiles/io.c:477:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (pos == 0)
               ^~~~~~~~
   fs/cachefiles/io.c:480:6: note: uninitialized use occurs here
           if (ret < 0) {
               ^~~
   fs/cachefiles/io.c:477:2: note: remove the 'if' if its condition is always true
           if (pos == 0)
           ^~~~~~~~~~~~~
   fs/cachefiles/io.c:422:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   1 warning generated.


vim +477 fs/cachefiles/io.c

   409	
   410	/*
   411	 * Prepare for a write to occur.
   412	 */
   413	static int __cachefiles_prepare_write(struct netfs_cache_resources *cres,
   414					      loff_t *_start, size_t *_len, loff_t i_size,
   415					      bool no_space_allocated_yet)
   416	{
   417		struct cachefiles_object *object = cachefiles_cres_object(cres);
   418		struct cachefiles_cache *cache = object->volume->cache;
   419		struct file *file = cachefiles_cres_file(cres);
   420		loff_t start = *_start, pos;
   421		size_t len = *_len, down;
   422		int ret;
   423	
   424		if (!file) {
   425			if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE))
   426				return -ENOBUFS;
   427			file = cachefiles_cres_file(cres);
   428			if (!file)
   429				return -ENOBUFS;
   430		}
   431	
   432		/* Round to DIO size */
   433		down = start - round_down(start, PAGE_SIZE);
   434		*_start = start - down;
   435		*_len = round_up(down + len, PAGE_SIZE);
   436	
   437		/* We need to work out whether there's sufficient disk space to perform
   438		 * the write - but we can skip that check if we have space already
   439		 * allocated.
   440		 */
   441		if (no_space_allocated_yet)
   442			goto check_space;
   443	
   444		pos = cachefiles_inject_read_error();
   445		if (pos == 0)
   446			pos = vfs_llseek(file, *_start, SEEK_DATA);
   447		if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
   448			if (pos == -ENXIO)
   449				goto check_space; /* Unallocated tail */
   450			trace_cachefiles_io_error(object, file_inode(file), pos,
   451						  cachefiles_trace_seek_error);
   452			return pos;
   453		}
   454		if ((u64)pos >= (u64)*_start + *_len)
   455			goto check_space; /* Unallocated region */
   456	
   457		/* We have a block that's at least partially filled - if we're low on
   458		 * space, we need to see if it's fully allocated.  If it's not, we may
   459		 * want to cull it.
   460		 */
   461		if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE) == 0)
   462			return 0; /* Enough space to simply overwrite the whole block */
   463	
   464		pos = cachefiles_inject_read_error();
   465		if (pos == 0)
   466			pos = vfs_llseek(file, *_start, SEEK_HOLE);
   467		if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
   468			trace_cachefiles_io_error(object, file_inode(file), pos,
   469						  cachefiles_trace_seek_error);
   470			return pos;
   471		}
   472		if ((u64)pos >= (u64)*_start + *_len)
   473			return 0; /* Fully allocated */
   474	
   475		/* Partially allocated, but insufficient space: cull. */
   476		pos = cachefiles_inject_remove_error();
 > 477		if (pos == 0)
   478			ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
   479					    *_start, *_len);
   480		if (ret < 0) {
   481			trace_cachefiles_io_error(object, file_inode(file), ret,
   482						  cachefiles_trace_fallocate_error);
   483			cachefiles_io_error_obj(object,
   484						"CacheFiles: fallocate failed (%d)\n", ret);
   485			ret = -EIO;
   486		}
   487	
   488		return ret;
   489	
   490	check_space:
   491		return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE);
   492	}
   493	

---
0-DAY CI Kernel Test Service, Intel Corporation
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