Re: [PATCH RFC 2/2] erofs: add KUnit test for memory-backed compressed mount

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

Hi Alberto,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on 6b5a2b7d9bc156e505f09e698d85d6a1547c1206]

url:    https://github.com/intel-lab-lkp/linux/commits/Alberto-Ruiz-via-B4-Relay/erofs-add-memory-backed-mode-for-non-page-aligned-mount/20260622-162856
base:   6b5a2b7d9bc156e505f09e698d85d6a1547c1206
patch link:    https://lore.kernel.org/r/20260618-erofs-memback-v1-2-5aa7006a241a%40redhat.com
patch subject: [PATCH RFC 2/2] erofs: add KUnit test for memory-backed compressed mount
config: x86_64-rhel-9.4-ltp (https://download.01.org/0day-ci/archive/20260622/202606222038.4MTbEObD-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260622/202606222038.4MTbEObD-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/202606222038.4MTbEObD-lkp@intel.com/

All warnings (new ones prefixed by >>):

   fs/erofs/memback.c: In function 'erofs_memback_scan_folio':
>> fs/erofs/memback.c:80:61: warning: variable 'attached' set but not used [-Wunused-but-set-variable]
      80 |         unsigned int cur = 0, end = folio_size(folio), len, attached = 0;
         |                                                             ^~~~~~~~


vim +/attached +80 fs/erofs/memback.c

    74	
    75	static int erofs_memback_scan_folio(struct erofs_memback_io *io,
    76					    struct inode *inode, struct folio *folio)
    77	{
    78		struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
    79		struct erofs_map_blocks *map = &io->map;
  > 80		unsigned int cur = 0, end = folio_size(folio), len, attached = 0;
    81		loff_t pos = folio_pos(folio), ofs;
    82		int err = 0;
    83	
    84		erofs_onlinefolio_init(folio);
    85		while (cur < end) {
    86			if (!in_range(pos + cur, map->m_la, map->m_llen)) {
    87				map->m_la = pos + cur;
    88				map->m_llen = end - cur;
    89				err = erofs_map_blocks(inode, map);
    90				if (err)
    91					break;
    92			}
    93	
    94			ofs = pos + cur - map->m_la;
    95			len = min_t(loff_t, map->m_llen - ofs, end - cur);
    96			if (map->m_flags & EROFS_MAP_META) {
    97				struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
    98				void *src;
    99	
   100				src = erofs_read_metabuf(&buf, inode->i_sb,
   101							 map->m_pa + ofs,
   102							 erofs_inode_in_metabox(inode));
   103				if (IS_ERR(src)) {
   104					err = PTR_ERR(src);
   105					break;
   106				}
   107				memcpy_to_folio(folio, cur, src, len);
   108				erofs_put_metabuf(&buf);
   109			} else if (!(map->m_flags & EROFS_MAP_MAPPED)) {
   110				folio_zero_segment(folio, cur, cur + len);
   111				attached = 0;
   112			} else {
   113				loff_t pa = map->m_pa + ofs;
   114	
   115				if (pa + len > sbi->memback_size) {
   116					err = -EFSCORRUPTED;
   117					break;
   118				}
   119				memcpy_to_folio(folio, cur,
   120						(char *)sbi->memback_data + pa, len);
   121				attached = 1;
   122			}
   123			cur += len;
   124		}
   125		erofs_onlinefolio_end(folio, err, false);
   126		return err;
   127	}
   128	

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