Re: [RFC PATCH 7/8] iomap: Add bs<ps buffered atomic writes support

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

Hi Ojaswin,

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

[auto build test WARNING on brauner-vfs/vfs.all]
[also build test WARNING on next-20251112]
[cannot apply to xfs-linux/for-next tytso-ext4/dev trace/for-next linus/master v6.18-rc5]
[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/Ojaswin-Mujoo/fs-Rename-STATX-_ATTR-_WRITE_ATOMIC-STATX-_ATTR-_WRITE_ATOMIC_DIO/20251112-191001
base:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link:    https://lore.kernel.org/r/8a836debf47e9bcbf42aeaaa93fd67be18f1768a.1762945505.git.ojaswin%40linux.ibm.com
patch subject: [RFC PATCH 7/8] iomap: Add bs<ps buffered atomic writes support
config: i386-allnoconfig (https://download.01.org/0day-ci/archive/20251112/202511122005.2agCLN4v-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/20251112/202511122005.2agCLN4v-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/202511122005.2agCLN4v-lkp@intel.com/

All warnings (new ones prefixed by >>):

   fs/iomap/buffered-io.c: In function '__iomap_write_end':
>> fs/iomap/buffered-io.c:1106:23: warning: unused variable 'inode' [-Wunused-variable]
    1106 |         struct inode *inode = iter->inode;
         |                       ^~~~~


vim +/inode +1106 fs/iomap/buffered-io.c

  1102	
  1103	static bool __iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
  1104			size_t copied, struct folio *folio)
  1105	{
> 1106		struct inode *inode = iter->inode;
  1107	
  1108		flush_dcache_folio(folio);
  1109	
  1110		/*
  1111		 * The blocks that were entirely written will now be uptodate, so we
  1112		 * don't have to worry about a read_folio reading them and overwriting a
  1113		 * partial write.  However, if we've encountered a short write and only
  1114		 * partially written into a block, it will not be marked uptodate, so a
  1115		 * read_folio might come in and destroy our partial write.
  1116		 *
  1117		 * Do the simplest thing and just treat any short write to a
  1118		 * non-uptodate page as a zero-length write, and force the caller to
  1119		 * redo the whole thing.
  1120		 */
  1121		if (unlikely(copied < len && !folio_test_uptodate(folio)))
  1122			return false;
  1123		iomap_set_range_uptodate(folio, offset_in_folio(folio, pos), len);
  1124		iomap_set_range_dirty(folio, offset_in_folio(folio, pos), copied);
  1125		filemap_dirty_folio(iter->inode->i_mapping, folio);
  1126	
  1127		/*
  1128		 * Policy: non atomic write over a previously atomic range makes the
  1129		 * range non-atomic. Handle this here.
  1130		 */
  1131		if (iter->flags & IOMAP_ATOMIC) {
  1132			if (copied < len) {
  1133				/*
  1134				 * A short atomic write is only okay as long as nothing
  1135				 * is written at all. If we have a partial write, there
  1136				 * is a bug in our code.
  1137				 */
  1138				WARN_ON_ONCE(copied != 0);
  1139	
  1140				return false;
  1141			}
  1142			iomap_set_range_atomic(folio, offset_in_folio(folio, pos), len);
  1143		} else {
  1144			if (folio_test_atomic(folio))
  1145				iomap_clear_range_atomic(
  1146					folio, offset_in_folio(folio, pos), len);
  1147		}
  1148	
  1149		return true;
  1150	}
  1151	

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