Re: drivers/md/dm.c:1324:9: sparse: sparse: cast from restricted blk_opf_t

[John Garry <john.g.garry@oracle.com>]

On 18/03/2026 14:12, Mikulas Patocka wrote:
> Hi
> 
> Could you please describe what's wrong here?
> 
> If I grep the kernel for 'bi_opf.*REQ_ATOMIC', there are 14 places where
> bi_opf is tested or manipulated with the REQ_ATOMIC flag.
> 
> What should I use instead of 'bio->bi_opf & REQ_ATOMIC'?

If you can recreate, could you please try the following:

BUG_ON(!!(bio->bi_opf & REQ_ATOMIC))

Maybe it's upset with being passed a blk_opt_t to BUG_ON()

Thanks!

> 
> Mikulas
> 
> 
> 
> On Wed, 18 Mar 2026, kernel test robot wrote:
> 
>> tree:   https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git__;!!ACWV5N9M2RV99hQ!OmRe9qEu3kUbFAxqlOLx9d_2e3W5yQy0bEmI1otyyZgomwTxboZhSPfIfq8xAdHD31rRUtdcL9O71Ff6tw8E$  master
>> head:   a989fde763f4f24209e4702f50a45be572340e68
>> commit: de67c139b3846ece6b8bbb62abf1f010ae85c083 dm: test for REQ_ATOMIC in dm_accept_partial_bio()
>> date:   3 months ago
>> config: mips-randconfig-r113-20260318 (https://urldefense.com/v3/__https://download.01.org/0day-ci/archive/20260318/202603181439.atBWgPQu-lkp@intel.com/config__;!!ACWV5N9M2RV99hQ!OmRe9qEu3kUbFAxqlOLx9d_2e3W5yQy0bEmI1otyyZgomwTxboZhSPfIfq8xAdHD31rRUtdcL9O71Jp0TXRZ$ )
>> compiler: mips-linux-gcc (GCC) 8.5.0
>> sparse: v0.6.5-rc1
>> reproduce (this is a W=1 build): (https://urldefense.com/v3/__https://download.01.org/0day-ci/archive/20260318/202603181439.atBWgPQu-lkp@intel.com/reproduce__;!!ACWV5N9M2RV99hQ!OmRe9qEu3kUbFAxqlOLx9d_2e3W5yQy0bEmI1otyyZgomwTxboZhSPfIfq8xAdHD31rRUtdcL9O71Hod7K3l$ )
>>
>> 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://urldefense.com/v3/__https://lore.kernel.org/oe-kbuild-all/202603181439.atBWgPQu-lkp@intel.com/__;!!ACWV5N9M2RV99hQ!OmRe9qEu3kUbFAxqlOLx9d_2e3W5yQy0bEmI1otyyZgomwTxboZhSPfIfq8xAdHD31rRUtdcL9O71LBaMQ9b$
>>
>> sparse warnings: (new ones prefixed by >>)
>>>> drivers/md/dm.c:1324:9: sparse: sparse: cast from restricted blk_opf_t
>>     drivers/md/dm.c:689:16: sparse: sparse: context imbalance in 'dm_get_live_table' - wrong count at exit
>>
>> vim +1324 drivers/md/dm.c
>>
>>    1283	
>>    1284	/*
>>    1285	 * A target may call dm_accept_partial_bio only from the map routine.  It is
>>    1286	 * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_* zone management
>>    1287	 * operations, zone append writes (native with REQ_OP_ZONE_APPEND or emulated
>>    1288	 * with write BIOs flagged with BIO_EMULATES_ZONE_APPEND) and any bio serviced
>>    1289	 * by __send_duplicate_bios().
>>    1290	 *
>>    1291	 * dm_accept_partial_bio informs the dm that the target only wants to process
>>    1292	 * additional n_sectors sectors of the bio and the rest of the data should be
>>    1293	 * sent in a next bio.
>>    1294	 *
>>    1295	 * A diagram that explains the arithmetics:
>>    1296	 * +--------------------+---------------+-------+
>>    1297	 * |         1          |       2       |   3   |
>>    1298	 * +--------------------+---------------+-------+
>>    1299	 *
>>    1300	 * <-------------- *tio->len_ptr --------------->
>>    1301	 *                      <----- bio_sectors ----->
>>    1302	 *                      <-- n_sectors -->
>>    1303	 *
>>    1304	 * Region 1 was already iterated over with bio_advance or similar function.
>>    1305	 *	(it may be empty if the target doesn't use bio_advance)
>>    1306	 * Region 2 is the remaining bio size that the target wants to process.
>>    1307	 *	(it may be empty if region 1 is non-empty, although there is no reason
>>    1308	 *	 to make it empty)
>>    1309	 * The target requires that region 3 is to be sent in the next bio.
>>    1310	 *
>>    1311	 * If the target wants to receive multiple copies of the bio (via num_*bios, etc),
>>    1312	 * the partially processed part (the sum of regions 1+2) must be the same for all
>>    1313	 * copies of the bio.
>>    1314	 */
>>    1315	void dm_accept_partial_bio(struct bio *bio, unsigned int n_sectors)
>>    1316	{
>>    1317		struct dm_target_io *tio = clone_to_tio(bio);
>>    1318		struct dm_io *io = tio->io;
>>    1319		unsigned int bio_sectors = bio_sectors(bio);
>>    1320	
>>    1321		BUG_ON(dm_tio_flagged(tio, DM_TIO_IS_DUPLICATE_BIO));
>>    1322		BUG_ON(bio_sectors > *tio->len_ptr);
>>    1323		BUG_ON(n_sectors > bio_sectors);
>>> 1324		BUG_ON(bio->bi_opf & REQ_ATOMIC);
>>    1325	
>>    1326		if (static_branch_unlikely(&zoned_enabled) &&
>>    1327		    unlikely(bdev_is_zoned(bio->bi_bdev))) {
>>    1328			enum req_op op = bio_op(bio);
>>    1329	
>>    1330			BUG_ON(op_is_zone_mgmt(op));
>>    1331			BUG_ON(op == REQ_OP_WRITE);
>>    1332			BUG_ON(op == REQ_OP_WRITE_ZEROES);
>>    1333			BUG_ON(op == REQ_OP_ZONE_APPEND);
>>    1334		}
>>    1335	
>>    1336		*tio->len_ptr -= bio_sectors - n_sectors;
>>    1337		bio->bi_iter.bi_size = n_sectors << SECTOR_SHIFT;
>>    1338	
>>    1339		/*
>>    1340		 * __split_and_process_bio() may have already saved mapped part
>>    1341		 * for accounting but it is being reduced so update accordingly.
>>    1342		 */
>>    1343		dm_io_set_flag(io, DM_IO_WAS_SPLIT);
>>    1344		io->sectors = n_sectors;
>>    1345		io->sector_offset = bio_sectors(io->orig_bio);
>>    1346	}
>>    1347	EXPORT_SYMBOL_GPL(dm_accept_partial_bio);
>>    1348	
>>
>> -- 
>> 0-DAY CI Kernel Test Service
>> https://urldefense.com/v3/__https://github.com/intel/lkp-tests/wiki__;!!ACWV5N9M2RV99hQ!OmRe9qEu3kUbFAxqlOLx9d_2e3W5yQy0bEmI1otyyZgomwTxboZhSPfIfq8xAdHD31rRUtdcL9O71IiRgk5v$
>>
>