Hi Nikolay,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on v5.7-rc1]
[also build test ERROR on next-20200416]
[cannot apply to btrfs/next]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Nikolay-Borisov/btrfs-Make-btrfs_read_disk_super-return-struct-btrfs_disk_super/20200416-230011
base:    8f3d9f354286745c751374f5f1fcafee6b3f3136
config: x86_64-randconfig-s1-20200416 (attached as .config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   fs/btrfs/volumes.c: In function 'btrfs_scan_one_device':
>> fs/btrfs/volumes.c:1341:10: error: assignment from incompatible pointer type [-Werror=incompatible-pointer-types]
      device = disk_super;
             ^
   cc1: some warnings being treated as errors

vim +1341 fs/btrfs/volumes.c

  1309	
  1310	/*
  1311	 * Look for a btrfs signature on a device. This may be called out of the mount path
  1312	 * and we are not allowed to call set_blocksize during the scan. The superblock
  1313	 * is read via pagecache
  1314	 */
  1315	struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags,
  1316						   void *holder)
  1317	{
  1318		struct btrfs_super_block *disk_super;
  1319		bool new_device_added = false;
  1320		struct btrfs_device *device = NULL;
  1321		struct block_device *bdev;
  1322		u64 bytenr;
  1323	
  1324		lockdep_assert_held(&uuid_mutex);
  1325	
  1326		/*
  1327		 * we would like to check all the supers, but that would make
  1328		 * a btrfs mount succeed after a mkfs from a different FS.
  1329		 * So, we need to add a special mount option to scan for
  1330		 * later supers, using BTRFS_SUPER_MIRROR_MAX instead
  1331		 */
  1332		bytenr = btrfs_sb_offset(0);
  1333		flags |= FMODE_EXCL;
  1334	
  1335		bdev = blkdev_get_by_path(path, flags, holder);
  1336		if (IS_ERR(bdev))
  1337			return ERR_CAST(bdev);
  1338	
  1339		disk_super = btrfs_read_disk_super(bdev, bytenr);
  1340		if (IS_ERR(disk_super)) {
> 1341			device = disk_super;
  1342			goto error_bdev_put;
  1343		}
  1344	
  1345		device = device_list_add(path, disk_super, &new_device_added);
  1346		if (!IS_ERR(device)) {
  1347			if (new_device_added)
  1348				btrfs_free_stale_devices(path, device);
  1349		}
  1350	
  1351		btrfs_release_disk_super(disk_super);
  1352	
  1353	error_bdev_put:
  1354		blkdev_put(bdev, flags);
  1355	
  1356		return device;
  1357	}
  1358	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org