Hi Miklos,

I love your patch! Yet something to improve:

[auto build test ERROR on miklos-vfs/overlayfs-next]
[also build test ERROR on kdave/for-next ceph-client/for-linus xiang-erofs/dev-test ext4/dev f2fs/dev-test fuse/for-next gfs2/for-next linus/master v5.14-rc5 next-20210810]
[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]

url:    https://github.com/0day-ci/linux/commits/Miklos-Szeredi/allow-overlayfs-to-do-RCU-lookups/20210810-200939
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next
config: hexagon-randconfig-r032-20210810 (attached as .config)
compiler: clang version 12.0.0
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://github.com/0day-ci/linux/commit/7303859328569bbf653d8350215cd37b79486626
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Miklos-Szeredi/allow-overlayfs-to-do-RCU-lookups/20210810-200939
        git checkout 7303859328569bbf653d8350215cd37b79486626
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=hexagon 

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

All error/warnings (new ones prefixed by >>):

>> fs/overlayfs/inode.c:460:10: error: implicit declaration of function 'get_cached_acl_rcu' [-Werror,-Wimplicit-function-declaration]
                   return get_cached_acl_rcu(realinode, type);
                          ^
>> fs/overlayfs/inode.c:460:10: warning: incompatible integer to pointer conversion returning 'int' from a function with result type 'struct posix_acl *' [-Wint-conversion]
                   return get_cached_acl_rcu(realinode, type);
                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   1 warning and 1 error generated.


vim +/get_cached_acl_rcu +460 fs/overlayfs/inode.c

   449	
   450	struct posix_acl *ovl_get_acl(struct inode *inode, int type, int flags)
   451	{
   452		struct inode *realinode = ovl_inode_real(inode);
   453		const struct cred *old_cred;
   454		struct posix_acl *acl;
   455	
   456		if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode))
   457			return NULL;
   458	
   459		if (flags & LOOKUP_RCU)
 > 460			return get_cached_acl_rcu(realinode, type);
   461	
   462		old_cred = ovl_override_creds(inode->i_sb);
   463		acl = get_acl(realinode, type);
   464		revert_creds(old_cred);
   465	
   466		return acl;
   467	}
   468	

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