Hi Christian, I love your patch! Perhaps something to improve: [auto build test WARNING on 456af438ad490bac7ed954cb929bcec1df7f0c82] url: https://github.com/0day-ci/linux/commits/Christian-Brauner/ksmbd-fix-look... base: 456af438ad490bac7ed954cb929bcec1df7f0c82 config: s390-allyesconfig (attached as .config) compiler: s390-linux-gcc (GCC) 11.2.0 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/ebbc41b9d3f7b7f6c558cb5d5f12ecb81... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Christian-Brauner/ksmbd-fix-lookup-on-idmapped-mounts/20210816-200054 git checkout ebbc41b9d3f7b7f6c558cb5d5f12ecb8134c9c2e # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=s390 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): fs/ksmbd/vfs.c: In function 'ksmbd_vfs_lock_parent': fs/ksmbd/vfs.c:79:18: error: implicit declaration of function 'lookup_one'; did you mean 'lookup_bdev'? [-Werror=implicit-function-declaration] 79 | dentry = lookup_one(user_ns, child->d_name.name, parent, | ^~~~~~~~~~ | lookup_bdev 79 | dentry = lookup_one(user_ns, child->d_name.name, parent, | ^ fs/ksmbd/vfs.c: In function 'ksmbd_vfs_mkdir': fs/ksmbd/vfs.c:223:19: warning: assignment to 'struct dentry *' from 'int' makes pointer from integer without a cast [-Wint-conversion] 223 | d = lookup_one(user_ns, dentry->d_name.name, dentry->d_parent, | ^ fs/ksmbd/vfs.c: In function '__ksmbd_vfs_rename': fs/ksmbd/vfs.c:753:18: warning: assignment to 'struct dentry *' from 'int' makes pointer from integer without a cast [-Wint-conversion] 753 | dst_dent = lookup_one(dst_user_ns, dst_name, dst_dent_parent, | ^ fs/ksmbd/vfs.c: In function 'ksmbd_vfs_fp_rename': fs/ksmbd/vfs.c:816:19: warning: assignment to 'struct dentry *' from 'int' makes pointer from integer without a cast [-Wint-conversion] 816 | src_child = lookup_one(user_ns, src_dent->d_name.name, src_dent_parent, | ^ cc1: some warnings being treated as errors -- fs/ksmbd/smb2pdu.c: In function 'process_query_dir_entries': fs/ksmbd/smb2pdu.c:3542:24: error: implicit declaration of function 'lookup_one'; did you mean 'lookup_bdev'? [-Werror=implicit-function-declaration] 3542 | dent = lookup_one(user_ns, priv->d_info->name, | ^~~~~~~~~~ | lookup_bdev 3542 | dent = lookup_one(user_ns, priv->d_info->name, | ^ cc1: some warnings being treated as errors vim +79 fs/ksmbd/vfs.c 62 63 /** 64 * ksmbd_vfs_lock_parent() - lock parent dentry if it is stable 65 * 66 * the parent dentry got by dget_parent or @parent could be 67 * unstable, we try to lock a parent inode and lookup the 68 * child dentry again. 69 * 70 * the reference count of @parent isn't incremented. 71 */ 72 int ksmbd_vfs_lock_parent(struct user_namespace *user_ns, struct dentry *parent, 73 struct dentry *child) 74 { 75 struct dentry *dentry; 76 int ret = 0; 77 78 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT); 80 child->d_name.len); 81 if (IS_ERR(dentry)) { 82 ret = PTR_ERR(dentry); 83 goto out_err; 84 } 85 86 if (dentry != child) { 87 ret = -ESTALE; 88 dput(dentry); 89 goto out_err; 90 } 91 92 dput(dentry); 93 return 0; 94 out_err: 95 inode_unlock(d_inode(parent)); 96 return ret; 97 } 98 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org