Hi Theodore,

I love your patch! Perhaps something to improve:

[auto build test WARNING on ext4/dev]
[also build test WARNING on v4.20-rc3 next-20181119]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Theodore-Ts-o/ext4-add-ext4_sb_bread-to-disambiguate-ENOMEM-cases/20181120-070629
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: ia64-defconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 8.1.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=8.1.0 make.cross ARCH=ia64 

All warnings (new ones prefixed by >>):

   In file included from include/uapi/linux/posix_types.h:5,
                    from include/uapi/linux/types.h:14,
                    from include/linux/compiler.h:169,
                    from include/linux/init.h:5,
                    from fs//ext4/xattr.c:54:
   fs//ext4/xattr.c: In function 'ext4_xattr_block_list':

quoted

include/linux/stddef.h:8:14: warning: returning 'void *' from a function with return type 'int' makes integer from pointer without a cast [-Wint-conversion]

    #define NULL ((void *)0)
                 ^
   fs//ext4/xattr.c:699:10: note: in expansion of macro 'NULL'
      return NULL;
             ^~~~
--
   In file included from include/uapi/linux/posix_types.h:5,
                    from include/uapi/linux/types.h:14,
                    from include/linux/compiler.h:169,
                    from include/linux/init.h:5,
                    from fs/ext4/xattr.c:54:
   fs/ext4/xattr.c: In function 'ext4_xattr_block_list':

quoted

include/linux/stddef.h:8:14: warning: returning 'void *' from a function with return type 'int' makes integer from pointer without a cast [-Wint-conversion]

    #define NULL ((void *)0)
                 ^
   fs/ext4/xattr.c:699:10: note: in expansion of macro 'NULL'
      return NULL;
             ^~~~

vim +8 include/linux/stddef.h

^1da177e Linus Torvalds   2005-04-16  6  
^1da177e Linus Torvalds   2005-04-16  7  #undef NULL
^1da177e Linus Torvalds   2005-04-16 @8  #define NULL ((void *)0)
6e218287 Richard Knutsson 2006-09-30  9  

:::::: The code at line 8 was first introduced by commit
:::::: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Linux-2.6.12-rc2

:::::: TO: Linus Torvalds [off-list ref]
:::::: CC: Linus Torvalds [off-list ref]

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation