On Tue 22-11-16 04:17:11, Wu Fengguang wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
> head:   19b29dca7eef735531a2448e692bb1658c351887
> commit: 8b72e1435cd73926cba767fba3e957807a97069c [21/26] ext4: convert DAX faults to iomap infrastructure
> config: i386-randconfig-sb0-11212318 (attached as .config)
> compiler: gcc-5 (Debian 5.4.1-2) 5.4.1 20160904
> reproduce:
>         git checkout 8b72e1435cd73926cba767fba3e957807a97069c
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> All errors (new ones prefixed by >>):
> 
>    fs/built-in.o: In function `ext4_dax_fault':
> >> file.c:(.text+0x529f3): undefined reference to `dax_iomap_fault'
>    fs/built-in.o: In function `ext4_file_read_iter':
>    file.c:(.text+0x52bab): undefined reference to `dax_iomap_rw'
>    fs/built-in.o: In function `ext4_file_write_iter':
>    file.c:(.text+0x52dff): undefined reference to `dax_iomap_rw'
>    fs/built-in.o: In function `ext4_block_zero_page_range':
>    inode.c:(.text+0x57c8e): undefined reference to `iomap_zero_range'

Ah, I forgot to select FS_IOMAP when DAX was enabled and having ext2
enabled in my test builds has hidden this problem. Attached patch fixes the
build failure for me. Ted, please add this fix to your tree. Thanks!

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR