Re: [ext4:dev 21/26] file.c:undefined reference to `dax_iomap_fault'

[Dave Chinner <david@fromorbit.com>]

On Tue, Nov 22, 2016 at 01:08:05PM +0100, Jan Kara wrote:
> 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

> From 5954709eacfc3fd14b7109b01f5ee6e0a3f3874e Mon Sep 17 00:00:00 2001
> From: Jan Kara <jack@suse.cz>
> Date: Tue, 22 Nov 2016 12:51:36 +0100
> Subject: [PATCH] ext4: Add select for CONFIG_FS_IOMAP
> 
> When ext4 is compiled with DAX support, it now needs the iomap code. Add
> appropriate select to Kconfig.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/ext4/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
> index e38039fd96ff..7b90691e98c4 100644
> --- a/fs/ext4/Kconfig
> +++ b/fs/ext4/Kconfig
> @@ -37,6 +37,7 @@ config EXT4_FS
>  	select CRC16
>  	select CRYPTO
>  	select CRYPTO_CRC32C
> +	select FS_IOMAP if FS_DAX

Shouldn't the FS_DAX config select FS_IOMAP unconditionally because
it is now a hard config dependency in the DAX subsystem?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com