Re: [PATCH v2] xfstest: add detection for ext4.h presence in configure.ac

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Jan 04, 2024 at 12:12:08AM +0530, Disha Goel wrote:
> In some distributions, __u64 is already defined in system header files,
> causing compilation errors when building xfstest.
> 
>         # make
>             [CC]    ext4_resize
>         ext4_resize.c:17:28: error: conflicting types for '__u64'
>          typedef unsigned long long __u64;
>                                     ^~~~~
>         In file included from /usr/include/asm/types.h:26:0,
>                          from /usr/include/linux/types.h:5,
>                          from /usr/include/linux/mount.h:4,
>                          from /usr/include/sys/mount.h:32,
>                          from ext4_resize.c:15:
>         /usr/include/asm-generic/int-l64.h:30:23: note: previous declaration of '__u64' was here
>          typedef unsigned long __u64;
>                        ^~~~~
> 
> To address this issue, configure.ac now checks for the presence
> and compilability of <linux/ext4.h>. If found and compilable, the
> macro HAVE_LINUX_EXT4_H is defined. If not, a warning message
> is displayed. The commit also updates src/ext4_resize.c to
> conditionally include <linux/ext4.h> based on the presence of
> the header, ensuring compatibility with systems where ext4.h
> is either present or not. This change enhances the configure
> process and improves code consistency.
> 
> The changes were tested on various distributions on Power
> architecture, by successfully compiling xfstest. Additionally,
> verified the compatibility by running ext4/033 and ext4/056
> tests, both of which use ext4_resize and observed successful
> test execution.
> 
>         # make
>             [CC]    detached_mounts_propagation
>             [CC]    ext4_resize
>             [CC]    t_readdir_3
> 
> Signed-off-by: Disha Goel <disgoel@linux.ibm.com>
> ---
> 
> Changelog:
> v1 -> v2
> Drop usage of uint64_t to match the definition in the kernel uapi
> headers. Use <linux/ext4.h> or <linux/types.h> based on the
> presence of the header to get the __u64 definition as suggested
> by Darrick.
> 
> Link to v1:
> https://lore.kernel.org/fstests/20231221061231.44347-1-disgoel@linux.ibm.com/T/#u
> 
>  configure.ac      | 8 ++++++++
>  src/ext4_resize.c | 6 +++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/configure.ac b/configure.ac
> index b22fc52b..76378e6d 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -35,6 +35,14 @@ AC_CHECK_HEADERS([	assert.h		\
>  			sys/mman.h		\
>  ])
>  
> +AC_COMPILE_IFELSE([
> +    AC_LANG_PROGRAM([#include <linux/ext4.h>], [])
> +], [
> +    AC_DEFINE([HAVE_LINUX_EXT4_H], [1], [Define if ext4.h is present])
> +], [
> +    AC_MSG_WARN([ext4.h not found or not compilable.])
> +])

AC_CHECK_HEADERS does this.

> +
>  AC_CHECK_HEADERS([xfs/xfs_log_format.h],,,[
>  #define _GNU_SOURCE
>  #include <xfs/libxfs.h>])
> diff --git a/src/ext4_resize.c b/src/ext4_resize.c
> index 78b66432..51bd8d78 100644
> --- a/src/ext4_resize.c
> +++ b/src/ext4_resize.c
> @@ -14,7 +14,11 @@
>  #include <sys/ioctl.h>
>  #include <sys/mount.h>
>  
> -typedef unsigned long long __u64;
> +#ifdef HAVE_LINUX_EXT4_H
> +#include <linux/ext4.h>
> +#else
> +#include <linux/types.h>

You might as well include this unconditionally; there's no penalty
for including it multiple times.

--D

> +#endif
>  
>  #ifndef EXT4_IOC_RESIZE_FS
>  #define EXT4_IOC_RESIZE_FS		_IOW('f', 16, __u64)
> -- 
> 2.39.1
>