Re: [PATCH v3] xfstest: add detection for ext4.h presence in configure.ac

Darrick J. Wong
2024-01-09T17:04:28Z

On Tue, Jan 09, 2024 at 04:41:05PM +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. 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. Also include <linux/types.h> which gets __u64
> definition on systems where ext4.h is not present. 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:
> v2 -> v3
> Addressed below review comments from Darrick.
> Replaced the explicit AC_COMPILE_IFELSE block with a simplified
> check using AC_CHECK_HEADERS for <linux/ext4.h>.
> Added unconditional inclusion of <linux/types.h> regardless of
> the presence of <linux/ext4.h> in ext4_resize.c file.
>
> 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
>
> Link to v2:
> https://lore.kernel.org/fstests/20240103184208.80772-1-disgoel@linux.ibm.com/T/#u
>
> configure.ac | 4 ++++
> src/ext4_resize.c | 5 ++++-
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/configure.ac b/configure.ac
> index b22fc52b..8f9fb062 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -35,6 +35,10 @@ AC_CHECK_HEADERS([ assert.h \
> sys/mman.h \
> ])
>
> +AC_CHECK_HEADERS([linux/ext4.h], [
> +AC_DEFINE([HAVE_LINUX_EXT4_H], [1])
> +])

<cough> Quoting the autoconf documentation
https://www.gnu.org/software/autoconf/manual/autoconf-2.61/html_node/Generic-Headers.html

— Macro: AC_CHECK_HEADERS (header-file..., [action-if-found], [action-if-not-found], [includes = `default-includes'])

For each given system header file header-file in the blank-separated
argument list that exists, define HAVE_header-file (in all capitals)...

--D

> +
> 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..31779225 100644
> --- a/src/ext4_resize.c
> +++ b/src/ext4_resize.c
> @@ -13,8 +13,11 @@
> #include <string.h>
> #include <sys/ioctl.h>
> #include <sys/mount.h>
> +#include <linux/types.h>
>
> -typedef unsigned long long __u64;
> +#ifdef HAVE_LINUX_EXT4_H
> +#include <linux/ext4.h>
> +#endif
>
> #ifndef EXT4_IOC_RESIZE_FS
> #define EXT4_IOC_RESIZE_FS _IOW('f', 16, __u64)
> --
> 2.39.1
>
>