Re: [PATCH v4] xfstest: add detection for ext4.h presence in configure.ac

Darrick J. Wong
2024-03-01T18:06:32Z

On Fri, Mar 01, 2024 at 01:45:40PM +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
> checking linux/ext4.h usability... yes
> checking linux/ext4.h presence... yes
> checking for linux/ext4.h... yes
> [CC] detached_mounts_propagation
> [CC] ext4_resize
> [CC] t_readdir_3
>
> # make
> checking linux/ext4.h usability... no
> checking linux/ext4.h presence... no
> checking for linux/ext4.h... no
> [CC] detached_mounts_propagation
> [CC] ext4_resize
> [CC] t_snapshot_deleted_subvolume
>
> Signed-off-by: Disha Goel <disgoel@linux.ibm.com>

Looks great, thank you for getting this done!
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>
> Changelog:
> v3 -> v4
> Addressed review comment from Darrick by incorporating autoconf
> best practices by only using AC_CHECK_HEADERS which is by default
> going to define header file, to align with autoconf documentation.
>
> 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
>
> Link to v3:
> https://lore.kernel.org/fstests/20240109111105.28836-1-disgoel@linux.ibm.com/
>
> configure.ac | 1 +
> src/ext4_resize.c | 5 ++++-
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/configure.ac b/configure.ac
> index b22fc52b..f45bc68e 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -33,6 +33,7 @@ AC_CHECK_HEADERS([ assert.h \
> btrfs/ioctl.h \
> cifs/ioctl.h \
> sys/mman.h \
> + linux/ext4.h \
> ])
>
> AC_CHECK_HEADERS([xfs/xfs_log_format.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
>
>