Re: [PATCH v2] src: fix detached_mounts_propagation compile errors

[Ziyang Zhang <ZiyangZhang@linux.alibaba.com>]

On 2023/4/25 09:28, Yang Xu (Fujitsu) wrote:
> 

[...]

>>
>> Looks like not help [1]. The src/feature.c through global.h -> xfs/xfs.h
>> -> xfs/linux.h -> linux/fs.h to include linux/mount.h, then it include
>> "vfs/missing.h" manually. As you add "<sys/mount.h>" to vfs/missing.h,
>> so there's a conflict.
> 
> Yes, here is a complex problem than ltp because global.h includes 
> <linux/mount.h>. We don't include <sys/mount.h> or <linux/mount.h> 
> together on older glibc(glibc 2.36.6).  Newer glibc(glibc-2.37-1)[1] 
> seems has sloved this problem.
> 
> [1]https://sourceware.org/git/?p=glibc.git;a=commit;h=774058d72942249f71d74e7f2b639f77184160a6
> 
> I guess we can not use <sys/mount.h> header,
> then compile info as below:
> detached_mounts_propagation.c: In function 'main':
> detached_mounts_propagation.c:129:15: warning: implicit declaration of 
> function 'mount' [-Wimplicit-function-declaration]
>    129 |         ret = mount(NULL, base_dir, NULL, MS_REC | MS_SHARED, 
> NULL);
>        |               ^~~~~
> detached_mounts_propagation.c:176:23: warning: implicit declaration of 
> function 'umount2'; did you mean 'sys_umount2'? 
> [-Wimplicit-function-declaration]
>    176 |                 ret = umount2(target, MNT_DETACH);
>        |                       ^~~~~~~
>        |                       sys_umount2
> 
> 
> then we can use syscall wrapper directly instead of glibc wrapper
> --- a/src/detached_mounts_propagation.c
> +++ b/src/detached_mounts_propagation.c
> @@ -20,7 +20,6 @@
>   #include <stdio.h>
>   #include <stdlib.h>
>   #include <string.h>
> -#include <sys/mount.h>
>   #include <sys/stat.h>
>   #include <sys/syscall.h>
>   #include <sys/types.h>
> @@ -127,7 +126,7 @@ int main(int argc, char *argv[])
>          if (ret < 0)
>                  exit_log("%m - Failed to create new mount namespace");
> 
> -       ret = mount(NULL, base_dir, NULL, MS_REC | MS_SHARED, NULL);
> +       ret = sys_mount(NULL, base_dir, NULL, MS_REC | MS_SHARED, NULL);
>          if (ret < 0)
>                  exit_log("%m - Failed to make base_dir shared mountpoint");
> 
> @@ -174,7 +173,7 @@ int main(int argc, char *argv[])
>                  }
>                  close(fd_tree);
> 
> -               ret = umount2(target, MNT_DETACH);
> +               ret = sys_umount2(target, MNT_DETACH);
>                  if (ret < 0) {
>                          fprintf(stderr, "%m - Failed to unmount %s", 
> target);
>                          exit_code = EXIT_FAILURE;
> 
> 
> Best Regards
> Yang Xu
> 

Hi Yang,

You patch works for me(kernel: 5.10.134, glibc:2.36). I think we could just
modify detached_mounts_propagation.c to solve this problem.

Regards,
Zhang