回复: [PATCH] selftests/filesystems:fix build error in overlayfs

[Huyadi <hu.yadi@h3c.com>]

>On Fri, Jan 12, 2024 at 03:40:59PM +0800, Hu Yadi wrote:
>> One build issue comes up due to both mount.h included dev_in_maps.c
>> 
>> In file included from dev_in_maps.c:10:
>> /usr/include/sys/mount.h:35:3: error: expected identifier before numeric constant
>>    35 |   MS_RDONLY = 1,  /* Mount read-only.  */
>>       |   ^~~~~~~~~
>> In file included from dev_in_maps.c:13:
>> 
>> Remove one of them to solve conflict, another error comes up:
>> 
>> dev_in_maps.c:170:6: error: implicit declaration of function ‘mount’ [-Werror=implicit-function-declaration]
>>   170 |  if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) == -1) {
>>       |      ^~~~~
>> cc1: all warnings being treated as errors
>> 
>> and then , add sys_mount definition to solve it After both above, 
>> dev_in_maps.c can be built correctly on my mache(gcc 
>> 10.2,glibc-2.32,kernel-5.10)
>
>This is apparently the same error as in
>https://lore.kernel.org/all/11cdac1e-e96c-405f-63e8-35b0e2926337@arm.com/
>
>I'm getting the impression that we are fixing the issue at the wrong layer here?
>After all, the mount() syscall is supposed to be used with <sys/mount.h> according to the mount(2) man page?  It feels a bit like cheating to resort to
>sys_mount() instead...?

Headers conflict is known issue due to https://sourceware.org/glibc/wiki/Synchronizing_Headers
<linux/mount.h> and <sys/mount.h> (Note: no workaround)
So, it is incorrect to use both them.

>
>Do you have any deeper thoughts on what could be the underlying issue here?
>With my newer GCC toolchains, I have been unable to reproduce this.
>
gcc version 10.2.1 20200825 (Alibaba 10.2.1-3.5 2.32) (GCC)
ldd (GNU libc) 2.32
kernel 5.10.134-16.1.al8.x86_64
"Alibaba Cloud Linux 3(the most biggest public cloud provider's OS)


>Thanks,