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

["Yang Xu (Fujitsu)" <xuyang2018.jy@fujitsu.com>]

on 2023/04/25 5:06, Zorro Lang wrote:
> On Mon, Apr 24, 2023 at 06:17:55PM +0800, Ziyang Zhang wrote:
>> On 2023/4/22 21:54, Zorro Lang wrote:
>>> On Thu, Apr 20, 2023 at 10:11:06AM +0800, Gao Xiang wrote:
>>>> Newer glibc such as glibc 2.36 also defines 'struct mount_attr'
>>>> in addition to <linux/mount.h>.  It will report as below when
>>>> compiling with old linux kernel headers (without idmapped mounts,
>>>> such as kernel-headers 5.10.134) but with newer glibc (here checked
>>>> with glibc 2.36.6):
>>>>
>>>>      [CC]    detached_mounts_propagation
>>>> In file included from detached_mounts_propagation.c:29:
>>>> vfs/missing.h:115:8: error: redefinition of 'struct mount_attr'
>>>>    115 | struct mount_attr {
>>>>        |        ^~~~~~~~~~
>>>> In file included from detached_mounts_propagation.c:23:
>>>> /usr/include/sys/mount.h:210:8: note: originally defined here
>>>>    210 | struct mount_attr
>>>>        |        ^~~~~~~~~~
>>>> gmake[3]: *** [Makefile:102: detached_mounts_propagation] Error 1
>>>> gmake[2]: *** [include/buildrules:31: src] Error 2
>>>> make[1]: *** [Makefile:51: default] Error 2
>>>> make: *** [Makefile:49: default] Error 2
>>>>
>>>> Let's get rid of <linux/mount.h> as Christian suggested to avoid
>>>> potential incompatibility between these two headers.
>>>>
>>>> Cc: Christian Brauner <brauner@kernel.org>
>>>> Cc: "Yang Xu (Fujitsu)" <xuyang2018.jy@fujitsu.com>
>>>> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
>>>> ---
>>>
>>> This patch works on latest fedora, but it cause fstests can't be built on
>>> RHEL-8 [1] and RHEL-9 [2], please check this incompatible problem.
>>>
>>> Thanks,
>>> Zorro
>>>
>>> [1]
>>> ...
>>> Building include
>>> Building lib
>>> Building ltp
>>> Building src
>>>      [CC]    feature
>>> In file included from /usr/include/linux/fs.h:18,
>>>                   from /usr/include/xfs/linux.h:30,
>>>                   from /usr/include/xfs/xfs.h:9,
>>>                   from global.h:13,
>>>                   from feature.c:29:
>>> /usr/include/sys/mount.h:35:3: error: expected identifier before numeric constant
>>>     MS_RDONLY = 1,  /* Mount read-only.  */
>>>     ^~~~~~~~~
>>> gmake[2]: *** [Makefile:112: feature] Error 1
>>> gmake[1]: *** [include/buildrules:31: src] Error 2
>>> make: *** [Makefile:51: default] Error 2
>>>
>>> [2]
>>> ...
>>> Building include
>>> Building lib
>>> Building ltp
>>> Building src
>>>      [CC]    feature
>>> In file included from /usr/include/linux/fs.h:19,
>>>                   from /usr/include/xfs/linux.h:36,
>>>                   from /usr/include/xfs/xfs.h:9,
>>>                   from global.h:13,
>>>                   from feature.c:29:
>>> /usr/include/sys/mount.h:35:3: error: expected identifier before numeric constant
>>>     35 |   MS_RDONLY = 1,                /* Mount read-only.  */
>>>        |   ^~~~~~~~~
>>> In file included from feature.c:49:
>>> vfs/missing.h:116:8: error: redefinition of 'struct mount_attr'
>>>    116 | struct mount_attr {
>>>        |        ^~~~~~~~~~
>>> In file included from /usr/include/linux/fs.h:19,
>>>                   from /usr/include/xfs/linux.h:36,
>>>                   from /usr/include/xfs/xfs.h:9,
>>>                   from global.h:13,
>>>                   from feature.c:29:
>>> /usr/include/linux/mount.h:128:8: note: originally defined here
>>>    128 | struct mount_attr {
>>>        |        ^~~~~~~~~~
>>> gmake[2]: *** [Makefile:112: feature] Error 1
>>> gmake[1]: *** [include/buildrules:31: src] Error 2
>>> make: *** [Makefile:51: default] Error 2
>>>
>>>
>>>>   configure.ac                      | 2 +-
>>>>   src/detached_mounts_propagation.c | 1 -
>>>>   src/vfs/missing.h                 | 1 +
>>>>   3 files changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/configure.ac b/configure.ac
>>>> index 4687d8a3..bb29f37e 100644
>>>> --- a/configure.ac
>>>> +++ b/configure.ac
>>>> @@ -74,7 +74,7 @@ AC_HAVE_FIEXCHANGE
>>>>   
>>>>   AC_CHECK_FUNCS([renameat2])
>>>>   AC_CHECK_FUNCS([reallocarray])
>>>> -AC_CHECK_TYPES([struct mount_attr], [], [], [[#include <linux/mount.h>]])
>>>> +AC_CHECK_TYPES([struct mount_attr], [], [], [[#include <sys/mount.h>]])
>>>>   AC_CHECK_TYPES([struct btrfs_qgroup_limit], [], [], [[
>>>>   #include <stddef.h>
>>>>   #include <linux/btrfs.h>
>>>> diff --git a/src/detached_mounts_propagation.c b/src/detached_mounts_propagation.c
>>>> index 17db2c02..4041c75f 100644
>>>> --- 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>
>>>> diff --git a/src/vfs/missing.h b/src/vfs/missing.h
>>>> index 059e742d..04ab33d1 100644
>>>> --- a/src/vfs/missing.h
>>>> +++ b/src/vfs/missing.h
>>>> @@ -18,6 +18,7 @@
>>>>   #include <sys/types.h>
>>>>   #include <syscall.h>
>>>>   #include <unistd.h>
>>>> +#include <sys/mount.h>
>>>>   
>>>>   #ifndef __NR_mount_setattr
>>>>   	#if defined __alpha__
>>>> -- 
>>>> 2.24.4
>>>>
>>
>> Hi Zorro,
>>
>> Can you try this patch, which is inspired by Yang Xu[1].
>>
>> [1]https://lore.kernel.org/fstests/ed0bb9f0-c255-10d7-d711-36a464cd6512@fujitsu.com/T/#me981ae064b3ecb151b3321a4ee77f5d916cb017c
>>
>> Regards,
>> Zhang
>>
>>
>> Patch:
> 
> 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

> 
> Thanks,
> Zorro
> 
> [1]
> # make
> Building include
> Building lib
> Building ltp
> Building src
>      [CC]    feature
> In file included from /usr/include/linux/fs.h:18,
>                   from /usr/include/xfs/linux.h:30,
>                   from /usr/include/xfs/xfs.h:9,
>                   from global.h:13,
>                   from feature.c:29:
> /usr/include/sys/mount.h:35:3: error: expected identifier before numeric constant
>     MS_RDONLY = 1,  /* Mount read-only.  */
>     ^~~~~~~~~
> gmake[2]: *** [Makefile:112: feature] Error 1
> gmake[1]: *** [include/buildrules:31: src] Error 2
> make: *** [Makefile:51: default] Error 2
> 
>>
>> diff --git a/configure.ac b/configure.ac
>> index cbf83779..060c0a5d 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -16,6 +16,7 @@ AC_CHECK_HEADERS([	assert.h		\
>>   			sys/uuid.h		\
>>   			sys/file.h		\
>>   			sys/fcntl.h		\
>> +			sys/mount.h		\
>>   			sys/syssgi.h		\
>>   			sys/param.h		\
>>   			sys/stat.h		\
>> @@ -27,6 +28,7 @@ AC_CHECK_HEADERS([	assert.h		\
>>   			strings.h		\
>>   			err.h			\
>>   			linux/falloc.h		\
>> +			linux/mount.h		\
>>   			sys/fs/xfs_fsops.h	\
>>   			sys/fs/xfs_itable.h	\
>>   			xfs/platform_defs.h	\
>> @@ -35,6 +37,10 @@ AC_CHECK_HEADERS([	assert.h		\
>>   			sys/mman.h		\
>>   ])
>>   
>> +AC_CHECK_FUNCS_ONCE([
>> +	mount_setattr	
>> +])
>> +
>>   AC_CHECK_HEADERS([xfs/xfs_log_format.h],,,[
>>   #define _GNU_SOURCE
>>   #include <xfs/libxfs.h>])
>> @@ -68,7 +74,13 @@ AC_PACKAGE_WANT_LIBBTRFSUTIL
>>   AC_HAVE_COPY_FILE_RANGE
>>   AC_CHECK_FUNCS([renameat2])
>>   AC_CHECK_FUNCS([reallocarray])
>> -AC_CHECK_TYPES([struct mount_attr], [], [], [[#include <linux/mount.h>]])
>> +AC_CHECK_TYPES([struct mount_attr], [], [],[[
>> +#ifdef HAVE_MOUNT_SETATTR
>> +# include <sys/mount.h>
>> +#elif HAVE_LINUX_MOUNT_H
>> +# include <linux/mount.h>
>> +#endif
>> +]])
>>   AC_CHECK_TYPES([struct btrfs_qgroup_limit], [], [], [[
>>   #include <stddef.h>
>>   #include <linux/btrfs.h>
>> diff --git a/src/vfs/missing.h b/src/vfs/missing.h
>> index 059e742d..04ab33d1 100644
>> --- a/src/vfs/missing.h
>> +++ b/src/vfs/missing.h
>> @@ -18,6 +18,7 @@
>>   #include <sys/types.h>
>>   #include <syscall.h>
>>   #include <unistd.h>
>> +#include <sys/mount.h>
>>   
>>   #ifndef __NR_mount_setattr
>>   	#if defined __alpha__
>>
>