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linux-user: fix compat with glibc >= 2.36 sys/mount.h

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The latest glibc 2.36 has extended sys/mount.h so that it
defines the FSCONFIG_* enum constants. These are historically
defined in linux/mount.h, and thus if you include both headers
the compiler complains:

In file included from /usr/include/linux/fs.h:19,
                 from ../linux-user/syscall.c:98:
/usr/include/linux/mount.h:95:6: error: redeclaration of 'enum fsconfig_command'
   95 | enum fsconfig_command {
      |      ^~~~~~~~~~~~~~~~
In file included from ../linux-user/syscall.c:31:
/usr/include/sys/mount.h:189:6: note: originally defined here
  189 | enum fsconfig_command
      |      ^~~~~~~~~~~~~~~~
/usr/include/linux/mount.h:96:9: error: redeclaration of enumerator 'FSCONFIG_SET_FLAG'
   96 |         FSCONFIG_SET_FLAG       = 0,    /* Set parameter, supplying no value */
      |         ^~~~~~~~~~~~~~~~~
/usr/include/sys/mount.h:191:3: note: previous definition of 'FSCONFIG_SET_FLAG' with type 'enum fsconfig_command'
  191 |   FSCONFIG_SET_FLAG       = 0,    /* Set parameter, supplying no value */
      |   ^~~~~~~~~~~~~~~~~
...snip...

QEMU doesn't include linux/mount.h, but it does use
linux/fs.h and thus gets linux/mount.h indirectly.

glibc acknowledges this problem but does not appear to
be intending to fix it in the forseeable future, simply
documenting it as a known incompatibility with no
workaround:

  https://sourceware.org/glibc/wiki/Release/2.36#Usage_of_.3Clinux.2Fmount.h.3E_and_.3Csys.2Fmount.h.3E
  https://sourceware.org/glibc/wiki/Synchronizing_Headers

To address this requires either removing use of sys/mount.h
or linux/fs.h, despite QEMU needing declarations from
both.

This patch removes linux/fs.h, meaning we have to define
various FS_IOC constants that are now unavailable.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Message-Id: <20220802164134.1851910-1-berrange@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Daniel P. Berrangé 2022-08-02 12:41:34 -04:00 committed by Laurent Vivier
parent 61b6e67171
commit 3cd3df2a95
2 changed files with 20 additions and 0 deletions
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18
linux-user/syscall.c
View file

@ -95,7 +95,25 @@
#include <linux/soundcard.h>
#include <linux/kd.h>
#include <linux/mtio.h>
#ifdef HAVE_SYS_MOUNT_FSCONFIG
/*
* glibc >= 2.36 linux/mount.h conflicts with sys/mount.h,
* which in turn prevents use of linux/fs.h. So we have to
* define the constants ourselves for now.
*/
#define FS_IOC_GETFLAGS _IOR('f', 1, long)
#define FS_IOC_SETFLAGS _IOW('f', 2, long)
#define FS_IOC_GETVERSION _IOR('v', 1, long)
#define FS_IOC_SETVERSION _IOW('v', 2, long)
#define FS_IOC_FIEMAP _IOWR('f', 11, struct fiemap)
#define FS_IOC32_GETFLAGS _IOR('f', 1, int)
#define FS_IOC32_SETFLAGS _IOW('f', 2, int)
#define FS_IOC32_GETVERSION _IOR('v', 1, int)
#define FS_IOC32_SETVERSION _IOW('v', 2, int)
#else
#include <linux/fs.h>
#endif
#include <linux/fd.h>
#if defined(CONFIG_FIEMAP)
#include <linux/fiemap.h>

2
meson.build
View file

@ -1963,6 +1963,8 @@ config_host_data.set('HAVE_OPTRESET',
cc.has_header_symbol('getopt.h', 'optreset'))
config_host_data.set('HAVE_IPPROTO_MPTCP',
cc.has_header_symbol('netinet/in.h', 'IPPROTO_MPTCP'))
config_host_data.set('HAVE_SYS_MOUNT_FSCONFIG',
cc.has_header_symbol('sys/mount.h', 'FSCONFIG_SET_FLAG'))
# has_member
config_host_data.set('HAVE_SIGEV_NOTIFY_THREAD_ID',