From a7f14aae85022007a4c77e0792a1abb0509a08eb Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= <berrange@redhat.com>

Date: Tue, 2 Aug 2022 12:34:23 -0400

Subject: [PATCH] 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>

---

 linux-user/syscall.c | 18 ++++++++++++++++++

 meson.build          |  2 ++

 2 files changed, 20 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c

index b27a6552aa..52d178afe7 100644

--- a/linux-user/syscall.c

+++ b/linux-user/syscall.c

@@ -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>

diff --git a/meson.build b/meson.build

index 294e9a8f32..30a380752c 100644

--- a/meson.build

+++ b/meson.build

@@ -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',

-- 

2.37.1